CAST METAL RESTORATIONS IN PROSTHODONTICS.pptx

metal restorations in dentistry

1. CAST METAL RESTORATIONS Amisha Goyal BDS(FINAL YEAR)

2. CONTENTS INTRODUCTION INDICATIONS CONTRAINDICATIONS ADVANTAGES DISADVANTAGES TOOTH PREPARATION FOR CLASS II CAST METAL RESTORATION TOOTH PREPARATION FOR FULL CAST METAL ONLAYS SECONDARY RESISTANCE AND RETENTION FEATURES

3. INTRODUCTION Cast metal restoration is an indirect restoration. DEFINITIONS:- Inlay: fixed intracoronal restoration,dental restoration made outside of a tooth to correspond to the form of prepared cavity,which is then luted into the tooth. Class II inlay: involves occlusal surface and proximal surfaces of a posterior tooth and may cap one or more but not all of the cusps.

4. Onlay : combination of intracoronal and extracoronal cast restorations that caps all the cusps of a posterior tooth that can be designed to help strengthen a tooth weakened by caries or previous restorative treatment. classII onlay : involves the occlusal and proximal surfaces of a posterior tooth and caps all of the cusps. ( Sturdevant )

5. MATERIALS FOR CAST METAL RESTORATIONS

6. CAST DENTAL ALLOYS CAN ALSO BE CLASSIFIED AS: 1.On the basis of use all metal inlays,crowns and bridges,metal ceramic prosthesis,posts and cores,removable partial dentures and implants 2.On the basis of major elements present gold-based,silver-based,palladium-based,nickel-based,cobalt-based,titanium-based

7. 3.On the basis of nobility high noble,noble,and predominantly base metal 4.On the basis of principal elements present ( Au-Pd- Ag,Pd -Ag- Sn,Ni -Cr- Be,Co -Cr- Mo,Fe -Ni-Cr 5.On the basis of dominant phase system single phase, eutectic, peritectic and intermetallic types

8. REQUIREMENTS OF DENTAL CASTING ALLOYS

9. INDICATIONS Large restorations Endodontically treated teeth Superior contact and contour Dental rehabilitation with cast metal alloys Posterior diastema closure and occlusal plane correction Removable prosthodontic abutment

10. CONTRAINDICATIONS High caries rate Young patients Esthetics Small restorations

11. ADVANTAGES Strength Biocompatibility Low wear Control of contact and contours

12. DISADVANTAGES No. of appointments and higher chair time Temporary restorations Cost Technique sensitivity Splitting forces

13. MOUTH PREPARATION PRIOR TO CAST RESTORATION Control of plaque Control of caries Control of periodontal problems Control of pulpal condition of tooth Occlusal equilibrium Diagnostic wax-ups and temporary restoration

14. BURS USED IN CAVITY PREPARATION

15. STEPS IN TOOTH PREPARATION OF CLASS 2 INLAY 1.INITIAL PREPARATION

16. A. Removal of infected carious dentin and pulp protection 1.Inspection 2.Removal of infected caries 3.Removal of old restorative material 4.Pulp protection with light cure GIC 5.Lining with calcium hydroxide(if required) B. Preparation of bevels and flares 1.Preparation of occlusal bevel 2.Beveling the axio -pulpal line angle 3.Preparing the secondary lingual flare 4.Beveling the gingival margin 5.Preparing the secondary facial flare 2.FINAL PREPARATION

17. 1.ORIENTING THE BUR No.271 carbide bur is held parallel to the long axis of tooth crown. For mandibular molars and second premolars,crowns tilt slightly lingually thus bur should also be tilted(5-10degrees) lingually

18. 2.OCCLUSAL PUNCH CUT Enter the fossa or pit closest to the involved marginal ridge,using a punch cut to a depth of 1.5mm to establish the depth of the pulpal wall

19. 3.OCCLUSAL EXTENSION Maintain the 1.5mm initial depth and same bur orientation , extend the preparation outline along the central groove or fissure to include the fossa or pit

20. 4.DOVETAIL RETENTION 169L carbide bur is used to make facial and lingual extension into the pit region This features resists displacement in mesio -distal direction.

21. 5.OCCLUSAL OUTLINE FORM No. 271 carbide bur is used to extend the occlusal step and progressively widen the preparation to the desired faciolingual width in anticipation of proximal box preparation Clears the adjacent tooth by 0.2-0.5mm And the width of the isthmus should only be slightly wider than bur.

22. 1.PROXIMAL DITCH PREPARATION Mesiodistal width of the ditch should be 0.8mm 0.5mm at the expense of dentin 0.3mm at the expense of enamel Ideal gingival extension provides a 0.5mm clearance of the unbeveled gingival margin with the adjacent tooth.

23. 2.PROXIMAL BOX PREPARATION With the no. 271 carbide bur make two cuts, one at the facial limit of the proximal ditch and the other at the lingual limit. These cuts are extended until the bur is nearly through the marginal ridge enamel

24. 3. PLANING OF THE WALLS By using bin-angle chisel or enamel hatchet,planing of the facial,lingual and gingival margins is accomplished Clear the adjacent tooth by 0.2-0.5mm

25. 4.PLACEMENT OF RETENTION GROOVES Shallow 0.3mm deep retention grooves may be cut in the facioaxial and linguoaxial line angles with the no. 169L CARBIDE BUR These grooves are indicated if the prepared tooth is short Grooves are in sound dentin,close to but not contacting the DEJ

26. FINAL PREPARATION A.REMOVAL OF INFECTED CARIOUS DENTIN AND PULP PROTECTION Inspection Removal of infected caries by slowly revolving round bur or spoon excavator

27. Removal of old restorative material Pulp protection with light cured GIC Lining with calcium hydroxide if required

28. B.PREPARATION OF BEVELS AND FLARES NO. 8862 BUR IS USED Beveling the occlusal and gingival margins and applying the secondary flare on the lingual and facial walls results in 30-40 degrees marginal metal on the inlay Cavosurface design helps seal and protects the margins and results in a strong enamel margin at an angle of 140-150 degrees.

29. BEVEL Inclination that one surface makes with another when not at right angles; in cavity preparation, a cut that produces an angle of more than 90 degrees with a cavity wall.

30. PARTIAL BEVEL Involves:part of enamel wall;not exceeding 2/3 of it’s dimension.Use:to trim weak enamel rods from margin peripheries.Usually not used in cast restorations SHORT BEVEL Involves:entire enamel wall;but not dentin This bevel is used mostly with classI alloys especially for type I and II(gold and platinum based alloys) LONG BEVEL involves:all enamel wall and upto ½ of dentinal wall most frequently used bevel for the first three classes of cast metals Advantage:preserves internal “boxed-up” resistance and retention features of the preparation.

31. FULL BEVEL involves: all the dentinal and enamel walls of cavity wall or floor. Use: usually not indicated Disadvantage: deprives the preparation of it’s internal resistance and retention features COUNTER BEVEL Use:when capping cusps;to protect and support them Prepared opposite to an axial cavity wall on facial or lingual surface of tooth It will have gingival inclination facially and lingually HOLLOW GROUND(CONCAVE)BEVEL Any bevel prepared in concave form Allows material for cast material bulk Ideal for class IV and V cast materials

32. 1.PREPARATION OF OCCLUSAL BEVEL Width of the cavosurface bevel on the occlusal margin should be approximately one-fourth the depth of the respective wall. occlusal marginal metal of the inlay: 40degree occlusal marginal enamel is : 140degree beveling helps in: increases strength of marginal enamel and helps seal the margins.

33. 2. BEVELING THE AXIOPULPAL LINE ANGLE - provides a thicker and stronger wax pattern - desirable metal angle at the margins of inlays is always 40degrees except at the gingival margins where the metal angle should be 30 degrees

34. 3.PREPARING THE SECONDARY LINGUAL FLARE - using the flame shaped diamond instrument - first flare that brings the proximal preparation out of the contact area is termed lingual primary flare -second flare that is given to provide a marginal metal angle of 40degrees is termed lingual secondary flare

35. Advantages of secondary flare Extend margins into the embrasures, making them self cleansing and accessible to finishing, along with the conservation of dentin Resulting in 40 degree marginal metal which is more burnishable More blunt and stronger enamel margin Convenience form to aid impression making , finishing and try in of castings

36. 4. BEVELING THE GINGIVAL MARGIN -Gingival bevel should be 0.5-1mm wide and should blend with the lingual secondary flare It helps in- -removal of weak enamel -30 degree metal margin that is burnishable . -Sliding fit is produced at the gingival margin.

37. PREPARING SECONDARY FACIAL FLARE Long axis of instrument tilted mesially and facially 40 degrees marginal metal results.

38. DIFFERENCES IN AMALGAM AND INLAY RESTORATIONS Amalgam 245 bur used for establishing the outline form Inverted pear shape bur Occlusally converging walls formed Inlay 271 bur used for establishing the outline form Tapered fissure bur Occlusally diverging walls formed with 2-5 degree taper on each side Tooth preparation differences

39. Amalgam Occlusally converging walls aid in mechanical retention via undercut formation Inlay Retention occurs by close approximation of casting to walls of preparation and cementation. No undercuts formation indicated, otherwise difficult seating and retrieval of restoration

40. Amalgam Indicated mainly for small restorations. 1/4 th intercuspal distance with faciolingual width not more than 1.5 – 2mm Inlay Larger restoration possible due to greater strength of metal Restorations can extend upto 1/3 rd intercuspal distance depending upon the tooth anatomy and extent of caries

41. Amalgam 90degrees cavosurface angle because thin marginal amalgam lacks strength and chips under occlusal stresses Inlay 140 degrees cavosurface angle resulting in 40 degrees marginal metal to remove all undermined enamel rods , better adaptation of metal and ease of burnishing

42. Amalgam Only primary flares provided. Gingival bevel of 15-20 degrees to remove undermined enamel Inlay Secondary flares given along with primary flares Gingival bevel of 30 degrees for thickness of metal and increase adaptation of casting that fail to seat by a slight amount

43. Differences in restorative technique Amalgam Prepared cavity filled in the same appointment Amalgam condensed in tooth preparation in increments Inlay Impression, temporary restoration and seating of cast require multiple appointments Casting is directly inserted and luted

44. Amalgam Burnished and carved intraorally Contact and contours average Inlay Tooth anatomy replicated accurately by wax patterns Superior contacts and contours by indirect method

45. Differences in properties Amalgam Low wear resistance Greater tendency to fracture under occlusal loads due to lower tensile strength than compressive strength Lesser durability due to tendency to undergo tarnish and corrosion Lesser biocompatibility due to presence of mercury, health hazard to dentist and hygienist more Inlay High wear resistance Less tendency to fracture under occlusal loads and better stress tolerance More durability, mostly of noble metals that do not show corrosion Made of mostly biocompatible noble metals, base metal alloys might show allergic reactions

46. INLAY AMALGAM VISITS At least two Single Procedure Indirect direct Size of restoration Large and bulky Relatively smaller Strength Superior Less Outline form Wide, occlusally diverging walls Narrow walls converge occlusally Cavosurface angle 130-140 degrees 90 degrees Bevels All margins beveled No bevels Gingival bevel 20-30 degrees 15-20 degrees Undercuts No undercuts should be present Improve retention Retention Close adaptation of casting, cementation Converging walls Secondary retention Grooves, slots, internal boxes, skirts, collars Grooves, pins, slots Proximal walls Primary and secondary flare Primary flare

47. TOOTH PREPARATION IN FULL CAST METAL ONLAY

48. 1.PREPARATION OF PULPAL FLOOR With a no.271 carbide bur a 2mm deep pulpal floor is prepared along the central groove. The groove should not be extended farther than two-thirds the distance from the central groove to the cusp tips Gingival to occlusal divergence of the preparation walls may range from 2-5 degrees

49. 2.PREPARATION OF DEPTH GAUGE GROOVES With the side of the no.271 carbide bur Uniform 1.5mm deep depth cuts are prepared on the remaining occlusal surface depth cuts are placed on -crest of the triangular ridges -facial and lingual groove regions

50. 3.CUSP REDUCTION Reduction should provide a uniform metal thickness of 1.5mm On maxillary premolars and first molars,the reduction should be minimal(0.75-1mm) on the facial cusp ridge to decease the display of metal

51. 4.OCCLUSAL STEP 0.5mm deep occlusal step should be present in central groove region between the reduced cuspal inclines and the pulpal floor It contributes to the retention of restoration and provides the wax pattern and cast metal onlay with additional bulk of rigidity

52. 5.REVERSE BEVEL OR COUNTER BEVEL A reverse bevel or counter bevel is a bevel of generous width,which is prepared on the facial(lingual ) margin of a reduced cusp with a flame shaped, fine grit diamond instrument

53. 6.PROXIMAL BOX 7.REMOVAL OF INFECTED CARIOUS DENTIN 8.PREPARATION OF BEVELS AND FLARES 9.VERIFICATION OF OCCLUSAL CLEARANCE

54. RESTORATIVE TECHNIQUES FOR CAST METAL RESTORATION Interocclusal records Temporary restoration Final impression Working casts and dies Wax patterns Spruing , investing and casting Seating, adjusting and polishing the casting Trying in the casting Cementation

55. The maximum intercuspation interocclusal record made from bite registration pastes Like heavily filled polyvinyl siloxane (PVS) impression materials Patient closing in maximum intercuspation position over the paste When held up to a light, areas where the adjacent unprepared teeth have penetrated through the material should be seen.

56. Temporary restoration Direct technique Flow mixed temporary material into preoperative impression of prepared tooth Seat preoperative impression with temporary material onto prepared tooth

57. Removal of temporary restoration from tooth preparation Thin excess removal by scissors Final trimming Cementation using temporary cement

58. Final impression Light and heavy body impression material Tray adhesive Accessory curved tip

59. Impression tray filled with heavy bodied material Tooth surface covered with light bodied material Seating of impression tray Retrieval of impression

60. Working casts and dies Die segment on Pindex machine, ready to drill hole for first molar die. A small red dot of light helps position the cast . Holes drilled for removable dies.

61. Flow a drop of cyanoacrylate glue into each hole. The cast must be dry for the glue to adhere. Immediately insert a dowel pin into the hole, being sure it is fully seated.

62. Place rope wax around the cast, flush with the die bases Place boxing wax around the rope wax to create a container for the base pour. A separating agent must be painted on die bases to prevent adherence with base pour.

63. Cast after removing boxing and rope wax Base pour completed. Leave at least 1 mm of the dowel pin protruding

64. Removing die segment from base Remove the excess die stone with a large crosscut carbide bur in slow speed handpiece Final trimming is completed with a sharp scalpel. Cast completed, facial view

65. Wax patterns To ensure optimal wax adaptation to preparation walls, first flow on a thin layer of wax Then apply finger pressure for several seconds while wax cools

66. Wax is carved to margins with warm No. 7 spatula. After marginal ridge is added to pattern base, fossae are waxed in, and grooves are carved to complete wax pattern

67. SPRUING INVESTING CASTING FINISHING SEATING ADJUSTING AND POLSISHING OF CASTING

68. Trying in the casting Use hand pressure initially to seat casting on tooth by applying ball burnisher in pit anatomy. Inspect marginal fit of tried-in inlay

69. Cementation Isolation Application of cement Seating using ball burnisher and hand pressure

70. Patient asked to apply masticatory pressure Excess cement removed using explorer and air water spray, removal of interproximal cement by dental tape Onlay after cementation

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