FIXED PROS - Resin Retained Bridges

Question 1

what is a bridge?

Answer 1

a prosthesis cemented to teeth or implants to replace one or more missing teeth

Question 2

describe the terminologies of a: abutment tooth, saddle, retainer, pontic and connector

Answer 2

abutment tooth = the tooth used to hold the false tooth

saddle = the missing gap

retainer = what is fixed to the tooth to hold the bridge

pontic = the fake tooth replacing the missing

connector = the metal in the middle connecting them all

Question 3

describe the difference between a cantilever and a fixed-fixed bridge.

Answer 3

cantilever = bridge is attached to one abutment tooth only

fixed-fixed bridge = the bridge is attached to 2 abutment teeth - on both sides

Question 4

why would a fixed-fixed bridge be used?

Answer 4

for strength as it can rely on two teeth

Question 5

disadvantage of using a fixed-fixed bridge.

Answer 5

• have to prepare two teeth = removing more natural tooth tissue
• if one side fails, might not know until later

Question 6

how are bridges classified?

Answer 6

by material, design and retention

Question 7

describe the classification of bridges.

Answer 7

material
- all ceramic
- metal-ceramic
- all metal

design
- cantilever
- fixed-fixed
- not used now - fixed movable, spring cantilever

retention
- conventional crown
- resin retained adhesion

Question 8

describe why conventional crown bridges may be used.

Answer 8

• good for replacing a small number of teeth
• when the abutment teeth would also benefit from being crowned

Question 9

how are bridges made?

Answer 9

• take wax pattern
• wax converted to metal by lost wax technique
• porcelain added over

Question 10

5 advantages of resin based bridges

Answer 10

1. rarely require LA
2. minium tooth prep
3. good gingival margins
4. simple impressions
5. cheaper than conventional bridge

Question 11

3 disadvantages of RBB

Answer 11

1. metal can cause dark, grey tooth
2. lower longevity than conventional
3. only one tooth per bridge

Question 12

survival of RBB?

Answer 12

7.8 years

Question 13

success rate of RBB in uppers and lowers, explain why?

Answer 13

uppers - 77%
lowers - 47%

uppers have easier moisture control

Question 14

what is the biggest cause of failure for RBB?

Answer 14

debonding = 16.7% of failures

Question 15

why may a RBB debond? - theres 2 types of failures depending on when it may happen.

Answer 15

early adhesion failure
- poor moisture control
- contamination
- inadequate enamel to bond to (SA)
- abutment tooth has existing restoration

late adhesion failure
- peel failure

Question 16

what is peel failure?

Answer 16

classes as a late adhesion failure for RBB
- if the metal wing is made too thin
- force makes the metal bend and distort
- bridge fails

Question 17

to avoid peel failure, how thick must the metal be?

Answer 17

0.7mm minimum

Question 18

what is the biggest concern with RBB debonding on one side?

Answer 18

failure can go unhidden
- caries can occur

Question 19

what bridge design has the best survival rate? how long?

Answer 19

cantilever - fixed one side
9.8 years

Question 20

when may you use a RBB?

Answer 20

• single tooth space
• patient is motivated with OH
• abutment tooth is suitable - no restorations, enough SA
• if implant isn’t preferred

Question 21

regarding failure, how much more likely is a fixed-fixed design to fail rather than a cantilever?

Answer 21

x2
x3 if there is already a restoration

Question 22

steps of placing a bridge.

Answer 22

1. patient assessment
   - good OH, motivated, access, adequate enamel
2. abutment selection
   - SA, existing restorations, vitality - PA radiographs
3. design and material selection
   - prefer cantilever
   - 0.7mm thickness
4. tooth prep
   - minimal
   - path of insertion in enamel
   - no undercuts
5. impressions
   - both full arches
   - silicone or digital
   - alginate occlusal
6. cementing
   - clean with pumice - SA
   - dry
   - etch, bond, cement