Provisional restorations in crowns and bridges

Provisional restorations in crowns and bridges

1. PROVISIONAL RESTORATIONS IN CROWN AND BRIDGES Paavana II MDS 1

2. C ontents Introduction Definition Synonyms Rationale Requirements Classification of provisional restorations Techniques of fabrication of provisional restoration Cementation Removal, Recementation Conclusion References 2

3. Introduction PROVISIONAL - established for the time being, pending a permanent arrangement. Provisional crowns or fixed partial dentures are essential to prosthodontic therapy. Even though a definitive restoration may be forthcoming, a provisional restoration must satisfy the important needs of the dentist and the patient. The success of fixed prosthodontics, to a large extent depends on the care and method in which the provisional restoration is designed and fabricated 3

4. DEFINITION “A provisional restoration is a transitional restoration that provides protection, stabilization, and function before fabrication of the definitive prosthesis. It may be also used to determine the aesthetic, functional and therapeutic effectiveness of a treatment plan”- GPT 9. 4

5. SYNONYMS I nterim Transitional Intermediate Treatment restoration. 5

6. RATIONALE T o protect pulp and sedate prepared abutments T o evaluate parallelism of abutments To immediately replace missing teeth T o prevent migration of abutments To improve esthetics T o provide an environment conducive to periodontal health To evaluate and reinforce the patient’s oral home care To aid periodontal therapy by providing visibility and access to surgical sites when removed T o provide a matrix for the retention of periodontal surgical dressings * Federick , D. R. (1975).  The provisional fixed partial denture. J Prosthet  Dent , 34(5), 520–526 6

7. To stabilize mobile teeth during periodontal therapy and subsequent repair To anchor orthodontic brackets during minor tooth movement To aid in developing and evaluating an occlusal scheme before the final prosthesis is made To allow evaluation of vertical dimension, phonetics, and masticatory function To aid in determining the prognosis of questionable abutments in the over-all restorative treatment plan. * Federick , D. R. (1975).  The provisional fixed partial denture. J Prosthet   Dent , 34(5), 520–526 7

8. REQUIREMENTS 8

9. Biologic requirements 1 . Pulp protection S eal and insulate the prepared tooth surface from the oral environment to prevent sensitivity and further irritation to the pulp . R estoration must be fabricated of a material that will prevent the conduction of temperature extremes . The margins should be adapted well enough to prevent leakage of saliva. 9

10. 2. Periodontal Health G ood margin fit, proper contours and a smooth surface . It is of utmost importance that the margins of a provisional restoration not impinge upon the gingival tissue If the gingival tissues remain healthy while the provisional crown is in place, there is less likelihood of a problem arising after cementation of the definitive restoration. 10

11. 3 . Occlusal Compatibility and Tooth Position P atient comfort, ward off tooth migration, and possibly prevent joint or neuromuscular imbalance. E stablish or maintain proper contacts with adjacent and opposing teeth Inadequate contacts - supraeruption and horizontal movement 11

12. 4) Prevention of enamel fracture Provisional restoration should protect crown preparation margin especially in partial coverage designs in which margins of the preparation is close to the occlusal surface of the tooth and could be damaged during chewing. 12

13. Mechanical requirements 1) Function Greatest stresses in provisional restorations are likely to occur during mastication. Fracture is not usually a problem with a complete crown interim restoration, as long as the tooth has been adequately reduced. Breaking is more common with partial restorations; they are weak as they are not covering the tooth completely. A partial FDP must function as a beam in which substantial occlusal forces are transmitted to the abutments . During function high stresses are created in the connectors, to reduce the risk of failure, connector size must be increased in the provisional as compared to the definite restoration . 13

14. 2) Displacement A displaced provisional restoration must be re cemented promptly to avoid irritation to the pulp. It is best prevented by proper tooth preparation and a provisional with closely adapted internal surface . 3 ) Removal for reuse : Provisional restoration often need to be reused and should not be damaged when removed from teeth 14

15. Aesthetic requirements Contour , colour , translucency and texture are the key elements of coronal appearance. 1. Contour - Diagnostic wax up 2 . Colour - Custom shade guide Resin coloring tints Provisional stain kit. 15

16. 3. Translucency- Incisal or occlusal third enamel show pronounced translucency. Two resins – one colored to match body and one to match the enamel of the tooth 4. Texture- Important in maxillary anterior teeth. Developmental lobes – wax pattern. Developmental defect – on restoration just before finishing. Imbrication lines – coarse diamond rotary instrument in slow rotating speed slowly moved across the facial surface from proximal to proximal. 16

17. A) ACCORDING TO METHOD OF FABRICATION Preformed Custom made B) ACCORDING TO TECHNIQUE OF FABRICATION Direct technique Indirect technique Indirect-direct technique 17 CLASSIFICATION

18. C. ACCORDING TO DURATION OF USE SHORT TERM ---- for few days ( upto 2 weeks) (Polycarbonate or aluminum crowns ) MEDIUM TERM ---- for few weeks ( > 2 weeks) ( R esin based provisionals ) LONG TERM ---- for months (mostly cast metal crowns) 18

19. D . ACCORDING TO MATERIALS USED: RESINS METALS 19 Polycarbonate Acrylics Bis acryl composites Preformed Custom made Preformed Custom made A luminium Tin-silver Ni-Cr Cast alloys Cellulose Acetate

20. TECHNIQUES STEPS IN FABRICATION 20

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22. 1. Diagnostic wax up The diagnostic wax-up is the method or process through which practitioners can fully visualize the true restorative needs of their patients . It is to be done to change or correcting occlusal abnormalities. To provide a guide for the technician To seek patient consent It also helps to fabricate the customized matrix form 22

23. I. PREFORMED RESTORATIONS Prefabricated crowns are purchased by the dentist in assortment kits. They come in a variety of materials and graduated sizes, and are simply thin, tooth shaped shells. Preformed crowns are generally limited to use as single restorations rather than for fixed partial dentures. The various materials from which preformed crowns are made include polycarbonate, cellulose acetate, aluminium , tin-silver, and nickel-chromium. 23 2. FABRICATING THE MATRIX OR EXTERNAL SURFACE FORM

24. A. POLYCARBONATE CROWNS G enerally called "Ion crowns" in deference to the company that first manufactured them . M ost natural appearance of all the preformed crown materials . hollow , tooth-shaped with walls about 0.3 mm thick . Their life expectancy depends upon how much the dentist has to modify them from their original state to make them fit, and how careful the patient is with them 24

25. W idely used as temporary crowns for several reasons :- • It is strong yet flexible enough to contour easily • It bonds chemically to a self-curing acrylic resin material used to fill the shell. Any area of a plastic crown, including the incisal edge, can be extended by adding layers of acrylic and smooth them. 25

26. 26 Indications Contraindication Advantages Disadvantages Single anterior teeth and premolars Short-term provisional restorations Long-term provisional restorations Less time consuming Tooth-colored making them aesthetically pleasing Easily adjustable Single shade. Reline required for adequate marginal fit and retention Single tooth restorations Require extensive alteration

27. B. CELLULOSE ACETATE CROWNS Cellulose acetate is a thin, transparent resin material available in all tooth shapes and a range of sizes. Shades are entirely dependent on the autopolymerizing resin. Once the resin has polymerized, the cellulose acetate is peeled off and discarded. 27

28. Indications Contraindication Advantages Disadvantages Short-term provisional restorations •Provisionalisation of anterior teeth Long-term provisional restorations Less time consuming Aesthetic They can be made to fit the preparation easily, as it can be shortened by cutting, or lengthened by adding resin Additional resin is needed for establishing proximal contacts Generally limited to single tooth restorations 28

29. C. ALUMINIUM and TIN-SILVER CROWNS Preformed metal temporary crowns typically are produced for both molars and premolars and differ in size and occlusal anatomy . They are thin-walled (slightly less than 0.5 mm) tooth-shaped shells commercially produced. These crowns are so soft, they must be handled gently . Provide good adaption due to softness and ductility of the material 29

30. Indication Contraindication Advantages Disadvantages molars premolars aesthetics is a primary consideration Allows for good occlusal adjustment available in a range of sizes sufficient to cover most preparations. are inexpensive Care must be taken during try-in verification to avoid fracture of their delicate margins Require modification Galvanic shock and metallic taste 30

31. E. STAINLESS STEEL CROWN M ost durable of the preformed anatomical crowns, which is used most often in restoring primary teeth S tainless steel ones are used to protect primary teeth from further decay until they fall out naturally. 31

32. Indications Contraindications Advantages Disadvantages Posterior teeth Long-term provisional restorations Aesthetic region provisionalisation Extremely durable Relatively inexpensive Subject to minimal technique sensitivity during placement Poor aesthetic quality for placing on an anterior tooth The difficulty of adapting its rigid metal margin to the prepared tooth margin 32

33. TECHNIQUES- PREFORMED PROVISIONAL CROWNS 33

34. FOR POLYCARBONATE CROWNS Additions to clinical armamentarium: Assorted polycarbonate crowns Green stone bur Straight handpiece Boley gauge or dividers 34

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39. PREFORMED METAL CROWNS Additions to clinical armamentarium: Assorted aluminium crowns Boley gauge or dividers Crown-and-collar scissors Contouring pliers Cylindrical green stone, straight handpiece Sandpaper disk (7/8 in diameter ) Stretching blocks 39

40. M esiodistal width of the crown space using a Boley gauge or dividers. 40 Cervical end expansion

41. Crown tried over preparation Gingival margin trimmed till the correct occlusogingival height The axial surface is contoured with pliers to obtain a convex surface. 41

42. Place the trimmed shell over the prepared tooth and apply slight apical seating pressure. Instruct the patient to close with moderate force Apply petroleum jelly to the prepared tooth and adjacent gingival tissues. Mix poly-R’ methacrylate and fill the crown . When the resin surface becomes matt, place the crown over the tooth. Instruct the patient to occlude . 42

43. Remove the marginal excess quickly. 43 Monitor the polymerization by light probing with a hand instrument. Remove it before it has fully polymerized and place it in warm water

44. After about 5 minutes, mark the margins and trim any excess. Replace the crown and adjust the occlusion as necessary using marking film and slow-speed handpiece .. Polish, clean, and cement the restoration. 44

45. II. CUSTOM-MADE RESTORATION A custom ESF is a negative reproduction of either the patient’s teeth before preparation or a modified diagnostic cast. Accurate reseating of the ESF is easier, and the mold cavity produces better results if thin areas of impression material are trimmed away . It provides intimate contact between provisional restoration and prepared tooth. 45

46. Most commonly used for fixed partial dentures. CUSTOM MADE MATRIX- 1 . irreversible hydrocolloid. 2 . putty/silicone impression 3. vacuum adapted thermoplastic sheet 4. wax 46

47. Advantages- • A wide variety of materials can be used. • Helpful in evaluating the adequacy of the tooth reduction; by measuring the thickness of the restoration, the preparation can be altered . Disadvantages- • Additional lab procedure involved • Time consuming 47

48. TECHNIQUES FOR CUSTOM PROVISONAL CROWNS 48

49. IDEAL PROPERTIES OF PROVISIONAL RESTORATIVE MATERIALS 1. Convenient handling: Adequate working time, easy moldability , rapid setting time . 2. Bio compatible: nontoxic, non-allergic , non-exothermic. 3. Dimensionally stable during solidification. 4. Ease of contouring and polishing. 5. Adequate strength and abrasion resistance 49 MATERIALS

50. 6. Good appearance: translucent, colour , colour stable. 7. Good patient acceptance- non irritable, odourless . 8. Ease of repairing . 9. Chemical compatibility with provisional luting agents 50

51. Currently Available Materials- The materials can be divided into four resin groups: Poly (methyl methacrylate) Poly (R’ methacrylate ) Bis -acryl composite Hybrids 51

52. Polymethyl Methacrylate These materials resemble those used for complete dentures, except that they are tinted with tooth- coloured pigments rather than varying shades of pink . The material is supplied in two parts: a monomer (methyl methacrylate) and a powder ( polymethyl methacrylate). The polymer contains: •pigments •initiator (benzoyl peroxide) to start polymerization •inhibitors ( usually a hydroquinone) to increase shelf life •cross-linking agents to prevent crazing 52 Duralay , Temp Bridge Resin, Jet

53. Advantages- High strength Good color stability Can be smoothed and polished Low cost Easily repaired High abrasive resistance 53 Disadvantages- Highly exothermic Prone to Shrinkage Odour Monomer is irritating to the pulpal and gingival tissues

54. Composites Bis -acryl resins can be used for most types of provisional restorations- chemically, light activated, dual activated Most products are available in automix systems. Bis -acryl resins are similar to BIS-GMA resins and possess several advantages : • less exothermic heat • minimal polymerization shrinkage • high tensile strength and surface hardness • improved marginal fit • good color stability 54 Protemp II (ESPE), Luxatemp , FlexSpan , Integrity

55. minimal odour high polishability Disadvantages- Greater cost More brittle than acrylic 55

56. PROTEMP 3 GARANT It is a self-cured bis -acryl composite recommended by 3M ESPE for the fabrication of provisional crowns, bridges, inlays, and onlays . The material is available in four shades (A1, A3, B0.5, and B3) and is supplied in cartridge form for use in an automix dispenser gun 56

57. The automix gun dispenser makes it easy to mix the product and produces homogeneous mixes. Restorations have excellent marginal adaptation and are fast and easy to polish. Protemp provides good detail reproduction in marginal areas and is fracture resistant 57

58. LUXATEMP Luxatemp was the first bis -acrylic composite that was offered in the advantageous 10:1 mixing ratio for automatic mixing. Advantages: • good adaptation and fitting • High flexural strength • High resistance to abrasion • Six aesthetic shades Highly biocompatible Automix safety cartridge delivers the ideal mixing ratio 10:1 58

59. PROTEMP II Excellent esthetics due to great color stability, high polishability and the choice of three intensive shades: A1 extra light, A3 light and B3 yellow . D irect chairside temporary restorations 59

60. REVOTEK LC 60 It is supplied in a "Putty Stick" form in a lightproof plastic tray. Since it is a one-component material, no mixing of powders and liquids is required Revotek LC is less messy than other types of provisional materials, handles without tackiness, and can be used quickly and easily to fabricate all types of provisional restorations.

61. Advantages :- A lower heat of polymerization (125˚F, 51.5˚C) Liquid is less irritating to soft tissues do not experience much polymerization shrinkage. They exhibit a long working time 61 Trim II , Vita KHB Disadvantages- Less esthetic Poor colour stability Poor wear resistance Polyethyl Methacrylate

62. The light-cured resin comes in a monomer and polymer form but because the resin does not cure without light, it allows the operator time for preparation and correction before curing . There are also light-cure resins that do not come in a monomer or polymer form but in a putty-like consistency. The product is available in five Vita shades and a translucent shade. The restoration is partially light-cured. It is then removed and final curing is done for 20 to 60 seconds, depending on the shade and thickness. 62 Unifast LC Light-Cure Resin-

63. Advantages- • Easy to use • Comes with an adequate number of shades • Adequately-long working time • Ability to be light cured, which saves chair time • Exhibits a very low fracture rate 63 Disadvantages- • Unifast has to be mixed by hand--it is not available in an automix form • Difficult to polish to a high luster • Finished provisionals exhibit a high degree of porosity

64. They are a combination of two or more types of materials A new hybrid material (Kind) is a polymethyl methacrylate filled with a bis -acrylic resin. It exhibits a very high heat of polymerization. It is also available with barium glass as a filler to make it radiopaque. Another material ( Dentalon ) is a polymethyl methacrylate meshed with an isobutyl methacrylate monomer. It has physical and handling properties that place it between the polymethyl methacrylates and the polyethyl methacrylates 64 Hybrids

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67. REINFORCEMENT Glass fibers, nylon fibers,metal strengtheners, and carbon graphite fibers. The effectiveness of these strengthening mechanisms varies with bond formation between the reinforcing material and the parent resin . Although the incorporation of materials such as polyethylene and carbon graphite fibers has shown to increase the moduli of elasticity of commonly used provisional fixed partial denture materials, but technical difficulties and aesthetic concerns have prevented their widespread use. 67

68. Review of literature Kapri et al in 2015 conducted a study to evaluate fracture load values of interim FPDs with different locations of glass fiber reinforcement It was concluded that occlusal third of the pontic region from mesial to the distal end of the connector was the best site of placement of the fiber for re inforcing the PMMA interim restorative resin . J Indian Prosthodont Soc 2015;15:142-7 . 68

69. Viswambaran et al in 2011 conducted an in vitro study to evaluate fracture resistance of interim fixed partial denture fabricated using polymethyl methacrylate and reinforced by different fibers of 10mm length for its optimal placement. The favorable site of placement in three different locations was occlusal, middle, and cervical third of the pontic . The results showed that glass fibers showed the highest fracture resistance and reinforcement in the occlusal third of the interim FPD produced the greatest fracture resistance Because the fiber stopped propagation of the initiating fracture through the restoration Med J Armed Forces India. 2011;67(4):343–347. 69

70. EXOTHERMIC REACTION A 10˚F (5.6˚C) increase in pulpal temperature resulted in 40 % loss of pulpal vitality, a 20ºF (11.2ºC) increase in pulpal temperature resulted in a 60% loss of pulpal vitality and a 30˚F (16.8˚C) increase in pulpal temperature resulted in 100% pulpal necrosis. PMMA exhibits the greatest exothermic reaction, followed by PVEMA, PEMA, bis -acryl composite resin, and VLC urethane dimethyacrylate resins The clinician should limit the thermal insult to the pulp by selecting an appropriate interim material, minimizing the volume of material, and choosing an appropriate fabrication technique. 70

71. Manak and Arora in 2011 did an in vitro study to compare the temperature changes in the pulpal chamber during fabrication of provisional restorations by direct method. Three different self-cure provisional restorative resins ( polymethyl methacrylate resin, polyethyl methacrylate, bis -acrylic composite resin) were tested for variations caused by them in the temperature of pulp chamber during fabrication of three unit FPDs. Results showed that polymethyl methacrylate showed the highest temperature rise value followed by PEMA and bis -acryl resin. J Indian Prosthodont Soc. 2011;11(3):149–155 71

72. Thus the resin material recommended for clinical use when direct technique was employed was bis -acryl composite resin as it caused minimal temperature rise in the pulpal chamber 72

73. COLOUR STABILITY Provisional restoration colour instability may be due to: • the incomplete polymerization of the material • sorption of oral fluids • surface reactivity • dietary habits • oral hygiene Surface finish also contribute to staining of provisional materials, with porous unpolished surfaces exhibiting significantly more darkening than highly polished material 73

74. Mazaro et al in 2015 conducted a study to evaluate the color stability of temporary restorative materials- acrylic and bis -acrylic resins after immersion in pigmenting solutions for different periods of storage . Artificial saliva, saliva + cola type soda, and saliva + coffee at 37 °C and the storage time intervals were 2, 5, 7 and 15 days Acrylic resin presented greater color stability in comparison with bis -acrylic resins and coffee was the solution responsible for the greatest color change in the temporary resins . Journal of odontologia 2015. 74

75. MARGINAL INTEGRITY The specific technique used in the fabrication of an interim restoration has a significant impact on the resultant marginal integrity . Although the indirect technique has been found to produce significantly more accurate marginal integrity than the direct technique and it requires a accurate impression of the preparation finish line. 75

76. Verma et al in 2012 conducted a study to evaluate the marginal accuracy of different provisional restoration materials ( Bis -GMA, PMMA) used in fixed partial dentures. It was concluded that Bis -GMA provisional restorative material showed the better marginal fit. This was due to the fact that polymerization shrinkage was less in composite resins as compared to PMMA resins. J Indian Prosthodont Soc. 2012. 76

77. Depending on the brand, the most commonly used monomers – methyl methacrylate ethyl methacrylate isobutyl methacrylate bis –GMA , and urethane dimethacrylate . 77 FREE-RADICAL POLYMERIZATION

78. Each of these monomers, whether used whole or in combinations, may be converted to a polymer by FREE-RADICAL POLYMERIZATION, although the conversion process is never perfectly complete. 78 INITIATION PROPAGATION TERMINATION

79. 1. Initiation Free-radical polymerization begins with the formation of a free radical (a process called activation) and the subsequent combination of this free radical with a monomer. Free radicals are formed by the decomposition of a chemical - the initiator). Benzoyl peroxide decomposes to free radicals at approximately 50° C or higher in a process called THERMAL ACTIVATION 79

80. Benzoyl peroxide also decomposes to free radicals when catalyzed by a tertiary amine; this process is called CHEMICAL ACTIVATION . Chemical activation occurs when the activator, initiator, and monomer are mixed together, so these materials are usually supplied separately-the monomer and activator are in one container, and the initiator and filler are in another. Camphorquinone decomposes to free radicals in the presence of both an aliphatic amine and blue light energy; this process is called VISIBLE-LIGHT ACTIVATION. 80

81. 2. Propagation 1 . The setting material undergoes an increase in density, causing contraction. 2 . The exothermic heat of reaction may cause a substantial increase in temperature, with subsequent increased contraction. 3 . Other physical properties e.g ., rigidity, strength, and resistance to dissolution increase. 81 3. Termination Due to the randomness of position of the growing chains, some of them may combine and terminate the growth process.

82. 82 1.INDIRECT - - Custom made with template 2.DIRECT - -Custom made with index 3.INDIRECT-DIRECT

83. ARMAMENTARIUM Mouth mirror Explorer Periodontal probe Saliva evacuator Cotton rolls Gingival displacement cord Astringent solution Cotton-roll pliers Articulating ribbon and holder Camel hair brush (no.0) Cup of warm water 83 Plastic filling instrument Cotton pellets Petrolatum jelly Autopolymerizing resin Dropper Dappen dishes Cement spatula Backhaus towel clamp forceps L ead pencil Straight handpiece with Carborundum disks Dental floss

84. • Tungsten carbide burs • High-volume evacuation • Cup of warm water 84

85. 1. INDIRECT PROCEDURE The provisional are fabricated outside the mouth. Advantages - There is not contact of free monomer with the prepared tooth or gingiva The procedure avoids subjecting a prepared tooth to the heat created from polymerizing resin. 85

86. The marginal fit of provisional restorations that have been polymerized undisturbed on stone casts is significantly better than that of provisionals that have been removed from the mouth before becoming rigid. This technique gives the patient a change to rest and lets the dentist perform other tasks, provided an assistant is trained to carry out the laboratory procedures. 86 Disadvantages - Takes more time as impressions are made after tooth preparation More cost

87. VACUUM / PRESSURE METHOD 87

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91. TEMPLATE FABRIACTED VLC PROVISIONAL 91

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93. OVERIMPRESSION Matrix for PROVISIONAL CROWN 93 Diagnostic cast Utility wax Wax spatula Impression trays Alginate Rubber bowl Quick set plaster Carmel brush separating medium Rubber band Acrylic burs Straight handpiece Abrasive discs Cement spatula Laboratory knife with no. 25 blade ARMAMENTARIUM-

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100. 2. DIRECT PROCEDURE Restoration is fabricated directly inside the patient’s mouth. This is convenient when assistant training and office laboratory facilities are inadequate for efficiently producing an indirect restoration. R outine use of directly formed provisional restorations is not recommended when indirect techniques are feasible . 100

101. Advantages : 101 Less time-consuming less cost Disadvantages- Patient cooperation is required Pulpal irritation Offensive odour May be difficult to remove Only used for short span bridges. Difficult to fabricate in case of limited mouth opening

102. 102 CUSTOM MADE WITH INDEX

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111. Advantages- Chairside time is reduced. Most of the procedures are completed before the patient’s visit. Less heat is generated in the mouth. The volume of resin used during lining is comparatively small. Contact between the resin monomer and soft tissues is minimized compared to the direct procedure Disadvantage - Adjustments are frequently needed to seat the shell completely on the prepared tooth. 111

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113. Prasad et al in 2012 published a review that described the various materials used for provisional restorations and also the techniques used to fabricate them. For both anterior and posterior teeth, they found that the bis -acryl materials were significantly superior to PMMA. Compared to custom fabricated restorations, preformed crowns resulted in improper fit, contour, or occlusal contact for a provisional restoration Indirect technique was generally preferred over the direct technique as it had overcome the potential hazards caused to the tooth during fabrication by the direct technique. 113

114. CEMENTATION 114

115. Ideal Properties- Ability to seal against leakage of oral fluid Strength consistent with intentional removal Low solubility Chemical compatibility with the provisional polymer Convenience of mixing Ease of eliminating excess Adequate working time and short setting time Compatibility with the definitive luting agent. 115

116. Cements used- Eugenol-containing Non-Eugenol–containing (also called eugenol-free) 116

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120. The benefit of these eugenol-containing cements was that eugenol acts as an obtundent to the pulp Eugenol has been known to affect bonding quality by inhibition of the setting reaction i.e. the free-radical polymerization of the dental resins Acrylic provisional may soften over time because of the eugenol in the provisional cement, leading to the possibility of early failure of the provisional. Because eugenol is a water-insoluble oil it is not readily removed through rinsing the tooth 120

121. Zinc phosphate, zinc polycarboxylate , and glass ionomer cements are not recommended because their comparatively high strength makes intentional removal difficult When a span is greater or long-term use is anticipated, or when Para function exists, using higher-strength cement may be desirable 121

122. Armamentarium- • Provisional luting agent • Mixing pad • Cement spatula • Plastic filling instrument • Petrolatum • Mirror and explorer • Dental floss 122

123. Step-by-step Procedure To facilitate removal of excess cement, lubricate the polished external surfaces of the restoration with petroleum Mix the two pastes together rapidly and apply a small quantity just occlusal to the cavosurface margin 123

124. Seat the restoration and allow the cement to set Carefully remove excess with an explorer and dental floss 124

125. REMOVAL and RECEMENTATION PROCEDURE- 1. If the provisional restoration is going to be recemented , clean out the bulk of cement with a spoon excavator 2. Then place the provisional in a cement-dissolving solution in an ultrasonic cleaner 3. Line it with a fresh mix of resin if necessary (as when a tooth preparation has been modified, for example) 125

126. Digital interim fixed restorations The emergence of computer-aided design/ computer-aided manufacture (CAD/CAM ) technology in dentistry has allowed the successful use of different materials. Interim restorations can be fabricated by means of digital workflow. 126

127. Comparative in vitro evaluation of CAD/CAM vs conventional provisional crowns ABDULLAH et.al J Appl Oral Sci. 2016;24(3):258-63 This study compared marginal gap , internal gap and fracture strength of CAD/CAM provisional crowns with that of direct provisional crowns . 127

128. The materials tested were: VITA CADTemp ®, Polyetheretherketone “PEEK”, Telio CAD-Temp, and Protemp™4 (control group ). Each crown was investigated for marginal fit, internal gap and fracture strength. CAD/CAM fabricated provisional crowns demonstrated superior fit , better strength than direct provisional crowns. 128

129. C onclusion Although provisional restorations are usually intended for short term use and then discarded, they can be made to provide pleasing esthetics, adequate support, and good protection for teeth while maintaining periodontal health. The success of fixed prosthodontic often depends on the care with which the provisional is designed and fabricated. 129

130. References Rosensteil , Land. Contemporary fixed prosthodontics.4th ed. Shillinburgh . Fundamentals of Fixed prosthodontics. 3rd ed. Tylman’s theory and practice of fixed prosthodontics 8 th ed. Federick , D. R. (1975). The provisional fixed partial denture. J Prosthet  Dent, 34(5), 520–526 Marginal integrity of provisional resin restoration materials : A review of the literature- Rakhshan V 2015 Evaluation of color stability of different temporary restorative materials – MAZARO. Journal of odontologia 2015 A Comparative Evaluation of Temperature Changes in the Pulpal Chamber during Direct Fabrication of Provisional Restorations: An In Vitro Study- J Indian Prosthodont Soc July-Sept 2011 An evaluation of fracture resistance of interim fixed partial denture fabricated using polymethylmethacrylate and reinforced by different fibres for its optimal placement: an in vitro study- 2011, AFMS 130

131. Influence of Matrix Type on Surface Roughness of Three Resins for Provisional Crowns and Fixed Partial Dentures—Montero et al. Journal of Prosthodontics 2009 The effect of glass fiber reinforcement on the fracture resistance of a provisional fixed partial denture- Journal of prosthetic dentistry 1998 Constructing direct porcelain laminate veneer provisionals . Kurtz et al, JADA 131

132. THANKYOU 132