FIXED PROS - Conventional Bridges

Question 1

define a fixed dental prosthesis.

Answer 1

any dental prothesis that is luted, screwed or mechanically attached to natural teeth, tooth roots and/or dental implant abutments

Question 2

what are the 3 components of a fixed bridge?

Answer 2

abutment - the teeth/implant
pontic - the artificial tooth
retainer - the component over the abutment tooth e.g. crown

Question 3

describe abutments.

Answer 3

can either be single - cantilever fixed bridge
or double - fixed-fixed bridge

= directly receives the pressure

Question 4

what are the 3 pontic designs, describe each

Answer 4

modified ridge lap - common

ovate - sinks the convex surface of porcelain into the mucosa
- most aesthetic, mainly anterior teeth

sanitary - allows space under pontic for cleaning

Question 5

what does an ovate pontic require?

Answer 5

electrosurgery to prepare the site and an impression taken before fitting the prosthesis

Question 6

describe a conventional fixed-fixed bridge

Answer 6

pontic is retained via 2 abutments

Question 7

describe a conventional cantilever bridge.

Answer 7

pontic is retained via crown, inlay or onlay

Question 8

what are the indications for bridgework?

Answer 8

• heavily restored abutments
• well motivated patient with good OH
• no active caries
• stable periodontium
• small edentulous spaces

Question 9

when would you not place a bridge?

Answer 9

• unrestored abutments
• poor motivation
• active caries or periodontitis
• poor manual dexterity to clean
• large edentulous spaces
• contact sports player

Question 10

which 3 teeth make ideal bridge abutments?

Answer 10

1’s
3’s
6’s

• best for them to have long roots or multi roots as it takes the pressure/load

Question 11

describe a resin retained bridge

Answer 11

pontic is retained via metal retainer cemented to the abutment

Question 12

why is it advised for RBB to have no prep/minimal preparation

Answer 12

allow max bonding to enamel layer
- shown to be superior for longevity

Question 13

give some design features for RBB for the abutment teeth

Answer 13

• minimal/no preparation
• cover maximal surface
• metal wing retainer needs to be 0.7-0.8mm thickness

Question 14

is it okay if RBB are a bit high, letting posterior teeth to over erupt

Answer 14

yes, to maximise retention for the bridge

Question 15

with RBB, what design should be avoided and why

Answer 15

a fixed-fixed bridge

fail at the wing tooth interface
theres a gap
allows space for caries to develop

when its failed you cant tell straight away because its attached to the other side

Question 16

describe a cantilever bridge

Answer 16

there is only one abutment tooth

Question 17

what are the steps of making conventional bridges?

Answer 17

• primary impression
• diagnostic wax up on study model
• prepare abutment
• silicon impression
• temporisation
• bridge construction on an articulator
• occlusion checked
• bridge trialled and cemented

Question 18

what should be regarded with the metal wing?

Answer 18

it may show through the abutment

may want to use a thicker opaque cement

Question 19

how is the pontic occlusion checked?

Answer 19

with high contact in ICP and no contact with lateral movements

Question 20

what are the long term complications of fixed fixed bridges?

Answer 20

38% caries risk
32% endo risk

Question 21

what is the survival rate of conventional cantilevers at 5 years and then at 10 years?

Answer 21

5 years - 91%
10 years - 81.8%

Question 22

what is the survival rate of resin retained cantilevers at 5 years and then at 10 years?

Answer 22

5 years - 80.8%
10 years - 80.4%

Question 23

what is the survival rate of conventional fixed fixed bridge at 5 years and then at 10 years?

Answer 23

5 years - 94%
10 years - 92%

Question 24

what are the differences between a RBB and a cantilever?

Answer 24

1. design
   - RBB - pontic held in place by wings
   - cantilever - pontic attached to one abutment
2. strength
   - RBB - relies on bond strength
   - cantilever - relies on abutment
3. preparation
   - RBB - minimal tooth prep
   - cantilever - prep required

Question 25

disadvantages of fixed fixed

Answer 25

• cementation problems - must be inserted in one piece
• paralleling can be difficult if the gap is big
• both preps ar major retainers - lots of healthy tooth loss

Question 26

advantages of fixed fixed

Answer 26

very practical
lots of support
robust design

Question 27

disadvantage of cantilever

Answer 27

• only one bridge to 1 pntic
• torquing forces must not act on the pontic

Question 28

2 types of cantilevers.

Answer 28

adhesive with wings+bond
conventional

Question 29

why do you want the pontic to have light contact, but no lateral or protrusive contact?

Answer 29

light contact will appear a natural tooth

if the pontic undergoes extra forces, the pontic will shorten and damage the aesthetics

Question 30

do cantilevers require more SA?

Answer 30

yes

Question 31

what should be on the lab prescription? (5)

Answer 31

seating
extent of wing coverage
pontic design
shade mapping
surface texture