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VanB. Haywood, DMD, isProfessor n the Department ofOral Rehabilitation, School ofDentistry, Medical College ofGeorgia. An alumni of theMedical College of Georgia,he was in private practice for7 years n Augusta, Georgia,and taught at the Universityof North Carolina School ofDentistry in Operative andProsthodontics for 12 yearsbefore going to the MedicalCollege of Georgia in 1993.In 1989, he coauthored thefirst publication on nightguardvital bleaching with Dr. HaroldHeymann. In 1997, he co-authored the first article onextended treatment of tetracy-cline-stained teeth. He hascompleted further researchon the NGVB techniqueand the topic of bleachingand esthetics.

After reading this article, the readershould be able to:.discuss trends in at-home vs

in-office whitening treatments..describe a differential

diagnosis of stained teethbefore treatment.

.explain the variable depth ofpenetration of several differentwhitening systems.

Richard Blankenau, DDS,was a 1966 graduate ofCreighton University Schoolof Dentistry. After 2 years ofservice in the Public HealthIndian Health Service, hereturned to CreightonUniversity to begin a career indental education. He held avariety of positions, includingUniversity Faculty President,Chairman of the Departmentof Operative Dentistry,Professor of OperativeDentistry, Associate Dean forAcademic Affairs, andChairholder of the Oscar S.Belzer Endowed Chair inDentistry. His research inter-ests ncluded operative den-tistry and lasers. He publishedmore than 60 papers and lec-tured internationally on avariety of topics dealing withhis research nterests.

Tooth whitening of vital teeth continues to have a major impact on the prac-tice of dentistry. The growing public interest in having whiter, brighter teethis clearly evident in the advertisements from toothpaste manufacturers on"whitening" formulations of their products and by the number of individualsseeking whitening procedures from their dentists. In addition, newover-the-counter whitening products continue to emerge in a marketplace that cannotseem to get teeth white enough, bright enough, fast enough.What new products and procedures have evolved over the past decade towhiten teeth? Are they better, safer, faster, and more effective now? Are den-fists meeting public demand for whiter teeth and is this quest having a posi-tive or negative impact on the practice of dentistry or the patient's dentalhealth? I posed these questions to a group of experts on whitening proceduresto get their oPinions and recommendationsVol. 20. No.8 Compendium / August 1999

Ronald E. Goldstein,DDS, is currently ClinicalProfessor of Oral Rehabili-tation at the Medical Collegeof Georgia School ofDentistry, Augusta, Georgia.Dr. Goldstein is coauthor ofthe text Complete DentalBleaching.He is cofounder andpast President of theAmerican Academy ofEsthetic Dentistry and is cur-rently the President of theInternational Federation ofEsthetic Dentistry. In 1997Dr. Goldstein was bestowedthe Alpha Omega Inter-national Fraternity's mostprestigious award for "merito-rious contributions to den-tistry and its allied sciences,"joining past recipients AlbertEinstein and Jonas Salk.


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Figures1A and 1B-Yellow discoloration sually espondswell either o several n-office reatments r to at-home reatment.

Figures2A and 2B-Banded discolorationmay not respondas well o treatmentas other ypesof extensive iscoloration.

Manufacturers of lasers, bleaching lights," andother in~office systemsare increasing advertis-ing to the dental community, and he sees atrend toward in~office methods in combina-tion with at~home echniques. Some manufac-turers of in~office whitening systemshave sug-gested n their advertisements that the desiredresults can be obtained in just one visit. Dr.Haywood says that his experience has foundthis not to be the case.And Dr. Goldstein esti~mates that it takes approximately three to fivein~office treatments to achieve reasonableresults. Dr. Haywood is also concerned thatthese in~office laser systemsare being advocat~ed for use with no clinical science to substan~tiate safety and efficacy. Dr. Goldstein agreesthat some advertising shows individuals withvery white teeth, which he believes are morethe result of the photography and printingprocesses han the actual whitening process.He also cautions that with the more intensivein-office treatments, rubber dam isolation andtooth desiccation can give the patient a falseimpression. After rehydration, the brightnessfades, and he is careful to advise patients ofthis phenomenon.

Increased Demand for Teeth WhiteningDr. Richard Blankenau saw the public

demand for whiter teeth increasing both in theprivate patient population and at his universi-ty dental school clinic. One survey suggeststhat patients between the ages of 40 and 50years nquire about whitening their teeth moreoften than any other dental health service.lThat same survey reports that more than 90%of dentists offer an at-home whitening proce-dure and 50% to 60% of them offer an in-officetechnique. According to a recent survey by Dr.Kevin Frazier from the Medical College ofGeorgia and Dr. Van Haywood { unpublisheddata, May 1999), most dental schools are offer-ing some orm ofat-home whitening and otheresthetic options in their dental curriculum.Because of this increased demand, Dr.Blaneknau's university {Creighton Universityin Omaha) has added tooth-whitening proce-dures to its educational curriculum. Providingwhitening not only teaches the students thetechnical aspectsof the procedure, but it alsogives them experience with the psychologicalimplications of trying to meet subjectivepatient expectations.Dr. Ronald Goldstein agrees that publicdemand is partially responsible for driving thetooth-whitening marketplace, but he also seesa large push by the product manufacturers.

Over-the-Counter ProductsDr. Haywood makes a specific distinction

between over-the-counter (OTC) home-Compendium I August 1999 Vol. 20. No.8


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Figures 3A and 3B-Example of brown luorosis staining,which may requireas long as 2 months of at-home reatmentor as little as1 week.

Figures4A and 4B-Blue-gray tetracycline iscolorationmay requireseveralmonthsof at-home reatment. n-office reatmentmay beused o shortenoverall reatment ime, but the effectiveness f additional n-office reatment annotbe determined eforehand.

Figure5-Example of a tooth being reatedwith a dual-activated35% hydrogen eroxide. issue solationwas performedwith arubberdam and igation.After application,he whiteningproductwas activatedwith a curing ight.

whitening. Teeth that are nonvital or discol-ored from dark tetracyclinelike stains will alsoshow poor results with OTC products.

applied systems and dentist-prescribed home-applied systems. The latter implies that anexamination and diagnosis has been made todetermine the etiology of the tooth discol-oration and the appropriate treatment methodand protocol has been prescribed.

Despite investigative reports by ABC's"20/20" and NBC's "Dateline" 2,3 hat foundthat OTC whitening products do not workvery well, Dr. Haywood's dissatisfaction is thatthere is still a strong marketplace for theseproducts, especially if they are priced below$50. He believes that a significant number ofpeople will not return a product-even if itdoes not perform according to the advertisedclaims-if it is priced below $50.According to Dr. Blankenau, one reasonthat patients may not get good results withOTC products is compliance: "They may justnot be using the products properly or longenough." Without a clear understanding ofwhat to expect in specific clinical circum-stances, outcomes can easily fall short ofexpectations. According to Dr. Goldstein,another reason that expectations may not bemet is that patients may not recognize thattheir teeth have discolored composite restora-tions or crowns that will not be affected by

In-Office Whitening and Energy SourcesDr. Goldstein has provided in-officewhitening for more than 30 years and has used

a variety of methods. He has a specific proto-col that he follows for every patient.4 Theassessments to determine the type of discol-oration and if it is of primarily one color ormultiple colors. If the discoloration is of a yel-low type, it will usually respond well to in-office and/or at-home whitening methods. For

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Figures6A and 6B-Enamel before A) and after (8) bleachingwith 10% carbamide eroxide el. The enamelwas reated6 hours perday or 5 days.

in reducing temperature sensitivity, particular-ly to cold.5 Dr. Goldstein feels that the argonlaser may eventually be proven to be helpful inreducing sensitivity, and he encourages urtherresearch in this area. And Dr. Haywood saysthere is literature to support the safety of 35%hydrogen peroxide with a minor amount ofheat.6,7 Dr. Goldstein, however, refers toresearch showing that although heat produceschanges {such as pulpal inflammation) , thesechanges are reversible.7 However, activatingthe peroxide with a COz heat source is not anADA-accepted technique for vital teeth.8

Dr. Blankenau took a strong position onthe issue of heating hydrogen peroxide or car-bamide peroxide with lasers.He felt that therewas a significant body of science o suggest hatit was known to be a "bad idea" before it wasever used.9-16 e referred to the fact that COzlasershad been used n the oral cavity for soft-tissue surgery for quite some time and thatproper technique specifically recommends thatthe teeth be protected from the laser becauseof potential pulpal damage rom heat.

brown discolorations, he recommends startingwith an in-office treatment followed by at-home tray whitening for a few months. Theblue-gray and the brown discolorations maytake much longer to alter with a similar treat-ment plan. Multicolored or "banded" discol-oration patterns are not as successfullywhitened as other types of discoloration.Although the teeth may exhibit lightening,the banded areas are usually not eradicatedcompletely. Typically, treatment for brown ordark yellow discolorations consists of 2 or 3 in-office treatments with 1 to 2 months of at-home treatment (Figures 1 through 4 ).

Safety and SensitivityThe issueof safety s alwaysa concern whendiscussing tooth whitening, especially in thepresenceof heat generators,such as a laser or ahigh-intensity light source. Dr. Blankenau saidwork he was doing in a study on extracted teethsuggested hat the enamel surface hardness isreduced on teeth that are subjected to whiten-ing procedures.However, Dr. Haywood referredto a body of papers hat report the opposite.17-21He says, The literature suggestshat there is nosurfaceor subsurface lteration in hardness romthe 10% carbamide peroxide whitening prod-ucts." His work on long-term exposure to 10%carbamide peroxide did not find any apprecia-

A number of new in-office whitening sys-tems use some form of peroxide formulation"activated" with an energy source. Argonlasers, CO2 lasers, plasma arc lamps, quartzhalogen lamps, incandescent lamps, andinfrared lamps have all been advocated, as wellas hand-held heating instruments. Dr.Goldstein chooses a system based on patientsensitivity. He finds that the argon laser incombination with 35% hydrogen peroxide(QuasarBriteTM,a) produces the least postopera-tive sensitivity (Figure 5). (However, onlyStarBrite@'a 35% hydrogen peroxide is ADA-approved for in-office use, although not with alight source. ) Dr. Goldstein points to Pick,who has demonstrated that lasers are effective'Spectrumentallnc,ulver ity,CA90232

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Figures7A and 7B-Before and after reatmentphotosshowinga mild color change hat may not be acceptableo somepatients.

ble changes rom scanning electron microscopystudies of in vitro enamel surfacesas a result ofexposure to as many as 1,000 hours of car-bamide peroxide}2.23Therefore, the fear thatthis process will eventually dissolve away theenamel surface is not supported by currentresearch (Figures 6A and 6B)}4

viscous, whereasothers are more water,soluble.Double,blind clinical trials demonstrate differ,ences in effectiveness as well as differences insensitivity}8-37 Some patients even exhibitedsensitivity with controls that did not containcarbamide peroxide, which suggests he sensi-tivity may have been related to the other com-ponents in the product being evaluated}8According to Dr. Haywood, there is notsufficient science to claim that high-energylight sourcesor lasersare safe o use or bleach-ing techniques. Dr. Goldstein cautions that if35% hydrogen peroxide is used, ocal anesthe-sia should not be administered because anyleakage of the rubber dam may result in a sig-nificant tissue bum that will not be noticed bythe patient}9 This method of whitening with35% hydrogen peroxide should not be used onyoung children because heir developing pulpchambers may be large. According to Dr.Haywood, at-home procedures are more appro,priate for young patients. And although thesematerials have low toxicity, he feels t would beprudent to avoid their use during pregnancy.

Tooth sensitivity is the most common sideeffect of whitening. Research on the effective,nessof using potassium nitrate to reduce toothsensitivity is making that side effect less of anissue. There are three commercially available5% potassium nitrate products from DenMatb,Ultradenrc , and Discus Dentald, that can beused within the whitening tray. In addition,desensitizing toothpastes have the same ngre-dient and can be used to decrease sensitivity,but they may cause some tissue irritation fromother components in the toothpaste. Jeromeand others described using Sensodyne@'eooth-paste in a whitening tray to reduce postopera-tive sensitivity from periodontal surgery.40-43

However, Or. Haywood cautions that thisinformation should not be extrapolated toother concentrations of carbamide peroxide.He says that most of the negative clinicalreports on the use of carbamide peroxide arerelated to higher concentrations, in the rangeof 16% to 35%.25-27r. Haywood also has con-cern for the use of 50% hydrogen peroxiderather than 35% hydrogen peroxide becauseno significant research exists on the safety ofthe higher concentration of peroxide on teethor pulps. He feels that dentists must carefullyconsider the downside of using even a 15%carbamide peroxide that is not AOA-approvedover the 10% formulations that have beenAOA-approved for six manufacturers. He fur-ther advises that dentists should not assume,just becauseone product is AOA-approved, allof the manufacturer's products are approved.

If 10% carbamide peroxide is the mostappropriate material to use for at-homebleaching, are all brands basically the same?According to Dr. Haywood, the pH, flavorings,and other components differ. Some are very

bDen-Mat, Santa Maria, CA 93456, Ultradent Products, Inc, South Jordan, UT 84095'Discus Dental, Culver City, CA 90232, Block Drug Company, Inc, Jersey City, NJ 07302

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Figures SA and SB-Before and after treatment photographs showing a dramatic color change.

lain veneers can be successfully lightened incolor with at-home carbamide peroxidewhitening.44.45This is because the peroxidetravels through the enamel and dentin, all theway to the pulp.46-48herefore, the lingual sur-face allows the peroxide access o the internalaspect even though the facial aspects of theteeth are covered with porcelain.

Neutral fluoride also can be used n the tray toreduce sensitivity. Dr. Goldstein adds,"Patients who have severe microcracks andlarge pulps may be especially sensitive."

Before initiating any bleaching treatment,screening radiographs are taken to ensure thatno periapical pathology is present and restora-tions are identified and charted. The mostimportant elements are that a preoperativephotograph is taken and one of the six ADA-approved 10% carbamide peroxide-containingproducts is used.

Patient ExpectationsThere will always be some patients whoeven the most experienced dentist cannotplease. They present a challenge because heirexpectations are difficult to "pin down." Dr.Blankenau believed that the "unhappy patientsyndrome" can be avoided by knowing whatthey want in advance, but this may not be pos-sible because often they do not know them-selves.Some of these individuals present to ouroffices specifically for elective esthetic changes.If they have no track record in the office,patient management ssuesare unknown.

Dr. Goldstein is a staunch advocate ofcomputer imaging, which allows estheticchanges to be simulated and viewed by thepatient before treatment is initiated. He hasdetermined three patient types and their reac-tions to imaging.49The first type can visualizethe simulated image as a representation oftheir final results and are pleased with thesimulated changes. The second type is notpleased with the simulated image or is veryjudgmental about it, which suggests thatbecause their expectations are somewhatunrealistic, they may be difficult to pleasewith the actual treatment. The third typecannot visualize how the image relates totheir appearance. These individuals may rep-resent the most difficult challenge becausethey cannot describe what they want and ifthey can, may not be able to recognize whenit is achieved. Some patients also change theirminds about what they view as successfultreatment and have difficulty seeing a positive

Tooth Whitening and Restorative ProceduresThe problem with all esthetic proceduresis that the personal, subjective elements can-

not always be accurately predicted becauseesthetic desire may change over time. Often,patients expressa desire to have teeth so whitethat there is little chance of reaching theirobjective with in-office or at-home whiteningalone. For those individuals, it may be moreappropriate to initiate a restorative procedure(porcelain veneers or crowns).

Because porcelain veneers are thin andsomewhat translucent, the underlying toothcolor can "bleed through," which lowers thevalue of the restoration. Trying to mask darkstains and still maintain some translucencycan result in a significantly lower value thanexpected. Also, as eeth age and become dark-er, the darker color can be transmittedthrough the surface of the porcelain veneer.All of our experts have observed some surpris-ing results with the in-office and at-homewhitening used in conjunction with restora-tive techniques. They say it is difficult to pre-dict with accuracy when the procedure willwork exceptionally well and when it may onlyprovide a moderate change. Therefore, theyoften will try some form of whitening ofunderlying tooth structure before initiatingrestorative efforts. In addition, Dr. Haywood'sresearch demonstrates that teeth with porce-

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result, even if the dentist and staff can easilysee t.Dr. Haywood refers to a tooth color rela~tibnship that beauty consultants look for: if thebrightness of the teeth is similar to the sclera(whites) of the eyes, then the value of theteeth is considered pleasing.5oHe agrees hatthis is subjective and patients need some visu~al guides o assist hem in communicating theirdesires and expectations. Fo example, a pho~tographic guide could assist dentists with thisdifficult issue. Patients would be able to ratetheir expectations by using a series of pho~tgraphso target their specific desires or theappearanceof the finished results.

resentative of actual colors found in nat~al,unaltered teeth. According to Dr. Goldstein,"the days when a Bl Vita shade was a very nicebright shade may be gone." This will certainlyimpact the entire arena of restorative materialshading, making it more difficult to matchcomposite resins and porcelain restorations tothe "new" tooth shades. Some of these prod-ucts (for both composite and porcelain) arenow available in "bleaching shades."

Dr. Haywood notes that some of the"fringe patient complaints" that used to becommonplace in "TM] patients" are beginningto emerge in the whitening patients.Therefore, if the inevitable complaint about adentist's whitening treatment is going to occur,it will be more defensible if the dentist usedADA-accepted products that by definitionhave good science to back them up. Accordingto Dr. Haywood, it is prudent that the dentistobtain an informed consent before bleachingtreatment is initiated.51

Photographs should playa role in baselinerecords whenever elective esthetic changes arecontemplated (Figures 7 and 8). After thetreatment is complete, the patient's baselineconditions are lost. Unless baseline pho,tographs are part of the patient records, here isno way to substantiate that a positive changehas taken place. Drs. Haywood and Goldsteinconcur that when litigation is initiated by apatient after receiving esthetic restorative den,tistry, it is much easier or the dentist to make astrong case f baseline, preoperative color pho,tographs are available. Unfortunately, the needfor baseline color images s not yet a standard ofcare, and it is rarely a part of undergraduatedental training. (see Photographic maging forEstheticRestorativeDentistry, this ssue

ConclusionIn the United States, whitening tech-

niques have become mainstream services inmany dental practices. One of the side benefitsfrom the increasedpublic interest in whiteningis the motivation of some patients to seek den-tal care for the first time in many years. Theinnocuous nature of tooth whitening proce-dures may be perceived as nonthreateningeven to phobic dental patients. This providesan ideal opportunity to educate these patientsabout good oral health and preventive care.

Research substantiates the safety and effi-cacy of six 10% carbamide peroxide formula-tions and one 35% hydrogen peroxide formu-lation, allowing them to earn ADA approval.Other more concentrated formulations areavailable that do not have ADA approval.New techniques are being advocated using awhitening agent and an energy source to pro-mote "activation." The energy sources varyfrom quartz halogen lights or plasma arc lampsto argon and CO2 lasers. Currently, however,these new techniques lack the science to makedefinitive statements regarding safety and effi-cacy. Experts suggest hat dentists take appro-priate preoperative records, including colorphotographs and informed consent. If a patientis dissatisfied with treatment or develops anunexpected result or complication, the preop-erative photograph(s) and the use of ADA-

The Negative Impact of WhiteningAlthough a desire for teeth whiteningbrings many patients in to see their dentists

who otherwise may not seek treatment, it alsohas some negative impact. The most obvious isthat it is changing our standards for toothshades and making it difficult to set any con-sistent shade objectives. Dr. Goldstein says thas created a false and misleading impressionof what natural teeth look like. He saysmanypeople want the "porcelain toilet bowl" shadeand the apparent computer-enhanced shadesthat they see n magazines,which are not rep-Compendium I August 1999 Vol. 20, No.8


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approved products places the dentist in astrong position for having practiced well with-in or above the standard of care.-M]F

26. Bitter NC: A scanning electron microsco[::: study ~f thelong-term effect of bleaching agents on the enamel surfacein vivo. Gen Dent 46(1):84-88, 1998.

27. Bleaching Agents: Letters. ] Am Dent Assoc 30:26- 28, 1999.28. Haywood VB: Nightguard vital bleaching: a history and

products update: part 1. Esthetic Dentisty Update 2(4):63-66, 1991.

29. Haywood VB: Nightguard vital bleaching: a history andproducts update: part 2. Esthetic Dentisty Update 2(5):82-85,1991.30. Haywood VB: Update on bleaching: material changes.Esthetic Dentistry UpdLlte6(1):24, 1995.

31. Haywood VB, Leonard RH, Nelson CF, et al: Effectiveness,side effects and long-term status of nightguard vital bleach-ing.]Am Dent Assoc 125(9):1219-1226,1994.

32. Barnes DM, Kihn PW, Romberg E, et al: Clinical evalua-tion of a new 10% carbamide peroxide tooth whiteningagent. Compend Contin Educ Dent 19(10):968-978, 1998.

33. Swift El, May KN, Wilder AD, et al: Six-month clinicalevaluation of a tooth whitening system using an innova-tive experimental design.] Esthet Dent 9(5):265-274, 1997.

34. Reinhardt lW, Eivins SC, Swift El, et al: A clinical studyof nightguard vital bleaching. Quintessence nt 24:279-284,1993.

35. Leonard RH: Efficacy, longevity, side effects and patientperceptions of nightguard vital bleaching. Compen ContinEduc Dent 19(8):766- 781, 1998.

36. Small BW: Bleaching with 10% carbamide peroxide: in 18-month study. Gen Dent 42(2): 142-146,1994.37. Matis BA, Cochran MA, Eckert G, et al: The efficacy and

safety of a 10% carbamide peroxide bleaching gel.Quintessence nt 29:555-563, 1998.

38. Leonard RH, Garland GE, Eagle lC, et al: Safety issuesof10% and 16% carbamide peroxide whitening solutions(abstract). ] Dent Res 78:145, 1999. Abstract 315.

39. Goldstein RE, Garber DA: Complete Dental Bleaching.Chicago, Quintessence Publishing Co, p60, 1995.

40. Jerome CE: Acute care for unusual casesof dentinal hyper-sensitivity. Quintessence nt 26:715- 716, 1995.

41. Hodosh M: A superior desensitizer-potassium nitrate.] Am Dent Assoc 88:831-832,1974.

42. Silverman G, Berman E, Hanna CB, et al: Assessing theefficacy of three dentifrices in the treatment of dentinalhypersensitivity. ] Am Dent Assoc 127:191-201, 1996.

43. Markowitz K: Tooth sensitivity: mechanism and manage-ment. Compend Contin Dent Educ 14(8):1032-1046,1992.

44. Haywood VB, Parker MH: Nightguard vital bleachingbeneath existing porcelain veneers: a case report.Quintessence nt 1999 (in press).

45. Haywood VB, Leonard RH: Nightguard vital bleachingremoves brown discoloration for 7 years: a case report.Quintessence nt 29(7):450-451, 1998.

46. Cooper lS, Bokmeyer TJ, Bowles WH: Penetration to thepulp chamber by carbamide peroxide bleaching agents.]Endod18(7):315-317,1992.47. Bowles WH, Ugwuneri Z: Pulp chamber pentration byhydrogen peroxide following vital bleaching procedures.]Endod8:375-377, 1987.

48. Bowles WH, Thompson LR: Vital bleaching: the effects ofheat and hydrogen peroxide on pulpal enzymes. ] Endod12(3):108-112, 1986.

49. Goldstein RE: Change Your Smile. 3rd ed. Chicago,Quintessence Publishing Co, pp33-34, 1997.

50. Haywood VB: Current status and recommendations fordentist-prescribed, at-home tooth whitening. ContemporaryEstheticsand Restorative Practice 3 (suppl1):2-9, 1999.

51. Haywood VB: Nightguard vital bleaching: informationand consent form. Esthetic Dentistry Update 6(5):130-132,100,

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2. Consumer alert: the color of your smile. "Dateline withStone Philips." NBC television. June 18, 1999.

3. Smile makeovers. "20/20 with Arnold Diaz." ABC televi-sion. March 5, 1999.4. Goldstein RE, Garber DA: Complete Dental Bleaching.Chicago, Quintessence Publishing Co, pp35-56, 1995.

5. Pick RM: Using lasers in clinical dental practice. ] AmDent Assoc 124(2):37-40, 1993.

6. McCann D: Lasers for bleaching: safe or not? ADA News28(3):1-30, 1997.

7. Goldstein RE, Garber DA: Complete Dental Bleaching.Chicago, Quintessence Publishing Co, ppI4-16, 1995.

8. ADA Council on Scientific Affairs: Laser-assistedbleach-ing: an update.] Am Dent Assoc 129(10):1484-1487, 1998.

9. Stern RH, Renger HL, Powell FV: Laser effects on vitaldental pulps. Br Dent] 127(1):26-28,1969.

10. Weesner BW Jr: Lasers: opportunities and obstacles.Compend Contin Educ Dent 16(1):72-88, 1995.

11. Wigdor HA, Walsh JT, Featherstone JDB, et al: Lasers indentistry. Lasers Surg Med 16(2):108-133, 1996.12. Cozean C, Arcoria CJ, Pelagalli J, et al: Dentistry for the

21st century? Erbium: YAG laser for teeth. ] Am DentAssoc 128:1080-1087, 1997.

13. Yu D, Powell GL, Higuchi WI, et al: Comparison of threelasers on dental pulp chamber temperature changes. ClinLaser Med Surg 11:119-122,1993.

14. Anic I, Pavelic B, Peric B, et al: In vitro pulp chamber tem-perature rises associatedwith the argon laser polymerizationof composite resin. LasersSurg Med 19:438-444, 1996.

15. Powell GL, Morton TH, Whisenant BK: Argon laser oralsafety parameters for teeth. Lasers Surg Med 13:548-552,1993.

16. Malcer J: Preliminary report on the effect of CO2 laserbeam on the dental pulp of the macaca mulatta primateand the beagle dog. ] Endod 11:1-5, 1985.

17. Lee CQ, Cob CM, Zargartalebi F, et al: Effects of bleach-ing on microhardness, morphology, and color of enamel.Gen Dent 43(2):158-162, 1995.

18. McCracken MS, Haywood VB: Effects of 10% carba-mide peroxide on the subsurface hardness of enamel.Quintessence nt 26:21-24, 1995.

19. McCracken MS, Haywood VB: Demineralization effects of10 percent carbamide peroxide. ] Dent 24:395-398, 1996.

20. Murchison DF, Char Iron DG, Moore BK: Carbamide per-oxide bleaching: effects on enamel surface hardness andbonding. Oper Dent 17(5):181-185, 1992.

21. Nathoo SA, Chmielewski MB, Kirkup RE: Effects ofColgate Platinum Professional Tooth Whitening Systemon microhardness of enamel, dentin, and composite resins.Compend Contin Educ Dent 15(SuppI17):s627-s630, 1994.

22. Haywood VB, Leonard RH, Dickinson GL: Efficacy of six-months nightguard vital bleaching of tetracycline-stainedteeth.] EsthetDent 9(1):13-19, 1997.

23. Haywood VB: Extended bleaching of tetracycline-stainedteeth: a case report. Contemporary Estheticsand RestorativePractice 1(1):14-21,1997.

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Compendium August1999 Vol. 20, No.8

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