Conventional laboratory polishing was found to produce the smoothest surface of denture base acrylic resin. Chairside silicone polishing kits produced a significantly smoother surface of acrylic resin than specimens polished with a tungsten carbide bur.
Abrasives and polishing agents in dentistry
Vinay PavanKumar .K
1st year PG Student
Dept of Prosthodontics
AECS Maaruti dental college
for different materials
Steps in finishing and
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
Harder material comes into frictional contact with the
Contact generates tensile and shear stresses
Break atomic bonds
Substrate particles are removed
1. Two-body abrasion
• Abrasive bonded to instrument
Eg - diamond bur abrading a tooth.
• Non bonded abrasives
• Abrasive particles are free
Eg - dental prophylaxis paste
• 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
• Use of any instrument in a bladelike fashion
• Regularly arranged blades that remove small
shavings of the substrate
• Unidirectional cutting pattern
• Removes small particles of a substrate through
the action of bonded or coated abrasive
• Predominantly unidirectional
• Innumerable unidirectional scratches
• Eg: a diamond coated rotary instrument
• Most refined of the finishing processes
• Multidirectional in its course of action
• Acts on an extremely thin region of the
• Use of progressively fine polishing media
• Final stage produces fine scratches - not
visible unless greatly magnified
• 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
• First ranking of hardness was published in 1820 by
• Knoop and Vickers hardness tests
• 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
• 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.
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
• Deeper and wider scratches are produced by
increasing the applied force from F1
Faster cutting rates
Greater danger of overcutting
• 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
• Abrasive Grits.
• Bonded Abrasives.
• Coated abrasive disks and strips
• Non bonded abrasives
• Derived from materials that have been crushed
and passed through a series of mesh screens
• Dental abrasive grits based on particle size are
• Medium coarse
• Abrasive particles are incorporated through a
binder to form grinding tool
• Particles are bonded by four general methods:
• Vitreous bonding
• Resinous bonding
• Rubber bonding (latex or silicon based)
1. Bonded abrasives that tend to disintegrate
• 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
• 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.
• supplied as disks and finishing strips.
• Fabricated by securing abrasive particles to a flexible
• available in different diameters with thin and very thin
• Moisture – resistant backings are advantageous
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
• 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
Based on surface removal
1. Cutting Instruments : Tungsten carbide
2. Bonded abrasive
• Silicon carbide
• White stone
• Semi translucent , light gray, siliceous
• Contains microcrystalline quartz.
• Attached to metal shanks and trued
to various shapes
• Fine grinding of tooth enamel and
• Mineral forms of calcite.
• White abrasive composed of
• Used as a mild abrasive paste to
polish tooth enamel, gold foil,
amalgam and plastic materials.
• Mineral form of aluminum
• Physical properties are
inferior to those of alpha
• Grinding metal alloys
• A bonded abrasive in several
• Used in instrument – White
• Transparent colorless mineral
composed of carbon
• Supplied in several forms
• Bonded abrasive rotary
• Flexible metal backed abrasive
• Diamond polishing pastes.
• Used on ceramic and resin based
Bur type Color Grit size ISO no
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
• Natural form of an oxide of
• Grayish- black corundum
• Coated abrasive disks
• Greater the content of alumina
- finer the grade of emery.
• Finishing metal alloys or
acrylic resin materials.
• 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
• Highly siliceous material of
• Powder-crushing pumice stone
• Abrasive action is not very high
• Polishing tooth enamel, gold foil,
dental amalgam and acrylic
• Very hard, colorless, and
• Crystalline particles are
pulverized to form sharp,
angular particles - coated
• Grinding tooth enamel and
finishing metal alloys.
• Predominantly composed of
• Particles represent a mixture of
• Rounded to angular shape.
• Applied under air pressure to
remove refractory investment
• Coated on to paper disks
• Derived from light weight, friable siliceous
• 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.
• Off -white mineral.
• Ground to various particle sizes - coated
abrasive disks and strips.
• Component of dental prophylaxis pastes
• Referred to as cuttle fish, cuttle bone, or cuttle.
• White calcareous powder
• Available as a coated abrasive
• Polishing of metal margins and amalgam
• Siliceous remains of minute aquatic plants -
• Coarser form - diatomaceous earth
• Excellent mild abrasive
• Risk for respiratory silicosis caused by chronic
• Extremely hard abrasive and 1st synthetic abrasive
• Highly effective cutting of metal alloys, ceramics
and acrylic resin materials.
• Abrasive in coated disks and as vitreous - bonded
and rubber instruments.
• White powder
• used as bonded abrasives, coated abrasives and air
• Finishing metal alloys, resin based composites and
• Pink and ruby variations- adding chromium compounds
• Consists of iron oxide, which is the fine red abrasive
• Blended in to various soft binders in to a cake form.
• Used to polish high noble metal alloys.
• Extremely fine abrasive.
• Less abrasive than quartz.
• Polishing teeth and metallic
restorations in the mouth.
• Produces excellent polish of
• Mixed with water or glycerin -
• 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.
• Available as toothpaste, gels and powders.
• The abrasive concentrations in paste and gel
dentrifices are 50% to 75% lower than those of
• Function :
Abrasive and detergent action
Act as vehicles
• 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
• 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
• Achieved during bulk reduction
• Finer instruments may be used
• Desired anatomy and margins must be
• 12 - 16 fluted carbide burs or 30 - 100 µm sized
abrasive particles used
• 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
• Provides enamel like luster.
• Smaller particles provide smoother and shinier
• Abrasives of 20 µm provide luster
• Importance of polishing dental restorations and teeth
• Less bacterial colonization
• Metallic restoration - prevention of tarnish and
• Comfortable for the patient
• To promote oral health and function
• Enhance strength of the restorative surface
• To improve esthetics
• Obtain the desired anatomy, proper occlusion
• Reduction of roughness, and scratches.
• Smooth surface
• Resist bacterial adhesion and excessive plaque
• Heat generation during cutting and contouring ,
finishing and polishing procedures is a major
• To avoid adverse effects to the pulp, cool the
surface using air water spray and intermittent
• Rubber abrasive points.
• Fine particle disks and strips.
• Fine particle polishing pastes – applied with
soft felt points, muslin wheels, prophy cups or
• Subjected to high temperature
• Glass like surface
• Electrochemical process
• Reverse of electroplating
• Excellent method for Co-Cr alloys
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.
• Slow speed hand piece should be used
• Contour with carbide burs, green stones, or heatless
• 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
• Critical area while polishing is the porcelain metal
• Using an air water spray and maintaining
• Several kits:Axis dental corp, Universal ceramic
• Recommended polishing speed -10,000 rpm
• Polishing at 20,000 rpm reduces flexural strength of
• Contour with tungsten carbide burs and sand
paper. Use a rubber point to remove the
• 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.
• Alternative to rotary instrument
• High pressure stream of 25-
• ‘Air polishing’- controlled
delivery of air, water and
Sodium bicarbonate slurry.
• 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
• Aerosols – silica based materials (smaller than
• Silicosis or grinders disease
• Precautions -adequate water spray, suction
• 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
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
• 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
• 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
• 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
• To find out the correlation between the roughness of
diamonds and roughness created on dentin after
tooth preparation & to 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 effect of grit size of diamonds on the dentinal surface : Dr. Shivangi
• 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
The effect of grit size of diamonds on the dentinal surface : Dr. Shivangi
• 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
• 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
• 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,
Anusavice, Phillips Science of Dental Materials, 12th edition,
2012, Elsevier publications, Florida, Pp 231-254
O’Brien W.J. Dental materials and their selection,3rd
edition,2002, Quintessence publications Canada, Pp 156-
Ferracane J.L, Materials in Dentistry, 2nd edition, 2001,
Susan Katz publishers, USA, Pp 293-308
Craig . Powers and Wataha, Dental Materials,
Properties and manipulation, 8th 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
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 April, 20,
Santing, H. J., Occlusal Wear of Provisional Implant-
Supported Restorations. Clinical Implant Dentistry and
Related Research, April 2013