FACTORS AFFECTING RATE OF ABRASION DIFFERENCES BETWEEN CUTTING, GRINDING & POLISHING METHODS DESIGN OF ABRASIVE INSTRUMENT CLASSIFICATION OF ABRASIVES STEPS IN FINISHING & POLISHING POLISHING INSTRUMENTS NON ABRASIVE POLISHING FINISHING & POLISHING PROCEDURES IN DIFFERENT RESTORATIONS RECENT DEVELOPMENTS BIOLOGICAL HAZARDS OF THE FINISHING PROCEDURE CONTRA INDICATIONS OF POLISHING

1. SHARI S R
1st YEAR MDS
GDC TVM
ABRASIVES & POLISHING
AGENTS

2. GOOD MORNING

3. CONTENTS
1. INTRODUCTION
2. DEFINITIONS
3. FACTORS AFFECTING RATE OF ABRASION
4. DIFFERENCES BETWEEN CUTTING, GRINDING & POLISHING METHODS
5. DESIGN OF ABRASIVE INSTRUMENT
6. CLASIFICATION OF ABRASIVES
7. STEPS IN FINISHING & POLISHING
8. POLISHING INSTRUMENTS
9. NON ABRASIVE POLISHING
10. FINISHING & POLISHING PROCEDURES IN DIFFERENT RESTORATIONS
11. RECENT DEVELOPMENTS
12. BIOLOGICAL HAZARDS OF THE FINISHING PROCEDURE
13. CONTRA INDICATIONS OF POLISHING
14. REVIEW OF LITERATURE
15. CONCLUSION
3

4. 4 INTRODUCTION
1. All dental appliances and restorations be smooth to the
maximum.
2. Difference between abrasive and polishing agent.
DEFINITIONS:
 Abrasion: A process of wear whereby a hard rough surface
plough grooves in a softer material and cause materials from
these grooves to be removed from the surface(Craig)
 According to skinner abrasion
1. Two body process
2. Three body process

5. 5
Two-body abrasion
1. Abrasive bonded to instrument
Example : diamond bur abrading a tooth.
TYPES OF ABRASION

6. 1. Non bonded abrasives
2. Abrasive particles are free
Three body abrasion
Example : Dental prophylaxis paste
6 TYPES OF ABRASION

7. • Wear caused by hard particles impacting a substrate
surface, carried by a stream of liquid or stream of air.
• Examples:
• Sand blasting a surface
• Acid etching
• Enhance bonding
EROSIVE WEAR7
Chemical Erosion is different from erosive wear.
Example : Acid etching.
It enhances bonding.

8. 1. Hardness
2. Shape
3. Size
4. Pressure
5. Speed
6. lubricants
FACTORS AFFECTING ABRASION8

9. 9
1. Hardness
a) Relates to durability of an abrasive
b) Measure of a material’s ability to resist indentation
c) Abrasive particle must be harder than the surface
to be abraded
d) First ranking of hardness was published in
1820 by Friedrich Mohs
e) Knoop and Vickers hardness tests
FACTORS AFFECTING ABRASION

10. 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
6-7 200
10

11.  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
SHAPE11

12. • 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.
SIZE12

13. 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
13

14. Deeper and wider scratches are produced by
increasing the applied force from F1and F2
14

15. Faster speed
Faster cutting rates
Temperature increases
Greater danger of overcutting
SPEED15

16. 1. Minimize the heat buildup
2. Facilitates removal of debris
3. Cooling action and removal of debris
enhances the abrasion process.
4. Water is the most common lubricant
5. Eg. Water, glycerin or silicone
6. Excess lubrication – prevent abrasive
contact
LUBRICATION16

17. 17
DIFFERENCE BETWEEN CUTTING,
GRINDING & POLISHING

18. 18
CUTTING PRINCIPLES
1. Use of any instrument in a bladelike fashion
2. Regularly arranged blades that remove small
shavings of the substrate
3. Unidirectional cutting pattern

19. 19 GRINDING
1. Removes small particles of a substrate
through the action of bonded or coated
abrasive instruments
2. Predominantly unidirectional
3. Innumerable unidirectional scratches
4. Eg: a diamond coated rotary instrument

20. 20 POLISHING
1) Most refined of the finishing processes
2) Multidirectional in its course of action
3) Acts on an extremely thin region of the
substrate surface
4) Use of progressively fine polishing media
5) Final stage produces fine scratches - not
visible unless greatly magnified

21. 1. Abrasive Grits./loose abrasives
2. Bonded Abrasives.
3. Coated abrasive disks and strips
4. Non bonded abrasives
ABRASIVE INSTRUMENT DESIGN21

22. 1. Derived from materials that have been crushed
and passed through a series of mesh screens
2. Dental abrasive grits based on particle size are
• Coarse
• Medium coarse
• Medium
• Fine
• Superfine
ABRASIVE GRITS22

23. 1. Abrasive particles are incorporated through
a binder to form grinding tool
2. Particles are bonded by four general
methods:
• Sintering
• Vitreous bonding
• Resinous bonding
• Rubber bonding (latex or silicon based)
23 BONDED ABRASIVES

24. 1. Bonded abrasives 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,
• Increased finishing time
24 TYPES OF BONDED ABRASIVE
BEHAVIOUR

25. • 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 MAINTENANCE OF THE EFFICIENCY OF
ABRASIVE

26. Dressing : (shape the instrument)
1. Reduces instrument to correct working size,
shape.
2. Removes clogged debris (abrasive blinding) -
Restores grinding efficiency
Truing
26
Dressing

27. 1. Supplied as disks and finishing strips.
2. Fabricated by securing abrasive particles to a
flexible backing material
3. available in different diameters with thin and very
thin backings.
4. Moisture – resistant backings are advantageous
27 COATED ABRASIVE DISKS & STRIPS

28. Abrasive discs :
1. Gross reduction, contouring, finishing, and
polishing of restoration surfaces
2. 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

29. 1. Polishing pastes - final polishing.
2. Applied to substrate with a nonabrasive device
synthetic foam , rubber, felt, or chamois cloth.
3. Dispersed in water soluble medium such as
glycerin for dental appliances.
4. Aluminium oxide and diamond
29 NON BONDED ABRASIVES

30. CLASSIFICATION OF ABRASIVES30
 Natural Abrasives
 Manufactured Abrasives

31. NATURAL ABRASIVES31
1. Arkansas Stone
2. Chalk
3. Corundum
4. Diamond
5. Emery
6. Garnet
7. Pumice
8. Quartz
9. Sand
10. Tripoli
11. Zirconium silicate
12. Cuttle
13. Kieselguhr

32. 1. Silicon carbide
2. Aluminium oxide
3. Synthetic diamond
4. Rouge
5. Tin oxide
32 SYNTHETIC ABRASIVES

33. 1. Semi translucent , light gray, siliceous
sedimentary rock.
2. Contains microcrystalline quartz.
3. Attached to metal shanks and trued to
various shapes
4. Fine grinding of tooth enamel and metal
alloys
33 ARKANSAS STONE

34. 1. Mineral forms of calcite.
2. White abrasive composed of calcium carbonate.
3. Used as a mild abrasive paste to polish tooth
enamel, gold foil, amalgam and plastic materials.
34 CHALK

35. 1. Mineral form of aluminum oxide
2. Physical properties are inferior to those of
alpha aluminum oxide.
3. Grinding metal alloys
4. A bonded abrasive in several shapes.
5. Used in instrument – White stone
35 CORUNDUM

36. 1. Transparent colorless
mineral composed of carbon
2. Super abrasive
3. Supplied in several forms
a) Bonded abrasive
rotary instruments
b) Flexible metal backed
abrasive strips
c) Diamond polishing pastes.
4. Used on ceramic and resin
based composite materials
36 NATURAL DIAMOND

37. Bur type Color Grit size
37
Supercoarse Black ring 181μm 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
DIAMOND BLUR COLOR CODING & GRIT
SIZE
ISO no

38. 1. Natural form of an oxide of aluminium
2. Grayish- black corundum
3. Coated abrasive disks
4. Greater the content of alumina - finer the grade
of emery.
5. Finishing metal alloys or acrylic resin materials.
38 EMERY

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

40. 1. Highly siliceous material
of volcanic origin
2. Powder-crushing pumice stone
3. Abrasive action is not very high
4. Polishing tooth enamel, gold
foil, dental amalgam and
acrylic resins
40 PUMICE

41. 1) Very hard, colorless, and
transparent.
2) Crystalline particles are
pulverized to form sharp,
angular particles - coated
abrasive discs.
3) Grinding tooth enamel and
finishing metal alloys.
41 QUARTZ

42. 1. Predominantly composed of
silica.
2. Particles represent a mixture of color.
3. Rounded to angular shape.
4. Applied under air pressure to
remove refractory investment
materials
5. Coated on to paper disks
42 SAND

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

44. 1. Off -white mineral.
2. Ground to various particle sizes - coated
abrasive disks and strips.
3. Component of dental prophylaxis pastes
44 ZIRCONIUM SILICATE / ZIRCON

45. 1. Referred to as cuttle fish, cuttle bone, or cuttle.
2. White calcareous powder
3. Available as a coated abrasive
4. Polishing of metal margins and amalgam
restorations.
45 CUTTLE

46. 1. Siliceous remains of minute aquatic plants -
diatoms.
2. Coarser form - diatomaceous earth
3. Excellent mild abrasive
4. Risk for respiratory silicosis caused by chronic
exposure
46 KIESELGUHR

47. 1. Extremely hard abrasive and 1st synthetic abrasive
2. Highly effective cutting of metal alloys, ceramics
and acrylic resin materials.
3. Abrasive in coated disks and as vitreous - bonded
and rubber instruments.
47 SYNTHETIC SILICON CARBIDE

48. 1. White powder
2. used as bonded abrasives, coated abrasives
and air propelled abrasives.
3. Finishing metal alloys, resin based
composites and ceramic materials.
4. Pink and ruby variations- adding chromium
compounds
48 ALUMINUM OXIDE

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

50. 1. Extremely fine abrasive.
2. Less abrasive than quartz.
3. Polishing teeth and metallic
restorations in the mouth.
4. Produces excellent polish of
enamel.
5. Mixed with water or glycerin -
abrasive paste.
50 TIN OXIDE

51. 1. Controllable, consistent size and shape.
2. Resin bonded diamonds have sharp edges
3. Larger synthetic diamond particles – greenish
4. Blocks with embedded diamond particles –
truing other bonded abrasives
5. Used primarily on tooth structure, ceramics and
resin based composites.
51 SYNTHETIC DIAMOND

52. • 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
52 DENTIFRICES

53. 1. Removal of exogenous stains, pellicle, material
alba, and oral debris.
2. contain moderately abrasive materials : pumice
3. Silcon dioxide and zirconium silicate are used
4. Applied to teeth through rubber cup on a slow
speed handpiece
53 PROPHYLAXIS PASTES

54. 54 BUR BLADE DESIGN
Each blade has two sides
1. Rake face (towards the direction of cutting)
2. Clearance face
Three important angle:
1. Rake Angle
2. Edge Angle
3. Clearance Angle

55. 55 NEGATIVE RAKE ANGLE
When the Rake face is ahead of radius:
1. Reduces the fracture of cutting edge.
2. This increases the life of bur.

56. 56 POSITIVE RAKE ANGLE
Increases the cutting efficiency but with following
drawback:
1. It tend to clog the cutting debris in the flute
space.

57. Bulk Reduction
1. Removal of excess material
2. Instruments - diamond, carbide and steel burs,
abrasive coated disks, or separating disks.
3. 8 - 12 fluted carbide burs or abrasives
with particle size of 100µm or larger
57 STEPS IN FINISHING & POLISHING

58. 58
1. Finer instruments may be used
2. Desired anatomy and margins
must be achieved.
3. 12 - 16 fluted carbide burs or 30 - 100 µm
sized abrasive particles used
CONTOURING
STEPS IN FINISHING & POLISHING

59. 1. Introducing finer scratches to surface of substrate
2. Provides a blemish free smooth surface.
3. 18 - 30 flute carbide burs , fine and super fine
diamond burs, or abrasives between 8 and 20 µm
in size.
59
FINISHING
STEPS IN FINISHING & POLISHING

60. 1. Provides enamel like luster.
2. Smaller particles provide smoother & shinier
surfaces
3. Abrasives of 20 µm provide luster
• Importance of polishing dental restorations & teeth
1. Less bacterial colonization
2. Metallic restoration - prevention of tarnish & corrosion
3. Comfortable for the patient
60
POLISHING
STEPS IN FINISHING & POLISHING

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

62. 1. Rubber abrasive points.
2. Fine particle disks and strips.
3. Fine particle polishing pastes – applied with
soft felt points, muslin wheels, prophy cups
or buffing wheels.
62 POLISHING INSTRUMENTS

63. 1. Composite glazing
2. Ceramic glazing
3. Electrolytic polishing
63 NON-ABRASIVE POLISHING

64. 1. Layer of glaze – unfilled resin
2. Smooth highly glossy surface
64 COMPOSITE GLAZING

65. 65 GLAZING CERAMICS
1. Subjected to high temperature
2. Glass like surface

66. 66 ELECTROLYTIC POLISHING
1. Electrochemical process
2. Reverse of electroplating
3. Excellent method for Co-Cr alloys

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

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

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

70. 1. Contour with tungsten carbide burs and sand
paper.
2. Use a rubber point to remove the scratches.
3. Apply pumice with a rag wheel, felt wheel,
bristle brush or prophy cup.
4. Apply Tripoli or a mixture of chalk and alcohol
with a rag wheel.
70 ACRYLIC RESINS FOR. DENTURE BASES
& VENEERS

71. 1. Alternative to rotary instrument cutting high
pressure stream of 25- 30µm - Al2O3.
2. ‘Air polishing’- controlled delivery of air,
water and Sodium bicarbonate slurry.
71 AIR ABRASIVE TECHNOLOGY

72. 1. Cavity preparation
2. Removal of defective restorations
3. Minimal preparation to repair crown margins
4. Superficial removal of stains
5. Roughening of internal surfaces of indirect
porcelains or composite restorations
72 USES

73. 1. Aerosols – silica based materials (smaller than
5µm)
2. Silicosis or grinders disease
3. Precautions - adequate water spray, suction
4. Eye ware ,facemasks
5. Proper ventilation
73 BIOLOGICAL HAZARDS OF THE
FINISHING PROCEDURE

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

75. 1. 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
75

76. 1) 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.
2) 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
76

77. 77 CONCLUSION
Though a varied range of abrasives and polishing
agents have been described with relation to
individual dental materials, an ideal abrasive or a
polishing agent which would satisfy all polishing
needs of the dental materials, one would say, is yet to
be developed.

78. 1. Anusavice, Phillips Science of Dental Materials,
12th edition, 2012, Elsevier publications, Florida,
Pp 231-254
2. O’Brien W.J. Dental materials and their
selection,3rd edition,2002, Quintessence
publications Canada, Pp 156- 164
3. Craig . Powers and Wataha, Dental Materials,
Properties and manipulation, 8th edition,2005,
Elsevier publications, India , Pp 110-28
78

79. 4. 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
5. The effect of grit size of diamonds on the
dentinal surface : Dr. Shivangi Sinha
6. Sturdevant’s Arts & Science of operative
dentistry 5th edition.
7. 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
79

80. THANK YOU
80