Restorative Dentistry

Use of 37% carbamide peroxide in thewalking bleach technique: A case reportErica Cappelletto Nogueira Teixeira, MS, DDSVAnderson Takeo Hara, DDS, MSVMonica Campos Serra, DDS, MS, ScD^

Dental bleaching represents an effective, conservative, and relativeiy low-cost metfiod for improving theappearance of discolored puipless teeth. Among tfie bleaching techniques, the walking bleach techniquewith sodium perborate associated with water or hydrogen peroxide stands out because of its esthefic re-sults and safety. A modified wali<ing bleach technique with the use of 37% carbamide peroxide as thebleaching agent is presented. Additionally, the adverse effects of dental bleaching in Ihe following restora-tive procedures are discussed, showing the advantages with the use of 37% carbamide peroxide.(Quintessence Int 2003:35:97-102)

Key words: carbamide peroxide, discolored tooth, nonvitai bleaching, walking bleach

The presence of discolored teeth is a serious estheticproblem, and bleaching is the most conservative

technique for improving their appearance-^^ Nonvitaitooth bleaching is a current procedure in endodonticsand esthetic dentistry with a high rate of success.'Three techniques have been successfully used in den-tistry for many years to reverse stains associated withnonvitai teeth: the thermocatalytic, the v/aOdng bleach,and the combination of both."*

The thermocatalytic technique uses 30"/Û to 35% hy-drogen peroxide placed in the pulp chamber and acti-vated by heat.* This combination of heat and hydrogenperoxide appears to be associated with tbe major con-cern in nonvitai bleaching treatment-external cervicalroot resorption.5-s The etiology of this pathology Is

'Graduate Student, Department ot Restorative Dentistry, Piracicaba Scfiociot Dentistry, State University of Campinas. Piracicaba, Brazil

^Associate Protessof, Department of Restorative Denlistry, Ribeirao PrêtaSchool ot Dentistry. State University of Sao Paulo. Sac Pauio, Brazif.

complex and also can be related to the age of the pa-tient when the tooth became pulpless and to the pres-ence of a cervical barrier. ''

The most popular bleaching technique is the walk-ing bleach technique in which many bleaching agentshave been used. Generally, a paste of sodium perboratemixed with either hydrogen peroxide or water is sealedin the pulp chamber by a temporary restoration andchanged every 3 to 7 days, until tbe desirable sbade re-sults.'•' •'•'*' This technique is widely used in dentistrybecause less clinical time is required. !n vitro studies"'^suggested that sodium perborate mixed with water is aseffective a whitener as when mixed with hydrogen per-oxide and is considered clinically safe. An additionaladvantage is the safety of this procedure.'''"'""

Recently, a modified walking bleach technique, in-side/outside, was proposed. It consists of the patientadministering 10% carbamide peroxide inside and out-side tbe tooth simultaneousiy. ' ^ This agent appearsto be another option for bleaching a discolored nonvi-tai tootb. However, for internal bleacbing, a higherconcentration could be necessary to obtain better es-tbetic results.

Tbe purpose of this article is to discuss the indica-tions, limitations, and clinical procedures for nonvitaitooth bleaching with 37% carbamide peroxide.

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Fig 1 (iett) Initial appearance ot tne lateralincisor discoiored from trauma.

Fig 2 (right) Close-up view ol the lateralincisor.

CLINICAL APPLICATION: CARBAMIDE PEROXIDE

Historically, carbamide peroxide was used as an oral an-tiseptic in concentrations of 10% to 15%,^ hut since1989, this material has heen commonly used as awhitening agent for nightguard vital hleaching.'^ TWoprimary transient side effects, tooth sensitivity and gingi-val irritation, 1= are related to this procedure. Tooth sen-sitivity occurred due to the passage of the small hydro-gen peroxide molecules through the enamel and dentinto the pulp,' and gingival irritation resulted because oftbe excess bleaching solution in the nightguard tray."

Although 10% carbamide peroxide was first indi-cated for vital teeth, the use of this agent was pro-posed for lightening nonvital discolored teeth, usingthe inside/outside technique.'='^ With this technique,the bleaching time range is reduced, usually to a fewdays, depending on the severity of the discoloration.""However, the pulp chamber is kept open until thefinal restoration. The risk of coronal microleakage isincreased, contributing to the access of fluid and fail-ure of the endodonfic treatment.''''''-^' In spite of thesatisfactory esthetic results obtained with 10% car-bamide peroxide in the outside/inside technique,^''^this material was shown to be less effective than 30%hydrogen peroxide mixed with sodium perhorate, asan intracoronal bleaching agent. ^

Ten percent carbamide peroxide breaks down to3% hydrogen peroxide, ^ while 37% carbamide perox-ide to approximately lP/o, the same amount as forsodium perhorate mixed with water."'^ The potentialside effects of carhamide peroxide are less severe thanthe complicafions associated with hydrogen peroxide,since an indirect release of hydrogen peroxide is ex-pected to occur. ' '

Carbamide peroxide has not been found to be car-cinogenic in humans, Carhamide peroxide-containingproducts were not genotoxic, nor were they any moretoxic than dentai materials curretitly in use." More-over, the transient effects with nightguard vital bleach-ing do not assist the walldng bleach technique.

Special care must be taken for successful and ade-quate internal bleaching. Some principles are very im-

portant, such as: case selection, the condition of theoral environment, and the individual patient's desiresand expectations concerning the esthefic outcome. Thechoice of the bleaching agent, the clinical protocol,and the time needed to restore the coronal access or toreplace restorations play an important role in the treat-ment's success.

CASE REPORT

A 43-year-old woman presented a single, discolored,maxillary right lateral incisor (tooth 12[7]) (Figs 1 and2). Visual examination and behavioral history revealedthe darkened color of the tooth to he the result oftraumatic injury. The tooth was structurally sound andasymptomatic hut associated with a pulp necrosis.Radiographie examination revealed a periapical lesionin the lateral incisor apex without root canal therapy(Fig 3). A pulp vitality test also was peribrmed in theadjacent central incisor (tooth 11[8]) to exclude its re-lation with the lesion, and no alteration was detected.The endodontic treatment was resumed with a com-plete and adequate root canal ohturation (Fig 4). Thepatient was given an explanation of the risk, henefits,and limitations of the options available for restoringthe esthefics of the tooth. The intracoronal bleachingtechnique with 37% carbamide peroxide was proposedto and accepted by the patient.

A haseline tooth shade was recorded, and clinicalphotographs were taken, providing a reference formeasuring the progress of color enhancement. Rubberdam isolation was achieved for the coronal and rootcanal access (Fig 5). All dehris was eliminated, and thecanal restorative material was removed 2 mm belowthe level of the cementoenamel junction, using a ro-tary instrument. A cervical barrier with a 2-mm thick-ness of Cavit (3M Espe) was done (Figs 6 and 7).

The bleaching agent, 37% carbamide peroxide gel,was placed in the pulp chamher with a plastic instru-ment (Fig 8). The excess gel was removed with a cot-ton pellet, and the tooth was sealed with a temporaryrestorafion (Cavit, 3M Espe) (Fig 9).

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Fig 3 (left) Initiai radiograph reveals a periapical iesion in tooth 12,

Fig 4 (right) Penapical radiograph, showing the sucoessfui endodontic treatment.

Fig 5 Lingual view of tooth 12 demon- Fig 6 Placement of the intracoronal isolât- Fig 7 The pulp chamber without debrisstrating the coronal access. Dental dam ing base with Cavit at !he cementoenamei and the cervicai barrier view,isolation taciiitates access to the pulp junction,chamber. The 2-mm gutta-percha was re-moved with rotary instruments.

F¡g e (left) Application of 37% carbamideperoxide gel.

Fig 9 (right) Ttie pulp chamber is provi-sionaliy seaied.

In four clinical appointments over 1 month, thetooth shade was evaluated (Figs 10 to 12), the pulpchamber was irrigated with distilled water, the bleach-ing agent was replaced, and a provisional restorationwas made. After 4 weeks, a satisfactory tooth colorwas obtained, according to the professional criteriaand the patient's desires. The coronal access was re-stored immediately following bleaching with a resincomposite (ZIOO, 3M) associated with an adhesivesystem (Single Bond, 3M) (Fig 13),

A clinical evaluation 10 months later showed thatthe lighter tooth shade was maintained (Figs 14 and

15}, Radiographie assessment revealed no evidence ofexternal cervical root résorption (Fig 16),

DISCUSSION

In dentistry, bleaching agents usually refer to productscontaining some form of hydrogen peroxide,'•''•^^Aithough not completely clear, the basic mechanismof bleaching agents is oxidation. In contact with thetissue, hydrogen peroxide molecules hreak up andform oxygen and peridroxil-free radicals.'"'

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Fig10 Appearance 7 days after begin- Figi i Result after 14 daysning the bleaching treatment.

Fig 12 Appearance atter 21 days.

Fig 13 (left) After 4 weei<s, the bleaohingagent was removed, the pulp chamberrinsed with water, and the coronai accesswas restored immediately after bieaching,showing the finai tooth shade.

Fig 14 (right) Resuits were exoeilent after10 months.

Fig 15 (ieft) Postoperative appearanceafter 10 months.

Fig 16 (right) Periapical radiograph fromthe lO-month foiiow-up. There is no evi-dence of external cervical root résorption.

Sodium perborate is stable when dry, btit whencombined with water, it decomposes to form metabo-rate hydrogen peroxide, and nascetit oxygen,'"'^ It ismore easily controlled and safer than concentrated hy-drogen peroxide solutions. This substance breaks upinto a less concentrated hydrogen peroxide that, at asecond stage, releases active oxygen and initiates thebleaching process. Such a combination reduces the ag-gressive power of 30% to 35% hydrogen peroxide,"'^

Another bleaching agent is carbamide peroxide,which has been successfully used since the advent ofnightguard vital hleaching,^ Materials that contain car-bamide peroxide can also elicit the same oxidation re-

actions that result in bleaching with the application ofhydrogen peroxide and sodium perhorate,''^ Carba-mide peroxide breaks down into urea, ammonia, car-bon dioxide, and hydrogen peroxide, which releasesmore or less nascent oxygen, according to the agent

Some authors suggested the use of calcium hydrox-ide after the bleaching treatment and prior to the ñnalrestoration to prevent cervical resorption,^''^^ However,this material failed to prevent résorption in an animalstudy, The th er mo catalytic technique and the \3se ofhydrogen peroxide, a caustic substance that could causea drop in pH at the cervical leveV^ are associated with

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cervical résorption.^-^ On the contrary, pH cfiangescould be avoided with the use of sodium perbo-ra gii.iZH.26 Qj carbamide peroxide.'^ The risk of résorp-tion can be prevented when a cervical barrier is cor-rectly placed. Materials, such as gutta-percha, zincphosphate, Cavif (3M Espe), and glass-ionomer materi-als have been used-' Cavit (3M Espe) was chosen dueto the reduced linear leakage and because it is an easilyhandled material,'^

The use of 37% carbamide peroxide is a new ap-proach to internal bleaching. The esthetic outcomecould be acceptable, and the potential for résorptionmay be minimized. However, the use of any of the cur-rent bleaching agents is not completely without risk,and care must be taken with their storage, application,and monitoring."* Another important aspect to discussis the material that should be used after bleaching tomaintain the esthetic results.

New composite, resin-bonded, and glass-ionomerrestorative materials bave been developed for restora-tion of endodontically treated and bleacbed teetb.'"^'The material used to restore the bleacbed tootb in thiscase report was a hybrid resin composite in associa-tion with dental adhesive systems. The restorationaimed to protect the remaining tooth structure, tominimize the risk of fracture, to seal the coronal ac-cess augmenting the new shade, and to prevent mi-crolcakage and recurrent caries. Moreover, the possi-ble interference of the bleaching agents in thefollowing restorative procedures was evaluated.

Some studies have shown significant lower bondstrengths obtained when glass-ionomer and resin com-posites are bonded to dentin and enamel immediatelyafter bleaching with 30% hydrogen peroxide.^'"^^Microleakage also is increased around resin compositerestorations." This appears to be an effect of residual-peroxide substances and a consequence of morpho-logic changes. ^- ' Depending on the bleaching agentsused, the time elapsed after bleacbing is an importantfactor for obtaining an optimal adhesion.'""^^

In nonvital bleaching with sodium perborate mixedwith water or 30% hydrogen peroxide, the final restor-ation at the coronal access should also be deferred for2 weeks following bleaching treatment. '-^^ However,37% carbamide peroxide showed less influence in theadhesive procedures in comparison with theseagents.^'" The apphcation of carbamide peroxide sug-gests that a better seal is arranged even immediatelyafter the bleaching procedure." =

An adequate corona! access restoration is impor-tant for the longevity of the bleacbing results. It con-sists not only of the choice of the restorative materialthat could improve the esthetic appearance, but alsoprevents microleakage.'^'^" Color regression occurswith the access of fluid into the bleached and restored

cavity,' Although long-term studies of carbamide per-oxide application are lacking, studies presented sinceits use for vital bleaching suggest that this agent couldbe an option also for nonvital tooth bleaching.

The 37% carbamide peroxide gel is easy to manipu-late and to remove from the pulp chamber, and bas analmost neutral pH. Its clinical effectiveness, as anagent for the walking bleach technique was satisfac-tory in the 10-month follow-up examination.

CONCLUSION

The clinical result obtained with the use of 37% car-bamide peroxide suggests tbat it could be employed asa bleaching agent in the walking bleach tecbnique,when the indications and the treatment risk benefitsare known.

REFERENCES

1. Haywood VB. History, safety and effectiveness of currentbleaching techniques and applications of the nightguard vitalbleaching technique. Quintessence Int 1992;23:471-488.

2. Haywood VB, Heymann HO, Nightguard vital bleaching.Quintessence Int 1989;20:173-n6.

3. Abbott PV. Aesthetic considerations in endodontics: Inter-nal bleaching. Pract Periodontics Aesthet Dent 1997;9:833-840.

4. Maclsaac AM, Hoen CM. Intracoronal bleaching: Concernsand considerations. J Can Dent Assoc 1994160:57-64.

5. Harrington GH, Natikin E. Estemal résorption associatedwith bleaching of pulpless teeth. J Endod 1979;5:344-348.

6. Friedïnan S. Rotstein I, Liebfield H. Incidence of externalroot résorption and esthetic results in 58 bleached pulplessteeth. Endod Dent Traumatol 1988;4:23-26.

7. Gimlin DR, Schindler WG. The management of postbleach-ing cervical résorption [review]. J Endod 1990,16.292-297.

8. Rotstein 1, Friedman S, Mor C, Katznelson ], Sommer M,Bab I. Histological characterization of blcaching-inducedroot résorption in dogs, J Endod 1991;7:436-441.

9. Spasser HF. A simple bleaching technique using sodiumperborate. NY Dent 11961;27:332-334,

10. Nutting EG, Poe GS. A new combination for bleachingteeth. J South Calif Dent Assoc 1963 ;31:289-291.

11. Weiger R, Kuhn A, Lost C, Effect of various types of sodiumperborate on the pH of bleaching agents. J Endod 1993;19:239-241.

12. Weiger R, Kuhn A, Lost C. In vitro comparison of varioustypes of sodium perborate used for intracoronai bleachingof discolored teeth. ) Endod I994;20:338-341.

13. Hara AT, Pimenta LAR Nonvital tooth bleaching: A 2-yearcase report. Quintessence Int 1999;30:748-754.

14. Teixeira FB, Nogueira EC, Ferraz CCR, Zaia AA. Internaldental bleaching using sodium perborate/distiiled waterpaste. Rev Assoc Paul Cir Dent 2000;54:315-318.

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15. Caughman WF, Razier KB, Haywood VB. Carbamide per-oxide whitening of nonvitai single discolored teeth: CaseReports. Quintessence Int 1999;30:155-161.

16. Liebenberg WH. Intracoronal lightening of discolored pulp-less teetb: A modified walking bleach technique |review].Quintessence Int 1997 ;28:771-777,

17. Lyons K, Ng B. Nigbtguard vital bleacbing: A review andclinical study. N Zealand Dent ] 1998;94:100-105.

18. Rosenstiel SF, Gegauff AG, Johnston WM. Randomizedclinical trial of tbe efficacy and safety of a bomc bleachingprocedure. Quintessence Int 1996;27:413-424.

19. Barkbordar RA, Kempler D, Plesb 0 . Effect of nonvitaitooth bleaching on microleakage of resin composite restora-tions. Quintessence Int 1997;28:341-344.

20. Rivera EM, Vargas M, Williamson LR. Considerations fortbe aesthetic restoration of endodontically treated anteriorteeth following intracoronal bleacbing. Pract PeriodonticsAesthet Dent 1997;9:117-128.

21. daratieri NC, Ritter AV, Monteiro Jr S, Andrada MAC,Vieira LCC. Nonvitai tootb bicacbing: Guidelines to tbeclinician. Quintessence Int 1995;26:597-608.

22. Perrine GA, ReichI RB, Baisden MK, Hondruni SO.Gomparison of lOVo carbamide peroxide and sodium perbo-rate for intracoronal bleacbing. Gen Dent 2000;48:264-270.

23. Woolvertnn CJ. Haywood VB, Heyman HO. Toxicity of car-bamide peroxide products used in nigbtguard vital bleach-ing. Am J Dent 199î;6:310-314.

24. Demarco FF, Freitas JM, Silva MP, Justino LM. Micro-leakage in endodontically treated teetb: Influence of cal-cium bydroxide dressing following bleaching. Int Endod J2001;34495-500.

25. Smitb JJ, Cunningbam CJ, Montgomery S. Cervical canalleakage alter internal bleacbing procedures. J Endod 1992;18:476-481.

26. Rotstein L Friedman S. pH variation among materials usedfor intracoronal bleacbing. J Endod 1991;17:376-379.

27. Titley KG, Torneek CD, Ruse ND, Krmec D. Adhesion of aresin composite to bleached and unbleached bumanenamel J Endod 1993;19:112-115.

28. Titley KC, Torneek CD, Smitb DG, Applebaum NB.Adhesion of a glass ionomer cement to bleached and un-bleacbed bovine dentin. Endod Dent Traumatol 1989;5:132-128.

29. Torneek CD, Titley KC, Smith DG, Adibfar A, Adhesion oflight-cured composite resin to bleacbed and unbleachedbovine dentin. Endod Dent Traumatoi 1990;6:97-103.

30. Spyrides GM, Perdigào J, Pagani C, Araujo MAM, SpyridesSMM. Effect of wbitening agents on dentin bonding. JEsthet Dent 2000; 12:264-270.

31. Gavalli V, Reis AF, Giannini M, Ambrosano GMB. The ef-fect of elapsed time foiiowing bleaching on enamel bondstrength of resin composite. Oper Dent 2001,26:597-602.

32. Teixeira EGN, Hara AT, Turssi CP, Serra MG. Effect of post-bleacbing times on the microleakage of composite resinrestorations [abstract 411]. J Dent Res 2002;81(specialissue) :A76.

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102 Volume 35, Number 2, 2004