Bridgework 2 Flashcards
Local indications for bridgework
big teeth
heavily restored teeth
favourable abutment angulations
favourable occlusion
General contra-indications for bridgework
uncooperative patient
medical history contraindications
poor oh
high caries rate
periodontal disease
large pulps (conventional bridge as lots of tooth prep)
Local contra-indicaitons for bridgework
high possibility of further tooth loss within arch
prognosis of abutment poor
length of span too great
ridge form and tissue loss
tilting and rotation of teeth
degree of restoration
periapical status
periodontal status
types of bridges with conventional component
fixed-fixed
fixed cantilever
fixed-moveable
hybrid bridge (conventional +adhesive retainer)
spring cantilever
Replacing 12,11,21,22 (quite a big span - unusual)
abutments 13 and 23
can do although depends on occlusal relationship - class 2 ok due to less occlusal contact, also in AOB patients ok
advantages of fixed-fixed
robust design
maximum retention and strength (mechanical retention and bond with luting cement)
abutment teeth splinted together? (perio cases with mobile teeth as long as stable)
can be used in longer spans
lab construction straightforward
disadvantages of fixed-fixed
preparation difficult (parallel tooth preparations needed)
preparation must be minimally tapered
common path of insertion for abutments
removal of tooth tissue (danger to pulp)
what are the problems when abutment teeth are not parallel
8 has overhanging ridge so won’t fit
7 and 5 have different paths of insertion
describe a cantilever bridge
bridge provides support for the pontic at one end only
can be conventional/crown retainer or adhesive/resin retained (metal wing)
nb the pontic may be connected to one or more retainers
e.g. (retainer)-(pontic)
Advantages of conventional cantilever bridge
- conservative design (just one crown retainer)
- lab construction straightforward
-no need to ensure multiple tooth preparations are parallel
Disadvantages of conventional cantilever bridge
- short span only
- rigid to avoid distortion (fracture more likely)
- mesial cantilever preferred (otherwise get see-saw effect)
A potential solution to fixed-fixed designs when abutment teeth are not parallel?
Fixed movable bridge
- This type of bridge has a rigid connector usually at the distal end of the Pontic and a moveable connector mesially.
-allows some vertical movement at the mesial abutment tooth
Advantages of conventional fixed-moveable bridge
- preparations don’t require a common path of insertion (so can be more conservative)
- each preparation designed to be retentive independent of others
- more conservative of tooth tissue
- allows minor tooth movement
- may be cemented in two parts
Disadvantages of conventional fixed moveable bridge
- length of span limited
- lab construction more complicated
- possible difficulty in cleaning beneath moveable joint
- can’t construct provisional bridge
What is a hybrid bridge
- one retainer = conventional preparation
- other retainer = minimal preparation
(Adhesive/resin retained/resin bonded)
Nb pretty rare
What is a spring cantilever bridge
Very rare
One Pontic attached to the end of a metal arm that runs across the palate to a rigid connector on the palatial side of a retainer
Advantages to conventional spring cantilever bridge
- useful if spacing present between upper incisors
- where adjacent teeth are unrestored
- where a posterior tooth would provide a suitable abutment (ie already has a crown/large direct restoration)
Disadvantages to conventional spring cantilever bridge
- can only be used to replace upper incisor teeth
- difficult to clean beneath palatial connector
- may irritate the palatal mucosa
- difficult to control movement of Pontic, due to springiness of metal arm and displacement of palatal soft tissues
What would you consider when evaluating abutments
- Must be able to withstand the forces previously directed to the missing teeth
- Supporting tissues should be healthy and free of inflammation i.e. periapical disease and periodontal disease
- Crown to root ratio - length of tooth coronal to alveolar crest compared to length of root embedded in bone. Optimum ratio 2:3, minimum ratio 1:1 (ideally more root than crown)
What is the optimum crown to root ratio of an abutment tooth
2:3
What is the minimum crown to root ratio for an abutment tooth
1:1
