Bridgework 2 Flashcards
What are the different types of conventional bridges?
Fixed-Fixed
Fixed Cantilever
Fixed Moveable
Hybrid- fixed retainer And adhesive retainer
Spring cantilever
What is a fixed-fixed bridge?
This type of bridge has a retainer at each end with a pontic in the middle joined by rigid connectors- can be all ceramic or metal/ceramic
E.g. (Retainer)-(pontic)-(Retainer)
What are the advantages of a conventional fixed-fixed bridge design?
Robust design- larger connectors to withstand occlusal forces
Maximum retention (chemical and mechanical) and strength
Abutment teeth splinted together -Perio cases with mobile teeth
Can be used in longer spans
Laboratory construction straightforward
Why are longer spans more achievable in patients with Class II or AOB?
Low levels of occlusal force on bridge due to minimal if any contact
-> Biting on pontics makes bridge more likely to fail
What are the disadvantages of conventional fixed-fixed design?
Preparation difficult- parallel tooth preparations needed to create single POI
Preparation must be minimally tapered (5-7 degrees is ideal)
Common path of insertion for abutments
Removal of tooth tissue (danger to pulp)
What is a cantilever bridge?
Bridge that provide support for Pontic at one end only
-> there is no retainer on other side of Pontic
What are the types of cantilever bridge
Conventional/crown retainer OR
Adhesive/resin retained – metal wing
What are the advantages of Cantilevers?
Conservative design- Compared to fixed-fixed conventional design
Laboratory construction straightforward
No need to ensure multiple tooth preparations are parallel
What are the disadvantages of Cantilevers?
Short span only
Rigid to avoid distortion- fracture risk
Mesial cantilever preferred- pontic tooth is more anterior
When may a distal cantilever be used?
Missing teeth
SDA
When would a fixed moveable bridge be used?
If abutment teeth aren’t parallel (different POIs)
How does a fixed-moveable bridge work?
A slot is made on the crown of distal marginal ridge of anterior tooth (female component), the pontic that is attached to the posterior crown has a male component which slots into the female component
What are the features of fixed-moveable bridges?
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
What are the advantages of fixed-moveable bridges?
Preparations don’t require a common path of insertion
Each preparation designed to be retentive independent of others
More conservative of tooth tissue
Allows minor tooth movement
May be cemented in two parts
What are the disadvantages of FM bridges?
Length of span limited- only used to replace one tooth
Laboratory construction more complicated
Possible difficulty in cleaning beneath moveable joint
Can’t construct provisional bridge- would need to accept space or provide denture/essix retainer
What is a hybrid bridge?
One retainer = “Conventional” preparation
Other retainer = minimal preparation
(Adhesive /Resin retained/Resin bonded)
Why are hybrid bridges considered obsolete?
metal adhesive wing is more likely to debond resulting in undetected leakage and caries
What is a spring cantilever?
One pontic attached to the end of a metal arm that runs across the palate to a rigid connector on a posterior retainer
-> adhesive preferred now
What are the advantages of SC?
Useful if spacing present between upper incisors
Where adjacent teeth are unrestored
Where a posterior tooth would provide a suitable abutment (i.e. already has a crown/large direct restoration)
What are the disadvantages of SC?
Can only be used to replace upper incisor teeth
Difficult to clean beneath palatal connector
May irritate the palatal mucosa- mucositis
Difficult to control movement of pontic, due to springiness of metal arm and displacement of palatal soft tissues
What are the requirements for abutment teeth?
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, but Minimum ratio 1:1)
