resin bonded prosthesis in fpd .pptx. .

Rbfpd in short(bridges)

1. RESIN BONDED PROSTHESIS IN FPD Presented by Zoya shaikh 4 th Year B.D.S. 76

2. A fixed partial denture that is luted to tooth structures, primarily enamel, Which has been etched to provide micro mechanical retention for the resin luting agent [GPT-10] The resin-bonded fixed partial denture (FPD) is the most conservative tooth-supported restoration because it is possible to leave the adjacent teeth almost untouched.

3. INDICATIONS For abutment teeth with sufficient enamel to etch for retention. For splinting periodontally compromised teeth For stabilizing dentition after orthodontic treatment For medically compromised or adolescent patients For replacing single missing teeth with caries-free abutments.

4. CONTRAINDICATIONS Patients with parafunctional habits.
Long edentulous spans.
Restored or damaged abutments.
Compromised enamel.
Deep vertical overlap(Deep overbite)
Nickel or any metal allergy

5. ACID ETCHING Buonocore Showed that Acrylic resin can be attached to human enamel in vivo, simply by acid etching the enamel with 85% phosphoric acid for 30 secs This changes the enamel by Larger surface area Exposure of organic framework Removal of inert enamel Absorbed Layer of Highly polar Phosphate groups Creation of Porous subsurface layer

6. ETCHING APPARATUS Electrodes: 0.036 Inches stainless steel Orthodontic wire or copper wire of 12 to 14 Gauge Electrolytes: (Varies according to metal) 1.NI-Cr Be alloys : 10% sulphuric acid 2.Ni-Cr/Co-Cr : 3.5% Nitric acid D.C. Power supply

7. Electrochemical Etching 1.The electrolytic solution consists of 10 % sulfuric acid mixed in methanol in the ratio of 9:1 respectively.  2.The surface of alloy sample that was to be etched is carefully dipped into the solution taking care only to etch the required exposed surface. 3.Specimens were attached to the anode. 4  The cathode was dipped into solution keeping a distance of 1.5 cm from anode which is constantly maintained by piercing holes in a thin thermocol sheet placed on top of the container 5.Specimens were washed under running tap water and cleaned ultrasonically in 18 % hydrochloric acid for 10 min. 6.They were removed and washed in water for 2 min. 7. Samples were stored in plastic packets at room temperature with 100 % relative humidity till they were bonded to the teeth.

8. Chemical Etching 1.Chemical etching was done using industrial grade solution of Aqua- regia , which is a combination of concentrated nitric acidand concentrated hydrochloric acidin the ratio of 3:1.
2. Solution was placed in a glass beaker and specimens were suspended from the center of beaker taking support from a plastic rod placed at the top
3.The etched specimen was taken out carefully and washed under tap water first, followed by ultrasonic cleansing in 18 % hydrochloric acid for 10 min
4.samples were washed in water for 2 min and air-dried. 

9. Etching of Teeth Surface of tooth beyond the area to be etched was blocked with wax. The enamel portion of teeth that was marked was etched using 37 % phosphoric acid gel for 15 s, washed and air-dried. Wax was removed and specimens were ready to be used.

10. BONDING Before bonding the etched alloy specimens to teeth, a wedge was fabricated in order to help in positioning the bonding of specimens without slippage. Enamel and metal interface was checked for close approximation to remove the error of irregular cement thickness. Specimens which were not in close approximation were discarded and replaced with new ones. Surface of enamel was conditioned (etched) Silane coupling agent was applied to the metal surface as per manufacturer’s instructions Resin cement applied first on the etched tooth followed by carefully placing the etched surface of the alloy sample on to the tooth A static load is applied for 5 min Excess cement was removed and the specimens were light cured

11. EVOLUTION Bonded pontics Cast perforated Resin Retained FPD Etched cast resin Retained FPD Macroscopic Mechanical retention resin Retained FPD Cast mesh FPD Chemical Bonding Resin Retained FPD Fiber reinforced Composite Resin FPD

12. BONDED PONTICS The earliest resin-bonded prostheses were extracted natural teeth or acrylic teeth used as pontics bonded to the proximal and lingual surfaces of abutment teeth with composite resin. 1.The composite resin connectors were brittle and required supporting wire or a stainless steel mesh framework. 2.These bonded pontics were limited to short anterior spans 3.They had a limited lifetime, with degradation of the composite resin bond to the wire or mesh and subsequent fracture. Thus such restorations should be presented to patients only as short-term replacements

13. Types: Composite resin crowns Natural Tooth pontics Acrylic resin denture tooth

14. ROCHETE BRIDGE(mechanical retention) By rochette in 1973 It is a resin bonded fixed partial denture that incorporates holes within the metal framework that lutes to the lingual aspect of the teeth adjacent to the edentulous space, replacing one or more teeth [GPT-10] They are wing like retainers with funnel shaped perforations that enhance resin retention Combines mechanical retention through silane coupling agents

15. Limitations of rochette bridge 1. Weakening of the metal retainer by the perforations.
2. Exposure to wear of the resin at the perforations.
3. Limited adhesion of the metal provided by the perforations

16. MARYLAND BRIDGE( micromechanical retention) Etched cast resin Retained FPD A Technique for the electrolytic etching of cast base metal retainers was developed at the University of Maryland by Thompson and Livaditis . Etched cast retainers have definite advantages over the cast-perforated restorations:

17. The need for a composite resin with a low film thickness for luting the casting became apparent. This led to the first generation of resin cements, which allowed micromechanical bonding into the undercuts in the metal casting created by etching and simultaneously provided adequate strength and allowed complete seating of the cast retainers Electrolytic etching of base metal alloys proved to be critically dependent on the base metal alloy Highly variable results were reported for dental laboratories in etching the same alloy. With time, surface contamination or electropolishing can severely degrade bond strengths in a moist environment.

18. The microstructure is selectively removed by electrolytic etching to create a highly undercut surface that can be wet by hydrophobic composite resins. Initially Chemical or gel etching was also done for nickle -chromium or nickel-chromium-molybdenum- aluminum -beryllium alloys

19. VIRGINIA BRIDGE(Macroscopic Mechanical retention) Developed at the Virginia Commonwealth University School of Dentistry and is known as the Virginia Bridge Due to concerns about etching base metal and the desire to use alternative alloys, several methods have been developed to provide visible macroscopic mechanical undercuts on the inner surface of FDP retainers

20. “lost salt crystal” technique On the definitive cast, the abutments are coated with a model spray, and a lubricant is then applied. Within the outlines of the retainers, specially sized salt crystals* (150 to 250 μm ) are sprinkled over the surface in a uniform monolayer, leaving a 0.5-mm border without crystals at the periphery of the pattern. Followed by application of a resin pattern.

21. ADHESION BRIDGE (Chemical retention) Adhesive systems for direct bonding of metal for retention of resin based FPDS were extensively researched in Japan The first of these resin systems† is based on a formulation of a methyl methacrylate polymer powder and methyl methacrylate liquid modified with the adhesion promoter 4-methacryloxyethyl-trimellitic anhydride 10-methacryloyloxydecyl dihydrogen phosphate-(MDP)-Based primers and MDP-based composite resin cements increase the bond strength between the resin cement and zirconi .A dual polymerizing system has some benefits that can be light polymerized as well as have the advantage of a chemical polymerization in areas that the polymerization light cannot reach.

22. Sand blasting with alumina (50 microns) demonstrates increased wettability of the Surface And results in a highly activated metal surface Small imperfections on the metal cylinders are trimmed with tungsten carbide bur (Fine grit).

23. DESIGN CONSIDERATION The principle underlying these restorations has always been that it is necessary to cover as much enamel surface as possible, as long as occlusion, aesthetics, and periodontal health are not compromised. Through the concept of minimally invasive dentistry, resin-bonded FPDs have evolved from a two retainer to a one-retainer design, independent of the framework material that is used. ["interproximal wraparound” ] Enamel preparations consisted of creating occlusal clearance, placing grooves or boxes, and creating a gingival finish line to minimize over contoured morphology and promote gingival health. Posterior frameworks should have a positive seat in an occlusogingival direction and should have no facio -lingual displacement

24. Proximal extensions are created by lowering the lingual and proximal heights of contour somewhat analogous to guide plane preparation for RPDs Contemporary design has improved retention with well-placed and precise grooves on abutment teeth

25. ADVANTAGES Rebonding possible Minimal removal of tooth structure Minimal potential for pulpal trauma Anesthesia not usually required Supragingival preparation Easy impression making Reduced chair time Reduced patient expense

26. DISADVANTAGES Maintenance cost of rebonding or replacement Enamel modifications: required Space correction: limited to one tooth as compared to three teeth with a classic fixed partial denture Good alignment of abutment teeth: required

27. REFERENCES 6 th edition of Contemporary fixed prosthodontics by stephen rosenstiel

28. THANK YOU