Contra-indications for bridgework (local factors)
- Poor prognosis abutment teeth
- High possibility of further tooth loss within arch
- Tilting and rotation of teeth
- Degree of restoration (how much tooth is left after preparation)
- Peri-apical status
- Periodontal condition - bone loss
- Length of span too great/ long
- Ridge form and tissue loss - denture would be better in this area
Indications for bridgework - LOCAL
- Big teeth- large SA
- Heavily restored teeth - if you are going to crown teeth anyway – indication for conventional bridge.
- Favourable abutment angulations
- Favourable occlusion
Indications for bridgework - general
- Co-operative patient
- Restore funcitonal stability
- Appearance
- Systemic disease - epileptics - better to have retained restorative work in case of seizure.
Advantages of resin bonded bridge
Minimal or no preparation
No anaesthetic needed
Less costly
Less surgery time
Can be used as a provisional restoration
If fails - usually less destructive than alternatives
Disadvantages of resin bonded bridges
Rigorous clinical technique
Metal shine-through
Chipping porcelain
Can de-bond - then high chance of it debonding again
Occlusal interferences
No trial period possible
Indications for RBB
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 RBB
Insufficient or poor quality enamel
Long spans- large edentulous areas
Excess soft or hard tissue loss
Heavy occlusal force e.g. Bruxist
Poorly aligned, tilted or spaced teeth
Conventional fixed-fixed bridge ADVANTAGES
- Robust design
- Max. retention an strength
- Can splint abutment teeth together?
- Can be used in longer spans
- Lab construction straightforward
Conventional fixed-fixed bridge DISADVANTAGES
- Preparation difficult (parallel tooth preparations needed)
- Preparation must be minimally tapered
- Common path of insertion for abutments
- Removal of tooth tissue (danger to pulp)
Conventional cantilever bridge ADVANTAGES
- Conservative design - compared to fixed-fixed conventional design
- Lab construction straightforward
- No need to ensure multiple tooth preparations are parallel
Conventional fixed-moveable bridge ADVANTAGES
- Preparations don’t require a common path of insertion
- Each prep designed to be retentive independent of others
- More conservative of tooth tissue
- Allows minor tooth movement
- May be cemented in two parts
Conventional fixed-moveable bridge DISADVANTAGES
- Length of span limited
- Lab construction more complicated
- Possible difficulty in cleaning beneath moveable joint
- Can’t construct provisional bridge
Requirements for a good abutment tooth (long things)
- good quality enamel
- Must be able to withstand the forces previously directed to the missing tooth
- Supporting tissues should be healthy and free of inflammation
- Crown to root ratio- Optimum ratio 2:3. Minimum ratio 1:1.
What is the ridge surface like in a dome-shaped pontic and when would it be used?
Useful in lower incisor, premolar or upper molar areas.
Shaped like a dome and touched ridge surface.
Acceptable if occlusal 2/3 of buccal surface visible - poor aesthetics if gingival 1/3 of tooth visible.
What is the ridge surface like on a “wash-through” pontic?
Makes no contact with soft tissue - functional rather than for appearance.
Consider in lower molar areas.
What 3 things do you need to consider in pontic design?
Cleansability - should be smooth and highly polished. Should not harbour join of metal and porcelain
Appearance
Strength
What is the function of a pontic?
Restore appearance of missing tooth
Stabilise occlusion
Improve masticatory function
What to evaluate about potential abutments?
- Root configuration
- Angulation/ rotation of abutment
- Periodontal health
- SA for bonding and quality of enamel
- Risk of pulpal damage
- Quality of endo treatment if applicable
- Remaining tooth structure present
What is a problem with modified ridge lap pontic design?
Problem with food packing on lingual surface of ridge.
What is the benefit of parallelism in fixed-fixed conventional bridge?
INCREASED RETENTION
Requires 2 or more teeth to be prepped in a manner to provide a common path of insertion
What should be considered in conventional bridgework prep to add retention in short clinical crowns?
Consider adding slots or grooves.
What cement should be used for metal conventional and metal ceramic bridgework definitive?
GI luting cement - aquacem
RMGI luting cement - relyX
What cement should be used for adhesive/ resin bonded/ RRB and all ceramic bridgework definitive?
Dual-cure resin cement e.g. Nexus 3
Why are distal cantilevers less preferable than mesial cantilevers?
When teeth occlude, they are more likely to contact teeth DISTALLY first.
If pontic is more distal, more likely to contact this first - you would get see-saw effect - bridge is more likely to lift up and fail.
