Revision Flashcards
2 implant mandibular overdenture:
Is not the gold standard implant therapy but it is the minimum standard that should be sufficient for most people
Contraindications for implant placement:
Anatomical limitations Medical contraindications Poor OH Non compliant patients Expensive !!!!! Non acceptance of surgical treatment !!!!! Poor communication
Irreversible bone loss is associated with:
denture use because it relies on the bone for support so it is problematic bc of bone having load
-complete dentures cause bone loss
Changes occurring following tooth loss are irreversible
The further bone loss progresses, the more difficult functional rehabilitation becomes
Use of complete dentures results in accelerated rate of bone resorption (compared to no dentures or having implants)
Use of poorly fitting complete dentures results in accelerated rate of bone resorption (compared to use of well fitting dentures)
SOS
Where are the occlusal forces transferred for CD?
What is the result of that?
To reduced surface area
Through the mucosa (not the teeth)
To supporting bone (damaging it)
Result:
Propriorecoetive mechanism of periodontal ligaments is lost
SA of supporting bone and mucosa is diminishing
Number 1 PRIORITY:
Screening for oral/head and neck cancer
When dentures require little/no modification consider doing the:
Copy denture technique = new denture production very similar to the old one but with improved fit
(refers to duplication of an existing denture)
They are a faster alternative to remake acrylic CD
Previous successful Vs unsuccessful dentures - treatment options:
Do nothing
Repair/modify existing denture
New CD
successful:
Copy denture
unsuccessful:
Implants
Psychological support
Irritated denture bearing tissues
- What causes it
- Localized or generalized
- Clinical symptoms
- Treatment
- Poorly fitting denture or poor OH or excessive use of denture adhesive
- Both
- Inflammation, redness, swelling, pressure spots, often no symptoms
- avoid use of dentures for several days; soft tissues rebound to normal morphology
-Alternatively: soft liners or tissue conditioners, Oral and denture hygiene
-in severe cases: permanent relining of existing dentures to allow sufficient time for healing
Occlusal adjustments may also be required
Denture related stomatitis:
- What causes it
- Factors
- Most commonly in
- Conservative approach
- If condition persists
- Aim
=chronic inflammation of mucosa
- Unknown etiology
- mucosal trauma, poor OH and denture hygiene, night time denture wear, bacterial/yeast infections (C albicans)
- maxilla
- avoid use of dentures as much as possible, oral and denture hygiene, drying of dentures overnight
- antifungals, antimicrobials, disinfection agents, antiseptic mouthwashes, microwave disinfection and photodynamic therapy have been used
- HOWEVER: there’s no significant difference between antifungals and disinfection treatment - to improve clinical appearance prior to secondary impressions
Treatment timing and patient compliance are critical to avoid condition relapsing with new dentures
Denture hyperplasia:
- Also known as
- Localised or generalised
- Clinical symptoms
- Treatment
- Cause
- ‘denture irritation hyperplasia’ or ‘epulis fissuratum’
- Localised hyperplasia of soft tissues
- The hyperplastic tissue forms single or multiple folds
- If small, recent and localised, may only require denture border relief +/- soft liner or tissue conditioner, more often requires surgical excision, care must be taken not to reduce the sulcus depth
- due to ill fitting, overextended, thin and sharp denture borders
Fibrous tissue proliferation =
- Also known as
- Most common
- Clinical symptoms
- Prosthodontic management
- Surgical management
- flabby ridge/fibrous tissue replacement
- Anterior maxilla - Often seen in complete dentures opposing natural teeth
- Accelerated residual ridge resorption results in excessive soft tissues over the ridge which is movable, poor foundation for new CD b/c of limited support offer
- modified impression procedure
-record secondary impression with selective compression of the main load bearing areas and a muco-static impression of the flabby ridge region
Can be achieved with a ‘windowed’ custom impression tray and recording the impression in 2
stages using different materials
Border moulding is carried out first; the main load bearing areas and sulci are recorded in ZOE paste and after any excess material is removed the flabby ridge area is recorded in thin mix of alginate syringed in the area, in light bodied silicone or impression gypsum - alternatively, excess soft tissue may be surgically removed
Care must be taken as the height of the residual ridge decreases significantly
Further bone loss should be anticipated due to the surgical intervention
Many complete denture wearers not very keen on surgical procedures!
Our duty for the risk management in CD is:
Prevent total tooth loss or any loss
Avoid use of CD
If CD will be used need to be made well done
Ensure CD will be maintained and re-adapted in time
Convinse them to have implants
What is the priority when patients want to change their existing denture?
To diagnose correctly what is wrong with that (the existing one)
SOS
Overextended borders:
- What does it cause?
- Localised or Generalised?
- Examples
- Causes pain/discomfort and/or displacement of denture in function
- Both
- Labial border -> loss of retention in speech and facial expressions
Maxillary posterior buccal border ->»_space; when mouth opens
Mandibular lingual border ->»_space; with tongue movements
Location of overextention determines clinical presentation - OPPOSITE FOR UNDEREXTENTION
-can result in hyperplasia
What determines whether there will be pain/ulceration or displacement of the denture?
Degree of overextension Amount of retention at rest Border morphology Patient persistence Mucosa tolerance Location of the problem
SOS Underextended borders problems:
- What does it cause?
- Localised or Generalised?
- Causes lack of RETENTION of the denture in function and at rest
- Both
Lack of retention clinically is the same regardless of problem’s location
Thin borders problem:
- What cause?
- What can result in?
- Localised or Generalized?
- Overextended or Underextended?
- Causes pain/discomfort and ulceration in function
- Can result in HYPERPLASIA in the long term if patient persists using the denture and the problem is not rectified
- Both
- Both
Likely to also be sharp ended (hyperplasia)
Thick borders problem:
- Overextended or underextended
- What cause?
- underextended
due to:
incorrect stock impression tray size
no modification of the stock tray
excessive amount of impression material
use of high viscosity impression material
no border moulding (helps to record an accurate impression of the trays) during impression procedure
and due to: - retention loss in function due to muscle activity or even at rest
SOS
Non anatomical morphology problem:
- What does it cause?
- What happens if too bulky?
- Causes lack of retention at rest and in function
- If too bulky, muscular action distabilises denture
Incorrect border thickness and/or extension
Effective border seal cant be achieved
Problem with a poorly adapted base through the whole tissue surface:
Lack of retention and poor support
Overextended denture base problems:
- What does it cause?
- Mainly where?
- Causes difficulty and pain in swallowing, speech, problems and gagging
- Mainly in posterior maxillary region
May manifest immediately at placement through the day as soon as the food bolus enters the mouth cavity
Underextended denture base problems:
- What does it cause?
- Mainly where?
- Patient’s or Dentist’s fault?
- Causes generalized pain throughout the denture supporting area due to insufficient SUPPORT
- Most common in maxilla posterior palatal border
- Dentist’s fault
-training denture
The further the tissues/cheeks out -> sulcus goes up so underextended (unless you correct it in secondary impression)
SOS
Excessively thick denture bases problems
- What does it cause?
Cause discomfort, gagging, speech problems, difficulty in swallowing, pain
Common at posterior borders heel clush or b/w maxillary denture base and coronoid process of mandible - hamular notch
Also no retention
-causes dislodgement of the maxillary denture
during function
Excessively thin denture bases problems
- What does it cause?
Prone to cracks and fractures
-Especially if opposing natural teeth
Insufficient relief in areas of deep soft tissue undercuts:
- What does it cause?
- Symptoms?
- Causes pain during denture placement and removal
- Localised redness and ulceration on the slopes of residual ridge
Good retention
Pressure areas problems:
- What does it cause?
- Causes pain along large areas of fitting surface of the denture base, particularly in function
Poor support - rocking of the denture
May also be in relation to tori
Lack of relief along “knife edge” ridge:
- What does it cause?
- Causes pain across mandibular ridge crest, particularly in function
Thin mucosa crushes b/w rigid denture base and sharp ridge crest
Problems with JRR:
Increased OVD:
What does it cause?
Causes gagging, SPEECH problems and difficulty in SWALLOWING and mastication
Facial pain, pain along the denture borders and across the residual ridge
Destabilization of dentures in function, especially mandibular
Typically deteriorates the longer dentures are in situ until the patient has to remove them
-Teeth in occlusion with the mandible at rest position
- lack of free way space (measure it again with the formula)
- Lips unable to seal (struggle to close the lips)
- Stretched muscles of the lips and chin
- Patients may report the dentures feel too big = MEANS NO FREE WAY SPACE
- May also report the teeth look too big – meaning there is too much teeth showing
-reduced stability, loss of retention in function
Problems with JRR:
Decreased OVD symptoms:
Difficulty in mastication and tiredness, muscular pain, tongue biting
support, stability and retention are not directly affected…but other problems are caused (difficulty in eating, tongue and cheek biting, muscular tiredness, etc) - not a problem
-by decreased OVD the mandible is more protruded
- Excessive freeway space!
- Insufficient lip support
- Vermilion border of the lip turned inwards and thin
- Deep crease over the chin
- Patient may report cheek or lip biting
- BEWARE: possible that the patient reports they feel very comfortable, especially if they have been used to reduced OVD in previous set of dentures!
-we cannot allow it for too long since it will create future problems
Dietary selection & nutritional status of complete denture wearers - 4 factors:
Masticatory function & oral health
General health
Socioeconomic status
Dietary habits
Causes of malnutrition:
Poor general health Poor absorption of protein Intestinal, metabolic and catabolic disturbances Anorexia REDUCED SALIVARY FUNCTION
In order to improve the nutritional status, often necessary to modify dietary habits
Natural dentition > implant supported overdenture > conventional complete denture
✔️
How to establish the patient’s head to establish occlusion?
natural head position:
back - straight up
no neck support
mirror to look straight into eyes
Frankfurt Horizontal Plane:
=connects lowest left orbital and upper tragus
- important to find the correct position of the head
- Asians have lower occlusal plane and higher Frankfurt plane
Curve of Spee:
= connects tip of canine, all buccal cusps of premolars and molars and condyle center of TMJ
- important to find the cuspal ridge
- longitudinal plane of occlusion
Curve of Wilson:
= connects lateral teeth of the same size
- ex: M1
- important for inclination checking
SOS
Antero-posterior position of maxillary anteriors:
Lip support
Nasolabial angle
Amount of teeth ‘showing’
Smile line
-we aim almost 90angle b/w the nose
Balance in CD:
Balance in protrusion:
Very steep occlusal plane, or Exaggerated compensating curve, or Very high cusps
OR Reduced incisal guidance angle
=> possible speech & swallowing problems
-to correct this: set the posteriors, especially second molar higher up. but this will cause problems
-we don’t want balanced occlusion or canine guidance, we go for group function -> even contacts on C, P1, P2, M
balanced occlusion = bilateral even contact b/w upper and lower denture in the intercuspal position
Regarding the occlusion of complete denture it is desirable to create dentures with:
Group function:
- Even contacts on the working side (2 or more teeth other than the canine, preferably all!)
- Smooth path of movement between centric and eccentric positions
- No contacts on the non-working side (but a near miss is welcome!) or anteriors
-NOT canine guidance
Lingualised occlusion:
Monoplane occlusion:
Same principle as in balanced occlusion
Main contacts between upper lingual cusps
Buccal cusps have little or no function
Does not look nice! - everything looks flat
Increased forces transferred to supporting structures
-acrylic on last lower molar
Temporary/record Vs Permanent bases:
what material used?
when are they used:
after what?
Temporary/record bases:
-made of baseplate wax, autopolymerising or light polymerized custom tray resin or polymethyl methacrylate (PMMA)
Uses:
-carry the wax occlusion rims for jaw relationship registration
-used to articulate the working casts
-used to set up the teeth and carry out the trial insertion
-used until the trial insertion stage
-replaced with a permanent denture base material only during the final processing
-Must be well supported, stable and retentive!
Permanent bases: -can be done after secondary impression -made of heat polymerized or auto polymerised PMMA, or other permanent denture base material -can be fabricated early on -good retention and stability with it Uses: -articulation -teeth set up -trial insertion -jaw relationship registration -incorporated in the finished prostheses: these are secured in the mould and only the waxed up polished surfaces are replaced with PMMA during the final processing
Using a permanent base for jaw relationship registration ADV Vs DISADV:
Advantages:
Jaw relationship registration: easier and more accurate
Retention, support and stability can be assessed early on
Adjustments at the borders and/or fitting surface can be done early on
Only need to worry about the occlusion at placement
Disadvantages:
More work for the dental technician
Small extra cost
Risk of permanent deformation of the denture base during the 2nd processing/finishing if mishandled
What is ‘acrylic resin’?
= Any of numerous thermoplastic or thermosetting polymers or co-polymers of acrylic acid, methacrylic acid, esters of these acids or acrylonitrile
-no good properties so not ideal to use it to replace someones teeth
-Properties:
Hardness: soft
Strength: low
Toughness: low
Elastic modulus: low
Thermal conductivity: low
Thermal expansion: high
Density: low
Translucency: high
-Biocompatibility: ok-ish
-Cheap
SOS
What is a polymer?
= A molecule made up of many units
SOS
Oligomer =
a short polymer (2-10 units)
SOS
Monomer =
the molecules that unite to form a polymer with a chemical rxn termed polymerization
-can cause allergic rxns
SOS
Co-polymers:
= when 2 or more different types of monomers are joined
Degree of polymerization:
the total number of units in a polymer molecule
Molecular weight of a polymer molecule:
the sum of the molecular weights of the units it is made from
What is a polymerization reaction and what are its 2 types?
= a rxn of 2 molecules combined to form a larger molecule (ex: monomers to polymers)
- Addition polymerization: no by-product
- Condensation polymerization: low molecular weight by-products (such as water, alcohol)
-the more monomer, the greater the polymerization shrinkage
SOS
PMMA polymerization steps:
how to get PMMA
- Initiation:
- benzoyl peroxide is divided into two identical parts and each is binded to an MMA creating the initiation molecule to start the propagation
- generation of free radicals
- free radical addition polymerization chain reaction
- initiator: benzoyl peroxide (not a catalyst! - it doesn’t get consumed) – readily dissociated on heating to produce radicals
- opening of a double bond in the vinyl group of MMA results in formation of another free radical, which “attacks” another double bond…
- PMMA is prepared by addition polymerisation of MMA - Propagation:
- repeated rxn of same type
- two MMAs bond together
- free radicals react with unsaturation centers leading to chain lengthening
- growing (live) chains = chain lengthening
- for cross linking to occur - Termination:
- by self-limitation; rxn stops
- free radicals are consumed by a rxn with other two radicals by not producing any more radicals, thus terminating the process
- when two radicals come together
- growing chain interacts and then stops, so that another shorter chain starts propagating - Inhibition:
- hydroquinone used to increase storage life
SOS
What is a Cross-linking Polymer and why it is important?
- has the best mechanical properties so if needed to improve properties, we prefer this polymer
- does not soften on heating (we don’t want it to get soft anyway) = thermoset
- results in the formation of a network structure; primary linkages occur between chains, and the polymer becomes a GIANT MACROMOLECULE
SOS
Linear and branched molecules:
-are discrete but held together through weak physical bonds
- On heating, the mobility of the chains increases, the weak bonds break and the chains slide past one another, resulting in a softened material
- On cooling the chain mobility decreases, the physical bonds reform and hardening occurs
-they are termed thermoplastic !!!!!
PMMA properties affected by:
chemical composition
degree of polymerization
number of branches and/or cross-links
Generally, longer chains and higher molecular weight result in increased: strength hardness stiffness creep resistance brittleness
- heat accelerated
- herd base due to hard mechanical properties
Stiffness: Strength: Creep: Hardness: Glass transition temperature: Toughness:
Strength: ability to withstand applied load without failure or permanent deformation
Hardness: resistance to abrasion, indentation, penetration
Stiffness: resistance to elastic deformation
Toughness: ability to absorb energy and plastically deform without fracturing
Creep: slowly occurring plastic deformation under persistent mechanical stress
Glass transition temperature: the temperature at which a polymer ceases to be glassy and brittle and becomes rubberlike !!!
Plasticizers:
molecules which reduce a polymer’s rigidity by lowering the glass transition temperature
-these are small molecules which facilitate movement by surrounding larger ones
Fillers:
particles added to polymers to improve specific properties and lower the cost
Polymerization shrinkage:
up to 21% vol for unfilled resins
6% vol for denture resins
3% vol for resin composites
High impact PMMA:
Incorporation of a rubber phase in the polymer beads for improved impact strength and reduced stiffness
SOS
Advantages Vs Disadvantages of PMMA as a denture base material:
Advantages: Biocompatibility Aesthetics Dimensional stability (in use) Good adaptation Strength Bond with acrylic teeth - no need to worry about mechanical properties Ease of modifications Long shelf life Widespread availability No need for complex equipment Easy handling Cheap
Disadvantages: Residual monomer - toxic for patient (change water now and then and it will disappear) Low thermal conductivity Creep Water resorption - easier for bacteria to colonize Processing shrinkage (?) Fatigue Radiolucent
SOS
What do you think is the clinical significance of the polished surfaces?
Patient comfort Speech Deglutition (=swallowing) Retention & stability (helps to keep muscles and denture in place when polished - if not polished, when muscles contract then it will move the denture outwards thus distabilise it) Aesthetics Hygiene
Components of speech:
Respiration (=the movement of air in inspiration and expiration) Phonation Resonations !!!! Articulations !!!! Neurologic integrations Audition
SOS
Resonance:
The sounds produced by the vocal chords are modified in:
The pharynx
The oral cavity
The nasal cavity
The paranasal sinuses
-anything interfering with these 4 modifications will change the speech
SOS
Articulation:
The sounds are formed in meaningful words
The tongue, lips, palate and teeth play a crucial role
-anything interfering with those will interfere with speech
Speech considerations:
Anatomical classifications:
To check the position of anterior maxillary rim - which sound?
For free way space and medium space - which sound?
For the correct rest position of the mandible - which sound?
a) Which of those may be affected by the contouring polished surfaces?
Vowels are voiced sounds: a, e, i, o, u
-said with open mouth so not a problem; no need to worry about
Consonants may be either voiced or produced without vocal chord vibration in which case they are called breathed sounds: p, b, m, s, t, r, z etc…
Consonants are most important from Prosthodontic point of view
Various classification methods
Clinically significant:
according to anatomical parts involved in their production:
Bilabial: lips (m, p, b)
Labiodental: lips and teeth (f, v)
Linguodental: tongue and teeth (th)
a)LINGUOALVEOLAR: tongue and anterior palate (t, d, r) !!!!!
LINGUOPALATAL and LINGUOVELAR: tongue and palate (k, j, g) !!!!!
-affected more by the contouring of the polished surfaces: lingualveolar and linguopalatal and linguovelar
For free way space and medium space to say ‘s’
To check the position of anterior maxillary rim: the ‘f’ and ‘v’ sounds
For the correct rest position of the mandible: is the ‘m’ sound
When is polishing done?
after tooth positions
- First: establish occlusal plane level and orientation, anteroposterior tooth positions and OVD
- All the above also affect speech!
SOS
Cawood and Howell classification:
=
classes:
= classification of alveolar ridges
Class I: dentate
Class II: immediately post-extraction
-soft tissue / bony undercuts
Class III: well-rounded ridge form, adequate width and height
-favorable for complete dentures
Class IV: knife-edge ridge form, adequate height, inadequate width
-easily traumatized mucosa, painful
Class V: flat ridge form, inadequate in height and width
-reduced stability and support
Class VI: depressed ridge form
-reduced stability, support and retention
Border extension & shape:
Buccal sulcus:
Buccal frenum
Buccal shelf
Buccinator m.
Buccal frenum
Buccal shelf
- is NOT a relief area
- ONLY IN THE MANDIBLE
- important in the fabrication and wearing of mandibular CD
- primary stress bearing area in mandibular edentulous ridge (= areas that withstand functional forces applied to a denture)
- you cannot extend the border further back from the external oblique ridge -> place for buccal shelf
- area between the buccal frenum and the anterior border of the masseter
- The greater the access to the buccal shelf the more support is available for the denture. Access is determined by the attachment of the buccinator m
Buccinator m. !!!!!!!!!
- the way it attaches to maxilla (up, down and out)
- its action will determine the border of the extension
- border extension is limited by this muscle
- determines access to the buccal shelf space
Anatomy of the edentulous mouth:
maxilla:
mandible:
Palatal gingival remnant Incisive papilla Buccal sulcus Residual alveolar ridge Rugae Mental foramen Labial sulcus Lingual sulcus (posterior) Buccal Shelf Vibrating line Retromylohyoid fossa Hamular notch Retromolar pad Buccal sulcus Labial sulcus Maxillary tuberosity Fovea palatini
maxilla: Palatal gingival remnant Incisive papilla Buccal sulcus Labial sulcus Vibrating line Hamular notch Residual alveolar ridge Maxillary tuberosity Rugae Fovea palatini
mandible: Residual alveolar ridge Mental foramen Retromolar pad Buccal sulcus Labial sulcus Lingual sulcus (anterior) Lingual sulcus (posterior) Buccal Shelf Retromylohyoid fossa
SOS
Vibrating line:
- posterior palatal border
- not straight, not extended and very posterior
- imaginary line on soft palate dividing mobile and immobile parts from each other
- extend where the hard palate finishes
- do not extend up to vibrating line because no retention !!!!!!!!
- fovea palatini are in front of it !!!!!
Border extension & thickness:
Hamular notch:
- hamular process is a bony projection of the medial plate of the pterygoid bone and is located distal to the maxillary tuberosity
- lying between the maxillary tuberosity and the hamulus is the hamular notch, which is a key clinical landmark in maxillary denture construction because the maximum posterior extent of the denture is the vibrating line, which runs bilaterally through the hamular notches
Tensor veli palatini m.
Coronoid process !!!!!!!!
-should be avoided
Masseter m.
SOS
Border extension & shape:
Labial sulcus:
Orbicularis oris m.
Labial frenum
Mentalis m.
-determines the border extension of the denture
Orbicularis oris m.
-has an indirect effect on the extend of the
denture
Labial frenum -> needed to provide relief
- relevant to border extension
- big frenum Vs getting rid of it
Mentalis m. !!!!!!!!!
- affects the borders of the mandibular denture
- when people talk it can distabilise their denture
Border extension & shape:
Retromolar pad:
- limits the most posterior position of a mandibular molar
- it is located distal to the last mandibular molar
- it is extremely important in denture construction from both a denture extension and plane of occlusion standpoint
- the plane of occlusion is located at the level of the middle to upper 1/3 of this pad
- most compressible tissue in the lower arch
- Masseter m.
- should be covered by the mandibular denture for retention !!!!
Mental foramen:
- nerves passing from it: inferior alv n and mental n
- your denture can press on this and cause pain
- it determines the border
SOS
Border extension & shape: Lingual sulcus (posterior):
Mylohyoid m.
Retromylohyoid fossa
Lingual sulcus (anterior): Lingual frenum Genioglossus m.
Mylohyoid m.
-mylohyoid ridge !!!!!!!! -> sharp and has an undercut; it is painful if there’s increase in OVD
Retromylohyoid fossa
-area that determines the most distal lingual extent of a mandibular CD (most distal extension of the mandibular denture)
-the opposing areas are usually undercut in relation to each other
-1 difficulty encountered when fabricating the mandibular denture is that these bilateral undercuts may greatly complicate the process of making the preliminary and final impressions. the dentures may also require significant adjustments
in these areas at the time of insertion
What is a denture border?
= the margin of denture base at junction of the polishing surface and the impression surface
Retention =
Stability =
How to check if the denture lacks support?
retention = the ability of the denture to withstand dislodgement against its path of insertion / = the resistance to vertical forces of mastication, occlusal forces and other forces applied in a direction towards the denture bearing area / the ability to resist vertical dislodging forces
-to check it: pull AWAY from the tissues
stability = the ability of the denture to withstand horizontal forces / the ability to resist horizontal rotational displacing forces
support: if it moves TOWARDS the tissues, it lacks support
Which zone should the occlusal rims be designed within to be?
neutral zone
-zone where buccal and lingual forces are balanced
Where should the occlusal plane of occlusal rim be parallel to?
plane of the maxilla
While recording the rest position of the mandible, the patient ‘s head should be:
upright and unsupported
The correct buccolingual placement of teeth plays an important role in phonation. What should the relationship of the teeth and tongue be in pronouncing ‘t’ and ‘d’ sounds?
contact of the tip of the tongue with the anterior palate and lingual surfaces of the maxillary anterior teeth
A patient comes with a complaint of a newly made denture which is loose and causes soreness even after repeated adjustments. What is the most important protocol to follow in such a casa?
check the occlusion
SOS
What are the treatment aims for complete dentures?
- Aesthetics: retention, stability and support
- Speech: retention, stability and support
- Mastication: support, retention and stability!
What does the patient’s denture lack if every time they talk their denture drops?
retention
Which steps can guarantee that the denture will have all 3 qualities (aesthetics, speech and mastication)?
Primary impressions Custom impression trays Secondary impressions Temporary bases - how we record Jaw relationship registration Tooth setup Wax up - how we wax up the polish surfaces
Aim of primary impressions:
Record all the anatomy (full extent of denture bearing tissues) and the correct depth and width of the sulci
Underextended primary impression problem could result to underextended:
custom impression tray
secondary impression
record base
permanent denture base
Retention, support and stability may be compromised
Before the secondary impressions, the custom trays should have some of the desired qualities of the finished denture base when placed in the mouth:
Close adaptation throughout the entire denture bearing area
Anatomic border morphology (not too thick/thin)
Support and stability
What is the clinical significance of positioning, size and orientation of the custom tray handles?
for no lip displacement
Border moulding:
=
when is it done?
process:
= technique of properly extending the flange length
of an impression tray prior to making the final impression
- done BEFORE secondary impression
- ensures correct border extension
-green stick compound heated in flame and dropped in the place where needed for framing to ensure the frenulum is impressed by these sticks
-INCREMENTALLY add this softened thermoplastic impression material on the tray along the border
-activate the relevant muscles
-after this, the custom tray should demonstrate good retention
-then the impression is completed using Zinc Oxide Eugenol impression paste (already close-fitting so no need to add more material)
-then place it in the mouth
-deficiencies can be corrected by addition of more material (no need to add from scratch)
-once complete: rinse and place again in mouth to assess retention (tell patient to relax and pull away from tissues to check it), support and stability
=> if one of these qualities is lacking: the finished denture will also be lacking!
- if border moulding is insufficient repeat if needed
- border molding for mandibular denture should not extend over external oblique ridge
- if underextended borders then it is corrected by border moulding
- Mandible moved side to side to avoid clash with coronoid process
- If it is shiny and smooth the material has either set before or it was a bit inadequate – it didn’t reach the tissues as we wanted that
- We keep applying modelling compound until we capture all the anatomical structures mentioned and have a border seal
- We want to remove some material b/c we don’t want to build up excess as it will interfere with our impression
- The patient should be straight facing the dentist – maxilla is hard
- The line he made on the soft palate is it for the sole purpose of defining the posterior border
Trial Insertion:
=
when are errors detected?
why is it done?
= teeth set up and trying in mouth
- teeth are set in wax and small errors may easily go undetected
- they only become apparent after the dentures are finished (or not at all…)
- in occlusion the wax will be removed even if patient is in ICP, so even then you can identify errors
- it is done to make assessments of the aesthetic position of denture teeth, facial support, phonetics, OVD, occlusal scheme and the centric occlusal position
- gives the patient an opportunity to see the aesthetic results from the previous deliberations during the maxillomandibular records appointment and the tooth selection process
SOS
Jaw relationship registration:
importance:
when is it done?
- after V dimension determination
- important b/c it mounts the cast on the articulator (transfers the exact relationship of maxilla and mandible to the articulator)
- records the retruded position of the mandible at the selected vertical dimension of occlusion
- for a different vertical occlusion the antero-posterior position of the mandible will be also different !!!!!!!!!!
Tooth setup importance:
-3 things we need to include:
- to restore the natural occlusion
- helps you in JRR and diagnosis
-3 things we need to include:
Level and orientation of the occlusal plane
Antero-posterior position of maxillary incisors
Bucco-lingual (bucco-palatal) position of posteriors
SOS
Level and orientation of the occlusal plane (OP):
If OP too superiorly:
If OP too inferiorly:
OP too superiorly (high): (when the tongue moves in function it will hit the teeth and destabilize the lower denture) mandibular denture unstable, loses retention in function
-lower teeth will be too high
(the opposite will happen) OP too inferiorly (low): maxillary denture unstable, loses retention in function!
-upper teeth will be too low
-because horizontal relation changes
SOS
Antero-posterior (AP) position of maxillary incisors:
If set too anteriorly:
If set too posteriorly/palatally/back:
Set too anteriorly: lip pushes denture inferiorly, loss of stability and retention
-m of upper lip pushes the denture outwards
Set too posteriorly: tongue pushes denture labially (outwards), loss of stability and retention!
-will break the peripheral border seal
- Placing the maxillary anteriors too far palatally also usually results to increased OVD!
- set them in correct positions
Bucco-lingual / palatal position of posteriors:
If set too buccally:
If set too lingually:
Set too buccally: cheeks destabilize the dentures, loss of retention
Set too lingually: tongue destabilizes the dentures, loss of retention!
Wax up:
Wax up too bulky:
Wax up lacking in bulk:
-to restore the natural soft tissue contours
Wax up too bulky: cheeks destabilize the dentures, indirect loss of retention
Wax up lacking in bulk: incomplete peripheral seal, lack of retention!
-we need to have correct anatomy of the polished surfaces, that’s why it is important to have a correct anteroposterior position
- When considering the arrangement of the maxillary anterior teeth, what determines esthetics?
- What determines the fullness of the lips (lip support)?
- the position of their incisal edge
2. the cervical portion of teeth and the fullness of maxillary denture base
Most patients desire symmetrical arrangement of the anterior teeth with minimal variations that might provide a more natural look. Which 2 groups of patients might be an exception to this statement?
The patients with existing dentures, who would like the arrangement of the teeth of the new denture to mimic those of the existing denture.
AND
The patients receiving immediate CD also desire that the arrangement of the denture teeth match the arrangement of the natural teeth
In what direction do the crests of the residual ridges resorb following extractions, and what might these resorptive patterns result in?
when the natural teeth are lost:
the mandibular residual ridge resorbs Downward and Outward
the maxillary residual ridge resorbs Upward and Inward (lingually)
Because of these resorptive patterns, it is necessary to create a reverse articulation (cross bite) for the posterior teeth
If an adjustment is necessary to the vertical position of the plane of occlusion, which arch should be favored and why?
the position of the plane of occlusion may be adjusted either superiorly or inferiorly to a small degree
When making adjustments to the height of the occlusal plane, the MANDIBULAR arch should be favored because of its decreased stability
What is the objective of contouring the occlusion rims?
To shape the record bases and occlusion rim so that they will replace, in size and position, the teeth and supporting structures that have been lost.
Correctly formed occlusion rims serve as excellent guides in the initial placement of artificial teeth
Why is the centric relation position important for CD fabrication?
=
- it is the starting reference point for CD fabrication
- it is repeatable and can be verified
- it is a functional position for denture occlusion
- at the proper OVD this position then becomes the centric occlusion position for the patient
- it has nothing to do with the teeth, it has to do with the maxilla and mandible, determined by the condyle assembly
= the most anterior superior condyle position assembly w/in the glenoid fossa
- as we close the mouth the first tooth contact is the centric occlusal position
- to go into ICP the mandible needs to go slightly forward
Why is recording extreme accuracy of mandibular movements not possible with fully edentulous patients?
The record bases are mobile because they are resting on movable tissues
Why is it important to properly block out undercuts on the master cast prior to fabricating the record base?
Because of the possibility of cast breakage when initially separating the record base from the master cast
Why is the blocked-out master cast soaked in water for 5 minutes prior to fabricating the record base?
to minimize the formation of bubbles in the completed record base
What feature of a CD routinely increases the factors of retention?
Maximum tissue coverage
Why should a maxillary denture not be extended onto the movable soft palate?
Retention of the denture may be compromised and the denture may cause irritation and trauma to the soft movable tissues
SOS
Why is the incisive papilla a good landmark to note when contouring occlusion rims and positioning the denture teeth?
What is the importance of incisive papilla?
the facial surfaces of central incisors are 8–10 mm anterior to the middle of the incisal papilla, and the tips of the canines are approximately in line with the middle of the incisal papilla
-gives indication of the canine tips and the position of maxillary anteriors in anteroposterior direction
Why is the location of the fovea palatini important to note in the edentulous patient?
They are useful in the identification of the vibrating line because they generally occur within 2 mm of the vibrating line
-placed in front of the vibrating line
Clinical steps to assess a CD at trial insertion:
most common initial pressure areas will be:
what do you examine?
- Clinicians should open and inspect the processed
dentures prior to patient arrival. Obvious corrections can be made to sharp edges etc. The prostheses are then disinfected and will be ready for the initial insertion procedures - The dentures should be gently seated, and severe undercuts that limit placement should be adjusted. The dentures should seat easily with no discomfort reported by the patient. Any severe pressure or areas of extreme discomfort should be eliminated prior to proceeding
- Pressure Indicating Paste (PIP) or Pressure Disclosing Paste is placed uniformly on the intaglio surface of the denture.
- The denture is seated with firm pressure. Do not place both dentures and have the patient “bite.” This may introduce errors in the PIP from occlusal discrepancies.
- Pressure areas should be identified and eliminated
by judicious grinding. The most common initial pressure areas will be bony prominences and the
medial surfaces of the posterior buccal flanges. Excess pressure prevents the denture from fully seating and may cause soreness and poor retention until the excess pressure is eliminated. - Acrylic burs in a slow speed hand piece are the ideal method for eliminating these problem areas.
- Repeated testing. The mandibular denture is evaluated with the PIP in a similar manner. Border extension can be evaluated both visually and with Disclosing Wax™ to located possible problem areas.
- Active muscle groups should be evaluated for excessive pressure against the denture borders. The masseter muscle can pull across the distobuccal border of the mandibular denture and unseat the prosthesis during function. Proper adjustment of the border will eliminate that problem.
- Final occlusal adjustments should be accomplished by mounting the processed dentures on a properly set articulator. The maxillary remount cast is returned to the articulator to preserve the facebow orientation. A new centric relation record is used to mount the mandibular denture in the correct horizontal position for occlusal equilibration.
For complete dentures we aim for:
A jaw relationship record of the RETRUDED POSITION OF MANDIBLE at the SELECTED VERTICAL DIMENSION of occlusion
Why do we go for the retruded position of the mandible?
A dentate patient:
Retruded contact position (RCP) =
if ICP(/MIP) coincides with RCP, our job is done!
OR
if ICP is slightly anterior to RCP, the difference will be so small that patients can easily adapt!
We have no idea where the ICP was!
-the retruded position of the mandible is THE ONLY reproducible position !!!
= when the mandible closes in the terminal hinge axis position the first tooth contact
-guided plane
Clinical procedure for Jaw Relationship Registration (JRR):
- Prepare record bases (or permanent bases) and wax rims
- Place the MAXILLARY base and rim in patient’s mouth
- Add or remove wax to establish aesthetics (amount of teeth showing & lip support) - ask another person to evaluate it as well AND to determine the occlusal plane of the maxillary rim
- Measure the REST VERTICAL DIMENSION
- first we determine the vertical relationship and then the horizontal relationship
(so far ONLY maxillary base, not mandibular one, b/c we need the SUPPORT OF LIP FIRSTLY)
- Place the mandibular base and rim in mouth to make sure they have even contact in the desired OVD
- Add or remove wax to establish even contact between the 2 rims when the mandible is guided in retruded position; assess support of the lower lip as well as amount of mandibular anteriors showing!
- Measure the OVD in retruded position with the wax rims in contact
IMPORTANT: we use the same marks as previously!
- Calculate the freeway space
- cut grooves on rims and apply vaseline on 1 of them so that they can detach if needed !! - Carry out the JRR at the retruded position of the mandible (H dimension) with appliance of registration material and then:
- Mark the midline of the face and position of canine tips on the maxillary rim
- Remove the wax rims and registration record
- Create facebow record
Occlusal plane orientation determined according to:
ala-tragal line (draw a line from ala to tragus = Campers line) and interpupillary line (pupils connect when pt is viewed from the front)
-patient’s head needs to be in correct position
SOS
REST VERTICAL DIMENSION (RVD) =
OVD:
= vertical distance between 2 ARBITRARILY SELECTED points (1 above and 1 below the occlusal plane) along the midline when the mandible is in rest position
-these points are different every time you do the exercise, it might be nose tip and chin tip
OVD: closed mouth and measure again from those two points
-need even contact b/w the rims
Calculate the freeway space:
=
Free way space = RVD – OVD
Minimum required freeway space is: 2 mm (2-4 mm)
If the OVD is greater than the RVD: you need to re-adjust the occlusal plane level, by removing wax from either of the wax rims
In most cases we REMOVE WAX from MANDIBULAR rim, as the maxillary wax rim level has been established based on aesthetics
If the difference is significant, we may choose to split it between the maxillary and mandibular rim
The height of the wax rims should be equal between maxilla and mandible, taking into consideration the degree of residual ridge resorption!
Why do we need to cut some grooves/notches on the wax occlusion rims before applying the jaw relationship registration material?
Where should these grooves be placed?
if the 2 rims are separated at any time after we have made the registration record we are able to locate them correctly/accurately
- make them in the region of molars or second premolars (not than 1-2 mm deep, no undercuts, best if not parallel to each other and have a finger test not to cut yourself) b/c anteriorly there wouldn’t be enough material and also b/c the region of the first molars is as far as way from each other so more accurate
- If you make the notches perfectly parallel to each other on both, one rim will be sliding on top of each other when you reassemble them outside of the mouth, so if not this it will be stable
- make them DEEP enough
What materials can we use for the jaw relationship registration? What are the advantages and disadvantages of each material?
How should they be placed?
Wax: not as easy to use (b/c you need to place it in the right Tm), medium duration setting time, cheap, readily available, rigid once set, may soften if transported in hot climates, most commonly used
Zinc Oxide Eugenol: messy, not as easy to use, long setting time (problem-pt might move their mandible while it sets), very rigid once set but brittle (in transport it can crack if not careful enough), stable in hot climates
Fast setting registration silicone: the easiest to use, quick setting, more expensive, more elastic than ZOE or wax (problem b/c if it bounce back it will affect its accuracy; we want it rigid)
IMPORTANT: there MUST be wide area of contact between the wax rims
– do not fill the whole surface of the rim with
registration material!
-keep the mandible in retruted position until the material sets
Why do we measure the Vertical dimension first?
because as the V dimension increases, the mandible will be more open so it will have a different centric relation and as the V dimension changes so does the H dimension of the mandible
Why we shouldn’t fill the whole surface of the rim with excess registration material?
if too much material, we will have an increased OVD and excess material coming out will block our view if the rims are in contact of not and won’t be able to see while the material sets if the pt moved their mandible or not (you can avoid this by drawing a line on upper rim in the middle and continuing it on the lower rim as well)
easier for us to see if the wax rims have come into contact or not in the anterior region
SOS
Marking the midline of the face and position of canine tips on the maxillary rim:
Once the material sets or any other time:
Mark with a knife the midline of the face as it may or may not coincide with midline of the nose !!!!!!
Guide to position of canine tips: a vertical, straight line from inner canthi of the ear to lateral aspect of the ala
Mark the corners of the mouth on the mandibular rim: guide to position of mandibular first premolar cusps
Remove the wax rims and registration record:
-removed attached together (if the mouth opening is wide enough!)
or
-separated (Vaseline allows that); grooves carved earlier will allow precise repositioning
- vaseline preferable on the maxillary rim because:
1) for facebow record
2) silicone material easier to apply on mandible - If planning to make a facebow record: MUST separate wax rims, as only the maxillary base and rim are used
- Always create facebow record AFTER the jaw relationship registration (in order to go straight to the articulator for mounting the maxillary cast)
Facebow record:
it relates the MAXILLARY cast to the opening and closing hinge axis of the articulator
= A caliper-like instrument used to record the spatial relationship of the maxillary arch to anatomic
reference points and then transfer this relationship to an articulator
- helps in recording hinge axis record
- after JRR
- try to center the line of the bite fork with the midline we marked on the maxillary rim previously and then stick it into the wax (flame it to warm up first) - it wont interfere with the wax or the occlusion
Aims of the trial insertion appointment:
To ensure all aspects of the CD are correct prior to finish:
Occlusion Retention, support & stability Aesthetics Speech Polished surfaces
Trial denture =
= denture all waxed up with all teeth in position
-a final trial before we finish the prosthesis
Occlusion:
what we can check if occlusion is correct
-established after jaw relationship record was correct
- Horizontal position of the mandible (antero-posterior & lateral)
- Vertical position of the mandible (refers to freeway space)
SOS
Anteroposterior Horizontal error in jaw relationship registration:
retruted position of mandible for JRR - made a mistake of 1.5 mm (anterior) error:
A) If we haven’t understood yet that there’s an error and we try to close the mandible in retruted position and we persist trying to get the teeth to interdigitate, what will happen? (premature contact posteriorly and open bite anteriorly)
B) What should we do if this happens?
- What does it cause?
- Clinically manifests?
if we transfer them to the articulator we will have the same error in our tooth setup
Unable to achieve interdigitation when trying to guide the mandible in retruted position due to premature contacts prevent us to do so
Assumes that the OVD is correct and that this error is of a small magnitude
A)
1. The mandible will close into MIP eventually, but at a more anterior position
or
2. The teeth presenting the premature contacts will be pushed into the wax holding them
or
3. The mandibular denture will be forced to move out of position
or
4. Any of the above (combination)
B)
- Try to avoid getting the teeth pushed in the wax !!!!!!
- Repeat JRR: guide the mandible in retruded arc of closure and get the pt to close only up to the first premature contact! (note that)
- Raise the pin on the articulator
- Remount the lower cast on the articulator
- Remove the lower teeth from the lower record base and allow the pin to close back down to 0
- Reset the lower teeth in the new position
- Then repeat the trial insertion
- Causes localised pain/discomfort and redness/ulceration on the lingual slope of the anterior mandibular residual ridge (less support in mandible so less R for denture to move forward - prob in front)
- pain from the mandibular area due to low support - Clinically manifests as an anterior side from the position of first occlusal contact into the ICP
- as the pt tries to close in ICP, the 1st tooth contact will be slight forward causing pain on L aspect on the mandibular residual ridge
retruded position of the mandible is the most posterior possible position
- so the error is always forward
- when pt starts closing there will be a premature contact on posterior teeth
- maxilla has more support than MANDIBLE,so more area therefore not likely for this error to happen on the maxilla
- lingual aspect is the error b/c is where the mandible will slide towards to
Lateral Horizontal error in jaw relationship registration:
A) If we haven’t understood yet that there’s an error and we try to close the mandible in retruted position and we persist trying to get the teeth to interdigitate, what will happen? (open bite on 1 side and premature contact on the other side)
B) What should we do if this happens?
- What does it cause?
- Clinically manifests?
Unable to achieve interdigitation when trying to guide the mandible in retruted position due to premature contacts prevent us to do so
Assumes that the OVD is correct and that this error is of a small magnitude
The direction towards which the mandible must move to achieve interdigitation shows us the direction of the JRR error so its easier to diagnose such error (it moves the direction where the error is)
we try to have the mandible in retruted position and we try to have the midline at the center where it should be and as we do that we accidentally make a lateral error
The mandible is deviating now towards the right so the mandible doesn’t coincide the midline of the force
A)
1. The mandible will close into RP, but at a lateral position (1.5 mm to the right)!
or
2. The teeth with the premature contacts will be pushed out of the wax
or
3. The mandibular denture will be forced to move out of position
or
4. Any of the above (combination)!
B)
Exactly the same as in anteroposterior error
- Try to avoid getting the teeth pushed out of the wax!
- Repeat JRR: guide the mandible in retruded arc of closure and close only up to the first contact, making sure the midline is centered!
- Raise the pin on the articulator
- Remount the lower cast on the articulator using this first contact record
- Remove the lower teeth and allow the pin to close back down to 0
- Reset the lower teeth in the new position
- Then repeat the trial insertion
- Causes localised pain/discomfort and/or redness/ulceration on the lateral slopes of the mandibular residual ridge
- Clinically manifests as a lateral side from the position of first occlusal contact into the ICP
Loss of retention in function, but at rest might be adequate
The direction of the side will indicate the location of the premature contacts
If the error is significant and it isn’t of a small magnitude we will have to:
for mandible:
for maxilla:
for mandible:
- Remove all lower posterior teeth (and anteriors if needed)
- Replace teeth with new wax occlusion rim
- Repeat JRR (so the mandible needs to be centered in retruted position and at desired/correct OVD)
- Remount the lower cast back to the articulator and repeat tooth setup at new position of the mandible
- Repeat trial insertion
for maxilla:
- Assess position of the midline, lip support, aesthetics, occlusal plane, shape and shade of teeth etc
- Determine what changes should be made
- Since the mandibular cast will be remounted and the setup repeated, any changes to the setup of the maxillary teeth can be made at the same time
- Repeat trial insertion
Clinical management of vertical errors in jaw relationship registration: (increased/decreased OVD)
Measure the freeway space: determine the magnitude of the error (needs to be 2-4 mm; for older people more)
Provided there is no indication of a horizontal error, no need to repeat the JRR
Return to the lab and prescribe the desired change in OVD
Must also decide which arch should be reset (or both)
Will have to reset the pin on the articulator by a greater degree than the error measured !!!!!!! MEANS any mm change on the opening of the incisors, won’t be the same change with the mm opening of the pin since it is further away from the axis of rotation than the teeth
-At the trial insertion, the aim is to identify large scale errors in the occlusion and either correct those on the articulator or instruct the laboratory accordingly
Small errors can be adjusted at the chairside, but excessive chairside adjustments will eventually result in:
-displacement of the denture teeth in the wax holding them as the forces are of great magnitude and the wax softens at mouth temperature as it stays in for a while
If there are too many errors: safer to just create a new JRR (in RP), remount the lower cast and make the adjustments on the articulator!
Assessing occlusal contacts:
In ICP (RP)
-how to check them?
- Use articulating paper between the teeth and guide mandible to RP
- Must have bilateral even posterior contacts evenly distributed
- No anterior contacts desired in ICP for CD (b/c we want to allow at least 1-2 mm of free movement before the anteriors come into contact otherwise this will cause the dentures to destabilize!)
Areas to be adjusted to correct interferences on the path of closure into RP (ICP):
-we need to avoid premature contacts, but we also want to avoid any interferences = no tooth contacts during closure into RP
Fossae and/or marginal ridges of posteriors
Interferences on inclines of cusps near to the fossae
MUDL rule:
Mesial facing inclines of the Upper cusps
Distal facing inclines of the Lower cusps
-NO adjustments on upper palatal and lower buccal cusps (not on the functional cusps b/c that would affect the OVD)
If the discrepancy is > 1/3rd of a cusp: reset the tooth
Assess occlusal contacts:
In protrusion
a) Areas to be adjusted to correct interferences in protrusion if we do face such error:
Use articulating paper and guide mandible to slide from RP to ‘edge to edge’ position
Occlusal contacts should be evenly distributed on all anterior teeth (not only on 1 tooth)
Posterior contacts are not desirable
a) Adjust cingulum area of upper anteriors
Avoid excessive adjustment as thinning the teeth affects their appearance
Small adjustments can be made to lower incisors as well
In lateral movements what we want to achieve is:
group function on the working side with contacts on as many teeth as possible (at least 2 other teeth other than the canine)
No contacts on non working side because instead of balancing they become distabilizing
Which areas do we adjust to correct working side interferences?
The BULL rule!
- Buccal Upper cusps and Lingual Lower cusps
Which areas do we adjust to correct non-working side interferences?
We adjust the:
Distal inclines of upper palatal cusps
Distal inclines of lower buccal cusps
Aim: 0.25-0.5 mm clearance min
But if we make some of those adjustments doesn’t it affect the previous ones as well???
NO!
There is no overlap between these areas!
-the adjustments we made for working side won’t affect the adjustments we made for the ICP
Retention, support and stability:
Most important denture properties, BUT:
If using permanent bases:
We have either already assessed these when we first placed our permanent bases in situ, OR
We cannot assess these if we are using temporary bases
If using permanent bases: retention, support and stability should not be any different than before the tooth setup
If we have reduced retention and stability, tooth positions likely to be wrong > identify the problem and rectify!
Retention and Stability will be affected
Support won’t be affected
Retention
Ensure close fit over the entire tissue surface, assess border extension and border morphology
Support
Ensure close fit over the entire tissue surface
Stability
Assess thickness and morphology of the polished surfaces, adjust by trimming if needed
Aesthetics - Across the room:
Tooth positions
Tooth size
Tooth shade
Aesthetics - ‘Arm’s length’:
Tooth proportions
Tooth shape
Gingival margin level
Tooth arrangement
Aesthetics - ‘Close up’:
Individual tooth colour variation
Difference in colour of adjacent teeth
Characterization
Aesthetics - Outside of the mouth (on bedside table):
Gum staining & stippling
Finishing & polishing
Flaws
Anything the technician may have missed
Speech can be affected by many aspects of the complete denture:
which test is used to confirm upper and lower anteriors are correctly set up?
Denture thickness:
- assess which test there is a problem and make the adjustments (sounds)
- Speech deteriorates in direct proportion to the thickness of the denture in the palate
- Changes of 1 mm in thickness can have a significant impact
- Affects production of vowels, linguoalveolar (t,d,r) and linguopalatal (k,j,g) consonants
Vertical dimension:
- Speech problems with complete dentures often due to INCREASED OVD
- Difficulty pronouncing bilabial (m,p,b) and labiodental (f,v) consonants
-Silverman’s Closest Speaking Space: !!!!!!!!!!!!!!
-it is important as it will give you a confirmation that the upper and lower anteriors are correctly set up
(not the same as free way space. free way space assess b/w mandibular position at rest and the teeth in occlusion, while the silverman’s test assesses when the pt is trying to produce the ‘s’ sound so mandible will be protruted)
=> 2-4 mm distance between upper and lower incisal edges when making ‘s’ sound
=> Not affected by patient’s language!
The antero-posterior position of the incisors
The occlusal plane
The posterior palatal seal area
Width of the dental arch
SOS
Speech & polished surfaces:
If antero-posterior position of the incisors is incorrect, you have difficulty pronouncing which sounds?
-difficulty pronouncing labiodental sounds and ‘s’ sound
Labial angulation also important
Lower anteriors: if set too far lingually, they encroach on tongue space, forcing the tongue to arch itself up to a higher position
The airway is subsequently too small: faulty pronunciation of ‘s’ and ‘z’ sounds
Speech & polished surfaces:
The occlusal plane:
If the upper anteriors are set too superiorly:
If the upper anteriors are set too inferiorly:
Must establish correct antero-posterior position of upper anteriors first
Lower lip can then help to establish the occlusal plane using the labiodental consonants for
phonetic tests
If the upper anteriors are set too superiorly: ‘v’ sounds like ‘f’
If the upper anteriors are set too inferiorly: ‘f’ sounds like ‘v’
SOS
Speech & polished surfaces:
If posterior palatal seal area is positioned incorrectly:
- may affect the vowels ‘I’ and ‘e’
- Also, the velar consonants (k,j,g)
- Increased thickness impedes speech (but also causes gagging)
If lower anterior are set too far lingually:
-teeth encroach on tongue space
-this affects the pronunciation of all consonants where the lateral margins of the tongue make contact with the palatal surfaces of the upper posteriors
‘t’, ‘d’, ‘l’, ‘s’, ‘n’
Aims of the placement appointment:
To ensure all aspects of the CD are correct prior to finish confirm:
Comfort - assess firstly Occlusion - secondly Retention, support & stability Aesthetics Speech Polished surfaces
Aims of the placement appointment:
Comfort:
If we used temporary bases:
If we used permanent bases:
First ensure the fit of the new dentures is comfortable!
If we used TEMPORARY RECORD bases: almost certain ADJUSTMENTS will be required
Extra care: soft tissue undercuts which were blocked out on the master cast!
If we used permanent bases: unlikely that any adjustment is required
Already assessed before the jaw relationship registration and confirmed at the trial insertion
Aims of the placement appointment:
Comfort:
Complete denture fitting surface:
Process:
A) Pressure areas:
Streaks:
B) When we find areas presenting lack of contact with the supporting tissues, does that this mean our denture is not fitting well and should be remade?
-PMMA ‘pearls’, spicules and imperfections
-Use a gauze square and/or finger pressure to identify areas to correct (sharp areas)
-Inspect, manipulate and correct before placement
-Use a knife or tungsten carbide or polishing rubber at very low RPMs
-Take care not to alter the morphology of the fitting surface
-Use Pressure Indicating Paste (PIP) for pressure spots / sore areas
-Polysiloxane and zinc oxide based
-Comes off easily using the included PIP remover solution or Orange Solvent and is pretty much
impossible to completely remove in any other way!
-Apply a thin layer of paste throughout the entire fitting surface, forming streaks facing the same direction with the brush provided (you should see a little denture through it but have enough material)
-Assess each denture separately
-Press hard towards the tissues in the first molar region b/c we want to apply even pressure throughout
A) -Pressure areas: paste is very thin
-Streaks: no contact with the tissues!
B) -Adjust pressure areas carefully using a Tungsten -Carbide trim (trim less (with the paste there) to avoid over trimming - in low speed)
- Wipe any remaining paste away
- Re-apply paste and try again
- Repeat until there are no pressure areas and no visible streaks!
Aims of the placement appointment:
Complete denture borders: maxilla
Areas of overextension:
Adjust which areas?
- Once the base is fitting well and is comfortable, assess the borders
- Overextension, increased thickness, sharp edges
- Apply PIP incrementally
- Place each denture in the mouth, taking care not to wipe off the paste on the lip or cheek
- Hold it firmly in place
- Border mould and instruct the patient to make functional movements (suck on your finger)
-Examine carefully relief areas for the frenae
- ADJUST ONLY the areas WHERE there is NO PASTE
- Be very careful not to overtrim as there is a risk of losing the border seal
- Assess the width of the frenum attachment and only adjust accordingly
-Areas of overextension: will show through the PIP
-Assess the posterior buccal surfaces of the denture for interference with the coronoid process
-Apply paste over the border to the polished surfaces
Instruct the patient to make lateral movements with the mouth open
-Move the dentures to check where there’s pressure applied while your finger is on B side of M1/M2 in mouth
-Excessive thickness or overextension in this area will cause ulceration or displacement of the denture
-Make sure to extend the paste beyond the border onto the polished surfaces!
How to assess the posterior border for interference with the pterygomandibular raphe?
Instruct the patient to open wide
Aims of the placement appointment:
Complete denture borders: mandible
Carefully examine the:
lingual frenum area
buccal border extension
lingual border extension
mylohyoid ridge
Aims of the placement appointment:
Complete denture borders: mandible:
To assess buccal border extension:
To assess lingual border extension:
- Same technique
- To assess buccal border extension instruct the patient to bite with both dentures in situ
- To assess lingual border extension hold the denture firmly and instruct the patient to stick the tongue out and lick the upper lip from side to side
Aims of the placement appointment:
Complete denture borders:
mandible:
What happens if there is overextension of the lingual frenum area?
may cause severe ulceration and pain, and displace the mandibular denture in function
How do we know when we are done?
Patient feels comfortable when we apply pressure on the dentures towards the tissues in the first molar regions
The dentures do not get displaced during functional movements or when making border moulding manipulation of the muscles
Pressure Indicating Paste does not show areas of pressure or lack of contact with the tissues
SOS
Any areas we adjust at the borders or polished surfaces must be:
polished again!
Do not polish the fitting surface!
-if small adjustments then in office with rubber band
How is it possible that small magnitude JRR errors may have gone undetected?
good news: small errors
bad news: harder to identify them
- At the JRR appointment the occlusal rims are made of wax which may slightly distort under occlusal load while the record is being made
- At the trial insertion appointment, the teeth are set in wax: small errors, especially in the anteroposterior direction, may be difficult to detect
- At placement: the whole denture is rigid – JRR errors may now suddenly become apparent (either to our trained eyes or to the patient’s sensitive mucosa)!
Why the smaller the magnitude of occlusal errors, the harder it is to detect them clinically?
due to the displaceability of the mucosa
- depends how sensitive this area is
- ex: premature contact: it will sink and crash the mucosa
What is the patient more likely to complain about?
- Loss of retention of the mandibular denture in function
- Pain on the lingual slopes of the mandibular residual alveolar ridge (least supported area)
Clinical remount of the mandibular denture (‘check record’):
a) If the occlusion is correct with the clinical remount of the mandibular denture (‘check record’):
- Best practice
- We record a new maxillomandibular relationship record with the mandible in the most posterior path of closure (guide into retruded position)
BUT:
We do not allow the teeth to come in contact (pre-contact record)
Try to keep the separation of the teeth to a minimum!
Raise the pin on the articulator (to make up for the thickness of our record)
Remount the mandibular cast on the articulator
Remove the recording material
Reset the incisal pin to 0, then allow the upper arm of the articulator to close
- If there are occlusal errors, once we reset the incisal pin to 0 and allow the upper member of the articulator to close, the pin will stop short of making contact with the incisal guide table!
a) the dentures will come into maximum interdigitation and the pin will come in contact with the incisal guide table of the lower member of the articulator
Premature contacts:
what do they cause?
how to identify them?
how are they solved?
- prevent the dentures from interdigitating fully
- use articulating paper to identify them
- carry out adjustments until the pin can come into contact with the incisal guide table !!!!!!
Aesthetics - May have to adjust:
Labial flange thickness
Mandibular posterior buccal border extension
Any flaws on visible pink acrylic
Reduce height of anteriors
Make incisal edges more symmetrical
Reduce sharpness of incisal angles
Reduce sharpness or height of canine tips and premolar buccal cusps
Speech - May have to adjust:
Thickness of the polished surfaces, especially on the hard palate
Maxillary posterior border thickness and extension
If there is insufficient freeway space (increased OVD): the closest speaking space will be insufficient as well
Ensure the JRR is correct first; return to the articulator and readjust the occlusion in ICP to decrease the OVD: may gain about 1 mm
Will have to check for any anterior contacts introduced because of our adjustments and adjust again protrusive and lateral movements as well!
If the vertical error is significant: may have to reset the teeth on one or both arches!
Yes, this is as soul-crushing as it sounds!!!
Excessive thickness from Polishing corrected by:
Trim with tungsten carbide bur
Smooth and polish with rubber polishers
If extensive adjustments are made: best to return to the lab for proper smoothing and polishing!
Indications for Complete Dentures:
- A full arch of missing teeth
- Dental implants that have been deemed inappropriate by patient and/or doctor because of financial constraints, a medically compromised status that contraindicates surgery, or inevitable damage to vital structures such as maxillary sinuses, nerves, and vessels
- Intraoral cancer that has caused a loss of gross intraoral tissue, resulting in an edentulous dental arch
Contraindications to Complete Dentures:
- Patient does not desire to have a removable appliance to replace missing teeth
- Patient has an allergy to the acrylic used in the fabrication of the complete denture
- Patient has a severe gag reflex (although this could be controlled with gag reflex desensitization)
- Patient has severely resorbed dental alveolar ridges, which would compromise retention with a complete denture alone
SOS
Support mechanism for complete dentures:
- maxilla: half
- mandible: 1/4
- when the teeth are lost the overall area available for supporting the denture, compared to the overall area covered by the PDL is diminished
Case history: Focus on:
Cause of tooth loss Timing of tooth loss Denture wearing experience so far Medications which may cause xerostomia Oral mucosa conditions, e.g. lichen planus
Previous dentures:
extra oral assessment:
intra oral assessment:
extra oral assessment:
- Presenting condition: level of hygiene, defects, tooth wear
- Overall size, thickness, shape and symmetry
- Border extension and shape
- Previous repairs, modifications, additions etc
intra oral assessment:
- Support, stability, retention
- Occlusion, protrusion and lateral excursions
- Level and orientation of the occlusal plane, occlusal vertical dimension
- Border extension and shape
- Aesthetics, anterior tooth setup, midline
- Speech
Modifications of existing dentures:
Occlusal adjustments Temporary soft liners and tissue conditioners Tooth additions or replacement Flange extension Fracture repairs
Modifications to existing dentures may be carried out for functional or diagnostic purposes, or as the main treatment
Most common: to enable function until the new dentures are finished
Retained roots and impacted teeth:
- Surgical removal
- They cause problems if they cannot be used as overdenture abutments
- Following extraction, sufficient time should be allowed for healing of soft and hard tissues
- Impacted teeth may start erupting soon after dentures are placed
- Collaboration with Orthodontics may be considered
- If the impaction is deep there is less risk of eruption
- Impacted teeth in the mandible: risk of iatrogenic fracture of the jaw
Pre-prosthetic surgeries to improve denture foundation:
Frenectomy - most common Vestibuloplasty Soft tissue reduction - for knife edge alveolar ridges Bony exostoses Unfavourable bone morphology
If there are only few remaining teeth Vs several teeth - treatment options:
If there are only few remaining teeth:
patient likely to have a RPD
Simplest approach to add teeth to the RPD and use as interim prosthesis
Further modification might be required, e.g. border extension
Patient must be agreeable to having RPD sent to the lab for few days
Some patients might even choose to keep using existing RPD as is!
Alternatively, new immediate complete denture is finished before the extractions and placed at same appointment
Following healing completion, reline or replacement denture will be required
If there are several remaining teeth:
Treatment approach depends on their location (anterior/posterior) and patient preference
Best approach is staged: posterior tooth extractions are carried out as early as possible, some time is allowed for healing before procedures are carried out to fabricate immediate denture
Immediate denture is placed at the same appointment as anterior tooth extractions
-If not agreeable by the patient, ridge reduction and bone reshaping likely to be required to allow placement of the immediate denture
Very few patients might agree to full clearance without immediate dentures
Many clinical advantages but loss of OVD renders definitive restoration more challenging
Mouth preparation may include fabrication of radiographic guide / copy denture, soft tissue surgery, bone preservation procedures, etc.
Remember: not every missing tooth needs to be replaced!!!
SOS
Problems with the artificial teeth: cheek, lip & tongue biting:
Cheek biting:
Maxillary posterior teeth set up too palatally or in reverse occlusal relationship
Insufficient soft tissue support by the posterior flange/polished surfaces/teeth
Lip biting: Maxillary anteriors set up too palatally (leads to increased OVD) Insufficient overjet Insufficient lip support May also observe reduced OVD
Tongue biting:
Occlusal plane set too low
Posterior teeth set up too lingually
Errors related to the occlusal plane level and orientation, midline position, tooth positions, amount of teeth showing, tooth mould, size and shade, may all result to aesthetic problems
Often related to speech and mastication problems
Also related to lack of stability, particularly errors in the occlusal plane level and tooth positions
Problems with the polished surfaces:
Most common:
Other common problem:
Most common: speech problems and/or gagging due to excessive thickness, non anatomical morphology palatally and/or swallowing due to excessive thickness lingually on the posterior mandible
Other common problem: food particles sticking on the denture
This is due to poor morphology and/or insufficient thickness
Beware: may also be observed in xerostomia!
CD procedure in order:
- primary impression
- custom impression trays
- border moulding
- secondary impression
- temporary/record bases AND/OR permanent bases
- vertical dimension
- jaw relationship registration (transfers the exact maxilla to mandible relationship on the articulator)
- facebow record (to go straight to the articulator to mount the maxillary cast)
- tooth set up (to restore natural OCCLUSION)
- polishing
- trial insertion (aesthetic results seen by the patient)
- delivery
We extend the maxillary denture:
just beyond the hard palate, before becoming soft palate
- every time the soft palate raises up during speech you are breaking the seal
- you check if the mark we did on the palate is moving
How much space do we need to allow between the maximum sulcus depth and the border of our custom tray prior to border moulding?
1,5 mm
Relief areas of maxilla:
Relief areas of mandible:
Relief areas of maxilla: incisive papilla fovea palatini labial and buccal frenum genial tubercle
Relief areas of mandible:
mental foramen
labial and buccal frenum
mylohyoid ridge
What stuff do we use to determine the OVD?
wax rim and record base
-> determined by the free way space when in centric relation
SOS
What is the most reliable clinical indication that the vertical dimension of occlusion is correct or not? / With wax rims or previous dentures the most important clinical indication for a good OVD is:
the appearance (of the lip)
-most reliable
SOS
And what is the most reliable test to confirm that the vertical dimension of occlusion is correct after we make any adjustments?
phonetics test (to ensure the V dimension is cut correctly)
- swallowing as well but it has more to do with the extension
- NOT the free way space
When you apply the bite registration material for the JRR why do you need to stop the patient from closing the mouth completely?
to avoid compression of the tissues which might affect the accuracy of the registration and to prevent sliding of the mandible
Why is it important to hold the mandibular denture in situ when carrying out the jaw relationship registration?
to keep the denture stable
Why is it advisable to make 2 jaw relationship records for the check record procedure?
to be used as a check later
What is the purpose of the check record?
accurate method of verifying the occlusion of CD
The lingual extension of a lower CD is limited by:
- sublinual salivary gland
- modiolus
- mylohyoid muscle
- genioglossus muscle
sublinual salivary gland
mylohyoid muscle
genioglossus muscle
occlusal rims for CD provide the following info when trimmed
- centric jaw relationship
- dimension of freeway space
- overjet or horizontal incisor overlap
- orientation of occlusal plane
- centric jaw relationship
- overjet or horizontal incisor overlap
- orientation of occlusal plane
The ala-tragal line is:
a. line running from tragus to nose to the ala of the ear
b. parallel to the Frankfort plane
c. a guide to occluding face height in CD
d. a guide to the orientation of occlusal plane in CD
d. a guide to the orientation of occlusal plane in CD
b. is not correct, it forms a 15 degrees angle with that plane
c. is not correct b/c OVD is independent to the ala tragal line
The collection of info for use in denture tooth selection begins:
a) during contouring and marking of the occlusion rims
b) at the aesthetic try-in appointment
c) with the introduction of the dentist and patient
d) after the casts have been mounted on the articulator
c) with the introduction of the dentist and patient
Sources of info for anterior tooth mold selection include:
a) patient photographs
b) diagnostic casts of the patient’s natural dentition
c) existing dentures
d) record bases and occlusion rims
e) all of the above
e) all of the above
The high smile line scribed into the wax of the maxillary occlusion rim usually indicates the minimum incisogingival height of the maxillary anterior teeth to avoid a “gummy” smile
a) true
b) false
a) true
The selection of molds for denture teeth is the responsibility of the:
a) dental assistant
b) patient
c) dentist
d) laboratory technician
c) dentist
Recently extracted teeth may be unreliable sources of shade info due to the effects of drying or storage in disinfectant solutions
a) true
b) false
a) true
The overall mesiodistal width of the mandibular posterior teeth is governed by the amount of space available from the distal end of the canine tooth to the beginning of the slope to the retromolar pad
a) true
b) false
a) true
The most important source of shade information is the:
a) tooth manufacturer
b) dentist
c) patient
d) photograph
c) patient
Maxillary tori may present more of a problem for a CD patient if it extends past the vibrating line where the posterior palatal seal is usually placed.
- true
- false
- true
Which is the main cause of complication arising in prosthodontic treatment?
a) Human error
b) Impression materials
a) Human error -it’s your fault, either treatment planning, diagnosis or clinical stages
- Impression materials -these are very accurate
Which of the following is more likely to increase the residual ridge resorption?
- Do nothing
- Implants
- Denture
- Bridge
•Denture -if it’s a mucosa supported
The interarch distance measured when the occlusal rims are in uniform contact is: A. Freeway Space B. Vertical dimension of occlusion C. Vertical dimension of rest D. Christensen's space
B. Vertical dimension of occlusion
Fovea palatine are:
A. Structures through which blood supply takes place
B. Mucosal salivary glands
C. Palatal termination of maxillary denture
D. Found in every individual
B. Mucosal salivary glands
Mandibular complete denture should cover retromolar pad because:
A. More surface area gives better retention
B. Provides border seal
C. Resists movement of denture base
D. All of the above
D. All of the above
Vibrating line is on the :
A. Hard palate
B. Junction of the hard palate and soft palate
C. On soft palate
D. At the junction of the muscularis uvulae and palatine muscle
C. On soft palate
Why is support important?
- To avoid damage to the mucosa
- To avoid damage to the abutment teeth
- To avoid excess residual ridge resorption
- All of the above
•All of the above
To increase the stability of the lower denture:
A. The occlusal plane should be below the tongue
B. The occlusal plane should be above the tongue
C. The lingual flanges should be concave
A. The occlusal plane should be below the tongue
Instructing the patient to say "AH" with short vigorous bursts will help in visualizing : A. Soft palate B. Posterior vibrating line C. Anterior vibrating line D. Junction of soft and hard palate
C. Anterior vibrating line
Fovea palatine are situated in: A. Hard palate B. Soft palate C. At the junction of hard and soft palate D. Their position is not fixed
B. Soft palate
An example of a thermoplastic impression material is:
a. Plaster
b. Compound
c. Zinc oxide eugenol
d. Acrylic resin
d. Acrylic resin
Overextension of the posterior border of the denture causes: A. Gagging sensation B. Epulis fissuration C. Sagging of the corners of the mouth D. All of the above
A. Gagging sensation
Posterior palatal seal is present on: A. Hard palate B. Rugae area C. Movable soft palate D. Immovable soft palate
D. Immovable soft palate
How do we determine the posterior palatal border extension clinically?/ The function of the posterior palatal seal is:
A. To aid in balanced occlusion
B. To aid in insertion and removal of complete denture
C. To ensure a complete seal thus helping in retention of a denture
D. Retention of mandibular denture by sealing its posterior margin
C. To ensure a complete seal thus helping in retention of a denture
A 30 year old male with all upper teeth missing comes to the prosthodontic department, his main concern is esthetic and function, best esthetic for maxillary denture is achieved when:
a. Teeth are placed facial to the alveolar ridge
b. Teeth are placed at crest of the alveolar ridge
c. Teeth are placed lingual to the alveolar ridge
d. none of the above
a.Teeth are placed facial to the alveolar ridge
The coronoid process:
A. Limits the extension of maxillary posterior teeth setting
B. Limits the thickness of the distobuccal flange of the upper complete denture
C. Limits the thickness of the distobuccal flange of the lower complete denture
D. Determines Posterior palatal seal
B. Limits the thickness of the distobuccal flange of the upper complete denture
What interferes with maxillary denture in posterior vestibular fold:
A.Coronoid process
B.Condyle
C.Masseter muscle
A.Coronoid process
Resting face height in edentulous patients:
A. Decreases when head is tilted back
B. Increases when lower denture is inserted in the mouth
C. Does not change over time/ remains constant throughout the whole life
D. Is equal to the occluding face height together with the interocclusal clearance
B. Increases when lower denture is inserted in the mouth
The posterior palatal seal area must be visualized when trimming the tray
a. TRUE
b. FALSE
a. TRUE
Immediate dentures cannot be accessed for esthetic results prior to the insertion appointment
a. TRUE
b. FALSE
a. TRUE
Pt. wears complete denture for 10 years & now he has cancer in the floor of the mouth what is the first question the dentist should ask:
- Is your denture ill fitted
- Smoking
- Alcohol
- Does your denture impinge the mucosa
- Is your denture ill fitted
The distal palatal termination of the maxillary complete denture base is dictated by the:
- Tuberosity
- Fovea palatine
- Maxillary tori
- Vibrating line
- Posterior palatal seal
- Vibrating line
By increasing the vertical dimensions of occlusion all will result except:
- Improper aesthetics
- Trauma to TMJ
- Trauma to muscles
- Irritation at the corners of the lips
- Irritation at the corners of the lips
Which of the following area is not a relief area?
- Labial and buccal frenum
- Buccal shelf area
- Mylohyoid ridge
- Mental foramen
- Buccal shelf area
An articulator is an instrument which simulates the movements of the:
A. maxilla.
B. mandible.
C. mandible and the maxilla.
D. glenoid fossa.
B. mandible.
SOS
Papillary hyperplasia on the palate of a patient wearing a maxillary complete denture is most likely to be associated with:
A. occlusion with posterior natural teeth.
B. heavy smoking.
C. a sensitivity to the acrylic resin.
D. an ill-fitting denture and poor oral hygiene.
D. an ill-fitting denture and poor oral hygiene.
What is characteristic of a transitional immediate complete denture?
A. The denture can be relined once healing is complete.
B. The denture can be placed in the mouth after healing is complete.
C. The denture is temporary and is replaced after healing is complete.
D. The denture can be kept as a long-term prosthesis.
C. The denture is temporary and is replaced after healing is complete.
All of the following statements about denture stomatitis are true EXCEPT:
A. It is usually not associated with a sore mouth
B. It is usually associated with wearing a denture at night
C. It is more common in diabetics
D. It is more common in men
D. It is more common in men
SOS
In a denture wearing patient, there is:
A. no bone resorption
B. bone formation
C. Independent of denture, there is bone resorption
D. Initial bone resorption followed by bone formation
C. Independent of denture, there is bone resorption
SOS
Oral examination of an edentulous patient should include digital palpation. Why?
A. The arch form is more accurately evaluated
B. Undercut areas may be better evaluated
C. The ridge relationship may be better evaluated
D. None of the above
B. Undercut areas may be better evaluated
Which of the following is a major disadvantage to immediate complete denture therapy:
A. Trauma to extraction site
B. Increased the potential of infection
C. Impossibility for anterior try in
D. Excessive resorption of residual ridge
C. Impossibility for anterior try in
The patient complains of looseness of dentures within two hours of insertion. The most likely cause is:
A. Psychological
B. Adaptive unresponsiveness
C. Deflective occlusion
D. Unretentive denture
C. Deflective occlusion
When repairing a fracture of lower complete denture. Which statement is correct:
A. Self curing will distort the denture
B. Cold curing will not be strong enough because of small area of attachment
C. There is a possibility of occlusal disharmony
C. There is a possibility of occlusal disharmony
Which of these muscles may affect the borders of mandibular complete denture:
A. Mentalis B. Lateral pterygoid C. Orbicularis oris D. Levator angulioris E. Temporal
A. Mentalis
All are consequences of edentulism except:
A. Prognathic appearance
B. Thinning of lips
C. Decreased length of lip
D. Increase in columella phhiltrum angle
C. Decreased length of lip
Freeway space is defined as:
A. Vertical dimension at rest
B. Vertical dimension at occlusion + vertical dimension at rest
C. vertical dimension at rest - vertical dimension at occlusion
D. Vertical dimension at occlusion - vertical dimension at rest
C. vertical dimension at rest - vertical dimension at occlusion
Increased OVD results in:
A. Strained facial appearance
B. Trauma to underlying tissues
C. Clicking of teeth
D. All of the above
D. All of the above
The purpose of plane of orientation is:
A. To serve as a guide in establishing occlusal plane
B. To aid in measuring height and length of posterior teeth
C. To serve as an arbitrary plane when established on the articulator
D. To divide the distance between upper and lower cast equally
A. To serve as a guide in establishing occlusal plane
The occlusal plane for the complete denture patient is determined by:
A. The facebow device which determines the occlusal plane
B. The position of the upper first molar
C. The height of the retromolar pad and anterior aesthetic height
D. The curve of Spee and the anterior aesthetics
C. The height of the retromolar pad and anterior aesthetic height
???
Hinge axis face bow records:
A. relationship of teeth to the axis of rotation of jaw
B. relationship of maxilla to mandible
C. relationship of mandible to cranium
D. All of the above
A. relationship of teeth to the axis of rotation of jaw
If the interocclusal distance is increased beyond physiologic limits, the patient’s chief complaint may result from:
A. a muscular imbalance
B. an occlusal disharmony in centric
C. a displacement of the mandibular denture
D. a displacement of the maxillary denture while yawning
A. a muscular imbalance
A CD patient has difficulty in swallowing because of:
A. Decreased vertical dimension
B. Increased vertical dimension
C. Thickness of flange
D. Decreased retention
B. Increased vertical dimension (with resulting decrease in interocclusal distance)
+ Over extended lingual flange in retromylohyoid region
In making a final impression for a CD, the most important area of the impression is:
A. Ridge area of maxilla and buccal shelf of mandible
B. Lingual border area of mandible
C. Junction of hard and soft palate of maxilla and distolingual area of mandible
D. Mid palatal area of maxilla and ridge of the mandible
C. Junction of hard and soft palate of maxilla and distolingual area of mandible
The stability of a mandibular CD will be enhanced when:
A. the level of occlusal plane is above the dorsum of the tongue
B. the tongue rests on the occlusal surface
C. the lingual contour of the denture is concave
D. the posterior teeth on the denture have a broad buccolingual width
B. the tongue rests on the occlusal surface
The primary stress bearing area of maxillary complete denture is:
A. Alveolar ridge
B. Buccal flange
C. Palate
D. Posterior palatal seal area
A. Alveolar ridge
The primary stress bearing area of mandibular complete denture is:
A. Buccal shelf
B. Crest of the ridge
C. Retromolar pad
D. Lingual flange
A. Buccal shelf
Retromolar pad:
A. Should not be covered by lower denture
B. Should be covered by lower denture
C. Has tendon of temporal muscle attached to it
D. Disappears on eruption of mandibular last molars
B. Should be covered by lower denture
The main purpose of covering the Retromolar pad area is:
A. Stability
B. Retention
C. Support
D. Contraction
B. Retention
An important factor that aids in stability of complete denture is:
A. Harmonious occlusion
B. Proper extension of denture bases
C. Polishing of denture bases
D. None of the above
A. Harmonious occlusion
If a complete denture patient has genial tubercle at the level of the crest of mandibular ridge, the denture base:
A. can cover them
B. should not cover them
C. should cover them and relief is a must
D. should cover them but relief is not necessary
C. should cover them and relief is a must
The masseteric notch in distobuccal corners of the mandibular denture is due to:
A. action of buccinator on masseter
B. action of masseter on buccinator
C. action of palatoglossus on buccinator
D. action of superior constrictor on masseter
B. action of masseter on buccinator
Buccal shelf is a stress bearing area because:
j. It has cortical bone.
k. Buccinator fibers are parallel.
l. Mucosa is keratinized to the occlusal load.
m. All of the above.
k.Buccinator fibers are parallel.
The hamular notch is important in full dentures construction because it aids in the setting position of the artificial teeth
A.First statement is true, but the reason given is false
