Resin retained bridges

Question 1

how many sides are bonded in RR bridges? explain why

Answer 1

only one side retained by resin
if both sides were retained by resin one side would debond

Question 2

explain the rochette bridge desin - what is it used for today? what has it shown adv over?

Answer 2

RR bridge with countersunk holes through the metal retainers to give mechanical retention to the resin

used for temporary bridges today - not permanent

has shown adv over partial denture for provisionally replacing missing teeth

Question 3

explain the Maryland design

Answer 3

inner surface of metal alloy retainer is electrolytically etched in a bath of strong acid solution

Question 4

what is done to RR bridges at the try in stage? what resin is used and why?

Answer 4

metal retainer is sandblasted at try in w/ alumina particles of 50 micometre diameter

panavia resin is used as it bonds metal retainer to etched enamel

Question 5

Panavia - another name, how many cures, thickness, solubility, what component allows bonding to metal and enamel?

Answer 5

Kuraray
2 cures
thin - allows you to place retainer close to tooth and will not add to bulk
insoluble
MDP (phosphate monomer) allows bonding to enamel, dentine and metal alloys

Question 6

give 3 requirements for resin retained bridges

Answer 6

wing retainer must be rigid - made from metal or impregnanted resin
wing must fit close to the abutment
porcelain must be fused to metal

Question 7

list some indications for RR bridges

Answer 7

unrestored/minimally retsored abutments
good amount and quality of enamel on abutment
good interocclusal space
good alveolar bone shape - if lots of resorption denture may be better
should only replace 1 tooth (should not be more than 1 unit and wing)

Question 8

how does failure rate of fixed-fixed RR bridge compare to cantilever RR bridge?

Answer 8

Fixed-fixed failure rate nearly twice as high of cantilever

Question 9

what tooth prep should be done on abutment for RR bridge?

Answer 9

none
minimal
slots

Question 10

what tooth prep is done at DDH for RR bridge?

Answer 10

1. cingulum rest seat
2. sometimes gingival finish line - cervical chamfer
3. remove undecruts - removing convexity of molars
4. occlusal rest seats

Question 11

is LA required for RR bridge prep?

Answer 11

no as just enamel being cut

Question 12

why is good moisture control required for RR bridge seating?

Answer 12

as cementing involves etching and panavia resin