FIXED PROS - Conventional Bridges Flashcards
define a fixed dental prosthesis.
any dental prothesis that is luted, screwed or mechanically attached to natural teeth, tooth roots and/or dental implant abutments
what are the 3 components of a fixed bridge?
abutment - the teeth/implant
pontic - the artificial tooth
retainer - the component over the abutment tooth e.g. crown
describe abutments.
can either be single - cantilever fixed bridge
or double - fixed-fixed bridge
= directly receives the pressure
what are the 3 pontic designs, describe each
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
what does an ovate pontic require?
electrosurgery to prepare the site and an impression taken before fitting the prosthesis
describe a conventional fixed-fixed bridge
pontic is retained via 2 abutments
describe a conventional cantilever bridge.
pontic is retained via crown, inlay or onlay
what are the indications for bridgework?
- heavily restored abutments
- well motivated patient with good OH
- no active caries
- stable periodontium
- small edentulous spaces
when would you not place a bridge?
- unrestored abutments
- poor motivation
- active caries or periodontitis
- poor manual dexterity to clean
- large edentulous spaces
- contact sports player
which 3 teeth make ideal bridge abutments?
1’s
3’s
6’s
- best for them to have long roots or multi roots as it takes the pressure/load
describe a resin retained bridge
pontic is retained via metal retainer cemented to the abutment
why is it advised for RBB to have no prep/minimal preparation
allow max bonding to enamel layer
- shown to be superior for longevity
give some design features for RBB for the abutment teeth
- minimal/no preparation
- cover maximal surface
- metal wing retainer needs to be 0.7-0.8mm thickness
is it okay if RBB are a bit high, letting posterior teeth to over erupt
yes, to maximise retention for the bridge
with RBB, what design should be avoided and why
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
describe a cantilever bridge
there is only one abutment tooth
what are the steps of making conventional bridges?
- primary impression
- diagnostic wax up on study model
- prepare abutment
- silicon impression
- temporisation
- bridge construction on an articulator
- occlusion checked
- bridge trialled and cemented
what should be regarded with the metal wing?
it may show through the abutment
may want to use a thicker opaque cement
how is the pontic occlusion checked?
with high contact in ICP and no contact with lateral movements
what are the long term complications of fixed fixed bridges?
38% caries risk
32% endo risk
what is the survival rate of conventional cantilevers at 5 years and then at 10 years?
5 years - 91%
10 years - 81.8%
what is the survival rate of resin retained cantilevers at 5 years and then at 10 years?
5 years - 80.8%
10 years - 80.4%
what is the survival rate of conventional fixed fixed bridge at 5 years and then at 10 years?
5 years - 94%
10 years - 92%
what are the differences between a RBB and a cantilever?
- design
- RBB - pontic held in place by wings
- cantilever - pontic attached to one abutment - strength
- RBB - relies on bond strength
- cantilever - relies on abutment - preparation
- RBB - minimal tooth prep
- cantilever - prep required
disadvantages of fixed fixed
- 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
advantages of fixed fixed
very practical
lots of support
robust design
disadvantage of cantilever
- only one bridge to 1 pntic
- torquing forces must not act on the pontic
2 types of cantilevers.
adhesive with wings+bond
conventional
why do you want the pontic to have light contact, but no lateral or protrusive contact?
light contact will appear a natural tooth
if the pontic undergoes extra forces, the pontic will shorten and damage the aesthetics
do cantilevers require more SA?
yes
what should be on the lab prescription? (5)
seating
extent of wing coverage
pontic design
shade mapping
surface texture
