it describes resin bonded fixed partial dentures in detail from a undergradute aspect.

1. RESIN BONDED FPD

2. Contents
• Introduction
• Indications and contraindications
• Advantages and disadvantages
• Classification
Mechanical (Rochette bridge)
Micromechanical (Maryland bridge)
Macromechanical
Chemical (adhesive bridges)
• Fabrication
Tooth preparation
Impressions and provisionals
Bonding
Maintenance and recall
Failures
• Conclusion
• Reference

3. Introduction
DEFINITION:
A fixed dental prosthesis that is luted to tooth structures, primarily enamel, which has
been etched to provide mechanical retention for the resin cement.(GTP8)
It is also termed as ‘adhesivebridge’.
First described by Rochette in 1973 (mandibular anterior teeth)
It involves replacing teeth by attaching pontics to thin metal retainers, which are
bonded to the palatal/ lingual surface of the abutments using resin cements

4. Indications and contraindications
INDICATIONS CONTRAINDICATIONS
1. Replacement of missing anteriors in
children and adolescents.
1. Insufficient occlusal clearance
2. Abutments with sufficient enamel to etch
for retention
2. When facial aesthetics of the teeth require
a change.
3. Short span bridges 3. Short clinical crown.
4. Splinting periodontally weak teeth 4. Thin anterior teeth faciolingually
5. Medically compromisedpatients 5. Deep vertical overlap
6. As a long term temporary restoration in
patients with craniofacial anomalies
6. Insufficient enamel availablefor bonding-
caries, restorations, hypoplasia
7. Postorthodontic retention 7. Parafunctinal habits
8. Long span bridges
9. Sensitivity to base metal alloys

5. Advantages and disadvantages
ADVANTAGES
1. Conservation of tooth structure, preparation is confinedto enamel.
2. Tolerant to tissues with no pulpal trauma and supragingival margins.
3. Anesthesianot required.
4. Impression making is easy.
5. Provisional restorations are not required.
6. Less chairside time.
7. Does not require cast alterations or removable dies.
8. Reduced cost.
9. Rebonding possible.

6. DISADVANTAGES
1. Longevity is in question.
2. Technique is sensitive.
3. Space, contour and alignment correction of abutment not possible.
4. Possibility of over contouring is high which can lead to increased plaque accumulation
5. Can be used to replace only one tooth.
6. Can cause ‘greying’ in thin teeth.
7. Aesthetics is moderate.

7. CLASSIFICATION
• Resin bonded fixedpartial dentures are classified based on the type of retention
utilizedby the retainers
1. Mehanical
2. Micromechanical
3. Macromechanical
4. Chemical

8. Mechanical (Rochette bridge)
• It was developedin 1973 by Rochette
• This was the first resin-bonded prosthesis to be developed.
• Rochette utilizeda wing-like retainer with multipleflared perforations to provide
mechanical retention for resin cement
• This was used at that time for both anterior and posterior fixedpartial dentures
• A clinical study by Boyer et al. (1993) reported that anterior FPDs with perforated
retainers had a 50% failure in 110 months and 63% in 130 months.

9. Limitations
• Perforations weakened the metal retainers.
• The resin in the perforations was exposed to oral fluids,which caused wear and
microleakage.
• Retention providedby the perforations was limited.

10. Micromechanical (Maryland bridge)
• It was developed by Livaditis and Thompson at the University of Maryland in 1981
• Electrolyticetching was used to provide micromechanical retention to
nonperforated base metal retainers, bonded by resin cement
• For etching they used a 3.5% solution of nitric acid with a current of 250 mA/cm2 for 5
min followedby immersion in 18% hydrochloric acid solution in an ultrasonic cleaner for
10 min.

11. Advantages
• Better retention than perforated retainers
• Highly polishedretainers preventedplaque accumulation.
Limitations
• Highly technique sensitive depending on procedure adopted at laboratory.
• Variable results were reported for etching the same alloy
• Retention decreased with time

12. Macromechanical
1.Virginiabridge
• It was developed by Moon and Hudgins at the University of Virginiain 1983.
• Utilizedmacroscopic mechanical retention using ‘lost salt crystal technique’
Procedure
The die is lubricated and sievedcubic salt (NaCl) 150–250 microns is sprinkled on the
surface leaving out the margins.
• A resin pattern is now constructed over the salt allowing it to get incorporated in the
resin.
• The salt is then dissolvedby placing the set pattern in an ultrasoniccleaner. This leaves
behind voids in the pattern, which are reproduced in the casting. This provides the
retention.

13. Advantages
• Procedure can be used with any metal.
• Bonding to metal superior to electrolytic method.
Disadvantage
• Thickness of retainer is increasedto allow for retentivelayer.

14. 2. Cast mesh fixedpartial denture.
A nylon mesh is placed on the palatal/lingual surface of the abutment die and the
pattern is fabricated over this mesh.
The mesh gets incorporated and following casting provides retention for resin to metal
Disadvantages
• Adaptation of the nylon mesh to the cast is not good.
• The wax may flow in between the mesh locking all the undercuts.

15. Chemical (adhesive bridges)
These are now the most commonly used methods for bonding the resin cements to
metal.
Their high bond strength, fracture toughness and long-term clinical success have
rendered alloy etching and macroscopic retention mechanisms obsolete. The following
materials are employed
1. Modified bis-GMA cement
• This was developedin the mid-1980s.
• A metal primer (similar to a silanecoupling agent) is used to bond the resin cement to
metal alloys.
• This is effectivefor both noble and base metal alloys.
• A popular resin, cement Panavia uses 10-methacryloyloxydecyl dihydrogen phosphate
(10-MDP) as the adhesion promoter or primer.
• This primer is applied to the fitting surface of the metal retainer following sandblasting
with 50microns alumina, before cementing the prosthesis.

16. • 2. Superbond
• This resin cement was developedin Japan in the 1983.
• In this resin system,the powder is a polymer of methyl methacrylate and liquidis
composedof methyl methacrylate modifiedwith adhesion primer 4-META (4-
methacryloxyethyl trimellitic anhydride).
• A unique catalyst tri-n-butyl borane is added to the liquidbefore mixing with powder.
• The set resin cement has a chemical bond to base metal alloys. For bonding to noble
metal alloys, a special primer has been developed.
3. Rocatec system
This is a laboratory methodof bonding to both noble and base metal alloys.
• Fitting surface of metal is sandblasted (abraded) with 120microns alumina.
• This is followedby abrasion with a special silicate particle containing alumina, which
deposits a coating of silicaand aluminaon alloy surface.
• A silane coupling agent is then applied to bond the metal to the resin cement.

17. Fabrication
TOOTH PREPARATION
PRINCIPLES
• Lingual-axial reduction following the anatomic planes.
• Proximal preparation must extend labially just beyond contact dictated by aesthetics.
• Should encompass at least 180° of tooth.
• Supragingival chamfer finish line.
• Occlusal clearance of 0.5 mm where required.
• Resistance can be enhanced with proximal grooves, boxes
• Vertical stops or support can be provided by countersinks or cingulum rest in anterior
abutments and occlusal rests in posteriors

19. Anterior preparation design and sequence
Lingual cingulum
Depth orientation grooves are placed with a No. 1 round bur (1 mm diameter) on the
lingual cingulum surface and reduced with a wheel diamondto provide 0.5 mm
clearance. Preparation is terminated1.5–2 mm from the incisal edge.

20. Countersink or cingulum rest
Flat notches or countersinksare prepared on lingual surface using a flat-end tapering
diamond. Alternately, a cingulum rest can also be prepared.

21. Proximal
Proximal reduction adjacent to edentulous space shouldensure resistanceform and
prevent any unsightly metal display. It is prepared in two planes – labial and lingual using
round-end tapering diamond.
If creation of labial plane will display metal, then a proximal groove is placed far enough
labially as dictated by aesthetics. The groove is prepared with a flat-end tapering fissure
bur parallel to the incisal two-thirds of the labial surface

22. Lingual axial
The lingual-axial preparation is continuedfrom the proximal preparation adjacent to the
edentulous space, continuedaround the cingulum and stopped just short of the contact
on the other proximal surface. The surface is prepared with round-end tapering diamond
parallel to the path of placement

23. Posterior preparation design and sequence
Proximal and lingual-axial preparations are only aimedat lowering the height of contour
and creating parallel surfaces. Height of the contour is lowered to within 2 mm of the
gingival margin.

24. The proximal preparation adjacent to the edentulous space shouldextend beyond the
facial line angle. It is extended as far as possibleto the embrasure of the opposite side
such that 180° encirclement is achieved. A short thin tapering diamond/needle diamond
is used for the preparation which results in a knife-edge finish line.

25. An occlusal rest is prepared adjacent to the edentulous space similar to the removable
partial dentures. Its dimensions shouldbe 1.5–2 mm faciolingually and mesiodistally, and
1–1.5 mm in-depth. The vertical walls shouldbe very distinct unlike rests for RPD to
prevent lateral movement and preparation shouldbe progressively deeper as it moves
from the marginal ridge to fossa.

26. • In most cases occlusal clearance may not be needed because of placement of
centric stops away from the framework. If required, a clearance of 0.5 mm is given.

27. IMPRESSIONS AND PROVISIONALS
• Impression making is similar to any other fixed partial denture.
• Elastomeric impression materials are indicated.
• A single-impressiontechnique, double mix using putty and light body is preferred as
amount of tooth preparation is minimal.

28. BONDING
• The prepared tooth surface is cleaned using pumiceand water.
• 37% phosphoric acid is used to etch the prepared enamel for 15 s. It is then rinsed and
dried.
• Specially formulated composite resin cements are available for bonding RBFPDs
• A metal primer or silaneis applied on the fitting surface of the casting as
recommended by the manufacturer of the resin cement.
• A bonding agent or primer is also applied on the prepared enamel surface as
recommended by the manufacturer.
• Resin cement is mixedand placed on the internal surface of the retainer.
• The prosthesis is inserted and finger pressure is maintainedfor 60s till the initial set. The
excess cement is removedand material is allowedto completely set. The manufacturer’s
instructions are followedregarding protecting the margins from oxygen depending on
whether the cement is autopolymerizing or dual cured.
• The occlusion is adjusted and the margins are finished and polished.

29. MAINTENANCE AND RECALL
• Resin-bondedrestorations shouldbe reviewedand maintained through periodic recall
appointments.
• Any signs of debonding if detected early can prevent unnecessary damage to the
abutments.
• Periodontal health should also be reviewed and maintaineddue to the propensity of
the retainer to accumulate plaque and over contouring of lingual surface.

30. FAILURES
INAPPROPRIATE PATIENT SELECTION
1. Malalignment of teeth resulting in poor path of insertion
2. Short abutments
3. Thin abutments
4. Inadequate enamel for bonding
5. History of metal sensitivity
6. Heavy occlusal forces

31. INCOMPLETE TOOTH PREPARATION
1. Inadequate proximal and lingual reduction
2. Less than 180 extensionof the retainer
3. Lack of clearance in protrusion
BONDING FAILURE
1. Contamination
2. Prolonged mixing
3. Inappropriate luting agent

32. Conclusion
Resin-bondedprostheses are viable prostheses in select situations.They shouldreceive
the same attention to detail as conventional fixed partial dentures for long-term success.
Patient selection is vitally important and the tooth preparation or enamel activation is
mandatory. Although newer metal-free ceramicresin-bonded bridges show promising
results, we have to wait for long-term results to replace the conventional metal resin-
bonded restorations.

33. Reference
1. Textbook of Prosthodontics –V Rangarajan

34. Thank you