Temporization in fixed prosthodontics

temporization in FPD. a summary of the pre conference course

1. TEMPORIZATION IN FIXED PROSTHODONTICS -DR PALAK MISHRA 1 ST YEAR PG RESIDENT

2. DEFINITION According to GPT-9 Temporization is to establish esthetics , occlusal stability, and function for a limited time in preparation for the definitive prosthesis; to verify therapeutic outcome and patient acceptance before the definitive prosthesis.

3. SYNONYMS

4. ROLE OF PROVISIONAL RESTORATION

5. Rosentstiel,land,fujimoto;5 th ed

6. RATIONALE Protect pulpal tissue and sedate prepared abutments Provide an environment conductive to periodontal health Provide method for immediately replacing missing teeth Provide comfort and function Protect teeth from dental caries Improves esthetics Evaluate parallelism of abutments Prevents migration of abutments J Prosthet Dent 2003;90:474-97

7. Requirements BIOLOGICAL Pulpal protection Occlusal compatibility and tooth position Prevention of enamel fracture

8. MECHANICAL FUNCTION Greater stresses likely to occur during mastication. Strength of poly methyl methacrylate resin is about 1/20 th that of metal-ceramic alloy; fracture more likely. Partial coverage crown inherently weaker.

9. Displacement To avoid irritation to the pulp and tooth movement, a displaced provisional must be recemented promptly. Best prevented: proper tooth preparation and a provisional with a closely adapted tooth surface

10. ESTHETICS Color, contour , translucency and texture are key elements of coronal appearance Particularly important in anteriors

11. PROPERTIES Better fit, particularly at the margins Increased strength Better wear resistance Easier to keep clean Better esthetics and color stability Greater occlusal reliability and stability

12. TYPES Based on technique: Custom fabrication Fabrication with preformed material Based on material: Chemically activated auto polymerising acrlyic resin Polymethyl methacrylate (PMMA) Polyethyl methacrylate (PEMA) Polyvinylethyl methacrylate (PVEMA) Heat activated acrylic resins Light activated acrylic resins Dual light and chemically activated acrylic resins Alloys

13. POLYMETHYL METHACRYLATE (PMMA) Most preferred Various shades available; more color stable Greatest strength Flexural strength is higher than composite resins Contraindicated in direct technique Indicated in INDIRECT TECHNIQUE Low abrasion resistance; good polishability

14. POLYETHYL METHACRYLATE (PEMA) Best suited for DIRECT TECHNIQUE; less thermal reaction. Low polymerization shrinkage Good handling properties Good properties Good resistance

15. POLYVINYLETHYL METHACRYLATE (PVEMA) Low exothermic reaction while setting Color stability is less Lack of transverse strength

16. BIS ACRYL COMPOSITE RESINS Available as automix delivery system Low exothermic reactions Low shrinkage---good marginal fit and good transverse strength Expensive

17. Repair or modification of bis acryl restoration with composite : difficult ; dissimal chemistry Koumjian & Nimmo demonstrated an 85% decrease in transverse strength after repair ; suggesting that the fabrication of a new provisional restoration is more advantageous than repair

18. BIS GMA RESIN Good marginal fit Low shrinkage Stronger than bisacryls ; more brittle More likely to fracture in long span FPDs Castleneuvo and Tjan reported that bis -GMA resin had a lower rise in temperature than bis -acryl.

19. Tempspan - dual curing resin; automixing cartirage Protemp crown (3M ESPE, St Paul, MN) : preformed bisGMA provisional crown ; single unit posterior teeth and canine Preshaped as adaptable putty needing marginal trimming, adaptation to the preparation,light curing, removal, finishing and cementation.

20. Visible Light Cured Urethane Dimethacrylate Resins Poor stain resistance Urethanedimethacrylate added; resin requiring visible light and a camphoroquinine amine photo initiator ; polymerization Prestipino has shown that VLC resins are brittle; poor choice for a high strength posterior provisional restorations. Available in limited shades More expensive

21. Revotec LC (GC America, Alsip, IL) : moladble putty available as a thick rope Used for temporization of multiple adjacent crown unit and bridgeworks Flowable and hybrid composites can be used to repair However bisacryls and bis GMA resins are superior in so far as esthetics is concerned

22. PRE FORMED CROWN FORMS POLYCARBONATE Made of a polymer with high impact resistance. Have sufficient strength Name implies that it contain multiple carbonate groups LIMITATIONS Often too broad buccolingually so recontour gingivally

23. CELLULOSE ACETATE Thin, soft and transparent. Disadvantages Act as matrix, must be removed after their relining material is set. Refining material lock into undercut, thus compromising removal of the material from gingival area.

24. STAINLESS STEEL Available in various sizes Less malleable, harder to wear and less likely to deform under load. Success rate is high Usually not refined but trimmed approx. the size of tooth. Maintain the space that may be lost when a deciduous tooth is lost prematurely

25. ALUMINIUM Easy to manipulate Malleable and ductile in nature, easily bent and trimmed Corrodes with time Used as a posterior crown

26. ARMAMENTARIUM

27. techniques

28. FINISHING AND POLISHING Finishing : surface smoothness Polishing: surface luster For trimming: acrylic laboratory burs and discs are used

29. DEFICIENCY Marginal inaccuracy Dimensional unstablility Moisture of oral cavity, temperature changes and occlusal forces affect the fit Longer span of the prosthesis, greater is surface distortion Non integrity of external contour Correct shaping of external contour is mandatory Fracture To strengthen: fibers are used; possesses superior mechanical, esthetic characterstics

30. REPAIR Repair of aged restorations is less structurally effective Reduced number of free radicals and has absorbed water from saliva and other fluids into its surface

31. CEMENTATION

32. PROVISIONAL LUTING MATERIALS • Provisional luting agents should possess : -good mechanical properties, -low solubility, -tooth adhesion to resist bacterial and molecular penetration. • The most important function of these materials is to provide an adequate seal between the provisional restoration and prepared tooth. This is necessary to prevent marginal leakage and pulpal irritation.

33. There are a variety of luting materials used for interim purposes. The most common include (1) calcium hydroxide (2) zinc-oxide eugenol (3) non- eugenol materials.

34.   Some of the most commonly used cements with provisional prostheses are those containing zinc-oxide and eugenol . They provide: sedative effects that reduce dentin hypersensitivity possess antibacterial properties.

35. Unfortunately, free radical production necessary for polymerization of methacrylate materials can be significantly hampered by the presence of eugenol found in eugenol based provisional luting materials.; Eugenol interferes with the acrylic resin polymerization and hardening process . Therefore Eugenol -free provisional luting materials are commercially available Have gained popularity;the absence of resin-softening characteristics .

36.   Baldissara et al recommended that interim restorations be frequently evaluated and used for only short periods of time. Literature reports advise that if provisional treatment is required over a protracted time period, it is best to remove and replace the provisional luting agent on a regular basis.

37. REMOVAL OF PROVISIONAL Removed when the patient returns for definitive restoration Risk of damage to the prepared tooth can be minimized if removal forces are directed parallel to the long axis of the preparation. The BACKHANS or hemostaic forcep is effective Slight buccolingual rocking motion; breaks cement seal

38. PROVISIONAL VENEERS

39. Recent advancements TEMP TABS THERMOPLASTIC MATRIX WAFERS Multiuse matrix Easily adapted to desired shape No liberation of heat

40. TUFF TEMP PLUS Impact resistant rubberized resin No ploymerization shrinkage High flexural strength Eliminates fractures Marginal fit is perfect

41. CAD CAM PMMA PROVISIONAL Digitally fabricated from PMMA Highly precise temporaries Milled out from dense block and shows reduced porosity of traditional hand processed techniques BIOTEMPS provisional crowns and bridges are created with CAD/CAM technology

42. So the perfect provisional … Super strong Highly esthetic Gingival sculpting Patient fixed Universal use Cost Gentle