ACS Flashcards
1
Q
What are the different occlusal schemes (4)
A
Ideal occlusion - three contacts between mandible and maxilla when you move out of ICP
Group function
Gnathological occlusion - restoration made so each cusp tip intercuspates with its opposing fossa
Balanced occlusion
2
Q
What is ideal occlusion (3)
A
Load distributed in most favourable way
Workable and replicable occlusion scheme
Simple to apply principles (RCP=ICP, forces distributed through long axis of teeth, posterior disclusion in eccentric position, mutual protection)
3
Q
What teeth contact when RCP = ICP
A
Posterior teeth contact, anterior teeth have very light contacts
4
Q
When RCP = ICP explain load and condyle position
A
Occlusal load must be directed through long axis of the tooth
Condyles are positioned to distribute load into the bone with minimal muscular involvement
5
Q
If RCP doesn’t = ICP
A
Functioning in ICP requires muscular activity to position the condyle and intra articular disc
Can cause bruxism - function on the RCP contacts causing damage to vulnerable restorations and wear facets on sound teeth
Can also grind in/from ICP - will cause wear on anterior teeth then premolars due to increased muscular activity
6
Q
How to minimise large loads by RCP contacts (4)
A
Know if and where the RCP contacts are
Tough restorations
Provide multiple contacts in RCP to spread out the load
Minimise difference between RCP and ICP
7
Q
How to distribute forces in ideal occlusion and why
A
Distributes occlusal loads favourably
Contacts on inclines result in horizontal forces, which leads to wear, tooth movement, bone loss, fracture of restorations
8
Q
When would you want posterior discclusion
A
Lateral and protrusive excursion (eccentric positions) In this case, the anterior teeth discclude the posterior teeth
9
Q
Benefit of posterior discclusion
A
Avoids lateral forces on posterior teeth Simple to engineer - often just one tooth contact in eccentric positions
10
Q
What occurs if posterior contacts do occur
A
Working side - group function
Non working side - NWS interference (undesirable)
Protrusion - protrusive interference (undesirable)
11
Q
Anterior guidance (2)
A
Palatal surfaces of upper anterior teeth dictate the movement Interference would occur on mesial of lower and distal of upper teeth
Mutual protection occurs - in ICP posterior protect the anterior from large forces, in excursions the anterior protect posterior
12
Q
Canine guidance (3)
A
Canine morphology makes it an ideal tooth - Root of canine is longer than crown making it stronger
Distant from hinge and muscle
Highly innervated
13
Q
Group function
A
Multiple contacts on working side
14
Q
Class 1 incisor relationship
A
Lower incisors occludes behind the upper incisors cingulum plateau
15
Q
Class 2 incisor relationship
A
Div 1 - Lower incisor occludes behind the upper incisor cingulum plateau (may or may not be proclined)
Div 2 - Lower incisor occludes behind the upper incisor cingulum plateau, upper central incisors are retroclined
16
Q
Class 3 incisor relationship
A
Lower incisors occludes in front of the upper incisor cingulum plateau
17
Q
Anterior open bite
A
No contact on anterior teeth
18
Q
Occlusion in practice (3)
A
Know where tooth contacts are pre and post operatively
If conforming, don’t introduce unfavourable contacts
If reorganising, work to ideal occlusion
19
Q
If the tooth has to be restored in all situations…
A
No ICP contacts - consider whether the tooth would be better with an ICP contact or not
Contact on the incline of a cusp - reintroduce the contact or recreate ideal occlusion
A non working side interference - consider whether reintroducing contact once restored would be ideal?
An RCP contact
20
Q
What is the movement of the mandible dictated by (3) What can the movement be traced by
A
Position of the condyle in the fossa
Condylar pathway along the articular eminence
Teeth interfere with this border movement
Traced by Gothic arch Tracing
21
Q
Centric relation
A
Relation of the mandible to the maxilla when the condyles are seated in the uppermost, anterior most position in the glenoid fossa
Only position the mandible can rotate about a hinge without using lateral pterygoid muscles
Neuromuscular system can function optimally
Repeatable
22
Q
Why study occlusion (9)
A
Failure of routine restoration
Fractured teeth and restorations
Overeruptions
Fractured crowns
Worn teeth
Complex restorative tx
Localised periodontitis effects
Loss of tooth vitality
23
Q
ICP
A
Intercuspal position - position of mandible when there is maximum intercuspation of the teeth
24
Q
RCP
A
Retruded contact position - first contact when the condyles are fully seated in the glenoid fossa
25
RCP vs ICP
They do not usually coincide - close to RCP and slide to ICP
High cusps = vertical slide
Shallow cusps = horizontal slide
26
Terminal hinge axis
Condyles hinge about a horizontal axis when it is in CR
Lateral pterygoids can relax, NOT required to brace against closing muscles
27
How to find CR
Denture patients - ask to put tongue to back of the mouth and close slowly
Crowns/Bridgework - Dawson technique - easily learned, consistently repeatable, allows verification of position (firmly stabilise the head, position fingers on the lower border of mandible, thumbs of the symphysis, no pressure at this stage, next with a gentle touch manipulate so that jaw hinges slowly open and close freely, then gently but firmly guide condyles upward with little fingers, apply gentle posterior pressure with thumbs)
28
Recording CR
Used for patients difficult to manipulate
Anterior jig is a flat anterior stop which separates posterior teeth, allowing elevator muscles to seat condyles
Because teeth are separated for a while, patient falls into neuromuscular dissociation
Record using wax or silicone
29
When is CR useful in restorative dentistry (5)
Routine restorations
Occlusal reorganisation
Diagnosis of TMJ dysfunction
Occlusal analysis and equilibrium
Complete denture construction
30
Functions of articulators (4)
Hold models in ICP - limited, do not mimic opening/lateral movements of the jaw
Anatomical articulator - hinge in the same place as condyle, replicates jaw movements
Mounting models in CR
Correct relationship between teeth and condyle - position models by Bonwill triangle (average relationship OR record relationship with face bow)
31
Average value anatomical articulator (3)
30 degrees condylar angle
Straight condylar pathway
Doesn't replicate the exact movement of the condyle
32
Semi adjustable anatomical articulator (3)
Condylar path can be adjusted between 0 - 60 degrees
Condylar path is flat
Intercondylar width and Bennett movement may also be adjusted on some models to get a better replication of the patient
33
Fully adjustable (3)
Custom made condylar pathways
Mechanically replicate the movements of the condyles
Use a pantograph or stereograph to record the condylar movement
34
What three things to consider when selecting equipment
Occlusal schemes
Objectives of the treatment
Clinicians skills
35
Signs/symptoms showing loss of occlusal harmony (10)
Mandibular dysfunction
Mobility of teeth
Drifting of teeth
Fracture of restorations, cusps, teeth
Facetting of teeth
Fremitus
Parafunction
Loss of tooth vitality
Localised periodontitis
Facial pain
36
Concussion (4)
Injury to supporting tissues
No loosening or displacement or mobility
Tender to pressure
May be bleeding at gingival margin
37
Subluxation (4)
Injury to tooth supporting tissues with abnormal loosening
Slight mobility
Bleeding around gingivae
No displacement
38
Lateral luxation (4)
Bodily movement of the tooth within the socket
Root moves buccally and becomes wedged by bone - so not mobile
Rupture of neuromuscular bundle
Tearing and crushing of PDL cells in the palatal cervical region - tearing is repairable but not crushing
39
Extrusion (4)
Axial displacement partially out of the socket
Very mobile
Appears elongated
DONT USE HIGH SPEED SUCTION NEAR THESE TEETH
40
Intrusion (4)
Tooth forced upwards into the socket - difficult to tell in developing dentition as the teeth may be PE
Complex and severe injury
Crushing of PDL cells and neuromuscular bundles (non reversible)
If apices are closed, the tooth will not survive
41
Avulsion (3)
Tooth completely lost in the socket
Ischaemic injury to the pulp
PDL cell death
42
Prognosis of pulp depends on (3)
Type of injury - more serious = less likely to recover
Age of the patient and the stage of the apical development - open apex = room for blood supply to redevelop
Concomitant injury - fracture of the crown (another injury = another bacteria pathway)
43
Three ways of pulpal healing
Complete healing
Pulp canal obliteration
Pulp necrosis
44
What is complete healing in terms of pulpal healing
If the tooth is immature, complete healing means that the tooth will be able to develop normally
45
What is pulp canal obliteration in terms of pulpal healing
Pulp lays down secondary dentine leading to pulp canal obliteration
This is a sign of healing so does not need RCT
As time passes, root canal becomes thinner
Very few teeth become non vital after this stage
Tooth becomes yellower thus may need bleaching
46
What is pulp necrosis in terms of plural healing
Inflammatory response
Pulp is dead, bacteria thus leads into the PA space
This initiates an immune response - the cells also begin to destroy the tooth as well
Only way to stop this destruction is by removing the pulp and applying calcium hydroxide - this will allow PDL cells to heal
47
Types of resorption (3)
Inflammatory
Replacement
Internal
48
External inflammatory resorption
Continuation of surface resorption due to toxins from the necrotic pulp
It is progressive until the bacteria is removed (pulp extirpation)
It will be filled in with cementum or bone upon healing
Moth eaten appearance
49
Internal inflammatory resorption
Infrequent complication, necrotic pulp, ballooning/widening of canal, rapid progression, requires immediate extirpation and calcium hydroxide dressing, filled with thermoplastic GP
50
Replacement resorption
When root is replaced by bone
Usually from intrusion/extrusion
Extensive PDL damage - so cells can't close the gap fast enough
Osteoclasts are in direct contact with the dentine, so the osteoclasts treat the dentine as bone and break it down
Not much can be done to stop this
Normal bone turnover process leads to progressive replacement resorption
51
General advice/management after trauma (5)
Soft diet for 7 days - help PDL heal
Analgesics as necessary - paracetamol, ibuprofen
Good oral hygiene - inflamed gingivae slow down healing
Chlorhexidine mouthwash or gel - rub onto affected area
Review splint at 48hrs
52
Treatment for concussion
No treatment required
Monitor at 4 weeks, 6-8 weeks and 1 year
53
Treatment for subluxation
Flexible splint placed for up to 2 weeks
Monitor at 4 weeks, 6-8 weeks and 1 year
54
Treatment for extrusion
Reposition by gently repositioning - LA may be needed
Avoid high speed suction
Flexible splint for 2 weeks
Monitor at 2 weeks, 4 weeks, 6-8 weeks, 6 months, 1 year and yearly for 5 years
55
Treatment for lateral luxation
Reposition, disengaging tooth from any bony lock - with LA
Flexible splint for 4 weeks
Monitor at 2 weeks, 4 weeks, 6-8 weeks, 6 months, 1 year and yearly for 5 years
56
Treatment for intrusion
Leave - allow spontaneous eruption
Orthodontically extrude
Surgically extrude
57
Treatment for avulsion
Telephone advice - find tooth, hold tooth by crown, if dirty rinse with cold water for 10 seconds, put it in cold not flavoured milk or patients saliva
Replace tooth - place tooth in socket, get child to bite on rolled up tissue to hold in place
Unfavourable healing - occurs if tooth is out of mouth but in milk for over 90 mins, occurs after 30 mins if tooth not in fluid, 90% chance of ankylosis if replanted after this time
Replacement resorption - this occurs when PDL cells die, tooth becomes in contact with bone, causing ankylosis
58
Replant or not?
Consider prognosis, medical status, behavioural aspects, burden of care, child/parent wishes, advantages and disadvantages
59
Advantages of replanting (6)
Aesthetics
Space maintenance
Maintain options
Function
Prevent restorative treatment
Psychological benefit
60
Disadvantages of replanting (4)
Infraocclusion
Loss of gingival contour and bone
Multiple visits
Tooth will be lost eventually
61
Contraindications of replanting (5)
Immunosupression
Caries/periodontal disease
Severe cardiac disease
Children with severe learning difficulties - they might not be able to manage further treatment
Severe incisor crowding, supplement incisor
62
Management of avulsion
REPLANT AS SOON AS POSSIBLE
Store the tooth in saline or milk
Hold tooth at crown not root LA if required
Gently irrigate the socket with saline to remove the clot
If tooth contaminated, clean with debris If stubborn debris, dab with saline soaked gauze (May want to measure the root of the tooth before replanting for RCT WL)
Gently replant, if it doesn't plant, STOP!
Reposition any bony fracture with blunt instruments
Flexible splint for 7 - 14 days
Systemic antibiotics
Etirpate in mature tooth between 0-10days
63
Systemic antibiotic indication for trauma (3)
Contamination
Multiple injured teeth
Medical conditions rendering child susceptible to infection
64
What antibiotics to give with paediatric trauma
Over 12 year olds - doxycycline 200mg twice daily for 1st day, then 100mg twice daily for 10 days
Under 12 year olds - amoxicillin 250mg 3 times a day for 5-7 days
65
RCT on paediatric trauma teeth is....
Mandatory for teeth with mature apex
66
What is the ideal time for RCT of paediatric trauma teeth
0-10 days - before splint is removed so tooth is stable during treatment
If extirpation occurs prior to 7 days, odontopaste should be used instead of calcium hydroxide
Dress with non setting calcium hydroxide for 1 month and definitive obturation at this point
67
Extra oral endodontics
Usually in older patients where growth complete and excessive, there is extra oral dry time, so ankylosis is expected, replant tooth and flexible splint for 7-10 days
68
Types of splints (2)
Direct - aim for physiological splint to encourage healing and reduce risk of ankylosis
Indirect - Essix type retainer
69
How to splint
Reposition the tooth with or without LA
Control bleeding Bend wire into passive arch, extend to one stable tooth either side of mobile teeth and cut to size
Spot etch teeth mid crown and apply composite using dark shade
Place arch wire on uncurled composite, light cure
Place second composite layer over the arch white and light cure
Check no rough pieces of composite and no sharp edges of wire poking out
70
What are enamel infractions
Disruption of the enamel prisms, extends from surface to ADJ, usually seen when light is parallel to long axis of tooth
71
What are enamel fractures
Loss of enamel only, generally requires only smoothing
72
Treatment options for crown-root fracture
Fragment removal and restore tooth - can be difficult if the fragment extends subgingivally
Fragment removal and orthodontic extrusion - when fragment tooth subgingivally
Fragment removal and root burial and supply of removable denture
73
Root fracture healing is dependent on (3)
Approximation of two fragments at the time of injury
Stabilisation
Absence of infection
74
Root fracture healing process
Hard tissue healing/union Interposition of connective tissue
Interposition of bone and connective tissue
Granulation tissue
75
What may occur following root fracture healing (3)
Coronal pulp necrosis
Coronal segment pulp extirpation
Healing
76
Prognosis of root fractured tooth depends on (4)
Concomitant crown fracture
Maturity of tooth
Location of fracture
Degree of displacement
77
What happens in Alveolar fracture and the treatment for it
Fracture of segment, several teeth move as one block, gingival lacerations
Reposition, can be difficult due to bony lock, splint for 4 weeks
78
Uncomplicated enamel dentine fracture
Doesn't involve the pulp
Most common injury
Prognosis almost 100% maintain vitality
79
Emergency treatment for uncomplicated enamel dentine fracture
Ideally composite - flowable is easy and quick If excessive bleeding - RMGIC but not preferred due to leakage (weaker bond)
80
Definitive restorations for uncomplicated enamel dentine fracture
Long bevel before direct resin restoration
Fragment replacement - stick fragment back on
Complete coverage composite build up
81
Complicated enamel dentine fracture
Fracture that involves the pulp
Treatment options depending on extent, time of exposure, developmental stage
82
Treatment options for complicated enamel dentine fracture (3)
Pulp cap
Pulpotomy
Pulpectomy
83
Pulp cap
Pin point exposure, minimal exposure time (less than 24hrs)
84
Pulpotomy
Partial removal of the coronal pulp where there is an incomplete apex
Exposure bigger than pin point
85
How to do a pulpotomy
Amputate pulp to gingival level
Arrest haemorrhage with saline soaked pledget - if not achieved in few minutes, remove more pulp tissue
Place calcium hydroxide onto pulp to stimulate calcium hydroxide
Place setting calcium hydroxide and then restore composite
86
Pulpectomy
Complete removal of coronal and radicular pulp
Carried out on non vital teeth
87
Apexification
Chemically induced hard tissue barrier formation created by the placement of non setting calcium hydroxide dressing to apex
Dressing replaced at 3 month intervals, can take 12 - 18 months
88
Apexification process
Extirpation of pulp - with or without LA
Rubber dam
No mechanical prep required due to wide canal Irrigate with sodium hypochlorite or chlorhexidine
Non setting calcium hydroxide placed with syringe
Small file (25) placed to WL to ensure no air bubbles
Cotton wool placed in access cavity and CaOH compressed to be in contact with apical tissues
Dressed with IRM Replace every 3 months test for barrier with paper points
89
Problems with root fillings (3)
Too short
Deficiencies
Bubbles
90
Disadvantages of calcium hydroxide
Multiple visits
Dehydration of dentine
Cervical root fractures
91
Types of splints (5)
Occlusal splint
Mitchigan splint (upper)
Tanner appliance (lower)
Stabilisation splint
Interocclusal appliance
92
What is an occlusal splint
Removable device made of acrylic resin, which fits between the mandibular and maxillary teeth
93
Indications for splint therapy (5)
TMJ dysfunction and pain
Diagnosis of occlusal disharmony
To establish CR prior to extensive rehabilitation
Severe bruxism
Protection of extensive dental work
94
Goals of the splint therapy (4)
Isolate the contact relations of teeth from masticatory system - keeps teeth apart
Allow condyles to seat in optimal position - stabilise and improve TMJ function
Allow optimum function of neuromuscular system
Protect teeth from attrition and adverse loading
95
Features of occlusal splints (5)
Uniform contact in centric relation
Canine guidance - separate posterior teeth in eccentric excursions
Anterior guidance - separate posterior teeth in protrusion
Full coverage
Create artificial ideal occlusion
96
Clinical stages of splint construction
Visit 1 - Upper and lower alginate imps, jaw reg in CR, facebow
Visit 2 - Fit splint Subsequent visits - review and adjust
97
Soft splints advantages (4)
Sometimes tolerated better by patients
Easily constructed
Cheap
Useful for protection from trauma
98
Soft splints disadvantages (3)
Difficult to adjust
Can encourage bruxism
Research shows muscle pain either did not change or increased
99
What is occlusal adjustment
Occlusion adjusted to remove unwanted/interfering contacts, especially prior to restorative treatment
100
What is occlusal equilibrium
Reorganising the occlusion to give an ideal occlusion by selectively adjusting tooth tissue
101
What is the Dahl concept
Restorations placed in supra occlusion with the intention for the dentition to adapt to the altered occlusal scheme, in order to achieve even occlusal contact in ICP through over eruption/intrusion
102
Indications of Dahl concept (3)
Anterior teeth wear cases - due to loss of vertical tooth height
Teeth to be restored to normal contour by increasing the vertical dimension of selected teeth without necessarily requiring restoration of all teeth
However not an excuse to cement any restoration high where it is not previously planned
103
What do you need when planning a case using Dahl concept (6)
Impressions
Face bow
Occlusal records
Diagnostic wax up
Patient information and consent
Use hard splint to increase vertical dimension and check patient tolerance
104
Practical aspects of Dahl concept
Warn patient regarding functional problems for a number of weeks
Movement often occurs quickly with occlusal contact being achieved in 6-8 weeks - it can take months depending on amount of VD increase
Keep record of occlusal changes and review the patient regularly
Very large increases in VD can usually be tolerated
105
Why we need to restore root filled teeth (3)
Avoid bacterial leakage
Restore coronal structure
Restore aesthetics
106
Why does coronal leakage occur (2)
GP - dentine interface is weak link (GP is thermoplastic causing it to shrink on cooling creating a gap between itself and dentine - this is why a sealer is used)
Sealer gives limited protection
107
Challenges to root filler teeth (7)
Extensive coronal damage
Compromised mechanical integrity of remaining tooth
Reduced capability for stress distribution
Greater potential of bacterial leakage
Damage to periodontal structures
Changes to dentine physical properties
Loss of proprioception from the pulp
108
What materials can be used as intracoronal restorations
Amalgam - requires cusps coverage, not conservative, unaesthetic
Composite - adhesive, unpredictable bond strength to dentine, chemical degradation, adequate for small access cavities
109
Interradicular post considerations (4)
Parallel or tapered
Surface configuration
Active or passive
Design - length, width, ratio, depth, diameter
110
What are the different post systems
Parapost
Composipost
Cosmopost
Radix anker
Kurer
111
How to address failure of root filled teeth (4)
Analysis of cause
Elimination of cause
Prevention of recurrence
Restoration of function and aesthetics
112
How to increase the success of post crowns (5)
Keep to reliable methods
Lateral/vertical condensation with gutta percha and bland root sealer
Leave 3-5mm GP at apical root terminus
Use passive adhesively retained custom post
Use of ferrule
113
What is root surface debridement
Removal of deposits and a thin layer of cementum bound endotoxin from the root surface
114
Limitations of RSD (4)
May not stop progression completely
Deep complex bone defects make it difficult
Severe hyperplasia or tissue defamation
Pathology
115
Aims of periodontal surgery (7)
Gain access to root surface for debridement
Visualisation of bone defects
Improvement in tissue contour
Reduction in pocketing
Encourage regeneration of lost periodontal support
Removal of hyper plastic gingival tissue
Crown lengthening
116
Indications for periodontal surgery (3) and what type of surgery
Hyperplasia, pseudo pocketing = gingivectomy
Deep persistent bleeding pockets = reduced flap
Unsuccessful multiple RSD = apically repositioned flap
117
Considerations before periodontal surgery (6)
Has non surgical therapy tried and reviewed adequately
Is patient suitable - no anticoagulants
Consented by patient
Is it warranted based on pathology
OH compliance
Has restorative strategy been considered
118
How to carry out gingivectomy
LA
PD markings
Incisions with external bevels
Removal of excised tissue to base of the pocket depth
Scaling
Haemostasis
Periodontal dressing
119
Types of sutures (5)
Interrupted
Vertical mattress
Horizontal mattress - long wounds
Sling - when one side needs to be raised higher
Continuous - if multiple teeth have been under surgery
120
Post op care for periodontal surgery (6)
Analgesia
Suture removal at 7-10days
CHX MW 2 x day 2-3 weeks
No mechanical cleaning
Soft toothbrush after 3 weeks
Fortnightly dental visits
121
Signs of periodontal surgery success (8)
Decrease in inflammation
Less bleeding on probing
Decrease in pocket depth
Increase in attachment
Eliminate pus
No increase in mobility
Improvement in tissue contour
Stabilisation of bone levels
122
Options for missing teeth (4)
Do nothing
RPD
Bridges
Implants
123
Design criteria for bridgework (5)
Periodontal support
Occlusal loading
Conservation of tooth tissue
Cleansability
Appearance
124
Retention for bridges (2)
Full coverage crowns
Adhesive retainers
125
Types of abutments for bridges (2)
Fixed fixed - two abutments
Cantilevered - one abutment only
126
Factors to consider about abutments for bridges (4)
Tooth position
Crown shape
Restorative status
Endodontic status
127
What are typically poor abutments for bridges (3)
Maxillary lateral incisors
Tilted incisors
Root filled
128
Factors to consider with complete dentures (4)
Denture security (retention and stability)
Adhesives
Neutral zone
Pre contact check record
129
What is denture security
A fuunction of stability and retention
Patients main concern
Considers the three surfaces (polished, occlusal, fitting)
130
What is denture retention
Retention is the resistance of displacement in an axial direction
131
How is complete denture retention improved (2)
Cohesion between denture and oral mucsosa
Peripheral seal
132
How is RPD retention improved (2)
Cohesion between denture and oral mucosa
Tooth undercut
133
Why can RPDs not rely on peripheral seal for retention
Seal broken by the remaining teeth
134
How is complete denture retention compromised (3)
Poor denture adaptation
Unfavourable supporting anatomy
Dry mouth
135
What is denture stability
The ability to resist forces attempting to displace denture in directions other than at right andgles to the supporting tissue
136
What is denture stability dependent on
Size and shape of ridge - atrophic? torus palatinus bulbous ridge?
137
To increase denture stability, what do you need to take in to account
Periphery - muscle insertions (border moulding)
Occlusal surface - balanced occlusion and articulation
Polished surface - concave surfaces to allow muscles to stabilise denture, removal of undercut on lingual
138
Denture stability is compromised by
Uneven or unfavourable occlusal contacts
Lever arm forces that cause tipping effect
139
Lack of denture stability is caused by
Poor design of occlusal patterns
Retained teeth causing no peripheral seal
140
What are the aims of denture adhesives (4)
Help retain denture
Enable effective function
Avoid social embarrassment
Achieved with minimal inconvenience
141
What makes a denture adhesive a facilitator (5)
Clear need - pt driven
Largely effective
Temporary use = lack of adaptation
Permanent use = poor supporting tissues
Product/delivery/application is good
142
What makes a denture adhesive a barrier (6)
Need is often associated with failure
Customer confusion
Effectiveness is patient driven and variable
Problems of - perception, alteated taste/sensation
Does not focus on user
Poor instructions
143
Indications for thin film denture adhesives (3)
Dentures well adapted
Denture bearing anatomy is unfavourable for effective retention
There is a need to enhance salivary cohesion
144
Indications for volume filler denture adhesive (3)
Dentures are ill fitting
Poor adaptation between denture and mucosa
There is a need to fill the gap
145
What is neutral zone
Site where opposing forces exerted by the lips, cheeks and tongue are in balance
146
How to ensure the denture sits in the neutral zone (7)
Request heat cured base for registration rims after definitive impressions
Set registration rims in even contact
Remove most of the wax from the anterior region
Apply adhesive to the cut surface and repplace the missing wax with a small amount of stiff alginate or heavy bodied silicone
Place in mouth
Patient to touch palatal surface of upper anterior rim with tip of tongue, occlude, smile and relax
147
Why is pre contact check record carried out (5)
Ensure occlusal balance
Remove discrepancies due to errors when recording jaw relationship and processing of denture
Method of registering coincidence of RCP and ICP
Avoid contact between occlusal surfaces
Ensure balanced articulation
148
How to do the pre contact check record
Use articulating paper to find contacts
Deppend fossae using bur
Repeat until contact includes first molars at least
149
Problems when a complete denture opposes natural teeth (2)
Uneven occlusal plane due to overeruption/tipping
Stable/rigid natural dentition against mobile denture
150
What are the ideal properties of cement for fixed prostheses (11)
Low viscosity and film thickness
Long working time with rapid set
Low solubility
High compressive and tensile strengths
High proportional limit
Retrievability
Adhesion to tooth structure and restorative materials
Cariostatic
Biocompatibility
Translucency or opacity when required
Radiopacity
151
Properties of zinc phosphate cement (5)
Low film thickness
Non adhesive and low tensile strength
Poor acid resistance
Easy to dismantle
Largely superseded by modern materials
152
Properties of zinc polycarboxylate (2)
Similar to zinc phosphate but more soluble
Some adhesion, but less than GIC or resins
153
Properties of glass ionomer cements (4)
Releases fluoride
Acid soluble
Similar adhesion to zinc polycarboxylate
Superseded by resin modified GIC
154
Properties of RMGIC cement (3)
Higher tensile and bond strength than GIC
Low film thickness
Good acid resistance
155
Properties of resin cements (4)
Strong
Adhesive
Technique sensitive
Available as chemical, dual, light cured
156
Properties of hydrophobic resin cements (3)
Require bonding agents
Supplied as visible light cure and dual cure
Wide range of shades and opacities
157
Properties of hydrophilic resin cements (4)
High affinity to non precious metals
High cost
Chemical or dual cure
Highly oxygen inhibited
158
Properties of self etch resin cements (3)
Easy to use and clean up
Strongly self adhesive to dentine
Dual cure
159
What is primary occlusal trauma
Injury to a periodontium of normal bone height as a result of excessive occlusal forces
160
What is secondary occlusal trauma
Injury to a periodontium of reduced bone height as a result of excessive occlusal force
161
Aetiology of occlusal trauma (5)
Premature contacts
Parafunctional habits
Tooth drifting following tooth loss of periodontal disease
Loss of posterior teeth
Occlusal discrepancy
162
Clinical findings of occlusal trauma (6)
Increased mobility
Fremitus
Tooth migration
Pain and tenderness
Tooth surface loss
Temporomandibular signs
163
Radiographic findings (2)
PDL widening - primary occlusal trauma
Bone loss and PDL widening - secondary occlusal trauma
164
What can go wrong in tooth development (4)
Number
Shape/form
Size
Structure
165
Aetiology of dental anomalies (2)
Genetic - chromosomal, single gene syndromes, single gene localised effect
Environment - rubella, thalidomide, irradation
166
What is hypodontia
Developmental absence of one or more teeth excluding third molars
167
Aetiology of hypodontia (5)
Obscure
Polygenic plus intrauterine systemic factors
Increased frequency - low birth weight, multiple births, increased maternal age
Single gene mainly for upper 2s
PAX9, MSX1
168
What medical conditions is hypodontia linked to
Downs syndrome, rubella, thalidomide embryopathy
X linked hypohidrotic ectodermal dysplasia, AR chondroectodermal dysplasia, Ellis van Creveld syndrome
Cleft lip/palate
169
What is hyperdontia
Condition where there are suppernumerary teeth present
170
Types of supernumeray teeth (3)
Supplemental - normal size and form
Accessory - atypical form
Mesiodens - adjacent to midline suture
171
What are supernumerary teeth associated with (3)
Invaginated teeth
Palatal cleft
Syndromes - cleidocranial dysplasia, oral facial digital syndrome, Gardner syndrome
172
What is anodontia
Genetic disorder characterised by the absence of all teeth
173
What is microdontia
Atypically small teeth
174
Macrodontia
Atypically large teeth
175
Aetiology of atypically sized teeth
Multifactorial - polygenic and environment
Microdontia - single gene inheritence, associated with Dons syndrome and ectodermal dysplasia
176
What are double teeth
Fusion of two tooth germs or gemination of one tooth germ splitting into two
177
Aetiology of Double teeth
Unknown, genetic?
178
What does double teeth look like
Minor notch to almost separate crowns
+/- common pulp space, root canal
Do not confuse with concrescences in which two teeth become united after forming by excess cementum
179
What is an invaginated tooth
Where dentine is mssing and enamel may be incomplete, therefore the pulp is directly exposed when tooth erupts
180
Aetiology of abnormal root size (2)
Irradation
Racial variation
181
What is taurodontism
The crown of the tooth is elongated and the roots are short
182
183
What is the aim of obturation
Establishment of a fluid tight barrier with the aim of protecting the periradicular tissues from microorganisms which reside in the oral cavity
184
Well obturated system would serve three main functions
Prevent coronal leakage of microorganisms or potential nutrients to support their growth into the dead space of root canal system
Prevent periapical or periodontal fluids percolating into the root canals and feeding microorganisms
Entomb any residual microorganisms that have survived the debridement and disinfection stages of treatment in order to prevent their proliferation and pathogenicity
185
Ideal properties of root filling material (10)
Easy handling and ample working time
Seal canal laterally and apically conforming to complex internal anatomy
Dimensionally stable
Non irritant
Does not stain tooth structure
Antimicrobial
Impervious and non porous
Unaffected by tissue fluid
Radiopaque
Easily removed
186
What is the role of an endodontic sealer (4)
Seal the space between the obturating core material and the internal root surface
Fill the space between core and accessory filling materials
Seal irregularities of complex canal anatomy
Lubricate and facilitate seating of core and accessory filling material
187
Indications for RCT (7)
Irreversible pulpitis
Periapical pathology
Post retained restoration
Overdenture
Teeth with doubtful pulps
Periodontal disease
Pulp sclerosis following trauma
188
Contraindications for RCT (9)
Inadequate access
Poor OH/attitude
Medical conditions - vertigo, arthritis
Tooth unrestorable
Insufficient periodontal support
Non strategic tooth
Root fractures
Root resorption
Bizarre anatomy
