Operative techniques Flashcards
What are the principles of cavity preparation
- dentify and remove carious enamel
- Remove enamel to identify the maximal extent of the lesion at the ADJ & smooth the enamel margins
- Progressively remove peripheral caries in dentine - from the ADJ first then circumferentially deeper and only then remove deep caries over the pulp
- This is to ensure that if there is a pulpal exposure that the caries does not fall into the pulp and so gives a better prognosis
- Outline form modification
- Enamel finishing
- Remove any unsupported enamel
- Occlusion
- Requirements of the restorative material
- Enamel finishing
- Internal design medication
- Internal line and point angles
What are indications for crowns
- Protect weakened tooth structure
- Improve or restore aesthetics
- For use as a retainer for fixed bridge
- When indicated by RPD design
- Restore tooth function
What are principles of crown preparation (that can be used to evaluate a crown)
PRS MPA
- preservation of tooth structure
- retention and resistance
- structural durability
- marginal integrity
- preservation of periodontium
- aesthetic considerations
What are we looking at when preserving tooth structure
- Has it been over or under prepared?
What do we need to do to provide retention and resistance in a crown prep
- Is it tapered? Want taper of 6 degrees
- How long are the walls? Want longer walls for retention
- Want limited number paths of insertion
How do we provide structural durability in a crown prep
- Has enough been removed so there is adequate room for bulk of material
- Occlusal reduction
- Functional cusp bevel
- Axial reduction
How do we ensure marginal integrity in a crown prpe
- What is the finish line? Shoulder or chamfer?
- Chamfer more aesthetic
How do we preserve the periodontium in a crown prep
- Margins of restoration should be
- Smooth and full exposed to a cleansing action
- Placed where the dentist can finish them and px can cleen them
- Placed at gingival margin whenever possible
- Dont want to impinge on supracrestal attachment (junctional epithelium + connective tissue)
What are aesthetic considerations for a crown prep
- Does it work for px smile line
What is the axial reduction for a metal crown: full veneer gold crown
0.5mm
What is the axial reduction for ceramic crowns (traditional porcelain)
1mm
What is the axial reduction for a metal ceramic crown
1.3
What is the axial reduction for an all ceramic crown (porcelain bonded to alumina or zirconia framework
1.5
What is the occlusal reduction for the functional and non functional cusps for a metal crown (full veneer gold crown)
F - 1.5mm
NF - 0.5mm
What is the occlusal reduction for the functional and non functional cusps for a ceramic crown (traditional porcelain)
F - 1.5mm
NF - 1mm
What is the occlusal reduction for the functional and non functional cusps for a metal ceramic
F - 1.8mm
NF - 1.3mm
What is the occlusal reduction for the functional and non functional cusps for a all ceramic crown (porcelain bonded to aluminia or zirconia framework)
F - 2mm
NF - 1.5mm
What is the finish line for a metal crown (full veneer gold crown)
chamfer
.5
What is the finish line for a ceramic crown (trad porcelain)
shoulder
1mm
What is the finish line for a metal ceramic crown
chamfer 0.5 where only metal required
shoulder 1.3mm for where metal and porcelain required
What is the finish line for all ceramic crowns (porcelain bonded to zirconia/alumina)
chamfer
1-1.5mm
What are the types of inlays
- Gold
- Composite
- Porcelain
- Ceromeric
What are the uses of inlays
- Occlusal cavities
- occlusal/interproximal cavities
- Replace failed direct restorations
- Minor bridge retainers
What are the indications of inlays
- premolars/molars
- Occlusal
- Narrow MODs
- MOs/DOs
What are advantages of inlays
Better materials and margins
What are the tools for inlay and onlay prep
handpiece
burs (no 170L, 169L, flame)
enamel hcahets
binangle chisel
gingival magin trimmers
What is the inlay preparation for a ceramic inlay
- 5mm-2mm isthmus
- 5mm depth
- 5-2mm proximal box
1mm shoulder/chamfer margin
What is the inlay preparation for a gold inlay
1mm istmus width
1.5mm depth
1mm proximal box
0.5mm chamfer margin
What degree of tapered walls do we want for inlay
4-6 degrees
Where do we want our shoulder chamfer margins for an inlay
supra gingival
Where must the margins be for an inlay
clear of occlusal contact points
What sort of bevel do we want for inlays
none for ceramic
15-20 degrees bevel in upper ⅓ isthmus wall
What features do we want in an inlay
occlusal key/dovetail
grooves for retention (optional)
How are onlays differnet to inlays
- Similar to inlays but have cuspal coverage and so require some cuspal preparation
What are types of onlays
- Gold
- Composite
- Porcelain
- Ceromeric
What are indications of onlays
- Sufficient tooth substance loss
- Remaining tooth substance weakened
- Wide MODs
When are onlays preferable to a large amalgam
- when higher strength is needed and significant tooth recontouring is required
What are uses of onlays
- ooth wear cases
- Increase OVD
- Fractured cusps
- Restoration of root treated teeth
- Replace failed direct restoration
- Less destructive than crowns
What is the occlusal reduction for a porcelain onlay
non working cusp - 1.5mm
working cusp -2mm reduction
What is the occlusal reduction for a gold onlay
non working cusp - 0.5mm
working cusp -1mm reduction
how big should the proximal box be for a gold onlay
1mm
How big should a proximal box be for a ceramic onlay preparation
2mm
What are the margins for a porcelain onlay
1mm
shoulder or chamfer
What is the margins for a gold onlay
0.5mm chamfer
What are features of a onlay prep
no bevels for ceramic - butt joint CSM
bevels for gold - 15/20 degree bevel for upper ⅓ of isthmus wall
margins clear of occlusal CP
4-6 degree tapered walls
What is the first appointment for an inlay and onlay
LA
reduction template
impression for temp
tooth prep
make temp
impressions, bite registration and record shade
cement temp
What is the second appointment for inlays and onlays
remove temp
isolate, clean and dry prepared tooth
try in
cement
minor occlusal adjustment if needed
What are the types of veneers
- Ceramic
- Composite
- Gold
What are indications for veneers
- Aesthetic
- Change teeth shape/contour
- Correct peg shaped laterals
- Reduce or close proximal spaces and diastemas
- Align labial surfaces of instanding teeth
- Enamel defects
- Discoloration (intrinsic or bleach doesnt work for it)
What are contraindications for veneers
- Poor OH
- High caries rate
- Gingival recession
- Root exposure
- High lip lines
- Extensive prep needed
What is the cervical reduction for veneer
0.3mm
chamfer margin
within enamel
supragingival or slightly sub
What is the midfacial reduction for a veneer
0.5mm
within enamel
What is the incisal reduction for a veneer
1-1.5mm
What is the first appointment for a veneer
if tooth prep required
- LA
- putty index
- impression for temp
- tooth prep
- make temp
- impression, bite reg, record shade
- cement temp
What is the second appointment for a veneer
- remove temp
- isolate, clean and dry tooth
- try in and assess fit, adaption and occlusion
- cement
What are alternatives to veneers
- Bleaching/tooth whitening
- Microabrasion
- Direct composite restorations
- crowns
