Abrasives and polishing agents in dentistry

abrasives and polishing agents in dentistry, dental materials, rougue sand paper, three body abrasion two body abrasion.

1. Abrasives and Polishing Agents Vinay PavanKumar .K 1 st year PG Student Dept of Prosthodontics AECS Maaruti dental college

2. Abrasives and polishing agents Abrasion Erosion Classification Factors affecting abrasion Abrasive instrument design Finishing and polishing procedures for different materials Steps in finishing and polishing

3. Abrasion Abrasion is the process of wear on the surface of one material by another material by scratching, gouging, chiseling, tumbling, or other mechanical means The wearing away of a substance or structure (such as the skin or the teeth) through some unusual or abnormal mechanical process -GPT 8

4. Abrasive action- Principles Harder material comes into frictional contact with the substrate Contact generates tensile and shear stresses Break atomic bonds Substrate particles are removed

5. Types of abrasion 1. Two-body abrasion Abrasive bonded to instrument Eg - diamond bur abrading a tooth.  

6. Three-body abrasion Non bonded abrasives Abrasive particles are free Eg - dental prophylaxis paste

7. Erosion Wear caused by hard particles impacting a substrate surface, carried by a stream of liquid or stream of air. Eg . Sand blasting a surface Chemical erosion Acid etching Enhance bonding

8. Principles Cutting Use of any instrument in a bladelike fashion Regularly arranged blades that remove small shavings of the substrate Unidirectional cutting pattern

9. Grinding Removes small particles of a substrate through the action of bonded or coated abrasive instruments Predominantly unidirectional Innumerable unidirectional scratches Eg : a diamond coated rotary instrument

10. Polishing Most refined of the finishing processes Multidirectional in its course of action Acts on an extremely thin region of the substrate surface Use of progressively fine polishing media Final stage produces fine scratches - not visible unless greatly magnified

11. Factors affecting abrasion Hardness Shape Size Pressure Speed lubricants

12. Factors affecting rate of abrasion Hardness Relates to durability of an abrasive Measure of a material’s ability to resist indentation Abrasive particle must be harder than the surface to be abraded First ranking of hardness was published in 1820 by Friedrich Mohs Knoop and Vickers hardness tests

13. Material Moh’s Brinell Knoop Material Moh’s Brinell Knoop Talc 1 Alumnium oxide 9 1700 1900 Gypsum 2 Silicon carbide 9-10 3000 2500 Chalk 3 Boron carbide 9-10 2800 Rouge 5-6 Diamond 10 >3000 7000 Pumice 6 450 560 SUBSTRATES Tripoli 6-7 Acrylic 2-3 25 Garnet 6.5-7 550 Pure gold 2.5-3 30 Tin oxide 6-7 Porcelain 6-7 400 Sand 7 650 800 Amalgam 4-5 90 Cuttle 7 650 800 Dentin 3-4 Tool steel 800 Enamel 5-6 270 Zirconium silicate 7-7.5 Glass 5-6 Tungsten carbide 9 1200 2100 Resin composite 5-7 200

14. Shape Sharp, irregular particle produces deeper abrasion than rounder particle under equal applied force Numerous sharp edges - enhanced cutting efficiency Abrasion rate of an abrasive decreases with use

15. Size Larger particles size, abrade a surface more rapidly Particles based on their size: 1. Coarse -100 µm to 500 µm, 2. Medium -10 µm to 100 µm, 3. Fine - 0 to 10 µm.

16. Pressure Greater force during finishing Abrasive cut deeper into the surface More rapid removal of material Raise in temperature within the substrate Distortion or physical changes within the substrate

17. Deeper and wider scratches are produced by increasing the applied force from F 1 and F 2

18. Speed Faster speed Faster cutting rates Temperature increases Greater danger of overcutting

19. Lubrication Minimize the heat buildup Facilitates removal of debris Cooling action and removal of debris enhances the abrasion process. Water is the most common lubricant Eg . Water, glycerin or silicone Excess lubrication – prevent abrasive contact

20. Abrasive Instrument Design Abrasive Grits. Bonded Abrasives. Coated abrasive disks and strips Non bonded abrasives

21. Abrasive grits Derived from materials that have been crushed and passed through a series of mesh screens Dental abrasive grits based on particle size are Coarse Medium coarse Medium Fine Superfine

22. Bonded abrasives Abrasive particles are incorporated through a binder to form grinding tool Particles are bonded by four general methods: Sintering Vitreous bonding Resinous bonding Rubber bonding (latex or silicon based )

23. Type of bonding and grinding behaviour 1. Bonded a brasives that tend to disintegrate rapidly Used against a weak substrate Reduced instrument life 2. Abrasives that tend to degrade too slowly clog with grinding debris Loss of abrasive efficiency, increased heat generation, and increased finishing time

24. Maintenance of the efficiency of abrasive Truing : abrasive instrument is run against a harder abrasive block until the abrasive instrument rotates in the hand piece without eccentricity or runout when placed on a substrate.

25. Dressing : 1)Reduces instrument to correct working size, shape 2)Removes clogged debris (abrasive blinding) - Restores grinding efficiency Truing

26. Coated Abrasive Disks and Strips supplied as disks and finishing strips. Fabricated by securing abrasive particles to a flexible backing material available in different diameters with thin and very thin backings. Moisture – resistant backings are advantageous

27. Abrasive discs : Gross reduction, contouring, finishing, and polishing of restoration surfaces Coated with aluminum oxide abrasive Abrasive strips : With plastic or metal backing are available for smoothening and polishing the interproximal surfaces of direct and indirect bonded restorations

28. Non bonded abrasives Polishing pastes - final polishing. Applied to substrate with a nonabrasive device - synthetic foam , rubber, felt, or chamois cloth. Dispersed in water soluble medium such as glycerin for dental appliances. Aluminium oxide and diamond

29. Classification of finishing and polishing devices Based on surface removal 1. Cutting Instruments : Tungsten carbide 2. Bonded abrasive Diamonds Silicon carbide White stone Tripoli Rouge

30. 3. Impregnated abrasives- Aluminium oxide Emery Quartz Silicon carbide Garnet Zirconium silicate Cuttle 4. Loose abrasives Aluminum oxide Ultra fine diamond particles Tin oxide Pumice

31. According to Hardness Diamond - 7500 KHN Silicon carbide - 2500 KHN Aluminum oxide - 2100 KHN Emery - 2000 KHN Corundum - 2000 KHN Tungsten carbide - 1900 KHN Garnet - 1350 KHN Quartz - 800 KHN Sand - 560 KHN Pumice - 560 KHN Chalk - 135 KHN

32. Natura l abrasives Arkansas Stone Chalk Corundum Diamond Emery Garnet 7. Pumice 8. Quartz 9. Sand 10. Tripoli 11. Zirconium silicate 12. Cuttle 13. Kieselguhr

33. Silicon carbide Aluminium oxide Synthetic diamond Rouge Tin oxide Synthetic Abrasives

34. Arkansas stone Semi translucent , light gray, siliceous sedimentary rock. Contains microcrystalline quartz. Attached to metal shanks and trued to various shapes Fine grinding of tooth enamel and metal alloys

35. Chalk Mineral forms of calcite. White abrasive composed of calcium carbonate. Used as a mild abrasive paste to polish tooth enamel, gold foil, amalgam and plastic materials. 

36. Corundum Mineral form of aluminum oxide Physical properties are inferior to those of alpha aluminum oxide. Grinding metal alloys A bonded abrasive in several shapes. Used in instrument – White stone

37. Natural Diamond Transparent colorless mineral composed of carbon Superabrasive Supplied in several forms Bonded abrasive rotary instruments Flexible metal backed abrasive strips Diamond polishing pastes. Used on ceramic and resin based composite materials

38. Diamond burs color coding and grit size Bur type Color Grit size ISO no Supercoarse Black ring 181 μm 544 Coarse Green ring 151μm 534 Medium No ring 107-126μm 524 Fine Red ring 40μm 514 Superfine Yellow ring 20μm 504 Ultrafine White ring 15μm 494

39. Emery Natural form of an oxide of aluminium Grayish- black corundum Coated abrasive disks Greater the content of alumina - finer the grade of emery. Finishing metal alloys or acrylic resin materials.

40. Garnet Dark red, very hard . Comprise - silicates of Al, Co, Mg, Fe, Mn Garnet is coated on paper or cloth with glue. Fractured during grinding  sharp, chisel-shaped plates Grinding metal alloys or acrylic resin materials.

41. Pumice Highly siliceous material of volcanic origin Powder-crushing pumice stone Abrasive action is not very high Polishing tooth enamel, gold foil, dental amalgam and acrylic resins    

42. Quartz Very hard, colorless, and transparent. Crystalline particles are pulverized to form sharp, angular particles - coated abrasive discs. Grinding tooth enamel and finishing metal alloys.

43. Sand Predominantly composed of silica. Particles represent a mixture of color. Rounded to angular shape. Applied under air pressure to remove refractory investment materials Coated on to paper disks

44. Tripoli Derived from light weight, friable siliceous sedimentary rock. Rock is ground and made into bars with soft binders Color- white/grey/pink/red/yellow. Grey and red types Polishing for metal alloys and some acrylic resins.

45. Zirconium silicate / Zircon Off -white mineral. Ground to various particle sizes - coated abrasive disks and strips. Component of dental prophylaxis pastes

46. Cuttle Referred to as cuttle fish, cuttle bone, or cuttle . White calcareous powder Available as a coated abrasive Polishing of metal margins and amalgam restorations.

47. Kieselguhr Siliceous remains of minute aquatic plants - diatoms. Coarser form - diatomaceous earth Excellent mild abrasive Risk for respiratory silicosis caused by chronic exposure  

48. Synthetic Silicon C arbide Extremely hard abrasive and 1 st synthetic abrasive Highly effective cutting of metal alloys, ceramics and acrylic resin materials. Abrasive in coated disks and as vitreous - bonded and rubber instruments.

49. Aluminum oxide White powder used as bonded abrasives, coated abrasives and air propelled abrasives. Finishing metal alloys, resin based composites and ceramic materials. Pink and ruby variations- adding chromium compounds

50. Rouge Consists of iron oxide, which is the fine red abrasive component. Blended in to various soft binders in to a cake form. Used to polish high noble metal alloys.

51. Tin Oxide Extremely fine abrasive. Less abrasive than quartz. Polishing teeth and metallic restorations in the mouth. Produces excellent polish of enamel. Mixed with water or glycerin - abrasive paste.

52. Synthetic Diamond Controllable, consistent size and shape. Resin bonded diamonds have sharp edges Larger synthetic diamond particles – greenish Blocks with embedded diamond particles – truing other bonded abrasives Used primarily on tooth structure, ceramics and resin based composites.

53. Dentifrices Available as toothpaste, gels and powders. The abrasive concentrations in paste and gel dentrifices are 50% to 75% lower than those of powder dentrifices Function : Abrasive and detergent action Polish teeth Act as vehicles

54. Prophylaxis pastes removal of exogenous stains, pellicle, material alba, and oral debris. contain moderately abrasive materials : pumice Silcon dioxide and zirconium silicate are used Applied to teeth through rubber cup on a slow speed handpiece  

55. Steps in finishing and polishing Bulk reduction Removal of excess material Instruments - diamond, carbide and steel burs, abrasive coated disks, or separating disks. 8 - 12 fluted carbide burs or abrasives with particle size of 100µm or larger

56. Contouring Achieved during bulk reduction Finer instruments may be used Desired anatomy and margins must be achieved. 12 - 16 fluted carbide burs or 30 - 100 µm sized abrasive particles used  

57. Finishing Introducing finer scratches to surface of substrate Provides a blemish free smooth surface. 18 - 30 flute carbide burs , fine and super fine diamond burs, or abrasives between 8 and 20 µm in size.

58. Polishing Provides enamel like luster. Smaller particles provide smoother and shinier surfaces Abrasives of 20 µm provide luster Importance of polishing dental restorations and teeth Less bacterial colonization Metallic restoration - prevention of tarnish and corrosion Comfortable for the patient

59. Benefits of finishing and polishing restorative materials To promote oral health and function Enhance strength of the restorative surface To improve esthetics

60. Goals of finishing and polishing Obtain the desired anatomy, proper occlusion Reduction of roughness, and scratches. Smooth surface Resist bacterial adhesion and excessive plaque accumulation.

61. Precautions Heat generation during cutting and contouring , finishing and polishing procedures is a major concern. To avoid adverse effects to the pulp, cool the surface using air water spray and intermittent contact.

62. Polishing instruments Rubber abrasive points. Fine particle disks and strips. Fine particle polishing pastes – applied with soft felt points, muslin wheels, prophy cups or buffing wheels.

63. Non-abrasive polishing Composite glazing Ceramic glazing Electrolytic polishing

64. Composite glazing Layer of glaze – unfilled resin Smooth highly glossy surface

65. Glazing ceramics Subjected to high temperature Glass like surface

66. Electrolytic polishing Electrochemical process Reverse of electroplating Excellent method for Co-Cr alloys

67. Finishing and polishing procedures Resin based composite restorations Most difficult to polish and finish Depends on fillers, preparation design, curing effectiveness and the post curing time. Finishing & Polishing - in one direction only Should continue in a direction perpendicular to the previous one.

68. Gold alloys Slow speed hand piece should be used Contour with carbide burs, green stones, or heatless stones. Finish with pink stones ( aluminum oxide) , or medium grade abrasive impregnated rubber wheels and points( brown and green) Apply fine abrasive- impregnated rubber wheels, cups and points . Apply Tripoli or rouge with rag or leather wheels

69. Ceramometal restorations Critical area while polishing is the porcelain metal junction Using an air water spray and maintaining intermittent contact Several kits:Axis dental corp , Universal ceramic polishers, Dialite Recommended polishing speed -10,000 rpm Polishing at 20,000 rpm reduces flexural strength of ceramics

70. Acrylic resins for Denture Bases and Veneers Contour with tungsten carbide burs and sand paper. Use a rubber point to remove the scratches. Apply pumice with a rag wheel, felt wheel, bristle brush or prophy cup. Apply Tripoli or a mixture of chalk and alcohol with a rag wheel.

71. Air abrasive Technology Alternative to rotary instrument cutting. High pressure stream of 25-30µm Al 2 O 3 . ‘Air polishing’- controlled delivery of air, water and Sodium bicarbonate slurry.

72. Uses   Cavity preparation Removal of defective restorations Endodontic access through porcelain crowns Minimal preparation to repair crown margins Superficial removal of stains Roughening of internal surfaces of indirect porcelains or composite restorations

73. Biological hazards of the finishing procedure Aerosols – silica based materials (smaller than 5µm) Silicosis or grinders disease Precautions -adequate water spray, suction - eyeware ,facemasks -proper ventilation

74. Contraindications of Polishing • Exposed root surfaces • Newly erupted teeth • Patient sensitivity • Inflamed or bleeding gingival tissue • Xerostomia • Respiratory problems • Caries • Hypomineralization • Allergic reaction to pastes

75. Review of literature The objective of this study was to compare both qualitatively and quantitatively the effects of 4 chairside polishing kits ( Exa Technique, Acrylic Polisher HP blue, AcryPoint , Becht Polishing Cream) and conventional laboratory polishing (Universal Polishing Paste for Resins and Metals, Lesk Polishing Liquid) on 3 different types of acrylic resins: autopolymerizing , heat-polymerizing, and injected heat-polymerizing resin materials. Kuhar M et al, Effects of polishing techniques on the surface roughness of acrylic denture base resins, J Prosthet Dent, 2005;93(1):76-85

76. The aim was to study the effect of three polishing agents : pumice, universal polishing agent and brite -O on the surface finish and hardness of two types of acrylic material Universal polishing paste produced smoothest surface Irrespective of resin type and polishing methods it showed equal surface hardness. Srividya S etal . Effect of different polishing agents on surface finish and hardness on denture based acrylic resin : A comparative study IJOPRD, 2011, 1(1) 7-11

77. The purpose of this laboratory study was to evaluate three-body wear of three indirect laboratory composite resins, five chair side bis -acryl resin-based materials, and two chair side methacrylate-based materials used to fabricate provisional implant-supported restorations . The use of indirect composite resin is preferred over chair side methacrylate-based materials when the provisional implant supported restoration has to be in service for a long period of time Santing , H. J., Occlusal Wear of Provisional Implant-Supported Restorations. Clinical Implant Dentistry and Related Research, April 2013

78. To find out the correlation between the roughness of diamonds and roughness created on dentin after tooth preparation & t o measure the surface roughness of dentin after tooth preparation with different grit sizes of diamond rotary instruments There is positive correlation (r = 0.93) between the roughness of diamonds and roughness created on the dentin The effect of grit size of diamonds on the dentinal surface : Dr. Shivangi Sinha

79. Selection of correct grit size and their correct sequence for tooth preparation has an influence on the surface characteristics So completion of the tooth preparation with a finishing bur appeared to be the method of choice if a smooth tooth preparation surface is preferred The effect of grit size of diamonds on the dentinal surface : Dr. Shivangi Sinha

80. This study determined the two-body wear and toothbrushing wear parameters, including gloss and roughness measurements and additionally Martens hardness, of nine aesthetic CAD/CAM materials, one direct resin-based nano composite plus that of human enamel as a control group . Zirconium dioxide ceramics showed no material wear and low wear of the enamel antagonist. Mörmann.W.H etal Wear characteristics of current aesthetic dental restorative CAD/CAM materials: Two-body wear, gloss retention, roughness and Martens hardness. Journal of the Mechanical Behavior of Biomedical Materials ,2013, 20, 113–125

81. Two-body wear of CAD/CAM-silicate and -lithium disilicate ceramics, -hybrid ceramics and nano composite as well as direct nano composite did not differ significantly from that of human enamel Gloss retention was highest with zirconium dioxide ceramics, silicate ceramics, hybrid ceramics and nanocomposites . Temporary polymers showed least gloss retention Mörmann.W.H etal Wear characteristics of current aesthetic dental restorative CAD/CAM materials: Two-body wear, gloss retention, roughness and Martens hardness. Journal of the Mechanical Behavior of Biomedical Materials ,2013, 20, 113–125

82. CONCLUSION

83. References Anusavice , Phillips Science of Dental Materials, 12th edition, 2012, Elsevier publications, Florida, Pp 231-254 O’Brien W.J. Dental materials and their selection,3 rd edition,2002, Quintessence publications Canada, Pp 156-164 Ferracane J.L, Materials in Dentistry, 2 nd edition, 2001, Susan Katz publishers, USA, Pp 293-308

84. Craig . Powers and Wataha , Dental Materials, Properties and manipulation, 8 th edition,2005, Elsevier publications, India , Pp 110-28 Kuhar M et al, Effects of polishing techniques on the surface roughness of acrylic denture base resins, J Prosthet Dent, 2005;93(1): 76-85 Jefferies S R, Abrasive Finishing and Polishing in Restorative Dentistry: A State-of-the-Art Review, Dent Clin N Am 51 (2007) 379–397 The effect of grit size of diamonds on the dentinal surface : Dr. Shivangi Sinha

85. Srividya S etal . Effect of different polishing agents on surface finish and hardness on denture based acrylic resin : A comparative study IJOPRD, 2011, 1(1) 7-11 Mörmann.W.H etal Wear characteristics of current aesthetic dental restorative CAD/CAM materials: Two-body wear, gloss retention, roughness and Martens hardness. Journal of the Mechanical Behavior of Biomedical Materials , 2013 A pril, 20, 113–125 Santing , H. J., Occlusal Wear of Provisional Implant-Supported Restorations. Clinical Implant Dentistry and Related Research, April 2013