Operative Dentistry Flashcards
Fixed prosthodontics
Area of prosthodontics focused on permanently attached dental prostheses such as dental restorations/indirect restorations
Usually involves tooth prep
Types of indirect restoration
Veneers
Crowns
Bridgework
Post and cores
Inlays
Onlays
History and exam for fixed pros
Important to take full history for problem and diagnosis list as this will determine the fixed pros required
E/O exam for fixed pros
Pay special attention to lips, smile line, commisures etc
Linea alba
White line on buccal mucosa suggests bruxism
Canine guidance
On lateral movement canines guide occluding posteriors apart
Additional investigations that may be collected before creating a fixed pros treatment plan
Radiographs
Sensibility testing
Diet diary
Study casts
Describe stages of treatment planning
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
Reasons for veneers
Aesthetic
Change teeth shape and/or contour
Correct peg laterals
Reduce or close proximal spaces and diastemas
Align labial surfaces of instanding teeth
Contraindications for veneers
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
Reasons to restore with inlays or onlays
Tooth wear - increase OVD
Fractured cusps
Restoration of root treated teeth
Replace failed direct rests
Minor bridge retainers - not recommended
difference between inlay and onlay
Onlay provides cuspal coverage
Contraindications of inlays and onlays
Active caries or perio
Time - tooth prep and lab work required
Cost
Indications for crowns
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
Contraindications to restore with crown
Active caries or perio
More conservative options available
Lack of tooth tissue for prep
Unable to provide post and core
Unfavourable occlusion
6 principles of crown prep
Preservation of tooth structure
Retention and resistance
Structural durability
Marginal integrity
Preservation of periodontium
Aesthetic considerations
Why is preservation of tooth structure important in crown prep?
Avoid weakening the tooth structure unneccesarily or damaging the pulp
Result of under tooth prep for crown
Poor aesthetics
Overbuilt crowns with periodontal and occlusal consequences
Restorations of insufficient thickness
Retention of fixed pros
Prevents removal of the restoration along the path of insertion or the long axis of the tooth prep
Resistance of fixed pros
Prevents dislodgement of the restoration by forces directed in an apical or obliqui direction and prevents any movement of the rest under occlusal forces
Taper desired of crown prep
Ideal inclination tp opposing walls 6-10 degrees
What is meant by extra means of retention in crown prep?
Grooves or slots prepared into the tooth
Why is length of crown prep walls important?
Longer walls interfere with tipping displacement
Why is path of insertion an important consideration of crown prep?
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
How is path of insertion related to retention of crowns?
Retention is improved by limiting the number of paths of insertion
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
Finish line configuration options for crown margins
Knife edge
Bevel
Chamfer
Shoulder
Bevelled shoulder
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
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)
Reduction and finish line for metal crowns
0.5mm axial
1.5 occlusal functional cusps
0.5 nonfunctional cusps
Chamfer 0.5mm
Reduction and finish line for ceramic traditional porcelain crowns
1mm axial
1.5mm functional cusps
1mm non functional cusps
1mm shoulder
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)
Reduction and finish line for all ceramic crowns
1.5 axial
2mm functional cusps
1.5 non functional cusps
1-1.5mm chamfer
Main reason to replace teeth with bridgework
Aeshtetic
Reasons not to use bridgework
Damage to tooth and pulp
Secondary caries
Effect on periodontium
Cost
Failure
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
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
Conventional clinical stages of indirect restorations
Preparation
Temporisation
Impressions and occlusal records
Cementation
How are chairside indirect restorations achieved?
CAD-CAM
Restorations milled from blocks of ceramic
Quick
No temporary necessary
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)
Indications for inlays
Premolars or molars
Occlusal restorations
Mesio-occlusal or distal occlusal
MOD - if narrow ( if wide consider onlay)
Low caries rate
Advantages and disadvantages of inlays over direct rests
Superior materials and margins
Wont deteriorate over time
BUT
Time and cost
Ceramic Inlay preparation
1.5-2mm isthmus width
1.5mm depth
1mm shoulder or chamfer
Gold inlay prep
1mm isthmus
1.5mm depth
0.5mm chamfer
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
Lab instructions for inlay construction
Pour impressions
Mount casts
Construct restoration - tooth, material, thickness, shade, characteristics
Adhesive for ceramic inlays
NX3
ABC
RelyX Unicem - self adhesive resin cement
Gold inlay cement
AquaCem
Panavia
RMGI
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
Indications for onlays
Sufficient occlusal substance loss
Buccal and/or lingual cusps remaining
Remaining tooth substance weakened - caries or pre-existing large rest
Uses for onlays
Tooth wear - increase OVD
Fractured cusps
Rest of root treated teeth
Replace failed direct rests
Minor bridge retainers
Cast metal onlays are preferable to amalgam rests when..
Higher strength needed
Significant tooth recontouring required
Porcelain onlay prep
Non working cusp 1.5mm
Working cusp 2mm
1mm shoulder or chamfer
Gold onlay prep
Non working cusp - 0.5mm
Working cusp 1mm
0.5mm chamfer
Why not check occlusion with ceramic inlay or onlay before it is cemented?
Weak when not cemented, may fracture
Inlays onlays first appt
LA
Make reduction template
Impression for temp
Tooth prep
Make temp
Impressions, bite reg, record shade
Cement temp
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
Alternatives to inlays or onlays
Large direct rest with amalgam, GI or composite
Crowns - 3/4 crown, full crown (gold shell, MCC, PJC)
Extract
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
Indicators for veneers
Improve aesthetics
Change teeth shape or contour
Correct peg laterals
Reduce or close proximal spaces
Align labial surfaces of instanding teeth
Causes of discolouration
Non vital
Aging
Trauma
Medications
Fluorosis
Hypoplasia or hypomineralisation
Amelogenesis imperfecta
Erosion or abrasion
Staining
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
Veneer prep types
Feathered incisal edge
Incisal bevel
Intra-enamel
Overlapped incisal edge
Cervical reduction for veneers
0.3mm
Slight chamfer margin
Within enamel
Incisal reduction for veneers
1-1.5mm
Gurel technique
Veneer prep technique for minimal preparation
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
Veneer cementation
NX3
ABC
Relyx Unicem
Remove excess when not set with microbrush
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
Veneers 2nd appt
Remove temp
Isolate, clean and dry prepped tooth
Try in, assess fit, adaptation and occlusion
Cement
Alternatives to veneers
No treatment
Microabrasion
Penetrative resin rests
Direct composite
Crowns
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
Effects of tooth prep and need for temporary rests
Compromises aesthetics
Degrades tooth function
Renders teeth sensitive
In some RCTd teeth, compromises coronal seal
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
Types of provisional restorations
Custom formed
Preformed
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