Bridges (fixed partial dentures) Flashcards
5 parts of planning for missing teeth (5)
Need a predictable and durable solution Consider the need for transitional restorations Build-in contingency planning High pt expectations Realistic tx plan
Restorative options for replacing missing teeth (3)
RPD -tooth supported partial denture -removed and replaced by pt Bridges -conventional bridge -permanently retained by other teeth -cannot be removed by denture Implants
Describe removable partial dentures (4)
Replace whole dento-alveolar complex
Non destructive
Fully reversive
Effective permanent or transitional option
Describe implants (3)
Replace teeth
Can replace bone/ soft tissue with grafts
Surgical option with higher morbidity
Success rate for implants (1)
predictable >90%
What do bridges replace? (1)
Teeth only
Prognosis of bridges (2)
Destructive
Unpredictable long-term prognosis
Design of choice for bridges (1)
Single-unit adhesive cantilevered
Clinical examination for replacing missing teeth (7)
Occlusal relationship - guidance? Inter-occlusal space Centre line Lip smile line Position of teeth present Shape and position of potential abutments Restorative and vitality status of teeth
Radiographic examination for replacing missing teeth (+ study models + vitality tests) (6)
Position of normal anatomical features Pathological conditions Periapical status of abutment teeth Alveolar support of abutment teeth Root remnants and foreign bodies Alveolar height and width
Using panoramic radiograph vs intra-oral periapical to examine missing teeth (5)
Panoramic radiograph -distortion in the horizontal plane -shadowing of incisor region Intra-oral periapical better -using paralleling technique -to check individual teeth -to assess alveolar bone width
Aspects of design criteria (10)
- Periodontal support
- abutment teeth need to have adequate bony support
- perio condition must be stable - Occlusal loading
- magnitude and direction of forces
- peeling effect if abutment is put under tensile load - Conservation of tooth tissue
- adhesive bridges important for this. Minimal or no reduction - Cleansability
- ensure we can use Tepes/ superfloss - Appearance
- esp. in anterior region. Greying of teeth with metal adhesive section - Rigidity (of retainer/ connector)
- reduce flexion - Quality of abutments
- endo, heavily restored not good choices - Number of abutments
- Choice of adhesive lute
- can’t use luting cement for adhesive bridges - Contingency planning
Retention of bridges is achieved by (4)
Full coverage retainers
-prep of abutment tooth is a FGC, PFM or all-ceramic
Adhesive retainers
-prep of abutment tooth is minimal and involves palatal and proximal surfaces only
Use of fixed-fixed abutments (1)
The bridge spans from one abutment to another with the pontic in between
Abutment-pontic-abutment
Use of cantilevered abutments (1)
The bridge is retained by one abutment only
Abutment-pontic
Periodontal support (3)
Perio disease history not so important
Current and future periodontal health are critical
Maintenance of periodontal health
Types of occlusal loading (6)
Functional Para-functional loads Lateral excursive movements -canine guidance -group function -interferences
Metals used for bridges (3)
All cast metal -base metal or (better) 60% gold All ceramic -zirconia, lithium disilicate Metal-ceramic
Choice of abutments depends on (4)
Tooth position
Crown shape
Restorative status
Endodontic status
Poor abutment teeth (3)
Maxillary lateral incisors
Tilted incisor teeth (unfavourable pulp chamber morphology)
Root-filled teeth
What is the bridge design of choice and why? (6)
Single tooth, fixed-cantilevered
-e.g. upper lateral cantilevered off a canine
More retentive than fixed-fixed counterparts
Pontic allowed to move with abutment
Reduced shear forces on pontic
Debond leads to cleansable surfaces
Risk of caries eliminated
Describe best case for adhesive bridges (3)
Single tooth replacement
Fixed to only one carefully selected abutment
Cantilevered
Framework design for adhesive bridges (6)
Retainer thickness and configuration Bonding area: maximise Wrap-around Occlusal extension of metalwork (e.g. on premolars) Connector design Length of span
Retainer thickness and configuration (2)
Retainers for molars 0.8mm thick
Greater if retainer not joined over occlusal surface
-thickness provides rigidity
Bonding area (2)
Maximum enamel bonding
Extension of metal work as far occlusogingivally and circumferentially around tooth as is possible
-downside is metal shine through
Wrap-around maximum (1)
180 degrees
-mesial and distal groove
Occlusal / palatal extension of metalwork (3)
- Full palatal coverage with no tooth prep (maximise SA/ minimise prep)
- Reduced palatal coverage with tooth prep (finish 1-3mm short of incisal edge)
Posterior occlusal coverage to
-resist displacement apically or laterally
-increase rigidity of framework
-greater surface area for bonding
Connector design (4)
Significant width and height required
Need to resist bending of alloy
Must avoid putting adhesive lute under tensile loading
Height of connector at least 50% height of pontic
Length of span (2)
Ideally one tooth replacement
Longer spans not contra-indicated but tooth prep and framework design should be planned to reduce potential debonding stresses on retainer
Tooth prep features (5)
Axial tooth prep Grooves Occlusal rest seats Intracoronal prep Cantilevered resin bonded bridges
Axial tooth prep (3)
Increases area for bonding
Increases resistance and retention form
Minimal reduction with chamfer finish
Grooves (4)
Provide > resistance form to lateral displacement
May help > retention form
> structural rigidity of metal framework after cementation
Use of 2 grooves (1mm deep) per abutment significantly > resistance to debonding forces for both anterior and posterior bridges
Occlusal rest seats (3)
Allow transmission of occlusal forces along long axis of tooth
Provide resistance form
Possibly limit shear forces to cement lute
Intracoronal prep (3)
Joining of mesial and distal rest seats of retainer over occlusal surface to form occlusal bar to improve rigidity of retainer
Enhances retainer’s resistance to deformation
Improves resistance form and increase SA for bonding
What cements to use (4)
Always use an adhesive lute
Self-cure composite lute (e.g. RelyX Unicem)
-non adhesive
-REQUIRES: in combination with bonding system
-requires etched metal substrate
Anaerobic adhesive lutes - Panavia
-opaque
-specific adhesion to metal retainers
4-Meta adhesive lutes (methacylate based e.g. Calebra?)
-specific bonding to metal and ceramic retainers
Types of alloys for adhesive bridges (3)
Nickel chromium (cheap! so very common) -can be electrolytically etched -very rigid -work very well with composite luting systems Gold alloys -cannot be etched -not as rigid as Ni/Cr -need sandblasting -need specific adhesive systems Ceramics (e.g. Zirconia, lithium disilicate) -experimental -more aesthetic
Survival of metal vs non-metal framework - 5-year (2)
Metal framework 88%
Non-metal framework 84%
Choice of abutments for adhesive bridges (4)
Tooth position
Crown shape
Restorative status
Endodontic status
Quality of adhesive bridge abutments depends on (5)
Endodontic status and prognosis -elective endo not unheard of Restorative status -if heavily restored, maybe conventional bridge better Quality of bonding substrate Anatomical shape Retention/ resistance form
Poor abutment teeth for adhesive bridges (3)
Maxillary lateral incisors
Tilted incisor teeth
Root-filled teeth (not never, but best avoid - dry, brittle, prone to fracture)
Resin bonded bridges 5 year survival (1)
88%
Pjetersson et al SR 2008
Reasons for failure of resin bonded bridges (3)
Debonding -failure of bond -lack of rigidity leading to a "peel effect" Caries under retainer Aesthetic failure -show through of retainer
What are double abutments for adhesive bridges? (2)
2 adjacent teeth as abutments - NOT required
What are fixed-fixed adhesive bridges? (3)
Adhesive retainers with intermediate pontics
Generally not recommended
Only exception is the mandibular incisors, where the ‘peel-dislodgement’ effect is less
Minimal palatal and proximal preparation of two abutment teeth
What’s better, cantilevered RBB or fixed-fixed RBB (2)
Cantilevered siginificantly better success
Reason - debond of fixed-fixed
Why do fixed-fixed adhesive bridges fail? (4)
Significant stresses applied to retainers of fixed-fixed resin-bonded bridges because of differential tooth movements between abutments during functional and parafunctional tooth contacts
These forces tend to push one of the abutments away from the pontic
Tensile stress of the cement
Debonding of an abutment and caries under the retainer
Which patients are most suitable for adhesive bridges? (1)
Fairly intact dental arches: only 1 or 2 missing teeth, don’t want to resort to an RPD
Case selection v important
Adhesive bridges synonyms (4)
Resin-bonded bridges
Bonded bridges
Maryland bridges
Rochette bridges
Fixed partial denture =
Conventional bridge work
