Prosthodontics Flashcards
What are the general statistical trends for tooth loss, in Scotland?
More teeth are lost with age
More teeth are lost in more deprived areas, than less deprived areas
What are the 4 main impacts of tooth loss for the individual?
Mastication and speech
Pain/discomfort
Appearance/self-esteem
Social interactions
What are the 6 main reasons for tooth loss?
Congenitally missing Trauma Periodontal disease Caries Pulpal disease Other pathology
What is the typical pattern for tooth loss?
Lost either singly or in small groups
A partially dentate state may last many years and never progress to edentulism
What are examples of congenital disease that can lead to tooth loss?
Hypodontia
Ectodermal dysplasia
Cleft lip and palate
Why can periodontal disease lead to tooth loss?
Loss of periodontal ligament support, and so loss of anchor into the gomphosis
How does pulpal disease cause tooth loss?
Originates from infection
Dendritic cells differentiate into osteoclastic-like cells that resorb the dentine
What other examples can cause tooth loss?
Cancer treatment
Ameloblastoma in the mandible
What is the definition of a shortened dental arch?
A reduced dentition primarily resulting from the loss of mailar teeth with the aim of preserving a functional dentition for long-term use
What are the prerequisites for a shortened dental arch?
20 or more functional opposing teeth
Including anterior teeth
At least 4 occlusal units
Name different types of occlusal units and there values?
1 unit = occluding premolar
2 units = occluding molars
What are the pros and cons for a shortened dental arch?
Pros:
- adequate chewing
- aesthetics not significantly compromised
- tooth migration may occur but stability is maintained
- TMJ healthy
- no change in wear
- avoid use of potentially damaging partial dentures
What are the 3 main factors for damage to the oral cavity with a partial denture?
Biological
Direct trauma
Mechanical effects
Explain how biological damage can a partial denture cause?
Dental plaque:
- increase caries and perio as they are plaque traps
Explain how direct trauma can a partial denture cause?
Acrylic engages into the embrasure spaces for stability, resistance and retention
Can lead to accelerated alveolar bone loss and recession
Otherwise known as ‘gum stripping’
What is the definition of an extra-coronal restoration?
One that which is outside or external to the crown portion of a natural tooth
(sits over remaining tooth structure)
Name 3 types of extra-coronal restorations?
Full coverage gold shell crown
Ceramic crowns
Gold inlay onlay
Name the 4 different types of indirect extra-coronal restorations?
Veneer
Onlay
Partial coverage crown
Full coverage crown
What is the definition of a veneer?
A thin sheet of material used to finish or protect an ornamental facing. It is a superficial or attractive display with many layers
What is the definition of a onlay?
Partial coverage restoration that restores one or more, cusps and the adjoining occlusal surface, and is retained by mechanical or adhesives means.
What is the definition of a partial coverage crown?
An artificial replacement that restores missing tooth structure, surrounding the remaining structure with a dental material. Retained by mechanical or adhesive means
What is the definition of a full coverage crown?
An artificial replacement that restores missing tooth structure, covering the full coronal surface of with tooth with a dental material. Mechanical or adhesive means
What are the main reasons for the use of a indirect extra-coronal restoration?
Support for remaining tooth tissue in broken down teeth
To prevent microleakage (infection spread)
Aesthetics
In what order should treatment be planned?
- relieve pain
- cause related therapy
- initial reassessment
- basic operative care
- reassessment
- reconstructive therapy
- recall and maintenance
What are the risks of a extra-coronal restoration?
Pulpal inflammation Periapical periodontitis Poor plaque control Resto failure with poor occlusal management Loss of occlusal stability
What are the 4 golden rules to abide by when planning an extra-coronal restoration?
- Plan restoration that maintain structural integrity of the remaining sound tooth tissue
- Consider the least invasive and destructive option
- Always consider the effect on the pulp
- For endodontically treated teeth, provide the best coronal seal possible and support weakened tooth structure
What is a good alternative to ECR for prevention of microleakage?
Modern bonding systems
Gives excellent marginal adaptation and reliable bonding system
What is a good alternative to ECR for aestehtics?
Internal bleaching for non-vital teeth
Microabrasion for fluorosis
What are the advantages of good communication skills when trying to gauge what a patient is asking for?
Better diagnosis of patient’s problems
Increased adherence of patients to your recommendations and advice
Greater patient satisfaction
Reduce patient complaints and litigation
What to aim for when communicating to a patient needing a complete denture?
Keep expectations very low
Changes to their bone and co-morbidities may help this
Name 2 QoL questionnaries?
OHIP-14
GOHIA
What does OHIP-14 stand for?
Oral health impact profile
What does GOHAI stand for?
General oral health assessment index
NAme the 4 main features of assessment for QoL questionnaries?
Function
Pain
Psychosocial
Discomfort
Name 6 groups of people that have a reduced self-perception when assessing QoL for complete dentures?
Current users of removable prosthodontics Having less teeth Edentulous Women Nutritional deficit Cognitive impairment
How are nutrition and complete dentures related?
A poorly adjusted denture will lead to changes in mastication and food selection increasing soft diet which is usually highly fermentable carbohydrates leading to infection/caries
This can cause isolation of the patient (not leaving)
Identify what the patient wants and identify the changes that have occured orally such as?
Reasons for tooth loss and when
Resorption of residual alveolar bone
Systemic disease
Xerostomia
Name the 7 clinical stages of complete denture construction?
Patient assessment, treatment plan and informed consent Primary impressions Secondary impressions Recoding the jaw relationship Wax denture try-in Fit of complete dentures Complete denture review
What information must be gathered during the patient assessment stage?
General history
Extra-oral examination
Intraoral examination
Examine existing denture
What to identify in the extraoral examination?
Smile line Angular cheilitis Lower facial height Labial and buccal support tissue If teeth show on smile
What to identify in the intraoral examination?
Extent of ridge resorption Flabby ridge Mylohyoid ridge Frenal attachments Tuberosity Soft tissue overgrowths
What information must be gathered from the treatment planning and consent stage?
Formulate treatment plan:
- new denture or copy
- copy follow copy protocol (also note in notes)
Plan clinical and lab stages and appointments (follow NHSG lab protocol)
Discuss availability with patient
Approval from clinical supervisor
Gain informed consent
What to prepare for primary impressions for a complete denture?
Modify maxillary and mandibular disposable trays with putty or greenstick to correct extensions
If trimming needed, trim with acrylic trimming or tri-cutter bur
If single complete denture is being made use dentate poly tray or metal tray
Make impressions with alginate (can change but need explanation)
Once disinfected, mark required extensions of special tray (2mm above muco-buccal fold)
What document must you fill in when requesting a primary impression to be completed?
A complete student clinical prescription card for a non perforated 3mm spaced with tissue stops, custom special tray using a light cured resin extending to the marked border with a rim handle.
If flabby ridge eother space with another layer of wax or perforate tray
Alternatively construct tray with open window and lid
What to prepare for secondary impressions for a complete denture?
Assess special tray before insertion
Check extensions in mouth
Use greenstick or silicone putty to border mould the peripheral extension
Ensure good peripheral seal
A non-perforated tray will enable to confirm this peripheral seal at early stage
Make impression with alginate
For flabby or undercut ridge use spaced or perforated tray
Tray with a window and lid over flabby tissue can be used
If a flabby ridge is present, what should you change about the secondary impression?
If open tray with a lid is used, medium body silicone should be used over firm tissues and light body silicone applied through window over the flabby ridge
Place lid to close tray window
Consider a Piezograph for mandibular arch to record neutral space prior to occlusal rim wax
What document must you fill in when requesting a secondary impression to be completed?
Fill in a complete student clinic prescription card for working cats
Request for clear heat-cured acrylic denture bases to support maxillary and mandibular wax occlusal reg rims
If piezograph requested, use mandibular heat cured acrylic denture base for this
Piezograph and neutral zone can be made after maxillary occlusal rim if modified
Adjusted maxillary time useful during reg of neutral zone
Prescrie to convert the piezograph to mandibular wax occlusal rim on the heat cured mandibular acrylic denture base
Explain how to record the jaw relationship?
- Mand and Max?
- Check for what?
- Ensure that?
Check both max and mand base plates for extensions, stability and retention
Shape the labial and buccal surfaces of the max rim to provide correct soft tissue support and teeth-show
Adjust palatal slopes of max occlusal rim to ensure tongue space
Adjust max rim using a Fox’s occlusal plane indicator
Check the vertical dimension at rest with the adjusted max occlusal rim in place
Adjust the mand ri to fit max rim to provide free way space
Use willis gauge to establish adequate free way space (nose to chin)
Ensure the heel of the mand rim is not interfering with the heel of the max rim and base
Ensure the occlusal plane of mand rim is below dorsum of tongue and in level with retromolar pad at post ends
Ensure adequate tongue space
What is the equation for free way space?
FWS = VDR - OVD
must be a minimum of 2mm
What to measure after the vertical dimension of the occlusal rims have been adjusted and FWS dimension established?
The correct retruded jaw relationship
What are the 5 basic points to check before recording the retruded jaw relation?
FWS Stability Consistent horizontal jaw relationship Adequate freeway space Even occlusal rim contact Soft tissue support
What to mark on the maxillary rim after recording the retruded jaw relation?
Centre line
Symmetric canine lines
High smile line
Incisal edge level
What to mark on the mandibular and maxillary time after recoding the jaw relation?
Locating cones on both wax rims
How to explain to the patient to place jaw in RCP?
Ask the patient to curl the tongue towards the soft palate and close the mouth.
What material is used to record the RCP?
Silicone bite reg material
What can be helpful to complete if copying a denture?
Alginate impression of current denture
What to ask the patient about the aesthetics of their denture?
Prosthetic teeth shape, size and shade and engage dental nurse in discussion
Which document to fill in after recording the jaw relationship
mark the prosthetic teeth shade and mould choice on the Student Clinical Prescription Card. Enter patients gender, date of birth, race, relevant set up information and any characteristics that may be useful for the laboratory
Pick up red articulator from teaching lab and take to NHSG lab
Explain the process of the wax denture try-in stage?
Use average value articulator
Assess the seet in both occlusions
Ensure denture has smooth borders
Assess each trial denture separately in mouth to determine stability, retention, base extensions and neutral zone
Don’t leave wax trial denture in for too long will melt
Try ax and mand trial denture together to check occlusion, OVD, FWS, appearance and speech
Check shade, mould, tooth size, position, lip support and centre line
Check occlusal plane in relation to reference planes
Ensure mand occlusal plane is below dorsum of tongue and post line with retromolar pads
Adjust if necessary
What to do if there are occlusal interferences destabilising the denture?
adjust individual teeth by trimming the base of the prosthetic tooth and replacing it on the wax rim
remove involved teeth, add wax and re-record the jaw relationship using silicone bite registration material.
Ask the laboratory to rearticulate and re-set teeth for a re-try ensuring that you have given them as much information as possible about the required changes
When to proceed to the fit stage?
Only when the patient, yourself and clinical supervisor are happy
Encourage patient to bring friend to try-in appointment for their opinion
What document to fill in after the wax denture try-in stage?
Complete student clinical prescription card:
- flask pack and finish denture for fit
- label dentures with patient name
- return completed denture with the articulation and allocated articulator
Explain the fitting denture stage?
Check dentures of articulation and ensure occlusion
Check fitting surface of max and mand denture for irregularities
Sterilise before placing
Try each denture in separately
Use pressure indicating paste to identify any need for adjustment
Assess retention, stability, base extension and neutral zone
Check shade, mould, tooth size and position, level and angle of occlusal lane, lip support and centre line
Ensure denture fitting surfaces and borders are smooth
Insert dentures individually and confirm occlusal stability
COnfirm patient satisfaction
Denture advice on use, care and hygiene
Importance of annual checks
Replacement every 5 years
Periodic reline
What to do if the occlusion is not correct after minor adjustments?
If occlusion is not correct after minor adjustments, re-reg relationship using silicone bite reg
Prescribe lab remount new bite reg
Check the denture occlusion on this new articulation and make the required occlusal adjustments under supervision
What to assess at a complete denture review?
Review patient after 1 week Check denture bearing areas Carry out any refinements necessary Arrange further reviews Return to GDP for routine checks
How can the denture become destabilised?
If the muscle are encroached upon during contraction
Name the 12 muscles which play a part in denture stabilisation?
Frontalis Orbicularis oculi Zygomaticus Buccinator Orbicularis oris Platysma Cranial aponeurosis Temporalis Occipitalis Masseter SCM Trapezius
Name the 3 intraoral structures which a denture must form a good relationship with?
Pterygomandibular raphe Labial and buccal frenum Glandular tissues (retromolar pad)
What part of the denture can interact with the retromolar pad?
Posterior extension of denture base
How does the coronoid process and the buccal flange of the denture interact?
The buccal flange lies laterally to the maxillary tuberosity. It may impinge on the tuberosity and cause pain or instability
How far should the denture be extended?
Should be extended through the hamular notch via the area of the fovea palatinae
What is the definition of the hamular notch?
Junction of the maxillary tuberosity and the hamular process
What provides a guide to the position of the posterior palatal border for a denture?
Fovea palatinae
What is the definition of fovea palatinae?
Air of mucous gland duct orifices near the midline at the junction of the hard and soft palate
What guide can the incisive papilla give for a denture?
Where the incisors and canines should be set
What is the definition of the incisive papilla?
Mass of fibrous tissue
What is the definition of the palatal rugae?
Irregular mucosal transverse ridges found in anterior hard palate
Where is the vibrating line found?
Junction of moveable and immoveable part of the soft palate
2mm anterior to the fovea palatinae
What is the function of the vibrating line in terms of dentures?
Aids to establish the post palatal seal
Distal end of denture at least to the vibrating line
Where is the postal palatal seal?
From hamular notch to hamular notch
Anterior to vibrating line
Aids retention
Where is the posterior palatal seal?
From hamular notch to hamular notch
Anterior to vibrating line
Aids retention
What guides the saddle extension?
Where the hamular notch lies
Name 5 characteristics of the residual ridge that you must consider?
Height Width Form Thickness Consistency
Name the 2 types of maxilla vault shape?
U
V
How can the palatal vault shape affect the denture?
Retention
Resistance to lateral displacement
Tongue space
What is the definition of torus palatinus?
A bony enlargement occuring the the midline of the hard palate
Covered by thin incompressible mucoperiosteum
How can torus palatinus cause denture construction complication?
Bulk
Consistency
What is the definition of the buccal sulcus?
Extends from buccal frenum to hamular notch
Name 3 factors that change the size of the vestibule?
Contraction of buccinator muscle
Position of the mandible
Amount of bone loss
What can change the size and shape of the distal end of the buccal flange?
Movement of the ramus of the mandible at the distal end of the buccal vestibule
What is the definition of the labial sulcus?
Runs from one side of the buccal frenum to the other side, divided by the labial frenum to left and right
Outer surface is the orbicularis oris runs horizontally
Reflection of mm superioloy marks the height, no muscle attachment at reflection and moveable tissues here leads to overextension
How does the palatal mucosa change between people?
Differential compressibility
Where is the buccal shelf located?
Lies between the alveolar ridge and the external oblique ridge
Extend from buccal frenum to retromolar pad
How does the buccal shelf interact with the denture?
It is a flat horizontal shelf of bone, covered by mucosa that supports the distal part of the lower denture
How can the buccal shelf size and position vary?
From the degree of alveolar ridge resorption
What is the definition of the retromolar pad?
Pear shaped area containing glandular tissues, loose areolar CT, lower margin of pterygomandibular raphe, fibres of buccinator and superior constrictor, along with the fibres of the temporal tendon
Name 5 anatomical features of the mandibular arch?
Mylohyoid ridge Lingual tuberosity Mental foramen Genial tubercles Torus mandibularis
What happens to the mental foramen after severe residual ridge resorption?
It occupies a more superior position and the denture base must be relieved to prevent verne compression and pain
What is the definition of torus mandibularis?
A bony enlargement appearing unilaterally or bilaterally on the lingual aspect of the mandible in the canine-premolar region
What are the direct and indirect effects of the mylohyoid ridge?
Has an indirect effect on anterior lingual border up to second premolar & direct effect on
posterior lingual border in molar region
Where is the sublingual gland region located and how can it affect the denture?
In premolar region, when the floor of the mouth is raised, the gland comes close to the crest of the ridge & reduces the vertical space available for the extension of the flange in this region.
Why is the retromylohyoid space important?
For denture stability and retention
How is the retromylohyoid space formed?
Post: - superior constrictor Lat: - mandible and pterygomandibular raphe Ant: - lingual tuberosity Inf: - mylohyoid
Name the 5 muscles of the FoM?
Genioglossus Mylohyoid Hyoglossus Styloglossus Genioglossus
Name the 3 muscle in the facial curtain?
Buccinator
Orbicularis oris
How does the facial curtain change for edentulous patient?
Characteristic toothless look
Collapses
What is the definition of the modiolus and how it can affect the denture
Area where extrinsic perioral muscle decussate to join intrinsic fibres of the orbicularis oris muscle
Very forceful which can influence the labial flange thickness of a denture
What to do when there are limiting structures along the periphery?
Captured with a border moulded special tray
Allows muscles to trim impression material to their functional levels
How do the dentures stay stable during rest and function?
If the retentive forces acting on the dentures exceed the displacing forces
How is the support determined for a complete denture?
By the form and consistency of the denture-bearing tissues and the accuracy of the fit of the denture
Name the 3 surfaces of the the denture?
Occlusal
Polished
Impression
What do the 3 surfaces help to form?
The suction effect from the negative pressure formed
What can a patient learn to aid the stability and seal of their denture?
Patient acquired skills
What are the patient acquired skills?
Use of lips, cheeks and tongue to stabilise denture
Chewing on both sides at same time
Smaller portions and softer food
Name the 5 physical forces for a complete denture?
Adhesion Cohesion Surface tension Capillary action Atmospheric pressure & Peripheral seal
What is the definition of adhesion and what factors does it depend on?
Force of attraction between dissimilar molecules such as saliva, acrylic resin and mucosa Factors: - good adaption to oral cavity - size of denture bearing area - saliva best to be serous
What is adhesion directly proportional with?
SA of the denture base
Which denture arch has better retentive force?
Maxillary
What is the definition of cohesion and an example within a denture?
Forces of attraction between similar molecules
Maintains the integrity of the film of saliva
What is the definition of interfacial surface tension?
Is the resistance to separation of 2 parallel surfaces with a fluid medium in between
How is surface tension formed?
Results of the cohesive forces acting on the surface of the fluid
What factors affect surface tension and how it enhances retentive force?
Ability of the fluid to wet the rigid surrounding material
By promoting contact of saliva to both mucosa and denture base, surface tension works to enhance further retentive force
Explain why the interfacial surface tension plays more a role for the maxillary denture than the mandibular denture?
Most patients produce enough saliva to keep the external borders of the mandibular denture awash in saliva, therefore eliminating the effect of interfacial surface tension
What forms from surface tension and increased cohesive forces in a denture?
Cohesive forces result in the formation of a concave meniscus at the surface of the saliva in the border region of the denture
What relationship forms with the concave meniscus?
Between the width of the buccal channel and resistance to flow of saliva
A drop in pressure of the saliva film would cause what?
Cause impaction of the buccal mucosa and greatly increase retention
What effect occurs due to the fluid film bound by a concave meniscus having a lower pressure than the supporting medium?
A pressure differential exists between saliva film and air, therefore aids retention
What relationship does the size of the pressure differential have?
Inversely related to the diameter of the meniscus
Closer the fit to the tissues the stronger the retentive forces attributable to surface tension
What is the definition of capillary action and a denture example?
The quality or state because of surface tension causes elevation or depression of the surface of a liquids is in contact with a solid
Close adaption of the denture base to the mucosa cause the saliva in between to improve the contact between them
How is saliva important to physical forces to retention?
Presence of a continuous thin film of saliva between denture and mucosa, which wets both surfaces
What changes to retention if the viscosity of saliva increases?
Decreased retention due to the excessive viscosity resulting in a thick and discontinuous film between denture and mucosa
What mechanism is used to resist large displacing forces of a denure over a short duration?
Retentive mechanism from the viscosity of the saliva and the valve like action of the soft tissues
What mechanism is used to resist small forces acting over a long period of time (e.g. gravity)
Occlusal forces
Explain why the capillary action is more effective on the maxillary denture than the mandibular denture
Capillary attraction ceases to be effective is the tube is submerged under the surface of the liquid
Mandibular dentures saliva accumulates along the periphery and reduces the capillary effect
Explain why muscular forces play more of a role in mandibular dentures rather than maxillary?
Due to reduced denture bearing area
Difficulty in obtaining and maintaining a border seal
Name the 5 factors that are necessary to obtain an optimal physical retention?
Border seal Denture bearing area (largest( Accuracy of fit Bony undercuts Retention aids
What are the 5 main limitations for a denture?
Poor retention with the mandibular denture
Alveolar resorption reduces retention (but can be overcome by increase muscular control)
Patient dissatisfaction (after skills learnt)
Denture movement in function that are not detectable clinically
Varied tolerance
What are the 3 displacing forces acting through the occlusal surface?
Occlusal imbalance
Mastication
Forces related to the anterior teeth (lose seal)
Name 3 factors which reduce support and create instability?
Resorption in alveolar ridges and palate remain stable but can cause tipping during mastication
Ridges resorbed and are small resistance to lateral displacing forces will be poor
Flabby ridges
What is the definition of biomechanics?
Study of the mechanical nature of biological processes
What ae the effects of ageing on the oral cavity in relation to dentures?
Reduced functional capacity and precision control
Reduced ability for oral gymnastics
Restricted mouth opening
Describe the natural change of dentition?
Characterised by adaptive responses to constant dynamic changes, continuous reparative changes of the basal bone and alveolar process
What are the effects of tooth loss?
Periodontium involved with support and positional adjustment of the tooth as well as sensory perception are lost with tooth loss
Edentulous state has few adaptive mechanisms
Tissue changes are progress and mainly regressive
Name the 5 consequences of loss of periodontal ligament (with denture stability in mind)?
Viscoelasticity of PL missing
Sensory feedback mechanism missing
Osteogenic potential that responds to the forces applied missing
SUpport and sensory perception are therefore altered with complete denture
Mucous membranes serve the functions of PL with its attendant deficiencies
What is the periodontal ligament area?
45 cm2
What is the denture bearing area of the maxilla and mandible?
Maxilla:
- 22.96 cm2
Mand:
- 12.25 cm2
Cawood and Howell Classification: - class I tooth loss?
Dentate
Cawood and Howell Classification: - class II tooth loss?
Immediately post extraction
Cawood and Howell Classification: - class III tooth loss related to alveolar ridge?
well-rounded ridge form, adequate in height and width
Cawood and Howell Classification: - class IV tooth loss?
Knife edge ridge form, adequate in height and inadequate in width
Cawood and Howell Classification: - class V tooth loss?
Flat ridge form, inadequate height and width
Cawood and Howell Classification: - class VI tooth loss?
Depressed ridge form, with some basalar loss evident
Where is the greatest amount of bone loss seen on the maxilla and mandible?
Labial and buccal aspects of the maxillary alveolar ridges
Lingual aspect of the mandibular ridge
What reduces proportional to residual ridge resorb in relation to dentures?
Denture bearing area
Name 3 systemic conditions that affect the tolerance of tissues and increases inflammation?
Anaemia
Diabetes
Nutritional deficiencies
Supporting tissues have little or adaptability to functional forces applied
Name the 7 changes a patient will undergo in an edentulous state in relation to the maxilla and mandible?
Altered facial appearance due to changing maxillomandibular relationship
Altered and reduced support system
Compromised reflex adaptability
Decreased oral tissue tolerance
increases risk of pathological changes
Increases risk of maladaptive denture wearing experience
Increased functional and parafunctional movements
Name the 6 changes a patient will undergo in an edentulous state in relation to the oral cavity?
Reduced denture support area Reduced or altered neuromuscular control Reduced chewing forces Reduced salivary flow Reduced healing potential Resulting in compromised denture beating tissues
Name the 5 changes to forces of mastication in an edentulous patient?
20kg forces applied with natural dentition
6-8 kg forces applied with complete denture
5-6 times less maximum bite force with denture
Chewing efficiency reduced by 80%
Changes in food choices
Name the psychosocial effects of complete denture?
QoL
Emotional
Name the aesthetic effects of complete denture?
Lower facial height
Collapse of commisure
Cheeks
Lips
Name the functional effects of complete denture?
Mastication
Speech
Food choices
Name the systemic effect of complete denture?
Metabolic
CV
Cancer
Local tissue changes
What factors affect movement of dentures?
Stability of denture
Resiliency of mucosa
What can movement of the complete denture manifest as?
Displacement Lifting Sliding Tilting Rotating
Name the 3 muscles affecting retention and stability?
Orbicularis oris
Buccinator
Risorius
(Intrinsic and extrinsic tongue muscles)
What are the 2 main objectives for the construction of a complete denture?
Minimise the forces transmitted to the supporting tissues
Reduce the movement of the prosthesis
What are the factors under the clinicians control for complete denture?
Appropriate optimal extension of the denture base
Maximum intimate contact of the denture base with basal seat
Designing the smooth surfaces of the denture to utilise and balance perioral and tongue muscles activity to maximise retention and stability
Arrangement of the prosthetic teeth in the neutral zone
What is the definition of the neutral zone?
The potential space between the lips and cheeks on one side and the tongue on the other side; that area or position where the forces between the tongue and cheeks or lips are equal
What is the first stage of denture assessment?
Measuring the rest face height
This can be carried out with the Willis gauge:
- position of the fixed arm under the nose
- position of the sliding arm under the shin
- vertical orientation of the gauge
What is the second stage of denture assessment?
Record rims should be placed on well-fitting rigid bases
Try in record blocks and check adaptation and extensions starting with the upper
Modify where required but can only reduce any overextensions
Make adjustments to upper record block first
Blocks are bulky
Explain how to measure the maxillary jaw relationship?
Add or remove wax to modify occlusal surface of upper record block to change occlusal plane orientation: - should be parallel to Ala-Tragus line Fox's plane guide Add or remove wax to modify tooth position: - lip support - incisal level - incisal tooth position - buccal or palatal surfaces
Explain how to measure the mandibular jaw relationship? Part 2
Remove upper block and insert lower wax record block
Add or remove wax to modify tooth position:
- essential to place lower block (and future denture) in neutral zone:
- lip support, buccal and lingual surfaces (tongue space)
Again always check by replacing back in oral cavity
Decisions regarding occlusal plane should have previously been made as to
where modifications are to occur:
- care with position of occlusal surfaces in relation to tongue.
Add or remove wax to modify occlusal surfaces to achieve appropriate
occlusal vertical dimension (OVD).
Check that there is an appropriate amount of Freeway Space (FWS)
(usually 2-4mm)
Explain the replica technique for jaw relationship?
Modify extensions where required (should have been
done before taking primary impressions) and take light
bodied silicone elastomer impression (base will always be close fitting if this option chosen).
Carry out modifications to wax rims to prescribe for
‘try in’ stage.
These modification stages are exactly the same whichever process is followed.
If light bodied impressions are damaged during
modification process, retake impressions.
Use ‘closed mouth’ technique to retake impressions:
- maintains OVD
Explain the process of recording the jaw relationship?
Patient needs to be in a supine position.
Check relationship with both blocks in patient’s mouth
Ensure that it is as reproducible as possible.
Record ligamentous (or retruded contact position) if patient has moved to habitual
path of closure.
Ligamentous position is considered the most reproducible.
Recheck that there is an identifiable FWS.
Ensure center line is appropriate and marked if removed during modifications
What to do after measuring jaw relationship on wax blocks?
Cut two notches in posterior occlusal surface of upper block
Place upper record block in patient’s mouth.
Apply appropriate adhesive to lower block for bite
recording paste being used.
Apply sufficient bite recording paste to occlusal surfaces
of lower block
(NOT on to anterior segment, need to be able to observe anterior tooth relationship)
Insert block and guide patient into correct jaw
relationship.
Allow sufficient time for material to set before
removing from mouth.
What information to send to the dental technician, after bite block registration?
Remove both blocks carefully.
Separate blocks carefully so that dental technician can cast impressions in
upper and lower blocks where required.
Select appropriate anterior and posterior teeth.
This includes shade (DEPLHIC V or VITA), mould, arrangement and posterior cusp
form.
Prescribe for correct articulator:
Depends on posterior tooth prescription.
What is important to create a conventional bilateral balanced occlusion?
Inter-cuspal position = Retruded contact
position
ICP on posterior teeth
Working side and balancing side contacts in
lateral excursions
Anterior and posterior contact in protrusive
excursions
What is important to create a lingualised bilaterally balanced occlusion?
Maxillary palatal cusps contacting mandibular
central fossae.
Differs from Conventional bilateral balanced
occlusion by eliminating the contacts between
the mandibular buccal cusps and maxillary
central fossae.
Achieved by:
- modifying anatomical mandibular posterior teeth or
- by applying anatomical maxillary posterior teeth
against flat mandibular posterior teeth.
What is important to create monoplane occlusion?
Can establish balanced or non balanced
occlusion
Occlusal contact comprise surfaces rather
than point
When would you use LBBO teeth?
Severe ridge resorption
What are the 7 influencing factors for selection of teeth?
Previous dentures (if any). Age of patient. Size and shape of facial skeleton. Colour of complexion. Patient choice. Patient’s friend. Old photos
Name the 3 types of denture teeth materials?
Acrylic
Composite
Porcelain
What are the pros and cons for acrylic denture teeth?
Highly cross-linked acrylic (improves wear resistance and colour
stability).
Good appearance and adhesion to denture base.
Wears easily
What are the pros and cons for composite denture teeth?
Harder and longer lasting than acrylic.
Good aesthetic properties.
Reduced bond strength to underlying acrylic.
Can be modified/added
What are the pros and cons for porcelain denture teeth?
Retention to denture based through mechanical features called diatoric
holes (pins) designed into the teeth (can be dislodged).
Good appearance but can be noisy, chip with high occlusal forces
Name a denture shade guide?
Vita
DEPLHIC V
Explain how to position the denture teeth?
Using a straight edge aligned with the inner
canthus of the eye and the ala of the nose to
find the position of the canine (marked on the
wax rim).
Width of the 2 central incisors:
- using the philtrum width.
- the height of the central incisor should be equal
to or greater than the height of the smile line
above the incisal edge.
High smile should be marked on the wax rim.
When should larger central incisors be used?
High lip line.
Large stature.
Large face.
Explain the process of shape selection of denture teeth?
Use patient’s old denture (if happy with
previous one).
Inverted shape of the patient’s face.
Shape of the patient’s upper palate.
What face shape do square teeth fit?
Complement a square set face and strong features
What face shape do ovoid teeth fit?
Create a softer appearance and complement, delicate and rounded features
What face shape do tapering teeth fit?
Tapering face shape
What face shape do rectangular teeth fit?
Long square shaped faces
What are the changes of the oral cavity due to age?
Attrition of natural teeth:
- incisal edges will tend to be flattened.
Loss of muscular tone in lips and face:
- flanges and teeth will need to attempt to restore ‘appearance’ (can be difficult).
Need to place anterior teeth in correct position:
- lip support BUT if too far anterior causes denture displacement.
Amount of tooth showing:
- at rest and when smiling.
Name the antero-posterior, lateral and mediolateral posterior compensating curves?
AP: - curve of spee Lat: - Curve of monson ML: - Curve of wilson
What are the 5 main factors for prosthesis stability?
Occlusal relationship Base shape Fitting surface adaptation Tooth position Polished surface shapes
Name the 3 things that give optimal physical retention?
Border seal
Area of impression surface
Denture bearing area
Accuracy of fit
How far can the buccal surface of the denture be extended in the incisal, canine, premolar and molar area?
Incisal 6mm
Canine 8mm
Premolar 10mm
Molar 12mm
Name 3 types of impression materials to create a primary impression?
Impression compound Polyvinyl siloxane (elastomer) putty or irreversible hydrocolloid (alginate)
What is the process of border moulding?
Dry the tray then add compound to section A, then B and finally C
A is at the posterior ridges of the denture
B is at the middle part of the periphery of the denture
C is at the front and incisor area of the denture
Where should the posterior upper denture be extended to?
Between the junction between the hard and soft palate and the vibrating line
Describe the process of a closed mouth CD process?
Primary
Secondary:
- functional
- neutral zone
Describe the process of a open mouth 2 step CD process?
Primary Secondary Step one: border moulding - operator manipulated - functional moulded Step two: final impressions - mucostatic tech - selective pressure tech - functional tech - neutral zone tech
Describe the process of a open mouth 1 step CD process?
Border moulding and final impression:
- operator manipulated
- functional moulded
What materials can be used for border moulding?
Greenstick
Elastomers
What materials can be used for final impressions?
Impression plaster Elastomers Fluid wax Alginate ZOE impression paste
Explain the mucocompressive/mucodisplacive/definitive pressure impression technique?
Denture becomes unstable at rest, because the denture bearing tissues were captured in the impression in a compressed state on to which the denture base had a good fit.
But the denture base didn’t adapt well to the relaxed state
Made with a closed mouth so that the patient can bite together
Explain the mucostatic/minimal pressure impression technique?
Suitable for flabby ridges
Denture stable at rest
Flabby tissues distort in function, when the denture base does not fit this tissue state well
A pure mucostatic impression may not provide adequate border seal for retention
Explain the selective pressure technique?
Combines pressure over some areas and minimal pressures over other areas
Pressure applied over primary stress bearing area so that the denture base is well adapted to the tissues overlying these areas, allowing denture to be supported well in function
The non load bearing areas are captured with minimal support. Achieved by providing relief over aera with special trays, those areas with pressure will have no relief.
Idea is that if no relief more force is transmitted to the tissues which get derform as in function, so the resultant impresion is mucodisplacive over these areas. Whereas, where the relief provided minimal pressure applied on tissues
Explain the functional impression technique?
Impression that is made while the tissues are in function, using viscogel as a material, within the tissue surface of the denture base and sending the patient away. After a week patient is recalled, the viscogel would be moulded in a routine function and captured the denture bearing tissues in a functional state
How do faulty impression occur?
Usually due to clinicians lack of knowledge of anatomy of denture bearing tissues and structures along the periphery of the dentures
Adequate attention to detail is required
Primary impressions must be good (good foundation needed)
Clinician can imagine the impression surface
Name the 14 anatomical landmarks of the maxilla?
Incisive papilla Labial frenum Labial sulcus Rugae area Palatine raphe Buccal frenum Buccal sulcus Crest of alveolar ridge Posterolateral of residual alveolar ridge Posterior palate Tuberosity Hamular notch Vibrating line Fovea palatinae
Name the 13 anatomical landmarks of the mandible?
Labial frenum Labial sulcus Genial tubercle Lingual frenum Torus mandibularis Mental foramen Buccal frenum Buccal sulcus Alveololingual sulcus Mylohyoid ridge Buccal shelf Residual alveolar ridge Retromolar pads
Name the 6 maxillary denture bearing areas?
Valve seal area Primary stress bearing area Secondary stress bearing area Relief area Pterygomaxillary area Posterior palatal seal area
Name the 5 mandibular denture bearing areas?
Secondary stress bearing area (sliped of the ridges) Primary stress bearing area (buccal shelf area) Secondary relief area (ridge crest) Secondary stress bearing area Valve seal area (sulcus area)
Comparison between edentulous jaws?
Maxilla has more supporting areas
Limiting structures are less in number and have a less stronger influence over the denture border
The opposite is correct for the mandible
What should the preliminary impression aim to reproduce?
Sulcus depth
Sulcus width along the entire periphery
Certain anatomical landmarks which indicates the correct extensions of the customised tray such as
maxillary tuberosity and retromolar pads
What makes a good impression material for a primary impression?
High viscosity material which compensates for the poor fit of the stock tray
Such as impression compound or high viscosity alginate
What should the master impressions aim to reproduce?
Record the maximum denture bearing area and develop an effective border seal
Modified by reducing any over extension and the peripheries adapted by the addition of gree stick or impression compound
Why do we need to use impression materials?
Take an accurate impression of the patient’s anatomy
Control the contraction of the impression material during setting
Be more comfortable for the patient
Name 4 types of materials to be used for a special tray?
Light cure acrylic resin
Autopolymersing acrylic resin
Vacuum form thermoplastic materials
Shellac
What to mark and block out on the maxillary cast?
Mark: - a red line at the depth of the vestibule - a blue line 2mm above the red line, which determines the tray extension Block: undercut areas; - frenum - buccal surface of the tuberosity - rugae - flabby portions of the alveolar ridges
What to mark and block out on the mandibular cast?
Mark:
- a red line at the depth of the vestibule
- a blue line 2mm above the red line, which determines the tray extension
Block: undercut areas;
- mylohyoid ridge
- frenum
- lingual side of the mandible opposite the retromylohyoid space
What is the space required for ZOE paste?
0.5-1mm
What is the space required for silicone (medium)
1.5-2mm (1 layer of wax)
What is the space required for alginate?
3mm (2 layers of wax)
What is the space required for Silicone (heavy)
3-4.5mm (3 layers of wax)
What is the space required for impression plaster?
4.5m (3 layers of wax)
What is the average thickness of a sheet of baseplate wax?
1.5mm
What is the definition of tissue stops?
Help position the tray correctly in the mouth and ensure an even layer of impression material (better control of setting expansion and less likely to displace tissue)
Cut 2-4 mm square or round holes through the spacer wax in 4 area - highest/most bony points at the canine and molar regions
Don’t place over compressible or flabby tissues/incisive papilla area
Explain the process of making the tray for light cure resin?
Tray material adapted to the cast and excess removed with knife
Add tray stop gaps with some off-cuts of the tray material
Adapt a sheet of tray material to cover the wax, avoid thinning at the periphery
A handle can then be made from the excess material and added to the tray, the handle must be placed in line with the middle of the palate
Light cure on top side for 3-5 mins
Remove wax spacer and set inside 3 mins
Remember to set our tissue stops for 1 min before removing the wax
Smooth edges with an acrylic burr
At what height should the handle be stepped up by?
10mm, if no teeth in anterior
What are the functions of finger rests for denture construction?
Stabilise tray in mouth
Equal distribution of pressure
Reduces pressure applied to tissues
Where should to rest your fingers for the finger rest for denture construction?
Not impinge upon the tongue space and not extend above the occlusal plane and are placed near the 2nd premolar/1st molar teeth
What to do to create space for the frena?
Draw a pencil line along the trat at the same angle as the frena
Trim away a rounded noth to allow space around it
Notch out relief for muscle attachments and make sure there is a 2mm clearance for border moulding before smoothing off the edges
What are the necessary requirements of the completed maxillary special tray?
Tray periphery should be 2-3 mm thick
Edges should be rounded
Rest of tray should be about 1-2 mm in thickness
periphery should be flush with the blue line
Tray handle must extend vertically from the crest of the ridge and approx 10mm high and 15 mm wide
Finger rest not impinging
What are the clinical presentations and histology for a flabby ridge?
Alveolar ridge mobile, extremely resilient
Anterior part of maxilla, when remaining anterior in mandible
Marked fibrosis, inflammation and bone resorption
What are the causes for a flabby ridge?
Replacement of bone by fibrous tissue
Excessive load of the residual ridge
Unstable occlusal conditions
What are the problems and suggested solutions for flabby ridge?
Provides poor support of the dentures
Removed surgically to provide the stability required by dentures
Extreme cases, total removal not done, leads to elimination of vestibular sulcus
Resilient ridges provide support for retention
What questions should be answered when requesting creation of a special tray?
Which arch?
What material?
What thickness of spacer (and any border relief)?
Whether you need perforations?
Whether you require tissue stops + finger rests?
Extensions of any window area required?
Handle type/style?
What are the 11 ideal properties of an impression material?
Non toxic or irritant Cheap Long shelf life Taste Setting time Compatibility with other materials Surface reproducibility Dimensional stability Working time Ease of mixing Handling of material
What are the surface reproducibility, dimensional stability of ease of casting gypsum abilities of alginate?
Surface reproducibility: - good Dimensional stability: - poor Ease of casting gypsum: - good
What are the surface reproducibility, dimensional stability of ease of casting gypsum abilities of Medium bodied silicone?
Surface reproducibility: - excellent Dimensional stability: - excellent Ease of casting gypsum: - fair
What is the thicknesses necessary for the land area of a denture and what is used to create it?
4mm maxillary and mandibular
Beading wax
Where must a complete denture sit to have good stability?
In the neutral zone, for most CD construction techniques
Indications for the NZ technique of CD construction?
Proven instability problems which has not been possible to rectify with conventional techniques or implants
Name the 8 indications for use of NZ tech for a CD?
Resorbed ridges Enlarged tongue Migration of mentalis Facial reconstructive surgery Poor neuromuscular control Poor facial tonicity through age related degeneration Parkinson's Stroke
Why does alveolar ridge resorption cause denture instability?
As it flattens it has reduced ability to resist the lateral displacing forces
The distance from the occlusal surface to ridge increases in atrophic mandible therefore greater leverage applied causing denture instability
How to adjust a CD to accommodate alveolar ridge resorption?
These surfaces should be so contoured such that the horizontally directed forces applied by the peri -denture muscles to seat the denture
What does lateral spread of the tongue cause in relation to CD?
Reduces the width of the NZ
Managed by timely provision of RPD as teeth are lost
Name 5 degenerative changes following tooth loss that can affect CD construction?
Alveolar ridge resorption Lateral spread of tongue Migration of the mentalis muscle Loss of facial tonicity Diminished capacity for successful neuromuscular adaptation
Name 3 problems are caused with patients being older when they become edentulous?
Poor denture bearing tissues
Poor capacity for adaptation
Poor tolerance of complete dentures impacts on quality of life indices and nutrition
What is the GS treatment for stabilising lower complete dentures and its advantages?
2 mandibular implants
Improves function
Decreases pain
Improves QoL
Why did 36% of elderly patients with bad CD refuse free implant treatment?
Misconceptions held by elderly patients such as:
- fear of pain
- post OP complications
- social embarrassment
Why do some patient not have implants to aid CD stability?
Lack finances
Not understand necessity
Lack mandibular bone
Compromised medical status
What is the the alternative if implants are inappropriate for CD?
CD manufactured according to NZ principles
NZ can also be applied to implant retained lower CD
Name the 2 Neutral zone objectives?
Define the position of the lower anterior teeth, so they are in equilibrium between opposing muscular forces
Sculpt the polished surface so that the forces exerted by the muscles will tend to stabilise the denture rather than unseat it
What is the definition of quality of evidence?
Depends on the extent to which bias has been eliminated and generalisability to own patients
What are the GS guidelines for a clinical trial?
Sample size calculations Randomisations Blinding Statistical methods Limitations (bias) External validity
Why are clinical trials on removable prosthetics are not evidence based?
As they are largely based on opinions rather than sound evidence base`
What is the CONSORT statement?
An evidence based system for reporting RCTs
Ensures transparent and comprehensive thus ease of interpretation and appraisal
Why are studies on CD unreliable?
Not blinded, no randomisation, no sample size calculations, insufficient protocol detail, patients had good ridges vs cross-over design
What is the quality of current CD articles?
Only 2% are RCT
Majority don’t conform to CONSORT
A lot have poor methodology
Explain the process of the neutral zone technique?
Tooth position Teeth set up Trial fit Define polished surface Denture insertion Record labiolingual position of the lower anterior denture teeth Define the shape of the polished surfaces Denture insertion
What occurs during the tooth position stage of the NZ technique?
NZ tray usually made on working cast after bite reg
(occlusal stops and wire loops)
Try in of tray:
- check stability, fit and comfort
Load with impression material (greenstick and silicone) + mouth exercises?
Send impression to lab
Plaster index made
Impression material replaced with wax-rim
What occurs during the teeth set up stage of the NZ technique?
Wax rims mounted on the models which are placed on articulators
What occurs during the trial fit stage of the NZ technique?
Trial fit
What occurs during the define polished surface stage of the NZ technique?
Define polished surfaces (vaseline as a separator and silicone impression material applied)
Patient performs functional movements to mould the polished surface
Plaster index used to replace impression material with wax
What occurs during the denture insertion stage of the NZ technique?
Usual scheks at insertion stage but special attention to stability
What is the definition of a complete denture?
A type of removable prosthesis, that is designed to replace all or one arch of the natural teeth
What ae the 4 main parts of a complete denture?
Base
Flange
Teeth
Border
What are the 3 Fs for a good denture?
Fit
Form
Function
Describe what happens during clinical stage 1 for complete dentures?
History and examination
Provisional diagnosis
Preliminary impressions
(definitive diagnosis treatment plan)
Describe what happens during lab stage 1 for complete dentures?
Cast preliminary impression trays
Make custom trays
Describe what happens during clinical stage 2 for complete dentures?
Master impression
Describe what happens during lab stage 2 for complete dentures?
Cast master impression
Make registration rim
Describe what happens during clinical stage 3 for complete dentures?
Jaw registration
Describe what happens during lab stage 3 for complete dentures?
Articulate master casts
Make try-in denture
Describe what happens during clinical stage 4 for complete dentures?
Try in denture
Describe what happens during lab stage 4 for complete dentures?
Process and Finish denture
Describe what happens during clinical stage 5 for complete dentures?
Denture delivery
Denture review
Name the 2 muscles which ensure the stability of the maxillary denture?
Buccinator
Levator anguli oris
Name the 3 muscles which ensure the stability of the mandibular denture?
Buccinator
Superior constrictor
Depressor labii inferioris
Name the 4 support areas of the maxillary complete denture?
Alveolar mucosa
Hard palate
Zygomatic buttress
Ridge crest
Name the 3 support areas of the mandibular complete denture?
Alveolar mucosa
Buccal shelf
Pear shaped pads
Describe the process of jaw registration? Overall
Insert maxillary record block in mouth and check retention stability and extensions and adjust accordingly
Adjust lip support and teeth show, mark central and canine lines
Ensure the maxillary occlusal plane is parallel to the reference planes
Insert the mandibular record block in mouth and check retention stability and extensions and adjust accordingly
Adjust the mandibular occlusal plane in relation the the maxillary record block to give adequate freeway space
With both wax bite reg blocks in mouth, ensure heels are not in contact
Seal record blocks together using occlusal reg paste
Return sealed record blocks back to cast
Check position in mouth is same as cats
RInse and disinfect blocks
What is the definition of an articulator?
A mechanical hinged device used in dentistry to which plaster casts of the maxillary (upper) and mandibular (lower) jaw are
fixed, reproducing some or all the movements of the mandible in relation to the maxilla
Name the 2 lines for dentures?
Alla of the nose (tragus of the ear) Occlusal plane (parallels horizontal)
What is the definition of the facebow?
Orients condyle and maxilla relation and transfers this relation to the articulator
Name the 5 mandibular references lines of a mandibular cast?
1/2 way up retromolar Occlusal rim Centre of ridge anterior Land area Centre of ridge posterior
What are the indications for anatomic teeth?
Aesthetic concerns
Coordinated jaw movements
Denture opposing natural teeth
What are the indications for non-anatomic teeth?
Jaw size discrepancies (CIII)
Severe ridge resorption
Uncoordinated jaw movements
Poorer aesthetics, due to lack of cuspal inclines
How large to cut the centre line from the incisive papilla?
10mm anterior
How to prepare the wax to prepare teeth setting?
Cut out a tooth sixed price of wax, melt into the area with a heated knife, set each anterior tooth in place using occlusal table
Make sure the articulator incisal guide pin remains touching the incisal table and check angles
How to set the central incisors?
According to the arch shape
What is the definition of an overjet?
Overlap of 0.5-1mm
What is the definition of an overbite?
Overlap of 1-2mm
Describe a CI overjet?
Normal size (1-2mm)
Describe a CII overject?
Retruded (over 2mm)
Describe a CIII overject?
Protruded (edge to edge)
What is the definition of a crossbite?
Buccal cusps of the lower posterior protrude vestibular beyond those of the upper jaw
What is the definition of a edge to edge bite?
When the cusps of mand teeth bite onto those of max teeth
How are the maxillary central incisors set into the denture?
Long axis shows a slight mesial inclination to perpendicular
Midline down centre of the philtrum
Width the same size as the alar of the nose
How are the maxillary lateral incisors set into the denture?
Positioned with a slight mesial inclination and is usually 1/2 to 1 mm above the plane of occlusion
How are the maxillary canines set into the dneture?
Slight mesial inclination from the perpendicular and the incisa tip touches the occlusal plane
In line with the pupil of the eyes
Cervical and incisal edges of the cuspid are aligned vertically
What is a good biometric guide to identify where to set the anterior denture teeth?
Relation of central incisor is 8-10 mm anterior to the incisive papilla
Canine is perpendicular to the incisive papilla in the sagittal plane
How are the maxillary premolars set into the denture?
Both buccal and lingual cusp tips of the maxillary premolars should contact the plane of occlusion
How is the maxillary 1st molar set into the denture?
The MP cusp tip of 1st molar contacts occlusal plane but the buccal cusp tip and distal lingual cusp are elevated about 0.5mm off the occlusal plane
How is the maxillary 2nd molar set into the denture?
1.5mm above the occlusal plane
Only MB cusp of 6 touching table and 7 not touching with palatal cusp
How are the mandibular posterior teeth set up in the denutre?
Mand cusp tips are designed to engage the embrasures of the opposing maxillary teeth
What is the definition of the edentulous state?
The absence of a body part with specific morphological, functional or psychological sequelae
Name 2 epidemiological trends that have been found based on tooth loss?
Maxillary arch likely to become edentulous before mandibular arch
Mandibular incisors are only outlived by the mandibular canine teeth
What can a larger SA of the maxilla afford to the clinician?
Benefits distribution of occlusal forces over wider area and with improved retention and stability
What are typical findings of dentate maxillary arches with dentures present on the mandibular arch and what problems occur?
Severely resorbed mandibular ridges causing difficulty in obtaining good retention and stability
Limited quality of mucosa and amount of denture border around moveable tissues in mandibular arch cause difficult?
What is a solution to resorbed mandibular ridges?
2 mandibular implant supported overdenture
What are the challenges faced when 1 arch is dentate and the other is not bomechanically?
Dentate arch:
- presence of PL and its feedback mechanism resulting in greater load application and adaptability
Edentulous arch:
- absence of PL and feedback mech
- handicap of oral mucosal tissues overlying the denture bearing area in load bearing
- discrepancy in the occlusal plane and lack of interocclusal space
What are the consequences of a single complete denture?
Maxillary CD opposed by mandibular arch without posterior teeth
Occlusal forces leveraging in the anterior region of the max complete denture
Transmission of excessive forces into the denture bearing areas result in fibrous tissue replacement of the alveolar bone in anterior maxilla
Result lack of hard tissue support anterior leads to occlusal plane disruption due to displacement of denture
Growth of maxillary tuberosity, which can compromise interocclusal space for a mand posterior partial denture or later CD
How to manage a SCD with maxillary CD opposed by mandibular arch without posterior teeth?
Placement of a partial denture in mandibular arch to replace posterior
In a CIII jaw relationship (post-extract alveolar bone changes) the dentures can be placed in a cross-bite relationship so that the occlusal forces will be transmitted to the supporting tissues without generating leveraging forces
Axial tooth movement of retained teeth result in irregular occlusal plane, need for grinding or restoring to create acceptable occlusal plane
What is the definition of Kelly’s Syndrome?
Intraoral changes caused by partially dentate mandible opposing a maxillary CD
Name the 5 consequence sof Kelly’s syndrome?
FIbrous replacement of maxillary anterior alveolar ridge
Down growth of maxillary tuberosity bilaterally
Extrusion of mandibular anterior teeth
Severe bone loss in mandibular posterior edentulous ridge
Papillary hyperplasia of the tissue in the hard palate
What is the definition of a flabby ridge
Fibrous replacement of the max/mand anterior/posterior alveolar ridge
Explain why flabby ridges occur for Kelly’s syndrome?
Loss of maxillary anterior alveolar ridge to fibrous replacement is due to excessive forces applied to these supporting tissues through the maxillary CDs by the retained mandibular anterior teeth
Explain why maxillary tuberosity down growth occurs for Kelly’s syndrome?
Flabby ridge causes lack of stable vertical stop for the max denture in this area. With edentulous state and no natural support the is a lack of posterior occlusal support for maxillary denture. Resulting in the tipping of max denture leading to loss of peripheral seal at post dam area. Development of negative Pa during tipping attributed to enlargement of maxillary tuberosity
What is an alternative explanation for maxillary tuberosity down growth for Kelly’s syndrome?
Over eruption of maxillary molars prior to extraction
What can the consequences of Kelly’s syndrome lead to?
Loss of interarch space for the prosthesis
Occlusal plane discrepancy
Poor adaptation of prostheses
anterior spatial repositioning of the mandible
periodontal breakdown at retained mandibular anterior teeth
Epullis fissuratum
Name 4 factors compromising optimal denture construction?
Changes in quality and quantity of denture bearing tissues (flabby tissue and mental nerve exposure)
Changes in hard and soft tissues, and neuromuscular control (axial tooth movement and alveolar bone resorb)
Changes that may cause occlusal plane discrepancies (axial tooth move)
Changes that may cause the application of leveraging forces (axial tooth movement and alveolar bone resorb)
Name the 5 management strategies for construction of a optimal complete denture after Kelly’s syndrome?
Sufficient interocclusal space
Satisfactory occlusal plane
Stable jaw relationship compliant with retain teeth in RCP
Teeth set to facilitate axial transmission of occlusal forces
Use acrylic teeth with shallow cuspal inclines
Retain strategic teeth as overdenture abutments
How to prevent deep labial frenum and corresponding deep and narrow frenal notch on the labial flange?
Frenectomy
Broad U shaped frenal relief of the flange
How to prevent displacement/rotation of the denture anterior-post or side to side hanging on the palatal vault causing fracture due to fatigue or flabby ridge in anterior sextant or inevitable progressive tissue changes?
Mucostatic impression technique that register the denture bearing area in its rest position and to correct extensions
Set teeth so that forces is transmitted to residual ridges
Repeat fracture = metal base
How to prevent excessive occlusal forces due to high mandibular elevator muscle activity facilitated by PL feedback?
Metal palatal plate with acrylic base over bridges and posterior palatal dam area
How to prevent irregular or long term lack of review and monitoring if the denture causing tissue changes and poor fitting denture
Yearly review of denture bearing tissues, denture base, occlusion and provision of corrective procedures such as reline, occlusal refinement, denture care advice or remake.
How to prevent poorly constructed prosthesis?
Understand what you’re doing
Take more training
How to prevent lack of denture home care?
Education and regular review
How to prevent lack of review and maintenance?
Regular recall
Review nutritional intake
What are the indications of a reline?
Minimal to moderate changes occured in the CD
What are the indications of a rebase?
Moderate to maximal changes occured in the CD
Name 5 clinical changes that can occur during the use of a CD?
Loss of retention and stability Loss of vertical dimension of occlusion Loss of support for facial tissues Horizontal shift of denture (incorrect interocclusal relationship) Reorientation of occlusal plane
What is the definition of a reline?
Used to resurface the tissue side of a denture with a new base material that provides accurate adaptation to the changed denture foundation area
What is the definition of a rebase?
Lab process of replacing entire denture base
Explain the static closed mouth impression technique?
Record new CR if existing one is not correct.
Dentures used as impression tray.
Remove any tissue conditioner from the denture.
Apply adhesive on the fitting surface.
Apply impression material (wash impression).
Seat the denture in its appropriate position and ask the
patient to close to the CR recorded previously
Explain the static open mouth impression technique?
Dentures used as trays for making the impressions Tissue stops in the denture.
Apply impression material (wash impression).
Once material is set, take new CR.
Explain the functional impression technqiue?
ARDEE cushion liner
Explain the chairside technique?
Temporary reline
After immediate denture placement
Name the 4 possible causes of persistent pain under denture?
Usually lower jaw:
- mucosal atrophy
- irregular bony surface
- pathology of bone
- overloading mucosa
How to treat persistent pain under the denture?
Explain existence of FWS
Remove denture at night
Reduce size of occlusal table by removing second molar and decrease the buccolingual width of posterior teeth
Name the 2 causes of midline fracture?
Accidental dropping
Fatigue of acrylic resin
Over 3 yrs
Identify cause first
Name 7 denture factors that may increase risk of midline fractures?
Stress concentrations Absence of a labial flange Incomplete acrylic polymerisation Pervious repair Shape of teeth Poor fit Lack of adequate relief
Name 2 patient factors that increase risk of midline fractures?
Prominent labial frenum
high occlusal loads
What is the definition of a gag?
Ejectory contraction of the muscles of the pharyngeal sphincter. Protective of airway to remove irritant material from posterior oropharynx and upper GI
What are the triggers of the gag reflex?
Somatic - touching Psychogenic - no contact sight Anatomical variations Medical condition Iatrogenic factor Past dental experience
How to manage a patient with a gag reflex?
Hypnosis Systematic desensitisation (practice) Breathing techniques Acupuncture NO
How to manage gag reflex caused by CD?
Thin acrylic base
Use gradually
What is the definition of burning mouth syndrome?
Oral bruning or similar pain in the absence of detectable oral mucosa changes
What is Scala’s classification of BMS?
Primary or idiopathic
Secondary
What are the recommendations for a patient with BMS?
Treat as hypersensitivity
Allergen skin patch testing
Which sounds are harder to articulate with a CD?
S Z T D N
Why does speech disturbances occur with CDs?
If FWS is too big
How to produce /th/, /t/, /d/, /n/, /s/, /z/, /sh/, /zh/ (as in
measure), /ch/, /j/, /r/?
Lateral seal between tongue and posterior teeth
What can develop systemically due to poor oral health (edentulism?)
Endocarditis
Aspiration pneumonia
COPD
Generalised infection of resp tract
What is the definition of denture stomatitis?
Area of erythema beneath denture
Present in at least 67% of denture wearers
Name 3 products for dry moouth?
AS Saliva Orthana
BioXtra hel
Saliva-stim tablets
What are the transition of an immediate denture?
Immediate Clearance of remaining natural teeth prior to making dentures Transitional partial dentures Overdentures Implants
What factors favour the placement of an immediate denture?
Condition of teeth and supporting tissues Improvement of appearance Resolve malocclusion Natural teeth opposing edentulous ridge Age and health
What is the definition of an immediate denture?
One constructed to incorporate one or more teeth been deemed beyond restoration and are extracted just prior to insertion of appliance
New or addition
No more than 6
What factors are against the placement of an immediate denture?
Reduces masticatory efficiency by 20%
Loss of alveolar bone once removed and resorption of ridges
Loss of fit of prosthesis
Many reline appointments necessary
Reduced muscular skills to facilitate functioning of CDs
Becomes more pronounced in older adult due to age related changes
Medical condition
Name the 4 advantages of immediate denture for the patient?
Maintenance of dental appearance and facial contour
Minimise disturbance of mastication and speech
Facilitate adaptation to dentures
Maintenances of patient’s wellbeing
Name the 3 advantages of immediate dentures for the dentist?
reproduce jaw relation from natural teeth
Use key info regarding form and arrangement from natural teeth
Able to modify anterior tooth appliance if appropriate
Name the 4 disadvantages of immediate dentures?
Careful case selection
Difficulties with deep overbite and large overjet
Maintenance issues
early replacement 4-8 months
(staged extraction of remaining natural dentition - extract posterior first to allow initial healing provides better stability)
What are the contraindications for immediate dentures?
Patient at risk from bacteraemia
History of post extraction haemorrhage (allow initial healing to take place)
Gross oral sepsis (infected sockets)
Consult with GP
How can design vary after extractions for immediate dentures?
Shapes of flanges can vary depending on level of bone remaining and potential for further resorption
How can design vary with full depth of flange for immediate dentures?
Enhances retention and border seal, aids healing by protecting extraction sites, can make use of appropriate undercuts and can achieve better aesthetics
How can design vary with partial extension of flange for immediate dentures?
Provides same advantages but to lesser extent, only used where full flange impossible
How can design vary with open face for immediate dentures?
Essentially no flange: limited use and usually only in upper jaw where excessive bony ridge and undercuts
Tends to be avoided as limits ability to reline and maintain appearance
Cause serious damage to upper ridge
Problem with being able to provide full flange replacement denture
Describe the stages of treatment for processing of an immediate denture?
Initial stages are equivalent for conventional Take shade, mould and teeth arrangement 1st impression (alginate) Occlusion if required (record blocks) Design appliance (simple acrylic design) 2nd impressions Try-in stage Final decision regarding teeth to be replaced Clear instructions to technician Prep to cast
Describe what occurs during the try in stage of immediate denture placement?
Type and form of flange
Add teeth to try in and prepare wax up for flasking and packing
Final question - can immediate denture be readily inserted without major adjustments at chairside
Can cause trauma to tissue and disturb blood clots forming in sockets if immediate denture not carefully prescribed
Inform patient of procedures to be carried out at next visit and answer any questions
Recheck medical history and any radiographs
Describe what occurs during the finish stage of immediate denture placement?
Always check that correct teeth have been added to denture as immediate replacements before starting extraction process Check denture fits Teeth correct position Flange extensions correctly Appropriate thickness Carry out LA procedure Carry out extractions Insert denture after bleeding stopped Keep denture in Make adjustments with care Remove sharp edges
Describe the follow-up procedure of immediate dentures?
Healed tissues resorb and shrinkage (need reline)
Give full post extraction and insertion information to patient
Make further appointments within 2-3 days to review
What are the disadvantages of clearance of remaining natural teeth and allowing initial healing prior to making dentures?
Loss of masticatory function and appearance during healing period
Undesirable social, mental and physical effects on patient
Invasion of future denture space by tongue and cheek
Difficulties in assessing vertical and horizontal jaw relationship
Difficulty in restoring appearance if all information removed
Explain how can pre-extraction records overcome the disadvantages of tooth clearance and allowing initial healing?
Remaining dentition difficult to maintain
Consider pre-extraction records
Take impressions in alginate
Construct record blocks to be able to record occlusion next visit
Record occlusion at next visit and make arrangements to extract teeth
Articulate casts to recorded occlusion
Lay down layer of wav over mucosal tissue leaving teeth exposed
Take overall impression in putty impression material
(wax layer is used as a separator and allow laying down of shellac)
Remove teeth from stone cast
Lay down shellac over palate and ridge area
Place previous putty impression over cast with shellac base sealed in place
Pour wax into mould and allow set
Remove putty impression
Record block with pre-extraction records is produced
Take out teeth and allow 6-8 week initial healing
Try in pre-extract record block and modify if necessary
Wash impressions
Check occlusal relationship
Separate blocks carefully
Place back into mouth and take overall wash impression where standing seeth are still retained
Explain how can pre-extraction records overcome the disadvantages of tooth clearance allowing initial healing during the try-in stage?
Overall alginate impression provides clear relationship between IR and remaining natural dentition
Cast overall alginate and wash impressions
Articulate to recorded occlusion
Set up try in to prescription
Try in
Can also retake wash impressions to improve fit
Explain how can pre-extraction records overcome the disadvantages of tooth clearance allowing initial healing during the finish stage?
Complete IRs easily
Dentures should be able to be more table and retentive
Denture bearing area will be more stale as initial resorption has taken place
Less review appointments required
Fewer relines required
Describe the next stage for difficult IR denture patients for immediate denture placement?
Cast impressions and articulate to recorded occlusion. Fill in spaces on denture left by missing teeth with wax. Take putty impression over denture/wax rims. Remove denture from cast and lay down shellac base plate Place putty over cast and pour wax into mould: Replica record block.
Describe the try in stage for difficult IR denture patients for immediate denture placement?
Can then use record blocks to provide prescription. BUT if changes are minor: set up for try-in (having taken shade and mould at initial visit). Produce try-in and assess at chairside. Make appropriate modifications if required.
Describe the completion for difficult IR denture patients for immediate denture placement?
Take wash impressions to ensure good retention and
stability:
MUST check that occlusion is correct and maintained.
Go to finish.
What is the definition of an overdenture?
Is a denture (C/P) that rests on top of 2 or more retained teeth, that has been reduced in axial height to 3mm or less from the gingival margin or they rest on dental implants
What are the names for these overdenture teeth?
Overdenture abutments
Provide support and retention
What are the advantages of an overdenture compared to a conventional denture?
OD rests on retained abutment rather than the gums, forces are transmitted via roots and its PL to the bone
No alveolar bone resorption
PL presence allows proprioceptive feedback and therefore improved masticatory efficiency and comfort
Reduces loading of mucosal tissues
Alveolar ridge preservation (loss over 5yrs is 0.6mm)
Psychological trauma reduced
Can a single tooth present in an otherwise edentulous arch beneficial for abutment?
Facilitates increased retention and stability of partial denture
Name the 2 clinical considerations for placement of an overdenture?
Changes in alveolar ridges:
- most loss in anterior segment of lower law
Resorption:
- lower jaw moves lingually in anterior seg and buccally in posterior seg
- upper jaw moves palatally on both post and ant segments
Name the 3 factors which increases alveolar bone resorption?
Tooth loss
Periodontal diseases
Inappropriate prostheses
What does Newton et al find advantageous about using an overdenture?
Retention of small # of teeth used to support over dentures sustains the cross-sectional area of jaw closing muscles and maintains muscle tissue composition
Enhanced masticatory ability
What is GS first line treatment for edentulous patients?
2-implant denture
Not currently applicable due to financial restraints
Age doesn’t adversely affect implant success rate
What are the 50% survival rate age for overdentures?
8-20 years
What are the patient requirements to be eligible for an overdenture?
Careful patient selection
Selection of abutment teeth
Periodontal health and bone support at least 50%
Abutments on both sides of arch
Large root SA (canines)
Rct should be possible if necessary
Create dome shape with or without restoration (approx 3mm of tooth tissue supragingival)
What are the root SA for each tooth of the upper jaw?
Central: 1,3 Lateral: 1.1 Canine: 1.7 Premolar: 1.4 Molar 2.7
What are the root SA for each tooth of the lower jaw?
Central/Lateral: 1.0
Canine: 1.7
Premolar: 1.25
Molar: 2.7
When can coping or attachments be used for overdenture support?
Rotherman’s or Dalbo
Must have sufficient space within denture and between ridges
Diagnostic set up essential to determine space and plan
Name the 3 main failures for an overdenture?
Abutment teeth: - caries (Fl gel) - poor RCT - periodontal disease - denture hygiene (50% plaque free) Maintenance is vital
How do patients feel about overdentures?
Improve QoL
81% of adjustments happen only in first year
What is the definition of a copy denture?
To follow as a pattern or model; to imitate
What is the definition of replica denture?
Any close or exact copy or reproduction
Name 2 reasons for why a copy denture would be made?
Fit is good but:
- occlusal wear
- cleaning wear
Why is it essential to attend regular denture views yearly?
Regular appointments can reduce: Loss of denture bearing tissues Soreness Discomfort Unretentive Unstable Worn occlusal surface Reduced facial height Increased free way space Hyperplastic sulcular tissues
What do patients need to learn when using a complete denture?
Psychological perception
Learning to eat
New muscular skill
Motivation
What is the rationale for copy dentures?
Replacing successful existing denture with minimal essential changes, within the patient’s tolerance limits thereby correcting the cause for patient’s complaint
When considering a copy denture, what information from the patient about the denture may be useful?
List good features
Changes required
Name 8 clinical problems that can occur for a denture?
Occlusal wear Arch shape Tooth position Jaw relation Free way space Denture extensions Fitting surfaces Tissue changes
What is critical to preserve for a copy denture?
Spatial relationship between alveolar ridge and teeth
Polished surface of the denture
What changes can be done to the copy denture?
Denture extensions
Vertical dimension
Fitting surface
Explain the simple copy technique procedure?
Clinician: 1 - decision copy impression - shade taking 2 - try in replica - closed mouth tech 3 Insert and adjust 4 Review and monitor Lab 1 pour replica and cast articulate set up teeth for try in 2 Flash, pack, process and finish
Explain the modified copy technique procedure?
Same as simple but: Clinician 1: - correct extensions 2: - bite reg - shade take Lab: 1: - pour replica 2: - articulate - set up teeth 3: - flash, pack, process and finish
What to do if there are overextension for the denture?
Trimmed and corrected
underextension for the denture?
Self cure acrylic
Greenstick (temp)
What to do if there are facial tissue support problems for the denture?
corect on replica denture reg block with wax
What to do if there are tooth position problems for the denture?
corect on replica denture reg block with wax
Name 3 types of impression material for a copy denture?
Reversible and irreversible hydrocolloid
Silicone putty
Name 2 types of trays for a copy denture?
Stock
Murray Wolland
Name 3 types of replica base materials for a copy denture?
Shellac
Self-cure acrylic resin
Wax
Name 3 type of tooth material for a copy denture?
Wax self-cure acrylic resin
Why does the use of wax teeth improve the dimensional reproducibility of the replica denture?
Molten wax ashering and cooling towards the walls of the mould
Reduction in vol of acrylic resin help maintain dimensions in horizontal plane
Easier for lab
Errors that occur during a copy denture construction?
Not accurate Increased vertical dimension Loss of features Prescription ignored by lab Poor rational understanding Change in horizontal:vertical relationship Impression stage Reduction in free way space
What causes increased vertical dimension and what can be done to solve it?
Thick impression material
Use a thin layer of impression material
What causes anterior positioning of the upper denture and/or lower denture and what can be done to solve it?
Incorrect placement of denture on the ridge during closed mouth impression or thick material
Correct placement during impressions
What causes increased lip support and what can be done to solve it?
Incorrect placement of denture on the ridge during closed mouth impression or thick material
Correct placement during impressions
What causes speech problems and what can be done to solve it?
Incorrect jaw relation registration
Incorrect tooth positioning
Retake correct jaw relation
Reset teeth in correct biometrics
Name 7 common presenting complaints for an edentulous patient with a denture?
Looseness Pain Unable to chew Food packing under denture Speech disturbance Unhappy with appearance Damage
What good questions can you ask if the patient is wanting their first denture?
How long since lost teeth? Reason for tooth loss? If it was a long time ago, why now? What is the reason for change of mind? Reasons for no previous denture? Use of partial denture previously? How do they know about complete dentures?
What good questions can you ask for a patient with dentures to identify any problems?
Any problems with current denture? If problem exists, how long for? How long have you had the denture for? How many sets of dentures they've had? Any other previous problems? Have you had any repairs? Are your current dentures comfortable? How long since the teeth were lost? Why teeth were lost?
What to include for a patient’s medical history and how they could affect a denture?
Allergies Medically compromisation Medications (dry mouth) Diabetes Bleeding disorders Disability Autoimmune Neuromuscular disease General systemic disease
What social history may be relevant to dentures?
Attendance
Motivation for treatment
Motivation for maintenance
Habits
What to take note of for the extra oral examination for a denture?
Lower facial height and posturing
Check muscle tone and lip support
Asymmetry
Smile line
What to take note of for the intra oral examination for a denture?
Residual mand/max ridge quality (morphology) Incisive papilla Flabby ridge Papillary hyperplasia Overgrowth of oral mucosa Post-excision scar tissue Fissured tongue Dry mouth Genial tubercles Mylohyoid ridge High frenal attachment Dentate opposing arch Exostoses and Tori
What is the definition of a transitional denture?
From partial to complete
Dentate or partially dentate patient before being made edentulous, is provided a partial denture to get accustomed to wearing a prosthesis before being made edentulous and provided a CD
What is the process of treatment for a transitional denture?
remaining teeth have poor prognosis
Remove teeth sequentially and add to partial denture when removed
Get used to prosthesis
What is the definition of an immediate denture?
Replacement of extracted teeth with a completed denture immediately after extraction
What is necessary for a replica record block?
Primary and master impression
Primary cast, reg rims and custom tray superseded by technique
How does the replica block technique supersede need for primary impression for copy dentures?
Required changes to denture extension made with greenstick on current denture
Lab putty imp material supported by large perforated stock trays
How does the replica block technique supersede need for custom trays for copy dentures?
Shellac is used to make rigid bases over fitting surfaces All wax (possible warpage with no ridge base)
How does the replica block technique supersede need for bite reg rims for copy dentures?
Matrixes are held together together and ax/acrylic poured into join the base
Changes to occlusal/incisal/labial/buccal + wash/relining impression
Describe the main concepts of replica block technique?
(Primary impression) (Custom tray) (Bite reg rims) Bite reg recorded Shade or mould changes noted
What are alternatives to lab putty and shellac for replica block technique?
Alginate in a soap box
All acrylic in flask
When should material be used as an alternative to lab putty?
Add from page 95 fuck off
Describe the clinical and technical stages of the copy denture technique?
Diagnosis and treatment plan
Invest dentures to be copied
Construct template copy (wax teeth on rigid base)
Record occlusion (unstable use low viscosity silicone impressions before occlusion)
Pour cast, articulate copy and make trial denture (use teeth as guide, don’t remove too many)
Assess trial denture and take low viscosity silicone impression
Finish denture (remove acrylic palate of upper and lay down wax palate of correct thickness)
Fit dentures
Recall
What is the rationale for selective grinding?
Looking for a complete group function in complete dentures as bilateraL balanced occlusion.
Simultaneous contact of teeth in all excursions (3 points)
Explain the first step to selective grinding?
In premature contacts in centric position until even contacts are observed across the posteriors
How are vertical dimensions maintained in a CD?
By contact of the max palatal cusps and buccal of mandibular, avoid grinding these cusps
Follow the rule of B.U.L.L
How to check for even contacts on a CD?
Move the condyle part of the articulator to check for even contacts at each lateral movement
This is a sliding contact and the canines should not interfere and lift the incisal pin
What form of contact do the incisors show in protrusive movements?
Even edge to edge contact or slight disocclusion while posterior buccal and palatal/lingual cusps contact each other
When should we check and grind the bite?
Discrepancies between the mouth and models/articulated bites along the way
Differences in tissue adaptation with base materials at bite/try in to finish
Dimensional change of acrylic materials
Name the 6 principal components of a partial denture?
Rest seat Major connector Minor connector Abutment tooth Flange Clasp
What is the definition of the sulcus?
Space between the tongue, lips and residual alveolar ridge
How is the functional depth of the sulcus determiend?
By anatomy and movement
How is the width of the sulcus formed?
Created by the actions of the muscles and frenum on the impression material
What is the definition of support for a partial denture?
Resistance to vertical forces directed towards the mucosa
What can dentures be supported by?
Tooth borne
Mucosa borne
Combo of both
Name 3 types of mucosa borne support dentures?
Every denture
Spoon denture
Transitional dentures (um strippers)
Name 2 ways that mucosa support can be achieved for partial dentures?
Saddles
Connectors
Name 4 ways that tooth support can be achieved for partial dentures?
Rests
Connectors
Overdenture abutments
Occlusal onlays
What is the definition of a saddle?
Is an edentulous ridge of the alveolar ridge
Name 2 different types of saddles for partial dentures?
Bounded
Free-end
Explain the Applegate modification rules to the Kennedy classification?
Edentulous areas other than those determining the classification are referred to as modifications and are
designated by their number.
If the 3rd or 2nd molar are missing but are not going to be included in the
design of the denture they are not considered in the classification.
Class IV doesn’t have modification
The most posterior edentulous area
determines the classification.
Ex. Kennedy I modification 2
What is the definition and function of a connector?
Rigid components of a denture which hold all other components together
Provide cross-arch stability to help resist displacement by functional stresses
Name 4 examples of maxillary major connectors?
Palatal strap
Horseshoe (anterior bar)
Anterior-Posterior bar
Plate
Name 6 examples of mandibular major connectors?
Sublingual bar Lingual bar Dental bar Kennedy bar (Continuous clasp) Lingual plate Buccal bar
What is the definition and of a rest?
Any component of a partial denture on a tooth surface that provides vertical support
What is the function of a rest?
Maintains components in their planned position
Maintains establishing occlusal relationship by preventing settling of the denture
Prevents impingement of soft tissue
Direct and distributes occlusal loads to abutment teeth
What is the definition of retention?
Quality inherent in the denture that resists vertical forces of dislodgement (forces of gravity, adhesiveness of food, forces associated with opening of jaws) directed away from the mucosa
Retention is achieved by using clasps
Name 4 types of materials for a clasp?
Cobalt chromium
Stainless steel
Gold
Tooth coloured
How long must a clasp be and why?
To be flexible enough to go in and out of undercut without distorting beyond
its’ elastic limit a standard clasp needs to be 15mm long.
What horizontal depth of undercut engaged for Co/Cr?
0.25mm
What fraction of the clasp engages into the undercut?
Terminal 1/3
Give 3 examples of occlusally approaching clasps?
Three arm
RIng
Back of reverse action
Give 5 gingivally approaching clasp?
T Y U L I
What is the definition of the RPI system?
R: occlusal rest seat (mesial)
P: guide plate (distal)
I: I bar clasp
What is the function of the RPI system?
Designed to allow vertical rotation of a distal extension saddle into the denture-bearing mucosa under occlusal loading without damaging the supporting structures of the abutment teeth
What is the definition of bracing?
Resistance to a horizontal force
What is the definition of stability?
The quality of the denture to be firm or constant and to resist displacement by
functional, horizontal or rotational stress
What is the definition of reciprocation?
Resistance to the specific horizontal forces generated by a retentive clasp
E.g. bracing element which is in contact with the side of the tooth opposite the retentive clasp
Retentive clasps must always be reciprocated
Sit above the survey line
Where can rests be located?
Occlusally
Cingulum
Incisally
Where can minor connectors be located?
Proximal surfaces extending from a prepared marginal ridge to the junction of the middle and gingival one third of abutment crown
Where can clasp arms be located for bracing, retention and reciprocation?
Bracing - Middle one third of crown
Retention - Gingival one third of crown in
measured undercut
Reciprocation - Opposing surface of the active
arm
What is the definition of indirect retention?
It is the resistance to rotational displacement on a tooth and mucosa borne denture
What is the definition of guide plane?
Flat surfaces, cut into enamel of teeth, which are parallel to the path of insertion of a denture
What is the function of guide plane?
Improve retention and stability of the denture
Resists vertical displacement
How to prepare guide plane?
By adjusting contours of teeth to allow single straight line of insertion/removal of a saddle
Remove dead space/stagnation areas
Must be confined to enamel
Extend vertically for 3mm and away from gingival margin
How to prepare a guide surface?
Should be produced by removing a minimal and fairly
uniform thickness of enamel, usually not more than 0.5 mm, from around
the appropriate part of the circumference of the tooth
Not prepared as a flat plane
When is the partial denture the most suitable solution for a patient?
Patient preference Need for flange Limited dentition Limited bone Need for future additions/modifications Dentition with a range of tooth mobility 2 or more edentulous saddles Use of teeth as overdenture abutments Interim solutions
Name 7 categories for RPD assessment?
Teeth to be replaced Aesthetic needs Residual ridge reduction Unwanted tooth movement Strategic abutments Previous RPD experience Cost band
Name the 7 categories for prosthodontic assessment?
Patient wish and needs Caries status General restorative needs Specific restoration needs of abutment teeth Periodontal status Occlusion TMD
Name the 4 principles of design for a cobalt chromium denture?
Hygienic: - avoid gingival coverage - easy for patient to maintain Good Support Connector is rigid Keep it simple
Name the 8 steps to design cobalt chomium dentures?
Saddles Support Retention Bracing/Reciprocation Indirect retention Guide planes Connectors Review principles of design
Describe the process for the design of the saddles for partial dentures?
Flange design may be such as to utilise tissue undercuts (retention)
Avoid undercuts if too deep or wrong place (trauma)
Hygienic (avoid creating stagnation around abutment)
Ask do we need to fill?
Extension of denture base in saddle area
Required to cover maximum possible area to spread occlusal load as wide as possible
Minimum load area enhances possibility of patient comfort during denture use
Shape of polished surface
Placement of teeth in correct neutral space
Describe the process for support partial dentures with bounded and free saddles?
Bounded saddles: - nearest surface of each abutment tooth Free-end: - mesial side of abutment - check occlusion
Describe the process for retention for partial dentures with bounded and free saddles?
Bounded saddles:
- each saddle look initially for retention on both sides of abutment
- each saddle ideally have a slap on a east one abutment, unless aesthetically dictated
Free-end saddles:
- on abutment
- rotation about clasp axis, there is no point adding further clasps more anterior than this. They would just rotate down and not engage when pulling (sticky food)
Too much undercut or in wrong place, reshape tooth by cutting a guide plane or add composite
Describe the process for bracing/reciprocation for partial dentures?
Check resistance to lateral and anterior/posterior movement
Enagges flanges to the functional depth of each sulcus to assist with this
Check reciprocation of each retentive clasp arm
Consider using guide place for reciprocation in vulnerable teeth
Describe the process for indirect retention for partial dentures?
As far from the clasp axis as possible
Describe the process for guide plane for partial dentures?
For single path of insertion For reciprocation For indirect retention Create a path of insertion radically different from path of displacement Prevent distortion of Co-Cr clasp arm
Describe the process for connectors for partial dentures?
Max arch: - ant palatal bar - mid palatal bar - post palatal bar - horseshoe - palatal plate - ring Mand arch: - lingual bar - sublingual bar - lingual plate - dental bar - buccal bar
Why do dentures break?
Chemical:
- cleaning material bleach denture acrylic weaken structure
- medicines react adversely with acrylic
Poor design:
- incorrect placement of denture teeth
- incorrectly processed (internal porosities)
Ill fitting:
- masticatory forces displaced towards mucosa, if movement not even the base will flex, the base is made from acrylic or chromium will break after many flexures
- high stress
Where should the masticatory forces be directed towards?
To the residual ridge
What are the problems caused by masticatory forces not directed over the residual ridges?
Cause denture to flex in the middle and ultimately lead to breakage
Why should you never use superglue to repair dentures?
Contains cyanide which is highly toxic and not for intraoral use
How to prepare a denture for repairs?
Take an in-situ impression with alginate, and disinfect everything together to send to the lab
Explain how dentures are repaired?
Stuck back together accurately using sticky wax
Strengthener (wire) may be used to hold parts together
Model is made inside denture, plaster normally used but can use lab putty, or stone
Ensure flanges not buried in plaster
Once set denture removed and model checked to ensure denture parts stuck together
Errors shown by raised line
Denture trimmed forming a 2mm gap
Edges are chamfered by 2mm each side increasing SA for new acrylic to bond
Separating medium applied to model and parts stuck back to model using sticky wax + cold cure acrylic
Cold cure acrylic applied to fracture ara
Denture in hydro flask, at 2 Pa and 45C for 15 mins
Is high impact acrylic stronger than normal acrylic?
No, but butadiene styrene rubber added for some resistance to fracture
Higher flexural strength (good for hard bitters)
The use of stengethernes pros and cons?
Metal wires, bars and mesh have different thermal coefficients of expansion compared to acrylic, metal will expand more than acrylic and can cause breakages
Where is the force transmitted for a denture that have free end saddle (Kennedy 1 and II) in RPD?
The force is transmitted to the abutment teeth as well as the mucosa
There can be rotational movements due to the existence of 3 fulcrums
Describe the fulcrum in the horizontal plane in RPD?
Fulcrum line that goes through the 2 main abutment teeth localised next to the edentulous areas
Describe the fulcrum in the sagittal plane in RPD?
Fulcrum lines that goes through occlusal rests of the more distal tooth the residual ridge
Describe the fulcrum in the vertical plane in RPD?
Fulcrum line localised in the middle lingual line of the anterior teeth
Name 4 factors which influence the magnitude of forces transmitted to the abutment teeth in RPD?
Length of edentulous area
Quality of residual ridges
Type of clasp
Occlusion
How does the length of the edentulous area influence force on abutment teeth in RPD?
Greater length increases force to the abutment teeth
How does the quality of the residual ridge influence force on abutment teeth in RPD?
Worse the quality and the muscosa the higher forces transmitted to abutment teeth
How does the type of clasp influence force on abutment teeth in RPD?
Changes the way in which force is transmitted to abutment teeth, transmitting different magnitudes
How does the occlusion influence force on abutment teeth in RPD?
Different intensity of the force exerted by the occlusion of opposing teeth:
- natural
- full denture
- RPD
- others
- implies a different effect on the abutment tooth
How does medical history play a role in removable prosthodontic devices?
Patient may need invasive treatment to prepare oral tissues or may require extractions Consider diabetes Consider anticoagulation therapy Identify allergies Medical compromisation Plan to protect
Name 8 important questions to ask about the presenting complaint from the patient for RPD?
Opinion of denture? Loose? Eating habits? Swollen gums? Worn teeth? Soreness/pain? Broken? Expectations?
Name 7 important questions to ask about the history of the presenting complaint for RPD?
What is the problem?
When did it start?
Has it been good before?
Any previous adjustments, if so did they work?
When did you first start wearing dentures?
How many have you had?
Have previous ones been good?
How can past dental history influence the RPD needs and use?
Gives clues on cause of complaint Risk profile for patient Extent and complexity of past treatment Identify patient's dental awareness Identify phobia or anxiety Establish attitude, compliance and motivation
How can social and family history influence the RPD needs and use?
Attendance convenience Motivation and compliance Level of stress Dietary habits Smoking Alcohol Plaque control measures Drug use
Name the 7 areas to include in an extra-oral examination for RPD?
Face - asymmetry, trauma or palsy Skeletal profile - under, over E2E Smile line Lip competency Tenderness of muscles of mastication TMJ - tenderness, click, crepitus or locking Cervical lymph nodes
Name the 10 areas to include in an intra-oral examination for RPD?
Plaque control Oral soft tissues Salivary glands BPE Bleeding type Furcation Gingival recession Mobility Restorations Other
Name 6 important things to note during a intra-oral examination bar the basics?
Deviations from normal: - colour - size - shape - form - texture Missing Carious Fractured Abscess Malocclusion
What special investigations can be carried out after the clinical examination?
Sensibility testing: - electric pulp test Plaque distribution Bleeding indices Radiography Study casts Radiographs Photographs
How can tooth loss affect the design for RPD?
Bone resorption
Interocclusal space
Width of edentulous gap
What is included for treatment planning for a patient?
Data collection Need assessment Treatment plan Patient education Informed consent Caries control Replace defective restos Endo treatment
What is included for immediate care treatment planning?
Initial assessment Patient education Informed consent Emergency treatment Relief of symptoms Removal of aetiological factors (caries and deposits) Repair and maintenance
Name 3 types of treatment strategies?
Cause related
Corrective
Maintenance
Which comes first indirect restorations or RPD and why?
Indirect restorations so that you can design features for the RPD on your restoration
What is included during the stabilisation phase of treatment planning?
Control active disease Relief symptoms by removing aetiological factors: - plaque - calculus - overhangs - caries OHI - (20% plaque distribution)
What is included during the restoration phase of treatment planning?
Referral if necessary
Repair
Replace
Re-treat
What is included during the maintenance phase of treatment planning?
Monitor for change
Patient information leaflets
Education
What is included during the follow up phase of treatment planning?
Freq of appointments dependent on risk
Name factors that affect the treatment decisions for the patient?
Aetiological Systemic Patient Operator Finance Expectations Compliance
When planning treatment why should you avoid heroic maintenance of poor prognosis teeth/
Lead to undesirable consequences such as failure in function, aesthetics, comfort and extension of infection
Name the 5 factors to think about when planning treatment?
Function Occlusion Comfort Aesthetics Maintainability
Describe Kennedy Class I patient for RPD?
Bilateral free-end saddles
Have edentulous posterior areas bilaterally
What is the definition of a free-end saddle?
Saddle is not resting on teeth on both sides
Lack abutment teeth
Describe Kennedy Class II patient for RPD?
Unilateral free-end saddle
One sided posterior edentulous area
Describe Kennedy Class III patient for RPD?
Unilateral bounded posterior saddle
Edentulous area has teeth located anteriorly and posteriorly to it
Describe Kennedy Class IV patient for RPD?
Single, anterior bounded saddle
No anterior teeth present
Name rule 1 for applegate’s for RPD?
classification should follow rather than precede extractions that might alter original classification
Name rule 2 for applegate’s for RPD?
3rd molar missing and not to be replaced, not considered in classification
Name rule 3 for applegate’s for RPD?
3rd molar present, and is to be used as abutment, considered in classification
Name rule 4 for applegate’s for RPD?
2nd molar is missing and not to be replaced, not considered
Name rule 5 for applegate’s for RPD?
most posterior edentulous area or areas always determine classification
Name rule 6 for applegate’s for RPD?
edentulous areas other than those, which determine classification, are referred to as mod spaces and are designed by their number
Name rule 7 for applegate’s for RPD?
extend of the mod is not considered the number of edentulous areas
e.g. number of teeth missing in the mod space s not considered only the number of additional edentulous spaces are considered
Name rule 8 for applegate’s for RPD?
No mods for class IV, as any edentulous space will definitely be posterior to it and will determine classification
How to record the jaw relationship of the casts can not be hand articulated for the lab?
Wax occlusal rims on light cured acrylic resin base to be used for recording the jaw relation in a separate clinical stage
Occlusal rims must be well extended to be stape during jaw reg and try in stage
Occlusal reg blocks
How to estimate the correct path of insertion?
Use your eyes
Then use small amount of wax to block out the undercut
Where to wax block out on the cast?
Teeth: - marginal gingiva - proximal surfaces - embrasures ST: - gross undercut
Why to wax block out on the casts?
To obtain a stable and retentive record base and yet avoid damage on the cast
How to place and produce record blocks on a cast for an RPD?
Adapt the acrylic resin wafer onto cast with even pressure. 2-3mm thickness desired
Press excess against the edge of cast to trim it off
Extend the record base onto the proximal, palatal/lingual surfaces of the teeth to enhance retention, stability and support of the record base
Round, smooth and polish the record base
Add addition blocks over the edentulous areas and melt then on
How to record the bite for a RPD?
Record base extension:
- 2-3mm short of vestibule
- next to teeth
Check fit of base with muscle attachment relief and take down areas of occlusal contact first
What is the change in clinical protocol between CoCr vs acrylic?
Acrylic partial the bite blocks are prescribed to be constructed on the 2nd impression and so the special trays are required first
Explain the secondary impression protocol for RPD?
2nd impressions in alginate or medium bodied silicone main and light bodied silicone on teeth
Prescribe light cured acrylic resin based occlusal rims
How to prepare the casts to aid creation of a special tray?
Draw a clear pencil line around the depth of the sulcus allowing movement of the frena
Apply a single wax spacer over model and adapt tightly
Apply a second sheet and cut back to line
Cut tray stips into wax into 4 rough corners
Before adding tray material fill the stop holes with cut off tray material
Adapt a sheet of tray material to cover wax - avoid thinning at periphery
Handle stepped up by 10mm if no teeth in anterior
(allow 1m to set tissue stops before removing wax)
What may be different with cases of free-end saddles for creation of special trays?
Mucocompressive silicone impressions captured under load
How to adjust the special tray to allow for the frena?
Draw line along tray at same angle as frena, and trim away a rounded notch
Also notch out relief for muscle attachment
2mm clearance for border moulding before smoothing edges
How to measure a occlusion to identify whether a RPD patient has satisfactory occlusion?
Analysis of existing occlusion Correction of occlusal disharmony Recording ICP Recording RCP if no reliable occlusal contacts Favourable tooth-to-ridge relationship Try in of the teeth set up and harmonising occlusion Assess excursive relationships Correction of Occlusal Discrepancies
With articulating paper, what indicates a premature contact?
A dark ring with a
light centre
What to do if the patient doesn’t have enough teeth contact, to aid teeth contact?
Require jaw registration on stable bases
What is the recommended occlusion for a RPD patient?
Prosthetic teeth must be set to maintain existing occlusion between natural teeth
Name the 2 exceptions to recommended occlusion for RPD patients and how it is dealt with?
1. Partial denture oppose a complete denture or when 2. Only anterior natural teeth remain in a Kennedy Class 1 type dentition Jaw reg and teeth set up in same manner as complete denture
What can over-erupted teeth cause in RPD?
Occlusal plane discrepancy
Insufficient restorative space
Needs to be corrected
What occurs if posterior teeth support is lost?
May cause mandible to rotate upwards and backwards and over close
Loss of OVD (must be re-established)
What must occur in intercuspal occlusion?
Simultaneous bilateral contacts of opposing posterior teeth
What is essential for RPD occlusion and relation to natural teeth?
Occlusion for tooth supported RPD should be arranged such that natural tooth contacts are maintained when the denture is inserted in the mouth
What form of occlusion should be created in dynamic positions for RPD opposing a complete denture?
Bilateral balanced occlusion
Contribute to stability of complete denture
However, appearance, phonetics and occlusal plane gets priority over simultaneous contacts in protrusion
What information should be obtained for mandibular Kennedy CI and CII?
Working side contacts
Occur simultaneously with working side contacts of the natural teeth to distribute stress over he greatest possible area
What form of occlusion must be created for maxillary Kennedy CI?
Balanced
Occlusal scheme will compensate for buccal placement of teeth on denture base, in relation to ridge crest and offer stability
What information should be obtained for maxillary Kennedy CII?
Working contacts
WHat is GS to achieve for a Kennedy CIV case in term of occlusion?
Opposing anterior teeth contact in ICP to prevent over eruption of opposing anterior natural teeth
Where must prosthetic teeth not be set posterior to?
Ridge slop (retromolar pad) May cause movement of the denture base anteriorly
Name 3 materials a RPD can be made from?
Cast metal
Acrylic
Valplast metal-free flexible
How to select a mould for the posterior teeth of a RPD?
For replacing all posterior teeth follow the CD guidelines
E.g. distance from the distal surface of the natural
canine to the upward incline of the ramus or mesial aspect of maxillary tuberosity.
How to select a mould for the anterior teeth of a RPD?
Place the teeth as close as possible to where the original natural teeth were, mirroring the appearance of the other side of the arch for symmetry
What are the guidelines for setting maxillary teeth?
Use anatomical guides for setting teeth
How to adjust a toop for it to be butted against the edentulous ridge?
reshape the ridge lap portion of the artificial
tooth without shortening the crown length substantially so
that it can be butted against the edentulous ridge
Explain how to position a denture tooth adjacent to the abutment tooth/clasp or minor connector?
Requires careful
trimming of the proximal surfaces and the ridge lap portion of tooth. Take off both sides of the tooth as evenly as possible to maintain morphology
What is the cause of narrow space mesiodistally of the teeth? How to solve this issue?
Tilting or drifting of the adjacent teeth into the space
Regain original width by reshaping the proximal surfaces of adjacent natural or artificial teeth
Explain the process in developing functional contacts?
After establishing good centric occlusal contacts, lateral and protrusive contacts of the posterior teeth during function should be developed by moving the semi-adjustable
articulator and marking with articulating paper
Where should the distal denture flange be placed?
The distal extension saddle areas should be maximally covered for better soft tissue support
How to prepare new wax bases for try-in dentures?
Keep extensions as per bite block bases and add strengthening wires
Describe the process of setting maxillary 1st molar tooth?
The mesio-palatal cusp tip of the 1st molar contacts the occlusal plane but the buccal cusp tips and the distal lingual cusp are elevated about 0.5mm off the occlusal plane
Form a compensating curve
Arch form and symmetry
Describe the process of setting of mandibular central and lateral teeth?
The mandibular central incisors are set with the long axis perpendicular to the occlusal plane with the neck depressed
The mandibular lateral incisors are set with a slight mesial inclination
Vertical overlap 0.5-1mm
Horizontal overlap 2mm
Describe the occlusion for a CI mandibular partial denture opposing a complete edentulous maxilla?
Balanced occlusion:
- working balancing and protrusive contacts of the posterior teeth, with light contact of anterior)
Describe the occlusion for a CI maxillary partial denture opposing Mandibular CI partial denture
Working and balancing sides contact should be formulated
Describe the occlusion for a mandibular CI partial denture opposing natural dentition?
Simultaneous working side contact only should be formulated
Describe the occlusion for a CII mandibular or maxillary denture opposing any?
Only working side contacts should be formulated
Describe the occlusion for a CIV maxillary partial denture opposing natural dentition?
Contact of the opposing anterior teeth in centric occlusion
Contact of the opposing teeth in eccentric position should be avoided
Describe the occlusion for a Kennedy CIII partial denture opposing natural dentition?
Contact of the posterior teeth during functional movement is not desirable
Describe the meaning of denture debris?
Pellicle formation
Bacterial growth from sucrose
Favoured in slower salivary rate patients
Bacteria protected by plaque
Name the main bacteria of a denture?
Candida as it had a high affinity adherence to methacrylate resin
Name 7 other bacteria present in the mouth for denture wearers?
S. aureus, P. aeruginosa E. coli K. pneumoniae alpha-streptococcus beta-streptococcus Fusobacteria
Name the 3 types of denture stomatitis?
Newton’s TI/TII/TIII
Describe Newton TI denture stomatitis classification?
Pin-point hyperaemic lesions (local simple inflamm)
Describe Newton TII denture stomatitis classification?
diffuse erythema confined to the mucosa contacting the denture (generalised
simple inflammation)
Describe Newton TIII denture stomatitis classification?
granular surface
inflammatory papillary hyperplasia
What is the epidemiology for denture stomatitis?
Present in 60% of denture wearers
Associated with night wear
Describe the treatment for a denture stomatitis sufferer?
Good OH - rinse after meals
Avoid smoking
No sleep use
Denture cleaned with soapy, warm water and left overnight to soak in antiseptic
Denture fit and occlusal balance checked to avoid trauma
Antifungals if this doesn’t resolve it
Name the 2 types of denture clearners?
Mechanical
Chemical
Name the 5 ideal properties of a denture cleaner?
Must be easy to use.
Effective in the removal of denture deposits.
Have a bactericidal and fungicidal action.
Non-toxic to patient.
Harmless to denture materials
Describe the process of mechanical denture cleaning?
Soap (liquid), water and soft brush.
Effective at removing biofilm and debris.
May need to modify brush handle to facilitate manipulate by some patients e.g.
arthritis - use silicone putty or self cure
acrylic to adapt them
Avoid toothpaste - too abrasive
Name 6 chemical denture cleaners?
Alkaline hypochlorite Alkaline peroxides Abrasive cleaners Antibac and enzymes Acids Ultrasonics
Explain the basic instructions for denture care?
Rinse after every meal. Wash over towel or basin of water. Patient MUST not forget to clean any natural teeth (including overdenture abutments). Essential to remove denture during tooth brushing
Name contraindications when cleaning a denture?
Na hypochlorite
Water above 50C
CHX stain metal denture
Soft linings avoid scrubbing
Explain the process of using denture cleaning solutions?
20 mins hypochlorite, cool water (able to place fingers in water).
Max 10 minutes if metal components.
20 mins effervescent type cleaner, but NOT for soft linings.
Rinse with water and store in clean water
overnight.
How to prevent plaque forming on RDP?
It is effective to prepare the guide plane as close
to the gingival margin as possible to reduce the
plaque accumulation on the distoproximal
surface
What complications for plaque accumulation can occur for RDP?
Complicates oral environment and restrict the flow of food and self-cleaning action of the buccal mucosa
and tongue - dental plaque accumulation on the
prosthesis and surroundings.
Abutment teeth have more plaque accumulation and can
cause serious periodontal inflammation.
Clasps prevent from self-cleaning.The plaque formation on the buccal surface is not dependent on the type or placement of
clasps.
Describe the preventative treatment plan to reduce plaque accumulation for RPD?
Involve patient Varnish Toothpaste Chlorhexidine - 10ml of 0,12% rinse for a minute at least 30 minutes after brushing with fluoridated toothpaste.
Describe how Fl varnish can aid plaque control for RPD?
Uptake of fluoride during 12-48h.
Duraphat varnish (NaF 5% or 2600ppm). Hardens on
contact with saliva.
Clinpro White Varnish (1mg has 50mg of NaF)
Fluor Protector (Silane fluoride 0’1% (1000ppm). Blisters, needs relative isolation.
Teeth must be clean and dry.
Patient can’t eat or drink for the next 2 to 4 hours.
Do not brush the teeth until the following day
Describe how chewing gum can aid plaque control for RPD?
Xylitol:
- chew twice daily for 15 mins
Describe how Phosphopeptide-amorphous calcium phosphate can aid plaque control for RPD?
For root exposure patient and xerostomia
Follows use of Fl toothpaste 2 a day
Describe how saliva stim can aid plaque control for RPD?
Low sugar diet
Sip freq on water with baking soda
Describe the basic process of denture repairs?
Model is made from original
Old acrylic cut back and bevelled
New cold curing acrylic added
Processed as for additions and finished
Explain how to create a model for a broken denture?
overall alginate impression with the denture in the mouth and kept in the impression when sent to lab so that the subsequent cast shows how the denture fits against the standing teeth and tissues
A model can then be poured up to work on that replicates the fit of the denture in the mouth and relation to the standing teeth as closely as possible
Describe the best ways to increase the strength of a previously broken denture?
Strengthening wire or mesh if PMMA not too bulky
Thicken the acrylic
If repeated breakages occurs, try to understand why it is occurs?
check that the path of insertion is appropriate and the acrylic has been relieved from undercuts appropriately to this as otherwise torquing stresses will be unduly applied when the patient has to rotate the RPD in and out of the mouth
Why are denture connectors most prone to break?
where they shape round remaining teeth or muscle attachments
What usual reason is it for flange breakage in a denture?
Deep tissue undercut, that maybe opposing it at the distal of the denture
Partial flange more appropriate
Thin acrylic
What usual reason is it for a tooth to come off a denture?
Processing problem:
- waxy layer or cold mould seal not cleaned off the denture tooth ridge before the acrylic was packed affecting the bonding to the base material
Patient bite
What usual reason is it for a tooth to break on a denture?
Occlusion problem:
- assessed and an opposing impression and bite reg given to lab + an overall impression
What usual reason is it for a clasp to break on a denture?
Alginate impression Replaced Adjusted inapprop (metal very brittle) shaped too close too tissue or tooth deep into tooth undercut clasp arm at least 15mm Path of insertion and removal
What usual reason is it for a minor connector holding clasp/rest to break on a denture?
Leading up to the rest from the plate at least 1.5mm and is there enough room in the bite for this without prep this and or the emabrase area before
What usual reason is it for a major connector to break on a denture?
The whole saddle area could be temporarily replaced by thinning down and adding holes to the metal in the palate area to create a chamfered edge with mechanical retention for cold cure acrylic, but is the bite appropriate for this
Metal very thin over prominent rugae or a lingual plate eased away from a muscle attachment but no thick enough to fo so
When can chrome partial dentures be relined?
Tissue bearing extensions and not involving connectors
How to reline a partial chrome denture?
The undercuts and some of the fitting surface are removed and a light bodied silicone or wash impression as it is known is used to capture the tissue changes. This impression is kept in the mouth and an in-situ alginate taken over the top so the technician can reline to the fill in the space resorption has caused without changing the bite Cast model Plaster check bite Remove wash impression FIll with cold cure acrylic
What is essential to do if you do not want to reline an acrylic partial denture?
impression technique is spot on and that the light bodied material doesn’t come up past any areas where the denture meets the standing teeth before taking the overall impression or the cast produced will have a void/ false information in these areas and the denture will need A LOT of trimming to re-seat
Avoid creating voids (remove all wash impression)
