Bridgework Flashcards
why is cantilever bridges preferred in anterior teeth
anterior teeth have divergent guidance paths and the longitudanal pathways of teeth are all different along the arch
If a fixed-fixed bridge was placed there would be two different occlusal forces going in two different directions acting on it making it more likely to fail
what material should adhesive bridge retainer be
sandblasted CoCr or nickel chromium alloy
Aluminium oxide is used to sandblast
name a suitable luting agent for cementing a bridge with metal ceramic retainers
anaerobic dual cure composite luting cement with 10 MDP e.g panavia 21
10 MDP helps stick to metal
advantages of fixed fixed conventional bridges
robust
maximum retention
abutment teeth splinted together
more suitable for longer spans
disadvantages of fixed fixed conventional bridges
preparation difficult - parallel tooth prep needed to achieve common POI
destructive
preparation must be minimally tapered to prevent reduced retention
advantages of conventional cantilever bridge in comparison to fixed fixed
no need to ensure tooth preps are parallel
more conservative
disadvantages of conventional cantilever bridge
short spans only
rigid to avoid distortion makes them more prone to fracture
mesial cantilever only not distal
why is mesial cantilever preferred to distal cantilever
i.e abutment tooth more posterior
when patients occlude, more likely to occlude posterior teeth first. If pontic was distal, occlusal forces on pontic will produce leverage forces on abutment tooth causing it to tilt
what is a fixed moveable bridge
rigid connector at distal end and moveable connector mesially
Both abutment teeth crown prepped, mesial abutment has crown fitted with notch for subsequent bridge
Bridge has attachment to lock into mesial abutment as well as distal retainer
sees slight degree of movement at mesial abutment tooth
when may a fixed moveable bridge be useful
if abutment teeth cant have parallel preparations or it will be very difficult to achieve this
what is a hybrid bridge
one retainer is conventional preparation and the other is adhesive
Rarely used as adhesive likely to debond first and see extensive caries on palatal surface of tooth below detached wing
what is a spring cantilever bridge
rarely used nowadays
one pontic attached to the end of a metal arm that runs across the palate to a rigid connecter on the palatal side of a retainer
Idea was to preserve unrestored anterior tooth tissue and make use of an already restored posterior tooth
why are spring cantilever bridges very rarely used
difficult to keep mucosa under arm clean
arm may irritate palatal mucosa
Can be difficult to control movement of pontic due to springiness of arm and displacement of palatal soft tissues
minimum crown to root ratio for a bridge abutment
1:1
embedded root in bone : crown
wash through pontic
no contact with soft tissues of ridge
Gives additional occlusal surface to bite however poor aesthetics
easy to clean
may be used in lower molar region
