Bridgework 2 Flashcards
adhesive cantilever bridge
most common is the porcelain pontic & retainer made from metal work; usually CoCr but can be NiCr
+ of adhesive cantilever bridge
- minimal / no prep
- no anaesthetic needed
- less costly
- less surgery time
- can be used as a provisional restoration
- if it fails, usually less destructive than alternatives
- can be used an interim if young pt who has hypodontia until they are older & more perm measures can be used
- of adhesive cantilever bridge
- rigorous clinical technique
- metal shine through
- can debond & if so high chance of recurrence
- occlusal interferences
- no trial period possible; only perm cement can be used
- moisture control essential as held in with composite
indications for adhesive cantilever bridge
- young teeth (less destructive)
- good enamel quality
- large abutment tooth surface area
- minimal occlusal load
- good for single tooth replacement
- simplify partial denture design
contraindications for adhesive cantilever bridge
- insufficient / poor enamel quality
- long span bridge
- excess soft or hard tissue loss
- heavy occlusal force e.g. bruxist
- poorly aligned, tilted or spaced teeth
txp of bridgework
- history - establish habits e.g. bruxism
- exam - dynamic occlusal relationship, periodontal, radiological
- study models - mount on semi adjustable articulator with facebow registration & consider diagnostic wax up
occlusal considerations
- consider opposing dentition e.g. contact points & overeruption of opposing teeth
- parafunction
- dynamic occlusal relationships; clinically, mounted study models & consider diagnostic wax ups
direct resin retained bridgework
very useful in emergency situation i.e. if tooth needs XLA immediately or if tooth lost traumatically
ideally want to use pt own tooth i.e. if root # cut off root & remove pulp chamber using remaining crown as pontic
also place some composite in contact points to retain pontic
not permanent solution but good interim
indirect resin retained bridgework
no prep / minimal prep
a heavy prep is undesirable as dentine doesn’t give as good a bond as enamel
palatal / lingual coverage of adhesive bridgework
need generous palatal / lingual coverage; greater surface area of enamel covered = greater bond
need good quality enamel
keep supra gingival; ideally 0.5mm
care with coverage near incisal edge as enamel is translucent and may get metal shine through
why is fixed fixed adhesive rarely used nowadays
if 1 wing debonds there is space for bacterial ingress but can be used for lower anteriors or for pt who has had ortho tx in the past
preparation of anterior & posterior
anterior = generally cantilever
posterior = generally fixed fixed
why are cantilevers more successful anteriorly
due to divergent guidance pathways;
when looking at arch form of maxilla, the longitudinal axis of the teeth are different to one another so the occlusal forces are directed down each of these teeth in a different way. if you place a FF bridge there are 2 different occlusal forces going in 2 different directions and as a result the restoration gets moved about more & is more likely to come off
if abutment tooth is already restored
ideally want sound enamel
if composite; this is okay but consider replacement prior to prep. new comp will bond better or can roughen surface to help resin cement stick better
if amalgam; compromised bond to chemically cured composite cement so consider replacing
prep for bridge
180 degrees wrap around prep
rest seats in posterior & cingulum rest in anterior
proximal grooves
supra gingival chamfer finish line ~ 0.5mm
ideally prep should remain within enamel
anterior prep for cantilever design
- no prep
- minimal prep - occlusal contact reduction, cingulum undercut removal only, chamfer margin 0.5mm supragingivally
- heavy prep - 0.5mm palatal reduction (retainer wing should be 0.7mm thick), cingulum rest, +/- proximal grooves, chamfer margin 0.5mm supragingival
posterior bridge work prep
- no prep
- prep - occlusal rests, 180 degree wrap around with chamfer finish line (o.5mm supragingival), +/- proximal grooves
this can be cantilever or FF
describe modern bridgework cantilever
NiCr alloy
must be sandblasted to help improve bond between restoration & tooth via micromechanical retention
Al2O3 50 microns
temporisation in bridgework
- consider RPD - essix retainer
- if prep remains in enamel consider if any need for temp
- if prep into dentine & tooth becomes sensitive prescribe duraphat / place thin layer of DBA on prepared tooth surface
- fit bridge as quick as possible to minimise over eruption & tooth movement
tx of retainer at cementation
try in for fit & aesthetics
*ask lab for try in cleat which can help you place it and get it back out
chairside microetching with 50 microns of Al2O3 but this should be done by lab
clean retainer - ultrasonic bath if required, use ethanol to degrease if required (reduced surface tension)
apply chemical / dual cure composite luting cement prior to placement after tooth tx
tx of tooth at cementation
prophylaxis
isolate with dam
etch with 37% orthophosphoric acid
wash & dry
apply primer for 30secs
air dry for 2 secs
final steps of cementation
fit adhesive bridge retainer coated with luting cement to abutment tooth
remove excess cement
oxygen inhibitor (oxyguard II) placed around cement margins for 3mins then washed off
post cementation
check occlusion - confirm pontic does not have excess occlusal forces applied
demonstrate to pt how to clean around & underneath bridge
what is used for cementation
dual cure composite luting cement Panavia
