Treatment Planning for Fixed Pros

Question 1

indications for crowns

Answer 1

protect weakened structure
improve/restore aesthetics
retainer for bridgework
when indicated by RPD design
restore tooth function

Question 2

contraindications for crowns

Answer 2

active caries/perio
more conservative options available
lack of tooth tissue for prep
unable to provide post and core
unfavourable occlusion

Question 3

principles for crowns preparation

Answer 3

1. preservation of tooth structure
2. retention and resistance
3. structural durability
4. marginal integrity
5. preservation of periodontium
6. aesthetic considerations

Question 4

preservation of tooth structure considerations in crowns

Answer 4

avoid weakening, damaging pulp

under prep = poor aesthetics, overbuilt crowns with perio/occlusal consequences, insufficient thickness of restoration

over prep = pulp and tooth strength compromised

Question 5

why retention in crowns

Answer 5

prevents removal of restoration along path of insertion or long axis of tooth

Question 6

why resistance in crowns

Answer 6

prevents dislodgement of restoration by forces directed in apical or oblique directions and prevents any movement of restoration under occlusal forces

taper [inclination of opposing walls 6-10*]
length of walls [longer to sto stop tipping displacement]
path of insertion [limit to one]
extra means of retention [grooves, slots]

Question 7

structural durability considerations in crowns

Answer 7

need bulk of material that can withstand occlusal forces

achieved via occlusal/axial reduction, functional cusp bevel

Question 8

marginal integrity considerations in crowns

Answer 8

finish line configurations -

knife edge, bevel, chamfer, shoulder

Question 9

preservation of periodontium considerations in crowns

Answer 9

margins should be-

smooth and fully exposed to cleaning action
placed where dentist can finish them and pt can clean
placed supragingival or at margin

Question 10

bridgework
occlusal stability and functional reasons

Answer 10

prevent tilting/overeruption of adjacent and opposing teeth

mastication, speech, wind instrument players

Question 11

why would you not replace teeth

Answer 11

damage to tooth/pulp
secondary caries
effect of periodontium
cost
failure

Question 12

types of bridges

Answer 12

cantilever
fixed boned