Bridges Flashcards
tooth replacement options
bridge
implant
RPD
indication for bridgework
Function and stability Appearance Speech Psychological reasons Systemic disease e.g. epileptics Co-operative patient Big teeth Heavily restored teeth Favourable abutment angulations Favourable occlusion
contraind of bridgework
Uncooperative patient Medical history contra-indications Poor oral hygiene High caries rate Periodontal disease Large pulps High possibility of further tooth loss within arch Prognosis of abutment poor Length of span too great Ridge form and tissue loss Surface area of root insufficient tilting/rotation of teeth poor periodontal condition
name some type of bridge designs
Fixed-fixed bridge Cantilever bridge •Conventional (Fixed) •Adhesive/resin retained Fixed-moveable bridge Hybrid bridge •Fixed retainer and adhesive retainer Spring cantilever bridge
ADV of fixed-fixed design
Robust design Maximum retention and strength Abutment teeth splinted together ? (Perio) Can be used in a long span Laboratory construction straightforward
DIS of fixed-fixed design
- Need parallel prep
- Extensive tooth destruction
- Need minimal taper
- common POI needed
ADV of conventional cantilever
Conservative design
•Compared to fixed-fixed conventional design
Laboratory construction straightforward
No need to ensure preparations are parallel
DIS of conventional cantilever
Short span only
Rigid to avoid distortion
Mesialcantilever preferred?
important aspects of abutment evaluation
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.
oMinimum ratio 1:1
Root configuration
Root surface area (periodontal ligament area)
what is ante’s law
States that the root surface area of the abutment teeth should be equal or greater than that of the teeth being replaced with pontics.
ADV of Adhesive 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
DIS of Adhesive bridge
Uncertain longevity Rigorous clinical technique Metal shine-through Can debond •High chance of it debonding again Occlusal interferences No trial period possible
indication of adhesive bridgework
Young teeth Less destructive Good enamel quality Large abutment tooth surface area Minimal occlusal load Good for single tooth replacement Simplify partial denture design
contraind of Adhesive bridgework
Insufficient or poor quality enamel Long spans Excess soft or hard tissue loss Heavy occlusal force e.g. Bruxist Badly aligned, tilted or spaced teeth Contact sports?
Treatment planning for bridgework
History •Establish habits e.g. Bruxism Examination •Clinical oDynamic occlusal relationships •Periodontal •Radiological Study models •Mounted on semi-adjustable articulator with facebowregistration •Consider diagnostic wax-ups
RRB - direct vs Indirect
Direct •Very useful in emergency situation •If tooth needs to be extracted immediately •If tooth has been lost traumatically Indirect •No preparation •Minimal preparation •Heavy preparation (Undesirable
what happens to CoCr in order to make it more retentive
sandblasted with Aluminium oxide 50 microns
anterior prep for cantilever
180º ‘wrap-around’ preparation Rests •Rest seats (posterior teeth) •Cingulum rest (anterior teeth) Proximal grooves Supra-gingival chamfer finish line ~0.5mm Ideally prep should remain in enamel Cantilever design Chamfer preparation 0.5mm supra-gingival Cingulum rest Proximal grooves
Posterior prep - cantilever
Occlusal rests 180º wrap-around with chamfer finish line 0.5mm supra-gingival Proximal grooves Can be cantilever or fixed-fixed design
longevity
- cantilever
- fixed-fixed
27.88%failure rate 1-16 yrs •Djemal S et al.(1999) Overall survival after 4 years –79.6% Cantilever bridges had greater survival than other bridge designs Cantilever median survival: 9.8 yrs Fixed-fixed median survival: 7.8 yrs
Information for bridge prep
History •Presenting complaint •Medical and social history •Past dental history Clinical examination (Extra-and intra-oral) •Soft tissues •Periodontal •Caries risk assessment •Occlusion •Parafunction Abutment evaluation •Remaining tooth structure •Special tests oRadiographs
Abutment evaluation information
Root surface area and Crown-root ratio •Ante’s Law Root configuration Angulation/rotation of abutment Periodontal health Surface area for bonding & quality of enamel Risk of pulpal damage Quality of endodontics: •Re-root canal treatment? Remaining tooth structure present? Core •Remove and rebuild? Post & core •Remove and replace?
consideration for pontic design
Cleansability
•Should always be smooth, with highly polished or glazed surface
•Surface should not harbour join of metal and porcelain
•Embrasure space smooth and cleansable
Appearance
•Anteriorly:
oAs ‘tooth like’ as possible
•Posteriorly:
oMay compromise
Strength
•Longer the span -Greater the thickness required to withstand occlusal forces
wash through pontic design, considerations
Wash-through: (Hygienic or Sanitary)
•Makes no contact with soft tissue
oFunctional rather than for appearance
oConsider in lower molar area
types of pontic design
wash through
dome shaped
modified ridge lap
ridge lap/saddle
dome shaped design considerations
Dome-shaped: (Torpedo or Bullet-Shaped)
•Useful in lower incisor, premolar or upper molar areas
•Acceptable if occlusal 2/3 of buccal surface visable
oPoor aestheitcs if gingival 1/3 of tooth visable
modified ridge lap considerations
Modified ridge lap:
Buccal surface looks as much like tooth as possible
Lingual surface cut away
Line contact with buccal of ridge
Problems with food packing on lingual surface of ridge
ridge lap/saddle design considerations
Ridge lap/Saddle: Greatest contact with soft tissue If designed carefully: can be cleansed Less food packing than ridge-lap Care taken not to displace soft tissue or cause blanching of tissue
preparation stages for a bridge
- mounted study models/diagnostic wax up
- Select shade
Laboratory made stent or make pre-operative putty impression for provisional bridge
Occlusal or incisal reduction
Separation of teeth
Aim for parallelismof tapered surface of each preparation
•Example: Preparation of fixed-fixed bridge for 13 1211
oPrep mesial of 11, then mesial of 13
oPrep distal of 11, then distal of 13
oPrep labial (2-planes) of 11, then labial 13 …..etc - Confirm parallelism
Consider retentive features if short clinical crown height or overtapered
•Slots or
•Grooves
Construct provisional bridge
Make impression and occlusal registration
Temporarily cement provisional bridge
Demonstrate cleaning with Superfloss™
Write/draw prescription for technician
importance of parallelism
Consider for fixed-fixedconventional bridge
•Requires two or more teeth to be prepared in a manner to provide a common path of insertion
•No undercuts but to give retentive preparations
Paralleling by eye
•Direct vision, one-eye closed
•Large mouth mirror (posteriorly)
•Use of a straight (right angle) probe like a laboratory surveyor, but in the mouth
Extra-oral survey
•Quick impression
•Pour a model
•Use a laboratory surveyor; useful in long span multiple unit bridges
