abrasive finishing and polishing agents and methods

abrasive and polishing agents

1. FINISHINGANDPOLISHINGAGENTS
1

2. •INTRODUCTION
•OBJECTIVESOFFINISHINGANDPOLISHING
•RATIONALE
•TERMINOLOGIESASSOCIATED
•PRINCIPLES
•SPEEDS
•ABRASION
–TYPESOFABRASION
–FACTORSAFFECTINGABRASION
•CLASSIFICATIONOFFINISHINGANDPOLISHINGAGENTS
•STEPSINFINISHINGANDPOLISHING
•POLISHINGOFACRYLIC RESIN
•PRECAUTIONS
•RECENTADVANCES
•CONCLUSION
•REFERENCES
CONTENTS
2

3. Well finished restorationsoffer-
Highestheticresults
Longevityofrestorations
Maximaloralhealthforpatient
INTRODUCTION
3

4. 4.Achievingwelladaptedcavosurfacemargins
5.Eliminationofminutescratches
1.Removingmarginalirregularities
2.Defininganatomiccontours
3.Smootheningsurfaceroughness
4

5. •Roughsurfacesaremorelikelyto-
Retainplaque
Causesurface
breakdown
andcorrosion
Produce
stressconc.
points
Fracture
Causewearof
adjacenttooth
orrestoration
Compromise
esthetics
5

6. ABRASION
•Processofwearingawayofasurfacebyfriction
ABRASIVE
•Outermostparticleorsurfacematerialofan
instrumentthatproducesabrasion
SUBSTRATE
•Material/surfacebeingfinished
CUTTING
•Processofremovingmaterialfromthesubstratebyuseof
abladedburoranabrasiveembeddedinabindingmatrix
onaburordisk. 6

7. BULKREDUCTION:
Processofremovingexcessmaterialbycuttingor
grindingamaterialwithrotaryinstrumentsto
provideadesiredanatomicform.
CONTOURING:
Processofproducingadesiredanatomicalform
by
cuttingorgrindingawayexcessmaterial.
FINISHING:
Processofremovingsurfacedefectsorscratches
createdduringthecontouringprocessthrough
theuseofcuttingorgrindinginstrumentsorboth
7

8. Grinding:
8
Processofremovingmaterialfromasubstrate
byabrasionwithrelativelycoarseparticles
Polish:
Lustreorglossproducedonafinished
surface.
Polishing:
Processofprovidinglustreorglossona
materialsurface.

9. PRINCIPLES
1.CUTTING
Useofanyinstrumentinabladelike
fashion
Regularlyarrangedbladesthatremove
smallshavingsofthesubstrate
Unidirectionalcuttingpattern
2.GRINDING
Removessmallparticlesofa
substratethroughtheactionof
bondedorcoatedabrasive
instruments
Predominantlyunidirectional
3.POLISHING
Multidirectionalinitscourseofaction
Actsonanextremelythinregionofthe
substratesurfacefinescratches-notvisible
unlessgreatlymagnified 9

10. SPEEDSUSEDFORFINISHINGANDPOLISHING
LOWSPEED-
•<12000rpm
•Bettertactilesensation
•Lesserheatgeneration
•Cleaning,polishing
MEDIUMSPEED/INTERMEDIATESPEED
•12000-2,00,000rpm
•Contouring
HIGHSPEED/ULTRAHIGHSPEED
• >2,00,000rpm
•Faster,needlesserpressure,vibration
•Grossfinishingandcontouring
ThestandardMicomotor
handpiece-35000rpm
10

11. ABRASIONANDABRASIVES
11

12. ABRASIVEACTION-PRINCIPLE
Substrateparticlesareremoved
Breakatomicbonds
Contactgeneratestensileandshearstresses
Hardermaterialcomesintofrictionalcontactwiththesubstrate
12

13. TYPESOFABRASION
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1.TWOBODYWEAR-
•Abrasiveboundtoinstrumentandusedto
polishspecimen
•E.g.-Trimmers,abradingburs,bondedabrasives,
coatedabrasives
Abrasive Substrate
Twobodywear

14. 2.THREEBODYWEAR
•Abrasiveisalooseslurrybetweenpolishingsubstrate
andsurfaceofthespecimentobe polished
•Useoflubricant(water,glycerinorsilicone)
•E.g.-PolishingpastescontainingAluminium
oxide,diamondparticles
Rubbercup
Threebodywear
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Abrasivepaste
Substrate

15. EROSION
•Wearcausedbyhardparticlesimpactingasubstrate
surface,carriedbyastreamofliquidorstreamofair.
Eg.Sandblastingasurface
•Chemicalerosion
Acidetching
Enhancebonding
Notamethodof
finishing/polishing
15

16. Factorsaffectingabrasion
Hardness
Shape
Size
Pressure
Speed
Lubricants
16
Factorsaffectingrateofabrasion

17. Relatestodurabilityofanabrasive
Measure of a material’s ability to resist
indentation
Abrasiveparticlemustbeharderthanthe
surfacetobeabraded
Firstrankingofhardnesswaspublishedin1820byCarlFriedrich
Mohs
FRIEDRICHMOHS
KnoopandVickershardnesstests
17
HARDNESS

18. SHAPE
Sharp,irregularparticleproducesdeeperabrasionthan
rounderparticleunderequalappliedforce
Numeroussharpedges-enhancedcuttingefficiency
Abrasionrateofanabrasivedecreaseswithuse
18

19. SIZE
Largerparticlessize,abradeasurface
morerapidly
Particlesbasedontheirsize:
1.Coarse-100µmto500µm,
2.Medium-10µmto100µm
3.Fine-0to10µm
19

20. PRESSURE
Distortionorphysicalchangeswithinthesubstrate
Greaterforceduringfinishing
Abrasivecutsdeeperintothesurface
Morerapidremovalofmaterial
Raiseintemperaturewithinthe
substrate
20

21. Deeperandwiderscratchesareproduced
byincreasingtheappliedforcefromF
1
and
F
2
21

22. SPEED
Fasterspeed
Fastercuttingrates
Temperatureincreases
Greaterdangerof overcutting
22

23. LUBRICATION
Minimizetheheatbuildup
Facilitatesremovalofdebris
Coolingactionandremovalofdebrisenhancesthe
abrasionprocess.
Water,glycerinorsilicone;Watermost
common
Excesslubrication–preventabrasivecontact
23

24. ABRASIVEINSTRUMENTDESIGN
REQUIREMENTSOFANABRADINGINSTRUMENT-
Rightparticlesize
Notproducedeepscratches
Sharpedgesthatbreakdowntoexposenew
edgeparticles
Notgougethesubstrate
Notpermanentlydeformunderloadorhigh
temperature
24

25. Abrasivemotion
•Abrasivemotioncanbeclassifiedas
1.Rotary-burs
2.Planar-disk
3.reciprocalmotion.
•ROTARY
•Inrotarymotion,theburinahighspeed
handpiecerotatesinaclockwisedirection.
25

26. •Planarmotion
•disks
•removesmaterialalongaplane.
•preferablybedoneinonedirectionto
obtainasmoothersurface.
•Reciprocalmotion
•twodifferentmotionsatthesame
time:partcyclicandpartupanddown
motions.
•Thisisusefultoaccessinterproximal
areastoremoveoverhangs,tofinish
sub-gingivalmarginswithoutcreating
ditches,andtocreateembrasures.
26

27. 27

28. MAINTENANCE OFTHEEFFICIENCYOF
ABRASIVE
28
•Truing:
Abrasiveinstrumentisrunagainstaharder
abrasiveblockuntiltheabrasiveinstrument
rotatesinthehandpiecewithouteccentricity
orrunoutwhenplacedonasubstrate.

29. •Dressing:
1)Reducesinstrumenttocorrectworkingsize,
shape
2)Removescloggeddebris(abrasiveblinding)-
Restoresgrindingefficiency
Truing Dressing
29

30. 1
2 30

31. Classificationofabrasives.
ABRASIVE
VITREOUS
BONDING
RUBBER
BONDING
RESINOID
BONDING
BONDED
NON
BONDED
SINTERED
BONDING
DISPERSEDIN
WATERSOLUBLE
MEDIUM
POLISHING
PASTES
COATED
31

32. Bondedabrasives-Abrasiveparticlesare
incorporatedthroughabindertoformagrinding
tool
•Particlesarebondedbyfourgeneralmethods:
1.Sintering-
Strongest,producedbyfusingparticlestogether
2.Vitreousbonding-
Abrasive+glassyceramicmatrix,coldpressedtoshapeandfired
3.Resinoidbonding-
Particlescoldpressedwithresinsandthenheatedtocuretheresin
4.Rubberbonding-latex based or silicone based
32

33. SinteredDiamondpoints
33
Vitreousbondedabrasives
Siliconebondedabrasives
Resinoidbondedabrasives

34. Nonbondedabrasives-notbondedtoa
substrate(3bodywear)
•Dispersedingelorpasteform
•PolishingpastesFineorultrafine
Al2O3(<1μm)ordiamondparticles(1-
10μm)
•Appliedtosubstratewitha
nonabrasivedevice-synthetic
foam,rubber,felt,chamoiscloth,
wheel.
•Dispersedinwatersolublemedium
suchasglycerin
34

35. Coatedabrasivedisksandstrips
•Suppliedasdisksandfinishingstrips.
•Fabricatedbysecuringabrasiveparticlestoaflexible
backingmaterial
•Availableindifferentdiameterswiththinandverythin
backings.
•Moisture–resistantbackingsareadvantageous
35

36. Naturalabrasives
1.ArkansasStone
2.Chalk
3.Corundum
4.Diamond
5.Emery
6.Garnet
7.Pumice
8.Quartz
9.Sand
10.Tripoli
11.Zirconiumsilicate
12.Cuttle
13.Kieselguhr
SyntheticAbrasives
1.Siliconcarbide
2.Aluminumoxide
3.Syntheticdiamond
4.Rouge(Ironoxide)
5.Tinoxide
36

37. FINISHINGOF
ACRYLIC RESIN
37

38. STEPSINFINISHINGANDPOLISHING
1.BULKREMOVAL
2.CONTOURING
3.FINISHING
4.POLISHING
38

39. 1.Bulkreductionand
Contouring
•Removalofexcessmaterialthrough
cuttingandgrinding
•Instruments-diamond,carbideand
steelburs,abrasivecoateddisks
•Desiredanatomyandmarginsmustbe
achieved
39
BULKREDUCTIONCONTOURING
CARBIDEBUR 8-12FLUTED 12-16FLUTED
ABRASIVES >=100µm 30-100µm

40. 3.Finishing
40
•finerscratchestosurfaceofsubstrate
•Providesablemishfreesmoothsurface.
•18-30flutedcarbideburs,fineandsuperfine
diamondburs,orabrasivesupto20µminsize.

41. 4.Polishing
41
•Provideslustre.
•Smallerparticlesprovidesmootherandshiniersurfaces
•Abrasivesof8-20µm

42. 42

43. 43
•Contourwithtungstencarbidebursandsand
paper.Usearubberpointtoremovethe
scratches.
Applypumicewitharagwheel,feltwheel,
bristlebrushorprophycup.
ApplyTripolioramixtureofchalkandalcohol
witharagwheel.
•
•

44. 44

45. RECENTADVANCES
AIRABRASION
NANOPARTICLE
INCORPORATION
45

46. AIRABRASIVETECHNOLOGY
•Alternativetorotaryinstrument
cutting.
•Highpressurestreamof25-30µm
Al
2O
3.
•‘Air polishing’-controlleddeliveryof
air,waterandSodiumbicarbonate
slurry.
46

47. ApplicationOfNanotechnology
InAbrasives
•Nanosilicaabrasives
•Particlesizeofnanosilicarangesfrom10-90nmandis
sphericalinshape.
•Ithasbeenreportedthatpolishingwithnano-silica
provideshighpolishingandlowsurfaceroughness.
Alsopolishingofteethwithnanosilicahelpsin
preventionofdamagecausedbycariogenicbacteria.
47

48. Biologicalhazardsofthefinishing
procedure
•Aerosols–silicabased
materials(smallerthan5µm)
•Silicosisorgrindersdisease
•Precautions-adequatewater
spray,suction,eyegear,
facemasks,properventilation
48

49. Methodstoassesstheeffectiveness
offinishingsystemsanddevices
Themostcommontoassestheeffectivenessoffinishingand
polishingsystemanddevicesondentalrestorativematerialsinclude
aidedandunaidedvisualevaluation
a.Profilometer
b.Opticalmicroscope
c.SEM(scanningelectronmicroscope)
d.Reflectometer
49

50. Finishingand
polishingtechniques
areimportantin
preparingclinically
successful
restorations.
Adefinitesequence
shouldbeadopted
infinishingand
polishingofeach
restorationFinishing
andpolishingbegin
withcoarse
abrasivesandend
withfineabrasives
Theprocessof
abrasionisaffected
bypropertiesof
theabrasiveand
thematerialbeing
abraded.
Clinicallyitiseasier
tocontroltherate
ofabrasionby
speedratherthan
thepressure.Care
mustbetakento
avoidoverfinishing
marginsand
contoursof
restorationsandto
avoidoverheating.
CONCLUSION
50

51. REFERENCES
Anusavice, Phillips Science of Dental Materials, 12th edition, 2012
John J. Manapallil, textbook of basic dental materials. 4rth edition
Powers JM, Bayne SC. Friction and wear of dental materials
Effects of polishing techniques on the surface roughness of acrylic
denture base resins. Journal of prosthetic dentistry. Volume 93,
issue 1, January 2005, Pages 76-85
The effect of mechanical and chemical polishing techniques on the
surface roughness of denture base acrylic resins. The Saudi Dental
Journal Volume 22, Issue 1,January 2010, Pages 13-17
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52. THANK YOU..
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