Finishing & polishing materials in dentistry/ rotary endodontic courses by indian dental academy


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Finishing & polishing materials in dentistry/ rotary endodontic courses by indian dental academy

  1. 1. Finishing and polishing materials INDIAN DENTAL ACADEMY Leader in Continuing Dental Education
  2. 2. introduction Terminologies •Principles of cutting, grinding ,finishing and polishing Classification of materials Benefits of finishing and polishing Steps in finishing and polishing Finishing and polishing procedures Glass Direct fillingcomposites amalgam ceramics Ionomer gold cement Summary and conclusion Summary and conclusion
  3. 3. introductionFinishing, polishing of dental restorations are importantaspects of clinical restorative procedures that enhanceboth aesthetics and longetivity of restored teeth.Residual surface roughness, associated with improperfinishing and polishing of dental restorations ,can resultin number of clinical difficulties.The problems include excessive plaque accumulation,gingival irritation, increased surface staining, poor orsuboptimal aesthetics of the restored teeth.
  4. 4. Finishing and polishing refers to gross contouring of therestoration to obtain the desired anatomy, and the reduction and smoothing of the roughness andscratches created by finishing instruments. A number of methods and tools for finishing andpolishing restorations are available to cliniciansincluding: fluted carbide bur; diamond burs; stones;coated abrasive discs and strips; polishing pastes; andsoft or hard rubber type cups, points, and wheelsimpregnated with various abrasives grits.
  5. 5. Proper finishing of restorations is desirable not only foresthetic considerations but also for oral health.The primary goal of finishing is to obtain a restorationwhich has good contour, occlusion, healthy embrasureforms, and smoothness. Tight margins should blendesthetically into the tooth’s natural contours. The polish should be smooth enough to be toleratedwell by gingival tissue. It has been proven that rough surfaced restorations cancreate clinical problems such as plaque retention,gingival irritation, staining, higher wear rates, andrecurrent caries.
  6. 6. Preferential retention of microorganisms occurs on therough surface of the restorations Quiern et al 1995The efficacy of finishing and polishing materials andprocedures on contemporary composites is an importantand often formidable challenge within the restorativeprocess. Besategui et al 1992Restoration finish surface roughness and surfaceintegrity, as well as the physicochemical properties ofmaterial itself, can affect plaque retention periodontaldisease and recurrent decay Weitman et al 1994
  7. 7. DefinitionFinishing refers to gross contouring or reduction ofrestorations to obtain the desired contour, while polishingrefers to the reduction of roughness and surfacescratches . Auj.Yap Journal of Operative Dentistry. 2004
  8. 8. Finishing: process of removing surface defects orscratches created during the contouring processthrough the use of cutting or grinding instruments orboth.Polishing: the most refined of the finishingprocesses, removes the finest surface particle. Kenneth j. Anusavice
  9. 9. TerminologiesAbrasive: a hard substance used for finishing andpolishing a less hard substanceBuffing: process of producing a lustrous surface throughthe abrading action of fine abrasives bound to nonabrasive binder mediumBulk reduction: process of removing excess material withrotary instruments to produce a desired anatomic form.
  10. 10. Contouring: process of producing a desired anatomicform by cutting away excess materialCutting: process of removing material from the substrateby use of a bladed bur or an abrasive embedded inbinding matrix on a bur or diskFinished and polished restoration: a prosthesis or adirect restoration whose outer surface beenprogressively refined to a desired state of surface finishFinishing: process of removing surface defects orscratches created during the contouring processthrough the use of cutting or grinding instruments orboth.
  11. 11. Abrasivity: property of one material to abrade anothermaterial by means of frictional heatPolishing agents: any material used to impart luster to asurfaceAbrasion: the wearing away of substance or structurethrough or abnormal mechanical process
  12. 12. Glaze ceramic: specially formulated ceramic powder when mixed with liquid and applied to ceramic surface and heated to appropriate temperature produces a smooth glassy surface Grinding: process of removing material from a substance by abrasion with coarse particles. Polish: luster or a gloss on a material surface. Substrate;.. The material being finished is called the "substrate"[According to Journal of prosthodontic terms – 1991]
  13. 13. Benefits of finishing and polishing
  14. 14. Mainly provideOral healthFunctionesthetics
  15. 15. Oral health A well contoured and polished restorations promotes oral health by resisting the accumulation of food debris and pathogenic bacteria. This is accomplished through reduction in total surface area and reduced roughness of the restoration Smoother surfaces have less retention areas and are easier to maintain in a hygenic state.
  16. 16. ORAL FUNCTION A highly polished restoration show a very less tarnish and corrosion Oral function is enhanced with a well polished restoration because food glides more freely over occlusal and embrasure surfaces during mastication, and minimizes the wear rates. Rough surfaces will develop high contact stress that can cause the loss of functional and stabilizing contacts between teeth.
  17. 17. Finishing and polishing improves thestrength of the restoration especially in theareas that are under tension.
  18. 18. AESTHETICSFinishing and polishing gives lusture to visible surface ofa restoration thus increases the optical property ofmaterials. A high mirror like polish is preferred in highly visibleareas such as the labial surfaces of the maxillary anteriorteeth.These surfaces are not subject to high contact stressesand they are easily accessible for cleaning. Important anatomic features and textures may be addedto these area without affecting oral health or function
  19. 19. Principles of cutting grinding finishing and polishing
  20. 20. Even though there are distinct differences in function ofcutting grinding and polishing at times they overlapDepending on the hardness, shape and size of theabrasive particles used and the speed of the hand pieceeach of the process is done.Higher speed and higher pressure removes excessmaterial
  21. 21. Cutting: refers to the use of bladed instrument or the useof any instrument in a blade fashion.Substrate may be divided into large separate segments,or they may sustain deep notches or grooves.Grinding :removes small particles of the substratethrough the action of the bonded or coated abrasive Contains randomly arranged abrasive particlesEach particle contains several sharp points that runalong the substrate surface and removes particles.Cutting and grinding are uni directional.
  22. 22. Bulk reductionInstruments used are diamond, carbide, steel burs-coated discs,seperating discsDiamond , abrasive coated disks cuts by grindingactionSteel and carbide burs is by cutting actionAbrasive coated discs are popular instruments forbulk reduction of composites
  23. 23. ContouringEven though contouring can be achieved during bulkreduction ,in some cases it requires finer cuttinginstrumentsDesire anatomy and margins are obtainedThe smoothness depends on the instrument used andfurther requires further steps to achieve smoothness12 to 16 fluted carbide burs and abrasives ranging from30 to 100 micro meter provide fine contouring action
  24. 24. FINISHING.The term polish would remain an operative tem whereas finish would be the preferred term used, to describe the type and character of a final surfaceNot all finishes are achieved by polishingIn some instances the finish of a material is a coating that has been placed.Electro plated deposits, pit and fissure sealants covering etched white-spot on tooth enamel and thermally processed ceramic over glazes are examples of finishes produced by coatings.This type of glaze called an Auto glaze or Self glaze is an example of a finish that is not achieved by polishing or coating
  25. 25. The finishing process usually removes materials such that1. Surface blemishes and imperfections are removed2. The material is shaped to an ideal form3. The outermost surface of the material is developed to a desired state Particles of the substrate material are removed by the action of a harder material that comes into frictional contact with the substrate.
  26. 26. polishing It is the most refined of the finishing process which removes the surface particles Each type of polishing abrasive acts on an extremely thin region of the substrate surface Progress from the finest abrasive that can remove scratches from the previous grinding process and completed when desired level of smoothness is achieved The final stage produces scratches so fine they are visible when greatly magnified
  27. 27. The purpose of polishing is to provide an enamellike lusterSmall particles provide smoother and shinersurfacesIdeally abrasive particles size ranging 20micrometer provide luster at low magnificationThe surfaces must be cleaned between steps,the debris particles on substrate causesscratches
  28. 28. Examples of polishing materialsRubber abrasive pointsFine particles discsPolishing pastesSoft felt pointsMuslin wheelsProphylaxis rubber cupsA non abrasive material should be used as an applicatorwhile using polishing pastes.
  29. 29. Felt leather, rubber and synthetic foam are popularapplicator materials for buffingPorous texture allows fine abrasive particles to beretained during the buffing procedurePolishing is a multi directional, in its course of action.
  30. 30. Method to asses the effectiveness of finishing systems and devices
  31. 31. The most common methods to asses the effectiveness of finishing and polishing systems and devices on dental restorative materials include aided and unaided visual evaluation ,A. Profilo meterB. optical microscopeC. scanning electron microscopeD. reflecto meters
  32. 32.
  33. 33. Profilometer asses surface roughness of a restorativematerial after finishing and polishing proceduresIt’s a device that uses a diamond stylus of precisedimensions to trace a fixed linear distance over thesurfaceIt produces a tracing and using digital analog hardwareand software ,also calculates the average surfaceroughness (ra value) for the resultantant tracingAll the three methods ( visual, SEM, and profilometer)are technique sensitive ,but with care and attention todetail all three methods can yield reproducible andhighly useful information about the finishing andpolishing procedures
  34. 34. Relying on one single analytical method to asses maylead to misleading results and conclusionsVisual methods are prone to errors as a result of theinfluence on shading and influence composition of thestructure of the specimens under evaluationSEM must be done carefully to provide sufficient contrastto observe surface topography and with low angle viewsto detect clearly variations in the surface smoothness
  35. 35. Profilo meter data must be obtained in a reproduciblemanner and with prior microscopic visual evaluation ofthe finished samples to ensure that then stylus tracingsrun perpendicular to the pattern of surface scratchesproduced on the surface of the specimenwhen each method of analyses is done carefully andwith reproducible results , all three methods shouldvalidate each other in confirming the efficacy of finishingand polishing devices
  36. 36. Abrasion Wear of a material that occurs whenever two surfaces slide against each other Process of finishing involves abrasive wear of the particles Outermost particles on the surface of an abrading instrument is referred as abrasive The material being finished is called as substrate
  37. 37. The rotational direction of the rotary instrument is an importantfactor in controlling the instrument action on the substrate surfaceWhen hand piece and bur are in same direction of translation itproduces a rougher surface and rotational bur tends to run awayfrom the surface.When a hand piece and bur at the surface being abraded istranslated in the opposite direction smooth surface is achieved
  38. 38. Abrasion may be two body or three bodyTwo body abrasion occurs when abrasive particles arebonded firmly to abrasive instrument and no otherabrasive particles used eg:diamond burThree body abrasives occur when abrasive particles arefree to translate and rotate between two surfaces eg nonbonded surfaces :prophylactic paste
  39. 39. The cutting and grinding will be improved with the use oflubricantsWater, glycerin or silicone is used commonlyWater soluble lubricants are used most preferred.Excess amounts of lubricants will decrease the cuttingefficiency
  40. 40. erosionIs caused by hard particles impacting a substrate surfacecarried by either a stream of liquid or air such assandblasting a surfaceDental laboratories employ erosive methods of finishingand polishing the materialsTwo types of erosive process areA. chemical erosionB. hard particle erosion
  41. 41. Classification of finishing and polishing devices
  42. 42. All abrasive finishing and polishing devices fall into one three categories. Finishing and polishing devices:Cutting instruments tungsten carbide burs Abrasive finishing and polishing devicesBonded abrasives Coated Loose abrasives Elastic binder’s Aluminum oxide, silicon Aluminum oxide right binders carbide ,quartz ultra fine diamonds, white stones Steven.R.Jefferies DCNA ,1998
  43. 43. Natural abrasivesArkansas stones, chalk, corundum diamond, garnet,pumice, quartz, sand, Tripoli, and aluminum and silicate.Remnants of living-organismskieselghur and cuttle Manufactured abrasivessynthesized materials, that are generally preferred because of their more predictable physical properties. Eg silicon carbide Anusavice
  44. 44. According to Hardnessa) Hard abrasive - Diamond, Silicon carbide.b) Medium abrasive - Pumice, Silicates, Zirconates.c) Soft (Polishing) abrasive - calcites ( Robert g Craig)
  45. 45. According to usea) Finishing abrasive.b) Polishing abrasive.c) Cleansing abrasive. (Craig, Obrien, Powers)
  46. 46. Abrasive instrument design
  47. 47. Abrasive grits : derived from materials that have beencrushed and passed through a series of mesh screens toobtain different particle size Grits classified according to particle sizeA. coarseB. mediumC. fineD. extra fineCoarse and medium grit size are used for cutting andgrinding where as fine and extra fine are used forfinishing and polishing
  48. 48. A. bonded - diamond burs B. non bonded- prophylactic pastes Bonded abrasives The abrasive particles that are incorporated through a binder to form a grinding tools such as points ,wheels ,separating discs, coated thin discs.Particles are bonded by four general mechanisms A. Sintering B. vitreous bonding eg glass and ceramic C. resinoid bonding D. rubber bonding
  49. 49. Sintered abrasives are strongest of abrasives where theparticles are fused togetherVitreous abrasives mixed with a glass or ceramic matrixmaterial, cold pressed or hot pressed in instrumentshape and fired to fuse the binderResin bonded cold pressed or hot pressed and thenheated to cure the resinRubber bonded are cured same as the resin bonded
  50. 50. Ideal binder holds the abrasive particles in the toolsufficiently long enough to cut, grind, or polish thesubstrateBonded abrasives should be trued and dressed beforeits use.Truing is a procedure through which abrasive instrumentis run against harder abrasive block until it runs out. it indicates the efficiency of instruments, before clinicaluse.
  51. 51. Abrasive discsGross reductionContouring and finishing andpolishing of restorationsurfacesMost discs are coated withaluminum dioxide
  52. 52. Abrasive stripsBonded with either plastic or metal backing.used to smooth and polish the proximal surfaces of alldirect and indirect bonded restorationsMetal strips are usually limited when tight inter proximalcontacts are seen especially in ceramic restorationsPlastic strips primarily used for composites,compomers,hybridonomers and resin cements
  53. 53. Coated abrasives Coated abrasive is finishing devices usually in the form of a paper, nylon or polymeric backing on symmetric matrix. Most common example of coated abrasive include circular coated abrasives discs.
  54. 54. Sof-lex contouring and polishing discs arecoated abrasivesAluminum oxide particles constitute themost commonly used abrasive compoundon coated abrasive discsRotary diamond burs are also consideredas coated abrasives.
  55. 55. BONDED ABRASIVESAre devices in which theabrasive particles and mediaare uniformly dispersedthroughout the matrixMatrix is usually elastomericmaterial ,silicone rubberrigid and non elastic in nature,bullet shaped or pointed whitestone used in low or highspeed rotary hand piece forreduction of compositerestorations.
  56. 56. LOOSE ABARSIVESLoose abrasives are polishing pastes contain a fine particle sizedistribution of either aluminum oxide or diamond particles dispersedin water soluble vehicle, such as glycerin,Aluminum oxide particles pastes are designed for final polishing ofcomposite resin materialsParticles size ranging from 0.3m to 1mDiamond polishing pastes contain loose abrasive diamond particlesin size range less than 10m.Effective particles size distributions of diamonds polishing pastessize range0.3m to and 1m.
  57. 57. Indicated for final polishing of adjusted porcelain andceramic materials.Binders for diamond abrasives are manufacturedspecially to resist abrasive particles lossdiamond is his hardest particle and bonded to metalwheels and been blanks with special heat resistantresins such as polyamides.Super coarse and fine grades are then plated with nickel
  58. 58. Nickel plating provides improved properties and acts asa heat absorber.Titanium coatings are given to extend the longitivity.Finishing diamonds for composites contain particles40um or less in diameter.Diamond burs should be used with copious amounts ofwater spray and rotational speed less than 50.000 rpm.
  59. 59. COATEDAbrasive disks and strips: Are fabricated by securingabrasive particles to flexible backing material (heavyweight paper, metal or nylon) with a suitable adhesivematerial.Supplied as disks and finishing stripsMoisture resistant
  60. 60. ABRASIVE MOTION:The motion of abrasive instruments is classifiedasrotary, planar, reciprocal.Burs- rotaryDisks – planarReciprocating hand pieces cyclic motionProvide benefit of accessing interproximal andsub gingival areas to remove overhangs to finishsub gingival margins without creating ditchesand to create embrasures.
  61. 61. Hardness of abrasiveThe strength of an abrasive is often measured by thehardness of the particles of surface materialThe hardness is a surface measurement of theresistance of one material to plastic deformation ofanother material when the force is applied.The first hardness ranking was published by FredricMohs a German mineralogist in 1820He ranked 10 minerals by their relative scratchresistance to one anotherThe least scratch resistant mineral talc received a scoreof 1 and the most scratch resistant mineral diamond
  63. 63. Natural abrasivesArkansas stones, chalk, corundum diamond garnet, pumice, quartz, sand Tripoli, and silicates.Remnants of living-organisms kieselghur and cuttleManufactured abrasivessynthesized materials that are generally preferred because of their more predictable physical properties. Eg silicon carbide
  64. 64. DiamondsTransparent, colorless mineralcomposed of carbonit’s the hardest substance knownIt has the super abrasive ability toabrade any substanceBonded abrasive available inrotary instrumentsnon bonded will come in diamondabrasive polishing pastesFinishing diamonds are used tocontour, adjust, and smoothcomposites, or porcelain
  65. 65. These burs have bits of industrial diamond incorporated into their working surfaces.They are manufactured in a variety of shapes and sizes and come in different grits, ranging from 8µ to 50µ.In most cases, they are applied in sequence, starting with a coarser grit and progressing to a finer grit.Diamond burs should always be utilized with water spray and at speeds less than 50,000 rpm.
  66. 66. Other polishing instruments, such as rubber polishing instruments or pastes, will usually follow the use of diamonds.
  67. 67. Synthetic diamond abrasiveThey are primarily used on tooth structure, ceramic materials andcompositesAdvantage over natural diamonds include they are contourable,consistent in many sizes and shapesShape determines the binder needed to use binder can be eitherresin or metalUsed exclusively as abrasivePolishing pastes contain the particle size ranging from 1to 5 microns
  68. 68. ARKANSAS STONEIs a semi translucent light greysilicaSediment of rock mined inArkansas.It contains microcrystallinequartz and is dense hard anduniformity textured.Small pieces of this mineralare attached to metal shanksFor fine grinding of toothenamel and metal
  69. 69. CHALK:One of the mineral form ofcalcite is chalk,white abrasive component ofcalcium carbonate.Used as mild abrasives pasteto polish tooth enamel gold foiland amalgam restorativematerials
  70. 70. Emery Grayish black corundum in the fine grain form. Predominantly as coated abrasive disk. Finishing metal and acrylic resin.Corundum Mineral form of aluminum oxide is usually white Physical properties are inferior to those of manufactured aluminum oxide Used for grinding metal alloys, available as bonded abrasive in several shapes It is most commonly used in the instrument white stone
  71. 71. GARNETNumber of different minerals that possess similarphysical properties and crystalline forms.These minerals are silicates of aluminum cobalt, ironmagnesium, and manganese.Garnet is dark red.forms chisel shaped plates which make it highlyeffective.Used in grinding metal alloys and acrylic resin materials.
  72. 72. PUMICE:Volcanic activity produces this lightgrey highly siliceous material.Used mainly in the grit form butcan be found in some rubberbonded abrasives.Flour of pumice is fine grainedvolcanic rock derivative from Italypolishing of tooth enamel gold foil,dental amalgam, acrylic resins
  73. 73. QUARTZ:Most commonly used form ofquartz is very hard, colorlessand transparent.Most abundant andwidespread of minerals.Quartz crystalline particles arepulverized to form sharpangular particles used forcoated abrasive disks.Finish metal alloys, grinddental enamel.
  74. 74. SAND:Mixture of small mineral particlespredominantly composed of silicateparticles, represent a mixture of colorsmaking abrasive distinct in appearance.Particles are rounded to angular shape. Applied under air pressure to removerefracting investment materials from basemetal alloy castings.Coated on to paper.
  75. 75. TRIPOLI:Tripoli named after the place Tripoli in Africawhere the sediment rocks are obtained.This abrasive is derived from a light weightfriable silicones sedimentary rock ,can be whitegray ,pink, red or yellow.The gray and red type is most frequently usedin dentistry.The rock is in ground into very fine particlesand formed with soft binders.Used in the bar formUsed for polishing metal alloys and someacrylic resin materials.
  76. 76. ZIROCONIUM SILICATEThe material is ground tovarious particle sizes andis used to make coatedabrasive disks and strips. Component of dentalprophylaxis paste.
  77. 77. CUTTLE : Referred as cuttlefish ,cuttlebone, or cuttle white calcareous powder from the pulverized internal shell of a Mediterranean marine mollusk coated abrasive And is useful for delicate abrasive operations such s polishing of metal margins and dental amalgam restorations.
  78. 78. Kieslghurcomposed of silicones remainsof minute aquatic plants knownas diatoms.Mild abrasivechronic exposure will causerespiratory silicosis.
  79. 79. SILICON CARBIDEExtremely hard abrasive was first syntheticabrasives to be produced.Green and black types of silicon carbideare produced.Green form is most preferred becausesubstrate is more visible against greencarbide Silicon carbide extremely hard and brittle.particles are sharp this leads to highcutting efficiency.Metal alloys, ceramics, acrylic resinmaterialssilicon carbide available as an abrasive ascoated disk.
  80. 80. ALUMINIUM OXIDESecond synthetic abrasive developedmuch harder than corundum because of itspuritybonded abrasive and coated abrasive.Sintered aluminum oxide is used tomake white stonesFinishing metal alloys resin based compositeand ceramic materials.Pink and ruby variations are made by addingchromium oxide available in mounted stonesfor the preparation of metal ceramic alloys toreceive porcelain.
  81. 81. RougeIron oxide is the fine red abrasiveContraindicated in polishing ofchromium containing alloys as itcontaminates the surface andleads to corrosionUse to polish high noble metalalloys.
  82. 82. TIN OXIDEExtremely fine abrasiveused extensively as apolishing agent forpolishing teeth andmetallic restorations Mixed with alcohol, wateror glycerin
  83. 83. Abrasive pastesMost commonly containsabrasive such asaluminum oxide ordiamond particles.Abrasive pastes are usedin dry conditions.The instruments used toapply paste are ribbedprophy cups, brushes, feltwheels
  84. 84. DISADVANTAGESRelatively thick and cannot gain accessinto embrasuresPaste tends to spatter the instrumentsHeat is generated when insufficientcoolant is used.
  85. 85. Material f/ p Chem. Forms available uses CompPumice Polishing Silica Grit form, Rubber Acrylic, tooth bonded abrasive enamel, gold foil, amalgamQuartz Finishing Silica Coated Abrasive Metal alloys disksSand Finishing Silica Sand paper & Metal alloys, powder form for Acrylic resin sand blastingTripoli Polishing Silica Bar form Metal alloysZirconium Polishing Silica Coated abrasive Metal margins,Silicate disks, strips tooth enamelCuttle Polishing Silica (white Coated abrasive Metal margins, Calcereous Amalgam powder) restorationsKieslghur Polishing Silica Coated abrasive Amalgam restorationsTin Oxide Polishing Tin Oxide Paste Form High noble metal alloys
  86. 86. Material f/ p Chem. Comp Forms available usesArkansas stone Finishing Microcrystall Attached to metal Fine grinding of ine quartz shanks tooth enamelChalk Polishing Calcium Paste form tooth enamel, carbonate gold foil, amalgam.Corundum Grinding. Alpha bonded abrasive Grinding metal aluminium alloys oxideDiamond Finishing and Mineral of Bonded abrasive, Finishing and polishing carbon rotary instruments polishing of , abrasive strips porcelain and and polishing ceramics pastesEmery Finishing Grayish Coated abrasive Finishing metal black disks alloys and acrylic corundum resinSilicon Carbide Cutting Silica Coated discs MetalAluminium Oxide Finishing & Al203 Bonded abrasive Composites & polishing PorcelainRouge Polishing Iron oxide Cake Form High noble alloys
  89. 89. 1. SHAPE AND HARDNESS OF A PARTICLE: Abrasive must be harder than the material which it abrades. Abrasive must be strong and should show no permanent deformation under load. In other words the elastic limit should be equal to its maximum strength. Hardness is a surface measurement of the resistance of one material to plastic deformation by another material. Shape also plays an important role. Sharp edges will abrasive more than the dull particle and particle with acute angle will cut more than a particle with obtuse angle.
  90. 90. 2. SIZE OF PARTICLE: Large abrasive particles present inside the cutting edge and will cut large and deep grooves. Fine abrasive will remove small shavings. Therefore coarse abrasive instruments followed by finer one before the surface is polished. Taking a large and deep cut, the coarse abrasive is subjected to large force resisting its progress across material. Therefore such an abrasive is moved slowly over a surface, frequently fracture of grain of abrasive would be expected in this case if it is moved fastly.
  91. 91. SUBSTRATE PROPERTYBrittle surface abrade more than malleable and ductilematerial.
  92. 92. SPEEDSlower the speed more deep are the scratches and moreforce is required to dislodge the abrasive from thebinder.Faster the speed, the action become vice-versa. But since more particles will be followed in rapidsuccession, the total amount of material removed willremain approximately sameTherefore for the given abrasive particle size the highrotation speed does not alter the amount of materialremoved, but reduces the amount of wear of abrasive.
  93. 93. Sequential use of abrasives
  94. 94. 1)gross reduction ,contouring andmarginationThis step involves use of abrasive elements ofthe coated or bonded variety with abrasiveparticles in the order of 100 microns or larger topermit the efficient removal of the restorativematerials , usually minimal removal of the toothstructure .Tungsten carbide burs are used.
  95. 95. Instruments used for gross reduction and contouring A) DiamondsThe primary intended purpose for finishingdiamonds is to contour , adjust porcelain andcomposites especially microfilled composites,which are prone for surface micro cracks whenfinished with finishing fluted carbide bursThey come in various grit size ranging from 5 to60 microns
  96. 96. B) fluted finishing bursThey are available in 8,12 , 16, 20 and 30 fluted burdesignsThe fewer the flutes , the more aggressive is the cuttingThey are used for finishing composites30 fluted burs can be used to smooth, abrade porcelainsurfaces before application of diamond polishing pastesSeveral specific group of fluted finishing burs have beendeveloped for finishing of composites known as esthetictrimming burs
  97. 97. Abrasive finishing discsCoated abrasive discs are usedIn the coarse and medium grit size can be used for bulkreduction or gross reductionThe coarse abrasive disc of so flex finishing andpolishing disc is coated with 100 microns aluminumoxide particlesThe medium grit is coated with 40 microns to 100microns
  98. 98. The greatest ability to reduce composites , porcelain ,can be obtained with the coarse disc ,whereas mediumdisc can also be used to reduce the bulk of the materialAdvantage is it can access incisal edges , embrasures ,and line angles which is not possible with rotary orbonded abrasives
  99. 99. The sof-lex extra fine contouring and polishing wellsuited to access the embrasure areasDisadvantage of abrasive discs is they have tendency toflatten surface features and restoration contours,creating a less anatomic details
  100. 100. Instruments for inter mediate finishing and polishingCoated abrasive discAvailable as finer grit discs and mediumBonded abrasive discsFine diamond and multi fluted finishing burs
  101. 101. Materials for final finishingExtra fine coated abrasivesLoose abrasive polishing pastes
  103. 103. The larger the abrasive particles, the deeper the scratchwill be and conversely, the smaller the abrasive particle,the finer the scratch will be. If the particle size of the abrasive is decreasedsufficiently, the scratches finally become very fine andwith extremely fine abrasives, they may disappearentirely.The surface then acquires a smooth shiny layer knownas a polish.The most recent theory is that polishing agents actuallyremoves material from the surface, molecule bymolecule and thus produces very smooth surfaces.
  104. 104. In the process fine scratches and irregularitiesare filled in by the fine particles being removedfrom the surface.This microcrystalline layer is referred to as thePOLISH Layer or BEILBY layer.There evidence that a Beilby layer may beobtained on enamel surfaces as well as on metalsurfaces.
  105. 105. Advantages of highly polished surface- more resistant to cariogenic action than a surface which is not polished. For example it has been shown that a polished tooth surface is approximately 15% less soluble in acid than one with a rough surface.
  106. 106. Finishing and polishing of composites
  107. 107.
  108. 108. Once a composite has been cured, it must be finishedand polished to produce the final surface.This step removes the air-inhibited layer.It also removes the outer surface of the composite that isresin rich and actually is already a smooth surface. However, this cannot be avoided. The anatomiccontours of composites cannot be so well establishedbefore curing to avoid reshaping.
  109. 109. The trick to finishing and polishing is to gradually movefrom larger-to-smaller abrasive containing agents. This will produce finer-and-finer scratches in the surfaceas shown above.As a smooth surface is approached, there is more of achance to smear remaining polymer into the dips orgrooves remaining on the surface.
  110. 110. This generates a highly polished surface.However, some of this smoothness may be lost overtime and require re polishing. Composites with very small particle sizes (mini-hybridslike Kerr Point 4 and nano -composites) allow a highlypolished surface to be generated with impressive glossand good wear resistance.
  111. 111. The finishing procedure for composite restorations willusually consist of three to four steps involving a numberof instruments.Gross reduction where excess restorative material isremoved.
  112. 112. Contouring- includes the reproduction of the size,shape, grooves and other details of the tooth form.Re-establishing contact with adjacent teeth to anormal and functional form. Finishing and polishing establishes an even, well-adapted junction between the tooth surface and therestoration and removes scratches to produce avisually smooth and shiny surface.
  113. 113. Chemical cured materials must be accuratelytimed to complete polymerization. It has been suggested that before finishing therestoration it should be left undisturbed for aminimum of 10 minutes to allow the resin tocompletely polymerize. This may aid in reducing surface trauma fromthe finishing process.
  114. 114. Sof-Lex Finishing and Polishing Discs
  115. 115. The original Sof-Lex finishing and polishing discs are made from aurethane coated paper that gives the discs their flexibility. The system is comprised of four individual aluminum oxide gritsranging from coarse to superfine.The discs are available in three sizes; 13mm (1/2 inch), 9mm (3/8inch), and a 16mm (5/8 inch) size with a square brass eyelet.
  116. 116. Sof-Lex XT Finishing and Polishing Discs
  117. 117. The Sof-Lex XT (extra thin) finishing and polishing discsare made with a polyester film which is one third thethickness of the original paper discs. The thinner discs are slightly stiffer and allow moreprecise refinement of embrasures. These discs also have four individual aluminum oxidegrits, ranging from coarse to superfine.They are available in two sizes, 13mm (1/2 inch), or9mm (3/8 inch).
  118. 118.
  119. 119. Sof-Lex Finishing Brush
  120. 120. The Sof-Lex finishing brush is made from athermoplastic polyester elastomer that containsaluminum oxide abrasive particles molded into a shapesimilar to a prophy brush. The brush itself is detachable from a stainless steelmandrel. The Sof-Lex Finishing Brush is an easy to use,one-step, reusable brush developed for polishing theconcave and convex anatomy found on posteriorcomposite restorations.The soft bristles will conform to the restoration as ittravels across the surface resulting in a smooth polishedfinish.
  121. 121. Sof-Lex Finishing and Polishing Strips
  122. 122. The design of the Sof-Lex strips allows for easyinterproximal finishing.The strips are made of plastic and are coated with analuminum oxide abrasive.Sof-Lex strips are free of any abrasive coating at theircenters for easy interproximal insertion. Each strip contains two different grits; a coarse/medium,or a fine/superfine.They are also color coded similar to the discs. Thecoarser grit on each strip is a darker color than itsopposing side.
  123. 123. Directions for UsePlace the disc on the mandrel by firmly pushing theeyelet portion onto the mandrel until the disc is secureand does not wobble. The polishing motion should be constant and move fromthe bulk of the restoration toward the margins.A back and forth movement over the composite/enamelmargin is not recommended, as a white line may form.
  124. 124. Use light pressure when polishing; let the discs do thework. To produce a smoother, more uniform finish, keepthe tooth, restoration, and disc dry while polishing.Avoid touching the composite with the mandrel or disceyelet because discoloration may occur.This discoloration can be removed by repetition of thefinishing steps
  125. 125. Skipping a grit size in the finishing sequence maycompromise the quality of the restoration’s polish.Remove discs from the mandrel either by positioning athumbnail under the disc eyelet portion and pushing thedisc away from the hand piece, or by grasping the discand eyelet and peeling the disc upward and away fromthe hand piece. It is important to maintain a dry field when using thissystem. After rinsing, and before proceeding to the nextgrit sequence, dry the area.
  126. 126. The following procedure produces aquality polish regardless of the Sof-Lex disc system used.
  127. 127. 1. Remove excess composite and contour to desired shape using a fine diamond or a 12-fluted carbide bur.2. For gross reduction, use the Sof-Lex coarse-grit disc at medium speed (10,000 rpm). Rinse and dry.3. For final contouring, use the Sof-Lex medium-grit disc at medium speed (10,000 rpm) for 15 to 20 seconds. Rinse and dry.
  128. 128. 4.To finish, use the Sof-Lex fine-grit disc at high speed (30,000 rpm) for 15 to 20 seconds. Rinse and dry.5. Polish using the Sof-Lex superfine-grit at high speed (30,000 rpm) for 15 to 20 seconds.6. Wash away powder or debris from restorative surface
  129. 129. 7. Discard each disc after single use.8. For interproximal areas insert the abrasive free center of a Sof-Lex coarse/medium grit finishing strip (beige/white) between contact points.9. Position the beige portion of the strip over the composite surface to be finished, firmly grasp both ends of the strip and draw the abrasive over the composite in a vigorous, back and forth motion. Repeat the procedure using the white portion of the strip. Discard the strip after single use.10. Repeat steps 8 and 9 with the Sof-Lex fine and superfine strip (gray/blue) using first the gray and then the blue side.
  130. 130. Start with coarse discs to remove excess restorative material andestablish preliminary anatomy. Rinse and dry surface before moving ontomedium disc.
  131. 131. Use medium discs for advanced contouring,establishing marginal ridges and adjusting incisal edges.Rinse and dry before using the fine disc.
  132. 132. Follow with fine disc to further improve finish qualityand prepare surface for final polishing.
  133. 133. Conclude polishing with superfine discs for the mostdurable, smoothest, high gloss finish.
  134. 134. After contouring posterior composite, polish surfacewith Sof-Lex finishing brush at low speeds.
  135. 135. Use Sof-Lex strips for finishing proximal areas bygently inserting the center gapped area between teeth.Operating sequence of strips (coarse/medium,fine/superfine) is the same as discs.
  136. 136. Finishing and polishing of amalgam
  137. 137. AMALGAM RESTORATIONS a) OBJECTIVES Finishing and polishing should be considered as important as condensation and it does continue the objectives of carving through this process amalgam flash that was left behind after carving is removed. Major overhangs are removed and minor enamel under hangs are corrected thus assuring the continuity between tooth surface and amalgam surface Conversion of the superficial amalgam into a relatively inert layer galvanically (This minimizes electrolytic corrosion). The most important objectives of finishing & polishing is the removal flash and overhangs and corrects minimal enamel under hangs. polishing is the process, which creates a corrosion resistant layer by removing scratches and irregularities from the surface.
  138. 138. superficial scratches and irregularities.It will minimize fatigue failure of the amalgam under the cyclic loading of mastication.This failure occurs in the form of surface cracks which propagateinwards.If such cracks join together or subsequently connect with internal voidsor flaws, they can precipitate gross fracture and increase corrosion andmicro leakage.The scratch and irregular free surface layer created by the polishingprocedure minimizes the concentration cell corrosion and presents theadherence of plaque
  139. 139. b) PRINCIPLES Finishing and polishing procedures are necessary 1. To complete the carving. 2. Refine the anatomy contour and marginal integrity. Enhance the surface texture of the restoration. Finishing and polishing procedures for amalgam restorations are not attempted within 24 hours of insertion, since crystallization is not complete.
  140. 140. Polishing of high-copper amalgams is less important thanwith conventional amalgams because high copper amalgams are less susceptible to tarnish and marginal breakdown. Many operators prefer to polish all amalgam restorations to minimize their clinical performance. Some of the fast setting high copper amalgams can be polished about 8 to 12 minutes after placement because of their rapid development of strength.
  141. 141. c) RESULTS OF FINISHING AND POLISHING. The following conditions results from proper [finishing and polishing]: 1. Smooth and flush cavosurface margins. 2. Recreation of defined anatomy. 3. Decreased plaque retention. 4. Healthier surrounding tissue. 5. Higher resistance to tarnish and corrosion. 6. Increased longevity of the restoration. 7. Improved esthetics.
  142. 142. d) Determining factors for finishing and polishing versus replacementFinish and Polish Replace RestorationA. Overhangs A. Open contactB. Lack of functional B. Excessive corrosionanatomyc. Tarnish C. Amalgam fractureD. Overextension D. Open marginE. Premature occlusal E. Recurrent decaycontact Oleinisky JC, Baratieri LN. et. al www.indiandentalacademy.comDec Quintessence Int. 1996
  143. 143. A. Evaluate Restoration.1. SurfacesAlways examine the amalgam surfaces for functionalanatomy and defects.2. MarginsUsing the explorer (or a periodontal probe with a smalltip) in a zigzagmotion, determine if the cavosurface margins have anyexcessive discrepancies.The cavosurface margin is the area formed by the cavitywall and external tooth surface. Remember that a roughmargin is a poor predictor of recurrent decay. Thepatients risk for caries must also be considered
  144. 144. 3. Occlusion Evaluate the patients occlusion.a) Articulating paper Insert articulating paper along the occlusal surface and have the patient tap his teeth together.b) Determine intensity Observe all markings to determine if they have the same intensity.c) Reduce the amalgam if it exhibits Premature contacts or "high spots".
  145. 145. Premature contacts are areas where the amalgam has been under carved and these will register a darker areas when checked with articulating paper.Occlusal contacts registered by using articulating paper areas when checked with articulating paper.d) Even intensity Check these areas throughout the finishing procedure to ensure that occlusal markings of equal intensity are achieved.4. Proximal contacts Check proximal contacts with dental floss.
  146. 146. 1. Hand instruments a) Use a finishing knife and or dental file at the gingival and proximal margins to remove overhangs. b) Use short, overlapping shaving strokes to prevent the amalgam from fracturing. 2. Finishing bur a) A flame-shaped bur is recommended when the area is easily accessible. 3. Finishing discs Discs come in varying sizes and grits. Select a size easily adaptable to the proximal surface.
  147. 147. b) Technique Use short, overlapping strokes and move diagonally across the cavosurface margins.c) Sequence Discs are used in a sequence of more abrasive to less abrasive grits.d) Embrasures When using discs in embrasure areas, care must be taken not to damage the contact area or papilla.
  148. 148. 4. Finishing strips.a) Use fine or medium [finishing strips after using discs, burs, knives or files].b) Position the strip so that it is on both the tooth and the amalgam, and move in a back-and-forth motion.c) Avoid the contact area when using finishing strips, and use caution in areas of the inter dental papilla and surrounding tissue.Wider strips may be cut in half lengthwise to make narrow strips.
  149. 149. F. Remove occlusal excess and eliminate flash1. With burs or stones Use a round finishing bur or a green stone to remove excess material and irregularities from the occlusal surface, grooves and the cavosurface margin. 2. Sequence Begin with the largest finishing bur that will adapt to the surface and progress to smaller and less abrasive finishing burs.
  150. 150. 3. Technique Adapt the side of the bur or stone along the margin, contacting both tooth and amalgam.4. Direction of stroke Rotate the bur or stone from the amalgam to the tooth to avoid fracturing the amalgam margins.5. Direction of work Always begin at the centre of the restoration and work toward the cavosurface margin.
  151. 151. procedures for two method of amalgam polishing.a) Pumice and tin oxide slurries. This method is accomplished using a rubber cup, brush, and wheel brush. Prepare a slurry mix of pumice, and water in a dappen dish. Polish all surfaces of the restoration with a brush or cup and plentiful pumice. Remember, the pumice does the polishing, the cup only moves the pumice a smooth satin finish is accomplished The satin finish produced will exhibit a dull appearance. Polish the proximal surface with medium and fine polishing strips. Rinse and dry the mouth. Prepare the wet mixture of tin oxide and alcohol in a dappen dish. Water or mouth wash is an acceptable substitute for alcohol.
  152. 152. Polish all surfaces of the restoration with a new, clean cup or brush and the tin oxide slurry. An optimal final step may include using a soft wheel brush in a straight hand piece with tin oxide.Continue to polish the amalgam until the tin oxide begins to dry and a high luster is achieved. Rinse and dry the tooth. Examine with mouth mirror and explorer. ORb) Rubber cups and points impregnated with Abrasive particles
  153. 153. Colors. Abrasive-impregnated rubber cups and points are supplied in three colors: brown, green and yellow- banded green. Each color denotes different degree of abrasiveness. In some instances they are referred to as "brownies", "greenie" and "super greenies". use. The cups are designed for use on the proximal surfaces, and the points are used on the occlusal surface. Often, they are used interchangeably. They should be operated at a relatively low speed, using light, intermittent strokes under wet conditions.
  154. 154. Advantages.The cups and point will polish restorations quickly and tend to be less messy than using two slurries of different abrasives.Disadvantages.The cups and points wear quickly from use and autoclaving.Eventually a metal surface is exposed that will scratch the amalgam surface.The greatest disadvantage, however, is heat production.The amalgam surface MUST NOT be heated above 140F by thepolishing procedure. Heat is generated rapidly with the use of www.indiandentalacademy.comabrasive impregnated rubber cups and points.
  155. 155. Procedure for use.Brown abrasive cups and points are used first to produce an initial smooth satin finish.Polish the occlusal the proximal, and then finally the facial and lingual surfaces.Polishing is performed with fine pumice followed by tin oxide or white rouge applied with a soft webless rubber cup.
  156. 156. The green cups and points are used in the same manner as the brown.After use, examine to determine if a smooth shiny finish has been achievedA yellow banded green cup or point is used as the final step.These are used in the same manner as the brown and green cups and points.Examine to determine if a smooth lustrous polished finish has been achieved.
  157. 157. Rinse and evacuate debris.Evaluate the polished amalgam using a mouth mirror and explorer.The amalgam should appear smooth and highly polished, and should have a lustrous shineThere should be no damage to the adjacent
  158. 158. Evaluation criteria for amalgam polishing.Amalgam is void of scratches and appears smooth.Amalgam has a high polish and lustrous shine.There is no damage to adjacent tooth structure.
  159. 159. Finishing and Polishing of Ceramics
  160. 160. Ideal surface for ceramic restoration is a polished andglazed surfaceThe production of a glazed layer through natural glaze orover glaze processes will not necessarily yield a smoothsurface if initial ceramic surface has significantroughnessPolishing can improve strength within surface region of aceramic prosthesis because it removes pores and microcracks
  161. 161. Ideal surface for ceramic restoration is a polished andglazed surfaceThe production of a glazed layer through natural glaze orover glaze processes will not necessarily yield a smoothsurface if initial ceramic surface has significantroughnessPolishing can improve strength within surface region of aceramic prosthesis because it removes pores and microcracks
  162. 162. Adequate cooling is important in vivo when finishing andpolishing ceramic restorationUsing an air water spray and maintaining intermittentcontact between restoration and rotary instruments arecritical during operationContinuous contact between restoration and rotaryinstruments should be avoidedHeat less stone like silicon carbide provide heatreduction and can be used as an alternative
  163. 163. Techniques Contour with flexible diamond disc diamond burs, heatless or polymer stones or greenstones Finish with white stones or abrasives impregnated rubber disc, cups and points Apply over glaze or natural glaze on ceramic if necessary
  164. 164. Glass Ionomer Cement
  165. 165. Conventional versions of glass ionomer ideally require apolymerization period of 24 hours before final contouring andpolishingAfter removing the matrix the restoration gross excess is shavedaway with either no-12 surgical blade in bald parker handle or sharpknives of scalersMajor part of finishing and polishing should be accomplished byhand instruments to preserve the smooth surface if rotary instruments are used care must be taken not to dehydratethe surface
  166. 166. Fine disks are used for final finishingMicron finishing diamonds are used to contourA fine grit aluminum oxide polishing paste appliedwith a prophy cup to smoothen the surface
  168. 168. Once the final contour is been obtainedCuttle discs are used in decreasing abrasiveness to ready thesurface for final polishingpolishing is performed with fine pumice followed by tin oxideor white rouge applied with a soft rubber cupthe abrasives are therefore used dry so that the field kept maybe clean and exact position of the rubber cup seen at all thetimes
  169. 169. sharp gold foil knife is used to remove of the excessin the region of contactpermitting a fine finishing strip or a steel matrix stripto pass through the contact areaa pull cut shoosan or a gold knife may facilitateremoval of excess gold faciallyfinishing is performed with the extra –narrow extrafine cuttle stripfinal polishing is accomplished with a worn outcuttle
  170. 170. Summary and conclusion
  171. 171. Finishing and polishing techniques are important in preparingclinically successful restorations .The process of abrasion is affected by properties of the abrasiveand the material being abradedFinishing and polishing begin with coarse abrasives and end withfine abrasivesClinically it is easier to control the rate of abrasion by speed ratherthan the pressureCare must be taken to avoid over finishing margins and contours ofrestorations and to avoid over heating.A definite sequence should be adopted in finishing and polishing ofeach restoration.
  172. 172. ReferencesKenneth J. Anusavice - text book on dentalmaterials.Robert G Craig –dental materialsEdward c. coombe - dental materialsClliford m. Studavent- text book of operativedentistryGerald T. Charbenau –principles and practice ofoperative dentistryBaum, Philip and Lund –text book on operativedentistry
  173. 173. Auj.Yap Journal of Operative Dentistry. 2004Journal of prosthodontic terms – 1991Bower CF, Reinhardt RA .et. al Journal of Prosthodontics- 1986 SepBriseno B, Ernst et al 1995 May;26(5):361-5. 1996 Dec Quintessence Int. van Amerongen JP, Penning C .et al Journal of Prosthodontics- 1990 OctSteegmayer G, Lenz P et .al Dutch Dental Journal- 1989 AugSteven.R.Jefferies- DCNA ,1998
  174. 174.
  175. 175. A maximal speed of 4,000 rpm should be applied when polishing is carried outcontinuously without water coolant. When water cooling is used, flexible disks can safelybe used at a speed of 10,000 rpm and with continuous pressure.
  176. 176. Procedures carried out with low pressure showed a decrease in the pulpaltemperature of approximately 9 degrees C. High pressure decreased thetemperature of the pulp by only 4 degrees C. Therefore a water coolant is alwaysadvised when amalgam restorations are being finished and polished. van Amerongen JP,Penning C .et al J Prosthet Dent. 1990 Oct;
  177. 177. The life of a diamond instrument is limited by the wear ofits tip. Here the diamond layer wears off faster than onthe rest of the instrument. This calls for earlyreplacement of the instrument in clinical use even if theshaft still might be functionable. Steegmayer G, Lenz P et .al Dutch Dental Journal 1989 Aug;44(8
  178. 178. The life of a diamond instrument is limited by the wear ofits tip. Here the diamond layer wears off faster than onthe rest of the instrument. This calls for earlyreplacement of the instrument in clinical use even if theshaft still might be functionable. Steegmayer G, Lenz P et .al Dutch Dental Journal 1989 Aug;44(8
  179. 179. Bower CF, Reinhardt RA .et. al J Prosthet Dent. 1986 Sep; indicated that surfaces finished using the carve, floss, and finishing strip polish consistently produced a measurably smoother surface The use of finishing strips on the gingival margin of Class II silver amalgam restorations shows promise of improving interproximal surface smoothness.
  180. 180. The finishing and polishing procedures ofdental restorative uses three basicprocedures steps based on the sequentialapplication of progressively finer grit ofabrasive medium in various types ofdevices Steven. R.Jefferys Dental Clinics ofNorth America
  181. 181. Ottl P, Lauer HC et al .J Prosthet Dent. 1998Jul;80(1):12-9. That coarse diamond burs resulted in morepronounced temperature increases within thepulpal chamber during tooth preparation. Inaddition, the benefit of short intervals betweengrinding steps and a cooling water temperaturebetween 30 degrees C and 32 degrees C wasconfirmed.
  182. 182. G. Evaluate the finishing procedureA. Excessive amalgam has been removed from cavosurface margins.B. Amalgam appears to be smooth.C. Occlusion registers properly with articulating paper.D. Occlusal and marginal anatomy is better defined.E. Porosity and pits are removedF. Contour of the restoration approximates the original contour of the tooth.G. Adjacent tooth structure is left undamaged. When over heated, the surface of the amalgam will appear cloudy even though it may have a high polish.• This cloudy appearance indicates that mercury has been brought to the surface, which results in corrosion of the amalgam and loss of strength.