Operative Dentistry Flashcards
1
Q
Fixed prosthodontics
A
Area of prosthodontics focused on permanently attached dental prostheses such as dental restorations/indirect restorations
Usually involves tooth prep
2
Q
Types of indirect restoration
A
Veneers
Crowns
Bridgework
Post and cores
Inlays
Onlays
3
Q
History and exam for fixed pros
A
Important to take full history for problem and diagnosis list as this will determine the fixed pros required
4
Q
E/O exam for fixed pros
A
Pay special attention to lips, smile line, commisures etc
5
Q
Linea alba
A
White line on buccal mucosa suggests bruxism
6
Q
Canine guidance
A
On lateral movement canines guide occluding posteriors apart
7
Q
Additional investigations that may be collected before creating a fixed pros treatment plan
A
Radiographs
Sensibility testing
Diet diary
Study casts
8
Q
Describe stages of treatment planning
A
Immediate - relief of acute symptoms, consider endo and extractions, consider immediate denture/bridge
Initial (disease control) - Extractions of hopeless teeth, OHI and diet advice, HPT, caries removal, replace defective restorations, Endo, denture design, wax up for fixed pros
Re-evaluation - re-asses perio status, confirm denture/bridge design
Reconstructive - perio surgery, fixed and removeable pros
Maintenance - supportive perio care and review of restorations
9
Q
Reasons for veneers
A
Aesthetic
Change teeth shape and/or contour
Correct peg laterals
Reduce or close proximal spaces and diastemas
Align labial surfaces of instanding teeth
10
Q
Contraindications for veneers
A
Poor OH
High caries rate
Interproximal caries and/or unsound rests.
Gingival recession
Root exposure
High lip lines
If extensive prep needed (>50% of surface are no longer enamel)
Labially positioned, severely rotated and overlapping teeth
Insufficient bonding area
Heavy occlusal contacts
Sever discolouration
11
Q
Reasons to restore with inlays or onlays
A
Tooth wear - increase OVD
Fractured cusps
Restoration of root treated teeth
Replace failed direct rests
Minor bridge retainers - not recommended
12
Q
difference between inlay and onlay
A
Onlay provides cuspal coverage
13
Q
Contraindications of inlays and onlays
A
Active caries or perio
Time - tooth prep and lab work required
Cost
14
Q
Indications for crowns
A
To protect weakened tooth structure
To improve or restore aesthetics
For use as retainer for fixed bridge
When indicated by RPD design - rest seats, clasps, guide planes
To restore tooth function
15
Q
Contraindications to restore with crown
A
Active caries or perio
More conservative options available
Lack of tooth tissue for prep
Unable to provide post and core
Unfavourable occlusion
16
Q
6 principles of crown prep
A
Preservation of tooth structure
Retention and resistance
Structural durability
Marginal integrity
Preservation of periodontium
Aesthetic considerations
17
Q
Why is preservation of tooth structure important in crown prep?
A
Avoid weakening the tooth structure unneccesarily or damaging the pulp
18
Q
Result of under tooth prep for crown
A
Poor aesthetics
Overbuilt crowns with periodontal and occlusal consequences
Restorations of insufficient thickness
19
Q
Retention of fixed pros
A
Prevents removal of the restoration along the path of insertion or the long axis of the tooth prep
20
Q
Resistance of fixed pros
A
Prevents dislodgement of the restoration by forces directed in an apical or obliqui direction and prevents any movement of the rest under occlusal forces
21
Q
Taper desired of crown prep
A
Ideal inclination tp opposing walls 6-10 degrees
22
Q
What is meant by extra means of retention in crown prep?
A
Grooves or slots prepared into the tooth
23
Q
Why is length of crown prep walls important?
A
Longer walls interfere with tipping displacement
24
Q
Why is path of insertion an important consideration of crown prep?
A
Imaginary line along which the restoration will be placed onto or removed from the preparation - is set before the preparation is begum and all the features of the prep must coincide with it
25
How is path of insertion related to retention of crowns?
Retention is improved by limiting the number of paths of insertion
26
What is meant by structural durability with regards to crown prep?
Rest must contain a bulk of material that is adequate to withstand the forces of occlusion
Achieved through - occlusal prep, functional cusp bevel, axial reduction
27
Finish line configuration options for crown margins
Knife edge
Bevel
Chamfer
Shoulder
Bevelled shoulder
28
Important factors for preservation of periodontium in crown prep
Margins should be smooth and fully exposed to a cleansing action
Placed where the dentist can finish them and the patient can clean them
Placed supra-gingival or at gingival margin whenever possible
29
Aesthetic considerations of crown prep
Smile line
Material
Which material provides best aesthetics, has least destructive prep, is least destructive to opposing teeth, is best suited for bruxists (if relevant)
30
Reduction and finish line for metal crowns
0.5mm axial
1.5 occlusal functional cusps
0.5 nonfunctional cusps
Chamfer 0.5mm
31
Reduction and finish line for ceramic traditional porcelain crowns
1mm axial
1.5mm functional cusps
1mm non functional cusps
1mm shoulder
32
Reduction and finish line for MCC
1.3mm axial
1.8 functional cusps
1.3 non functional cusps
a) chamfer 0.5mm where only metal
b) Shoulder 1.3mm (0.4 metal 0.9 porcelain)
33
Reduction and finish line for all ceramic crowns
1.5 axial
2mm functional cusps
1.5 non functional cusps
1-1.5mm chamfer
34
Main reason to replace teeth with bridgework
Aeshtetic
35
Reasons not to use bridgework
Damage to tooth and pulp
Secondary caries
Effect on periodontium
Cost
Failure
36
Important things to explain in order to get informed consent specifically for fixed pros
Invasiveness
Likely longevity and success rates
Possible complications
Time involved
Costs
Alternative options
37
Necessary information for informed consent generally
Treatment to be performed
Why its necessary
Consequences of not having it
What risks may be involved
What alternatives are there (and their risks)
Relative costs
38
Conventional clinical stages of indirect restorations
Preparation
Temporisation
Impressions and occlusal records
Cementation
39
How are chairside indirect restorations achieved?
CAD-CAM
Restorations milled from blocks of ceramic
Quick
No temporary necessary
40
Inlays
Intra-coronal rests made in lab
Types - gold, composite, porcelain
Uses - occlusal cavities, occlusal interproximal cavities, replace failed rests, minor bridge retainers (not recommended)
41
Indications for inlays
Premolars or molars
Occlusal restorations
Mesio-occlusal or distal occlusal
MOD - if narrow ( if wide consider onlay)
Low caries rate
42
Advantages and disadvantages of inlays over direct rests
Superior materials and margins
Wont deteriorate over time
BUT
Time and cost
43
Ceramic Inlay preparation
1.5-2mm isthmus width
1.5mm depth
1mm shoulder or chamfer
44
Gold inlay prep
1mm isthmus
1.5mm depth
0.5mm chamfer
45
How to make temporary inlay
Take impressions and occlusal records, send to lab to fabricate a temporary (typically 2 weeks)
OR
Temporary direct restorative materials - ZOE, Clip (composite based), GI
46
Lab instructions for inlay construction
Pour impressions
Mount casts
Construct restoration - tooth, material, thickness, shade, characteristics
47
Adhesive for ceramic inlays
NX3
ABC
RelyX Unicem - self adhesive resin cement
48
Gold inlay cement
AquaCem
Panavia
RMGI
49
Onlays
Extra coronal restorations made in lab, like inlays but with cuspal coverage
Height of cusps needs to be reduced in prep
Types - gold, composite, porcelain
50
Indications for onlays
Sufficient occlusal substance loss
Buccal and/or lingual cusps remaining
Remaining tooth substance weakened - caries or pre-existing large rest
51
Uses for onlays
Tooth wear - increase OVD
Fractured cusps
Rest of root treated teeth
Replace failed direct rests
Minor bridge retainers
52
Cast metal onlays are preferable to amalgam rests when..
Higher strength needed
Significant tooth recontouring required
53
Porcelain onlay prep
Non working cusp 1.5mm
Working cusp 2mm
1mm shoulder or chamfer
54
Gold onlay prep
Non working cusp - 0.5mm
Working cusp 1mm
0.5mm chamfer
55
Why not check occlusion with ceramic inlay or onlay before it is cemented?
Weak when not cemented, may fracture
56
Inlays onlays first appt
LA
Make reduction template
Impression for temp
Tooth prep
Make temp
Impressions, bite reg, record shade
Cement temp
57
Inlays/onlays 2nd appt
Remove temp
Isolate, clean and dry prepared tooth
Try in, asses fit occlusion etc
Address problems if necessary
Cement
Minor occlusal adjustments if necessary
58
Alternatives to inlays or onlays
Large direct rest with amalgam, GI or composite
Crowns - 3/4 crown, full crown (gold shell, MCC, PJC)
Extract
59
Veneers
Porcelain laminate veneer
Laminate veneer - a thin layer of cast ceramic that is bonded to the labial or palatal surface of a tooth with resin
Types of veneer - ceramic, composite, gold
60
Indicators for veneers
Improve aesthetics
Change teeth shape or contour
Correct peg laterals
Reduce or close proximal spaces
Align labial surfaces of instanding teeth
61
Causes of discolouration
Non vital
Aging
Trauma
Medications
Fluorosis
Hypoplasia or hypomineralisation
Amelogenesis imperfecta
Erosion or abrasion
Staining
62
Contraindications for veneers
Poor OH
High caries rate
Gingival recession
Root exposure
High lip lines
If extensive prep needed
Labially positioned, rotated, overlapping
Extensive TSL
Heavy occlusal contacts
Severe discolouration
63
Veneer prep types
Feathered incisal edge
Incisal bevel
Intra-enamel
Overlapped incisal edge
64
Cervical reduction for veneers
0.3mm
Slight chamfer margin
Within enamel
65
Incisal reduction for veneers
1-1.5mm
66
Gurel technique
Veneer prep technique for minimal preparation
67
If temporary veneer required, what should be done?
Take impressions and occlusal records, send to lab for restoration (2 week wait)
OR
Spot bonded composite
No etch
Small spot of primer and adhesive
Directly apply composite
68
Veneer cementation
NX3
ABC
Relyx Unicem
Remove excess when not set with microbrush
69
Veneer 1st appt
If tooth prep required - LA, make putty index, impression for temporary, tooth prep, make temp
Impressions, bite reg, record shade
Cement temp
70
Veneers 2nd appt
Remove temp
Isolate, clean and dry prepped tooth
Try in, assess fit, adaptation and occlusion
Cement
71
Alternatives to veneers
No treatment
Microabrasion
Penetrative resin rests
Direct composite
Crowns
72
Provisional extra-coronal restorations
Provided between tooth prep and fit of indirect rest
High quality otherwise failures occur
Role in immediate and long term health of tooth and supporting structures, as well as the success of the definitive restoration
73
Effects of tooth prep and need for temporary rests
Compromises aesthetics
Degrades tooth function
Renders teeth sensitive
In some RCTd teeth, compromises coronal seal
74
Desirable characteristics of provisional materials
Non irritant
Low temp rise during setting
Dimensionally stable
Adequate working time
Adequate setting time
Adequate strength and wear resistance
Good aesthetics
75
Types of provisional restorations
Custom formed
Preformed
76
Method for provisional crown placement
Sectional impression
Prepare tooth for chosen restoration
Syringe bis-acrylic comp resin onto mixing pad to monitor setting and ensure its mixed
Syringe into sectional impression
Relocate impression in the mouth
Ensure fully seated
Remove before complete polymerisation
Polish, remove flash and ledges
Check fit and aesthetics
Cement in temp - temporary luting cement
77
Preformed temp crowns types
Tooth coloured: Polycarbonate, clear plastic
Metal - aluminium and stainless steel
Large variation of crowns needed, can be costly and unlikely to fit well
Useful in cases where no impression can be taken before prep e.g. trauma
78
Two types of tooth bleaching
External vital bleaching
Internal non vital bleaching
79
Vital external bleaching
Discolouration is caused by formation of chemically stable chromogenic products within tooth substance - long chain organic molecules
Bleaching oxidises these compounds which leads to smaller, often not pigmented molecules
80
Vital external bleaching
Discolouration is caused by formation of chemically stable chromogenic products within tooth substance - long chain organic molecules
Bleaching oxidises these compounds which leads to smaller, often not pigmented molecules
81
Active agent in vital external bleaching
H2O2 hydrogen peroxide
Forms an acidic solution in water, breaks down to form water, oxygen and free radical HO2(active oxidising agent)
Or active ingredient carbamide peroxide, which breaks down to produce H2O2 and urea
82
Constituents in vital external bleaching gel
Carbamide peroxide
Carbopol - thickening agent, slows O2 release and keeps gel in place
Urea - increases pH
Surfactant - allows gel to wet tooth surface
Pigment disperser
Preservative
Flavour
Potassium nitrate - tooth desensitising
Calcium phosphate - tooth desensitising
Fluoride - prevents erosion
83
Factors affecting external vital bleaching
Time - more time more effect
Clean tooth - better
Higher concentration - more and quicker effect
Temp - higher = quicker
84
Warnings for patient of external vital bleaching
Sensitivity
Relapse
Restoration colour
Allergy
Might not work
Compliance with regime
85
Advantages and disadvantages of in office bleaching
Controlled by dentist, can use heat/light, quick results for pt
Time for dentist, can be uncomfortable, results tend to wear off quicker, more expensive
86
In office bleaching technique
Thoroughly clean teeth
Ideally rubber dam
At least gingival mask
Apply gel
Apply heat/light
Wash dry repeat
Takes 30 mins to an hour
Protection of gingivae essential
87
Home vital bleaching technique
10-15% Carbamide peroxide gel (equates to 6% hydrogen peroxide, max legal strength)
Custom made tray - alginate impressions, 0.5mm thick soft, acrylic, vacuum formed soft splint made, buccal spacer for gel
Bleaches over several weeks
Easy
88
When to bleach?
Age related discolouration - yellow/orange responds much better than blue/grey
Mild fluorosis
Post smoking cessation
Tetracycline - can take months, better with brown/yellow than grey
89
Problems with tooth whitening
Sensitivity - common 60%+, worse initially
Wears off
Cytotoxicity
Gingival irritation - tray should stop 1mm short of gingivae
Tooth damage - no evidence
Damage to restorations - probably not but composite doesn't bleach
Problems with bonding to tooth - reduces with time
90
Causes of internal grey discolouration
Dead pulp - bleeding into dentine - blood products diffuse and darken giving grey colour
91
Indications for internal non vital bleaching
Non vital tooth
Adequate RCT
No apical path
92
Contraindications for internal non vital bleaching
Heavily restored tooth - better with crown or veneer
Staining due to amalgam
93
Advantages and risks of internal non vital bleaching
Easy, conservative and good pt satisfaction
External cervical resorption due to diffusion of H2O2 through dentine into periodontal tissues
94
Technique for internal non vital bleaching
Record shade
Prophylaxis
Rubber dam
Remove filling from access cavity
Removes GP from pulp chamber and 1mm below ACJ
Place 1mm RMGIC over GP to seal canal, seal dentine and prevent root resorption
Remove any really dark dentine
Etch internal surface with 37% phosphoric
Place 10% carbamide peroxide gel in cavity, cotton wool over it and seal with GIC
Repeat weekly until required shade achieved - usually 3-4 visits
If no change after 4 visits it isn't going to work
Once shade achieved place white GP or similar in pulp chamber and restore with a light composite shade
95
Combination bleaching technique
Remove GP as with internal, cover with RMGIC,
Make bleaching tray (palatal, not buccal reservoir)
Bleach placed in access cavity and in tray
Replaced frequently over about a week
Tricky for pt - must wear tray the whole time
96
Microabrasion as tooth whitening
Removes discolouration limited to the outer layers of enamel
Combination of erosion with acid and abrasion with pumice
97
Indications for microabrasion bleaching
Fluorosis
Post ortho demineralisation
Demineralisation with staining
Prior to veneering if dark staining present
98
Technique for microabrasion bleaching
Clean teeth thoroughly
Rubber dam
Mix 18% HCl (or37% phosphoric, less effective) and pumice
Apply to teeth
Gently rub with prophy cup 5 sec/tooth
Wash
Repeat up to 10x
Remove dam and polish with prophy paste
Apply fluoride gel or varnish to help reharden and decrease sensitivity
Review 1 month
Can be repeated but not too much - dentine yellow and sensitive
99
Advantages and disadvantages of microabrasion bleaching
Quick, easy , no long term problems
BUT
Acid, sensitivity, only works for superficial staining, works much better for brown stains than white marks
100
Outcome predictors of dental trauma
Severity of injury
Stage of root development
Timing of treatment
101
Where can guidance be found on the impact of injury severity on the longterm outcome be found?
Risk calculator IADT dental trauma guide
Prognoses for teeth with traumatic dental injuries
Copenhagen trauma database
Data from 2191 traumatised permanent teeth from 1282 patients
102
Risk at 10 years of crown fractures
Enamel dentine fracture - pulp necrosis 5.1%
Enamel dentine fracture - pulp canal obliteration 1.3%
Enamel-dentine-pulp fracture - pulp canal obliteration 20%
103
Risk of pulp necrosis following concussion
3.5% at 1, 3 and 10 years
104
Risk of pulp canal obliteration following concussion
4.4% at 1 year
7.2 % at 3 years
10.3% at 10 years
105
Risk of external root resorption following concussion
5.2% at 1yr
8% at 3yr and 10yr
106
Long term complications of trauma that may require specialist treatment
Inflammatory root resorption - external cervical, internal inflammatory or external inflammatory resorption
Altered tooth positions - may require multidisciplinary care
Root fracturs exhibiting developing pathology
Loss of >1 tooth from trauma
107
Injury classification
Simple - concussion, subluxation, enamel infraction, enamel dentine fracture, root fractur apical 2/3 no displacement, avulsion
Complex - extrusion, displaced or cervical 1/3 root fracture, lat luxation, dento alveolar fracture, intrusion, immature apex
108
Complications following subluxation
Pulp necrosis (most likely)
External root resorption
Bone loss
109
Complications following extrustion injury
Pulp necrosis - likely
Pulp canal obliteration
External root resorption
Bone loss
110
Complications following lateral luxation
Pulp necrosis - likely
Pulp canal obliteration
Ankylosis
Internal root resorption
External root resorption
Bone loss
111
Complications following dento-alveolar fracture
Tooth loss
Pulp necrosis (most likely)
Pulp canal obliteration
Ankylosis
Int root resorption
Ext root resorption
Bone loss
112
Complications following intrusion
Tooth loss
Pulp necrosis (100%)
Ankylosis
Int root resorption
Ext root resorption
Bone loss
113
Open vs closed apex
Open apex maintains pulpal vitality and preserves blood supply
Regeneration
Maintain pulpal vitality and preservation of blood supply
Closed apex prevents ingress or bacteria and toxins
114
Trauma treatment timings
Acute - <3hr
Subacute 3-24
Delayed >24hr
115
Potential longterm complications for traumatised teeth
Discolouration
Loss of vitality
Inflammatory root resorption
Unfavourable position
Defects in hard or soft tissues
116
What can yellow discolouration following trauma indicate?
Pulp canal obliteration
117
What causes pink discolouration?
Rupture of blood vessels during severe trauma may cause haemorrhage in pulp chamber
Blood components flow into dentine tubules causing discolouration - initially pink
Cervical root resorption can also present as pink - pink later
118
What causes brown, grey, black discolouration following trauma?
In non infected traumatised teeth accumulation of haemoglobin can cause discolouration
In non vital teeth hydrogen sulphates produced by bacteria convert iron to dark coloured iron sulphates
119
What occurs if revascularisation fails after trauma?
Pulp necrosis and apical periodontitis
120
Indicators of pulp necrosis
Periapical radiolucency
Discolouration (usually grey/brown)
Infection related external root resorption
Negative sensitivity test
TTP
Presence of fistula
121
Treatment of pulp necrosis
Primary endo
Internal bleaching
OR extraction and prosthetic replacement
122
Injuries likely to cause unfavourable tooth position
Luxation
Intrusion
Extrusion
Avulsion
123
Management of unfavourable tooth positions
Minimal - addition of composite/removal of tooth tissue
Significant alterations in apico-coronal position - extra coronal rests
Orthodontic reposition - risk of root resorption and loss of vitality
124
Management of hard and soft tissue defects following trauma
Bone deficiencies - bone grafting, ortho-extrusion
Soft tissue deficiencies - mucogingival surgery, connective tissue grafting to increase volume of keratinised mucosa
Implant treatment - complex
Aesthetic challenges
125
Follow up after crown fracture or crown-root fracture
Clinical and radiographic control at 6-8 weeks and 1 yr
126
Follow up after root fracture
Splint removal and radiograph - 4 weeks
Clinical and radiographic -6-8W, 4M, 6M, 1y, annual for 5y
127
Follow up alveolar fracture
Splint removal, clinical and radiographic - 4w
Clinical and radiographic - 6-8w, 4m, 6m, 1y, annual for 5y
128
Follow up for concussion, subluxation or extrusion
Splint removal, clinical and radiographic - 2W
Clinical and radiographic - 4w, 6-8w, 6m, 1y, annual for 5y
129
Follow up for lat luxation or intrusion
Clinical and radiographic at 2w, 4w, 6-8w, 6m, 1y, annual for 5y
Splint removal at 4w
130
TMJ anatomy
Joint between condylar head of the mandible and the mandibular fossa of the temporal bone
TMJ is a synovial, condylar and hinge type joint
Involves fibrocartilaginous surfaces and an articular disc which divides the joint into two cavities - inferior and superior synovial space, each lined with their own membranes
Capsule surrounds the joint and attaches to articular eminence, disc and neck of condyle, articular disc is a fibrous extension, with collateral ligaments attaching it to the condyle medially and laterally
The articular disc attaches to the joint capsule and the superior head of lat pterygoid
131
Suprahyoid muscles
Stylohyoid
Digastric
Geniohyoid
Mylohyoid
Elevate the hyoid bone or depress the mandible
132
Mylohyoid function
Elevates hyoid and floor of mouth
133
Stylohyoid function
Initiates swallowing by pulling hyoid bone up and back
134
Digastric and geniohyoid function
Depress mandible and elevate hyoid
135
Muscles of mastication
Involved in depression, elevation and lateral movements of mandible
Temporalis
Lat pterygoid
Medial pterygoid
Masseter
136
Temporalis
Elevates and retracts the mandible
Assists in rotation
137
Lateral pterygoid
Positions disc in closing
Protrudes and depresses mandible and causes lateral movement
138
Medial pterygoid
Elevates mandible
Lateral movement and protrusion
139
Masseter
Elevates and protracts mandible
Assists in lateral movement
140
Two major types of mandibular movement in occlusion
Rotation
Translation/lateral translation
141
Resting position of TMJ
Teeth slightly apart (freeway space), lips together
142
What happens to TMJ on small mouth opening?
Condyle hinges within articular fossa, no downwards or protruding movement
143
Facebow
Caliper like instrument that records relationship of the maxilla to the terminal hinge axis of rotation of the mandible
Allows a maxillary cast to be placed in an equivalent relationship on the articulator
144
Translation of the condyle
Lat pterygoid contracts
Articular disc and condyle move downwards and forwards along the incline of the articular eminence
May also travel laterally
144
Translation of the condyle
Lat pterygoid contracts
Articular disc and condyle move downwards and forwards along the incline of the articular eminence
May also travel laterally
145
Intercuspal position
Tooth position regardlaes of the condylar position
Comfortable bite
Best fit of the teeth
Max interdigitation of the teeth
Also called centric occlusion
146
Edge to edge position
Tooth position
Teeth slide forward from ICP guiding on palatal surfaces of anterior teeth
Incisal edges of upper and lower incisors touch
147
Protrusion
Condyle moves forwards and downwards on articular eminence
Only incisors +/-canines touch
No posterior tooth contacts
Eventually no tooth contacts
148
Maximum opening
No tooth contacts
Mouth wide open
Full translation of the condyle over the articular eminence
149
Retruded axis position
No tooth contacts
Most superior anterior position of the condylar head in the fossa
Terminal hinge axis
150
Retruded contact position
First tooth contact when the mandible is in retruded axis position
ICP is approx 1mm anterior to RCP in 90% of population
151
Bennett movement
Lateral translation of the mandible
Result of contraction of one lat pteryhoid muscle, and the mandible moving to the opposite side
Bony wall of the glenoid fossa stops the working side condyle moving any further to the side
152
Bennet angle
The path of the nonworking condyle in the horizontal plane during lateral movement
153
Tools for marking tooth contacts
Millers forceps
Fine articulating paper
154
When to mark tooth contacts
Before tooth prep
Before removing a restoration
After placing a crown
After placing a restoration
155
Checklist for examining the static occlusion
Incisor relationship
Molar relationship
Overjet/overbite
Cross bites
Open bites
Individual tooth contacts
RCP - ICP slide
156
Functional cusps
Cusps that occlude with opposing teeth in ICP
Lingual cusps of the upper posterior teeth and buccal cusps of lower posterior teeth
157
Non functional cusps
Cusps that do not occlude with the opposing teeth in ICP
Buccal cusp of upper posteriors and lingual cusps of lower posteriors
158
Fossa
Depression or concavity on tooth surface
Function cusp of a tooth contacts the fossa of opposing tooth
159
ICP contacts
Lingual cusp of an upper molar contacts the fossa of a lower molar
Buccal cusp of a lower molar contacts the fossa of an upper molar
160
Overbite
Vertical overlap of incisors
161
Normal overbite
2-4mm
162
Overjet
Relationship between the upper and lower teeth in horizontal plane
163
Crossbite
Condition where one or more teeth may be abnormally malpositioned buccal or lingually or labially with reference to opposing teeth
Can be anterior or posterior
164
Anterior open bite
Lack of vertical overlap of anterior teeth when posteriors in full occlusion
165
Posterior/lateral open bite
Failure of contact between posteriors when the teeth are in full occlusion
166
Canine guidance
Mandible moves to the side
Contact only between the canines
No posterior tooth contacts
167
Mutually protected occlusion
Gold standard
Canine guidance
Posterior disclusion in lateral excursions
No non working/working side contacts
No protrusive interferences
168
Group function
Mandible moves to the side, multiple teeth in contact on that side
Bilateral group function is frequently seen in toothwear
169
Occlusion in Protrusion
Condyle moves forwards and downwards on articular eminence
Only incisors +/- canines touch
No posterior tooth contacts
170
Occlusal interferences
Undesirable tooth contacts that may produce mandibular deviation during closure to ICP or may hinder smooth passage to and from ICP
171
Types of occlusal interference
Working side
Non working side
Protrusive
172
What is working side in lateral movement?
The side the mandible moves towards
173
Why avoid posterior contacts?
Teeth are designed to absorb heavy forces in the direction of the long axis of the tooth
Most teeth not designed to absorb significant lateral forces generated by occlusal interferences
Musculature gets a rest as less activity if no undesirable contacts
Occlusal trauma and undesirable tooth movements
174
Bruxism
Eccentric - parafunctional grinding of teeth, an oral habit consisting of involuntary rhythmic or spasmodic or functional gnashing, grinding or clenching of teeth in other than chewing movements of the mandible which may lead to occlusal trauma
OR
Centric - clenching, the pressing and clamping of jaws and teeth together, frequently associated with acute nervous tension or physical effort
175
Clinical signs and symptoms of bruxism
Toothwear
Fractured restorations
Tooth migration
Tooth mobility
Muscle pain and fatigue
Headache
Earache
Pain and stiffness in TMJ and surrounding muscles
176
Types of toothwear
Multifactorial
Abrasion
Attrition
Erosion
Abfraction
177
Occlusal trauma
Injury resulting in tissue changes within the attachment apparatus, including PDL, alveolar bone and cementum, as a result of occlusal forces
Primary - intact periodontium
Secondary - reduced periodontium
Fremitus - palpable or visible movement of a tooth when subjected to occlusal forces
178
Examination of occlusion checklist
Incisor relationship
Guidance
Overjet/overbite
ICP contacts
Working/non working/protrusive contacts
Pathology
179
Studying occlusion using casts
Arcon
Semi adjustable, allows you to set Bennet and condylar guidance angles
Can see full range of mandibular movements for occlusal diagnosis and evaluation
180
Face bow components
Bite fork
Earbow
Reference plane locator
Transfer jig assembly
181
Marking anterior reference point (facebow)
Mark the anterior reference point on the patients right side using the reference place locator and marker
This is 43mm apical to the incisal edge of the anterior teeth (12 ideally)
It is the approx position of the infraorbital foramen
182
Bite reg using facebow bitefork
Bite reg paste applied to the bite fork
Bite fork arm to the right and locating notch facing up
Firmly seat to record cusp tips of maxillary teeth
You can used rigid wax or bite reg paste
Do not engage undercuts
Check that it is parallel with pts coronal and horizontal planes
Align midline with locating notch
183
Mounting lower cast following facebow registration
An interocclusal registration can be used to mount the mandibular cast in relation to maxillary cast already mounted on the articulator using the facebow transfer
There are two choices of interocclusal registrations you can use to mount the lower cast
ICP or RCP
184
What is used to record ICP for articulation on casts
No material - ICP is obvious to technician, plenty of tooth contacts
Wax or paste if ICP is not obvious
Record blocks if there are free end saddles
185
What will happen if bite reg paste or wax is too thick?
OVD will be increased, restoration will be high in the bite when placed
186
Conformative approach
The provision of restorations in harmony with the existing jaw relationships
Occlusion of the new restoration is provided in such a way that the occlusal contacts of the other teeth remain unaltered
187
When is the conformative approach not used?
An increase in vertical height is needed to make space for restorations
Tooth/teeth significantly out of position
A significant change in appearance is wanted
There is a history of occlusally related failure or fracture of existing restorations
188
Reorganised approach
Plan to provide restorations to a different occlusion
The occlusion is defined before the work is started
Provide restorations, which change the occlusion but are well tolerated by the patient
189
Techniques to guide patient into terminal hinge closure
Bimanual manipulation
Chin point guidance
Chin point guidance with anterior jig
190
Reasons to take an RCP registration
ICP useless or non existent
Need space to place restorations
RCP is a reproducible position of the mandible independent of the teeth
