Carbamide peroxide whitening of nonvitai singiediscolored teeth: Case reports

W. Frank Caughman, DMD, MEdVKevin B. Frazier, DMD'Wan B. Haywood, DMD*"

Patients who present with a singie discolored tooth represent a significant restorative challenge. Thesecase reports desoribe an economic and conservative treatment option for these patients. The situationspresented demonstrate techniques for bieaching with carbamide peroxide in a traditional nightguard orwith an inside-outside technique to achieve acceptabie esthetic resuits on isolated nonvital discoioredteeth. Although these techniques may not be effective in ali cases, they do hot compromise or eliminateany future treatment options. (Quintessence Int 1999:30:155-161)

Key words: carbamide peroxide, discolored loolh, nonvital bleaching, tooth bleaching

Restoring a single discolored anterior tooth toesthetic harmony with the remaining dentition

often poses a significant challenge to the dentist.When a patient presents with a single discoloredtooth, it is incumbent on the dentist to determine thecause of the discoloration. A dark tooth can resultfrom a variety of conditions, including staining from acorroded or leaking restoration, trauma (vital or non-vital), incomplete removal of pulpal tissue at the fimeof root canal therapy, or internal résorption. Once ex-amination has ruled out an active pathologic condi-tion as the cause of the discoloration, the patient's cs-thefic concern may be addressed.

Traditionai restorative procedures for masking adark tooth range frotn veneering with composite orporcelain to complete coverage with a porcelain-fused-to-metal or an all-ceramic crown. Often the bestresult that can be achieved with these irreversible pro-cedures is an esthetic comprotnise, because of the dif-ficulty of matching the appearance of natural toothstructure. Bleaching, or whitening, of a dark tooth is aconservative alternative to more convenfional restora-five treatment. Additionally, bleaching does not com-promise or eliminate any future treatment options.

"Professor and Chairman. Oepartrrent ot Oral Rehabilitation, Medical

College of Georgia, Scfiool of Dentistry, Augusta, Georgia.

••Assistant Professor. Department of Orai Reliabiiilation, Medical College

of Georgia, School of Denhstry. Augusta, Georgia.

•"Proiessor. Department ot Oral Rehabilitation, Medicai College ofGeorgia, Scliooi o( Oentislry, Ajgjsta. Georgia.

Reprint requesls: Dr W. F Cauginman, Professor and Chairman, Deparl-ment of Oral Rehabilitation, Medical Coitege of Georgia, School of Dentis-try, Augusta, Georgia 30912-1260. E-mail; fcaughma@mail.mcg.edu

In-office bleaching of isolated teeth uses a 35% so-lution of hydrogen peroxide, which is applied to thesurface of the tooth for varying periods of time. Theseapplications may require several appointments.' A35% solution of hydrogen peroxide is very caustic, andgreat care must be taken to protect the patient's oraltissues whenever it is used.

If the discolored tooth has been treated endodonti-cally, the bleaching agent is often placed inside thecoronal pulp chamber and catalyzed by heat or lightto hasten the breakdown of the hydrogen peroxideand accelerate the bleaching process.- This processtnay be repeated as many times as necessary unfil anacceptable result is achieved. An alternative to thisprocedure is the "walking bleaching technique,"' inwhich a mixture of hydrogen peroxide and sodiumperborate crystals is sealed in the pulp chamber. Theadvantage of this technique is that less chair time isrequired, because the tooth whitening occurs outsideof the office over a period of days or weeks.

The disadvantages of these previously describedbleaching techniques are that they utilize very causticmaterials and that the results may be difficult to pre-dict or control. Addifionaliy, the use of 35% hydrogenperoxide with heat increases the possibility of internalresorpfion in pafients with a history of trauma.-* Thesetechniques may require several office visits, andpatients incur a fee each time. There is no way toaccurately predict the number of treatments requiredprior to initiation of treatment.

Nightguard bleaching with carbamide peroxide(CP) outside the dental office is an alternative to thein-oñíce bleaching techniques.' Usually, this techniqueis used to lighten the etitire dentition or at least onearch. However, nightguard bleaching may be modified

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and has been used successfully in many unique situa-tions to ligbten a single discolored tooth."-'" Comparedto bleaching witb 35% hydrogen peroxide, nightguardbleacbing requires less cbair time and is less expensivebut takes place over a longer period of treatment time.The slower results from this treatment may be viewedby some patients as a disadvantage, but the graduallightening may actually increase the probability of asuccessful color match. Tbe at-home application bythe patient allows extended treatment times withoutadditional office visits or fees. The potential side ef-fects of bleacbing with carbamide peroxide are alsoless severe than the complications associated witbSS /o hydrogen peroxide.'-^

The purpose of this articie is to present three casereports in which nightguard bleaching with a 10% car-bamide peroxide (Opalescence, Ultradent) was usedon selected nonvital darkened teeth to conscn'ativelytreat the patients' estbetic concerns.

CASE REPORTS

Case 1

A 33-year-old patient presented with a chief complaintof a single dark maxillary left lateral incisor (tooth 22[lOJ). Root canal therapy had been performed on thistootb 5 years previously as a result of a traumaticinjury. The access was restored with resin composite.Tbe patient's dentition also included two retained pri-mary maxiliary canines. The patient reported a previ-ous, unsuccessful attempt at in-office "power bleach-ing" on tooth 22. Two years earlier, direct resincomposite veneers had been placed on ber primarycanines to ituprove their contour, and a direct com-posite veneer had been placed on tooth 22 (Vita shadeBl) in an attetnpt to mask tbe shade discrepancy. Theattempted shade correction of tooth 22 was deemedunsuccessful by the patient {Fig la).

Tbe intraoral exatnination of the patient disclosedno pathosis, and the periapical radiograph of tooth 22revealed an intact tootb witb successful endodontictherapy. The structural integrity of this tooth was suffi-cient, so as not to require a casting as a final restora-tion. The patient inquired about placement of a porce-lain veneer on tootb 22, because she bad been told thatit could better mask the shade discrepancy. Tbe patientwas informed that placement of a porcelain veneeronly on this tooth could mask the dift'erence in shadebut rnight provide an unsuccessful esthetic result whenplaced next to the primary canine (tooth 53[H]) thathad been veneered with composite. If tbis outcomeoccurred, the only alternative would be to place addi-tional porcelain veneers on both primary canines. The

possibihty of having to place three porcelain veneerswas economically impractical for this patient.

The treatment option of internal bleaching with10% CP in a nightguard was presented to the patient.Compared to placing porcelain veneers, this alternativewas much more conservative and less expensive.Internal bleaching with 10% CP instead of a traditionalwalking bleaching technique was chosen because thereis less risk of internal résorption associated with theuse of carbamide peroxide, and the treatment timecould be customized, for a more predictable result. "The patient was informed of the potential treatment se-quelae of sensitivity of the vital teeth and irritation ofgingivai tissues. The patient elected to pursue this con-servative method of treatment.

At the first treatment appointment, a maxillary algi-nate impression was made and a nightguard bleachingtray was fabricated. While the nonscalloped tray wasbeing fabricated, the cotnposite was removed from theendodontic access preparation on tooth 22, and pulpalremnants were removed frorn the pulp charnber. Alight-cured glass-ionomer cement (Vitrebond, 3MDental) was used to seal tbe root canal orifice. Theglass-ionomer material was placed over the canal en-trance at the level of the cementoenamel junction in athickness of about 0.5 tnm and light cured for 30 sec-onds (Fig lb).

The patient was then instructed in the use of 10%carbamide peroxide (Opalescence) as the bleachingagent via the "inside-outside teehnique."-'"^^ Sbe wasinstructed to inject a small amount of 10% CP Into thepulp chamber of tooth 22 for the inside bieaching.Because the facial aspect of the tooth was coveredwith a composite veneer and thus inaccessible to thebleaching agent, the 10% CP for the outside bleachingwas placed into the nightguard so tbat it would con-tact the lingual surface. The patient was instructed towear the nightguard while she slept. Each tnorning thechamber was to be irrigated with water from a Mono-ject syringe [Sherwood Medical), and a cotton pelletwas to be placed in the chamber to prevent foodentrapment during the day.

Wbile in the office, the patient rehearsed the place-ment of the 10% CP as well as tbe insertion atidremoval of the cotton pellet. The pellet was manipu-lated witb a toothpick. Prior to dismissal, the patientwas instructed to monitor the daily progress of thewhitening process and to stop treatrnent if tbe tootbmatched the adjacent teeth. If no match was achieved,she was to note if a stable color level was achieved (nofurther color change for several days) and return in 1month.

At the 1-month recall visit, the bleaching result wassatisfactory, and the endodontic access was sealedwith Cavit (ESPE Premier) for 2 weeks before the

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Fig la Tooth 22 at initial presentation, atter in-office bleachingprocedure tollowed by restoration with a direct composite veneer.

Fig 1b Lirtgual view of tooth 22 demonsliatingthe giass-ionomer base at the entrance of tine rootcanai orifice. Note the contras! in shades be-tween the darker lingual enamel and the lighterfacial composite veneer.

placement of a definitive composite restoration(Herculite XRV, shade ßl, Kerr/Sybron). This 2-weekdelay was necessary to ensure an adequate bondbetween the composite restoration and the toothstructure--* and to allow the shade to stabilize beforethe color of composite was selected. Prior to the incre-mental placement of the composite, the pulp chamberand margins were etched with 37 /0 phosphoric acidfor 15 seconds. The preparation was rinsed for 10 sec-onds and lightly air dried to remove standing water.Then Optibond Fl adhesive system (Kerr/Sybron) andthe composite restoration were placed according tothe manufacturer's recommendations (Fig lc).

The facial composite veneer on tooth 22 was nolonger necessary to mask the shade discrepancy. How-ever, because tooth structure had been removed fromthe facial surface of the tooth prior to its originalrestoration, the composite was left in place.

Case 2

This 36-year-old patient presented after endodontictherapy had been completed on the maxillary left lat-eral incisor and canine (teeth 22[10] and 23[11]).Tooth 23 had no proximal restorations and was onlyslightly discolored. The lingual access opening ontooth 23 had been closed with an acceptable compos-ite restoration. Tooth 22 had a mesioincisal compositerestoration, which showed clinical signs of leakage,and the entire tooth was severely discolored (Fig 2a).Treatment choices for tooth 22 ranged from bleaching,followed by restoration with a resin composite, toplacement of a post and core and crown on the tooth.

The walking bleaching technique was not the treat-ment of choice for this patient, because the leakingrestoration present in tooth 22 made it impossible toachieve an adequate seal of the pulp chamber from the

Fig 1c Tooth 22 14 montiis after completion of the inside-outsidebleaching procedure and restoration of the endodontio accesspreparation with resin composite The originai veneer is still inplaoe and could not be eliminated because the tooth had beenpreviously prepared.

oral enviromnent without replacing the composite. Ifthe composite were replaced prior to bleaching, selec-tion of the appropriate composite shade would be dif-ficult. Even if a shade were selected to match the adja-cent teeth there would be no guarantee that it wouldmatch tooth 22 after it was bleached.

In-office power bleaching was considered for thispatient, but the severe discoloration present in thistooth would necessitate more than one appointmenttu achieve an acceptable result, thus increasing thecost and time commitment of the patient and dentist.Placetnent of a crown, with or without a post andcore, involves removal of a significant amount ofsound tooth structure and would have dramaticallyincreased the cost to the patient. The choice was madeto try nightguard bleaching first, because other optionswere not compromised by tbis approach.

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Fig 2a Pretreaiment condition of tooth 22 shows the severe ais-coloration that has resuited from the leai<ing composite restoration.

Fig 2b Tooth 22 after a combination of nightguard and mside-outside bieaching procedures.

In contrast to the previous case, for which an inside-outside bleaching technique was used, traditional night-guard bieaching was initially chosen for this patient he-cause of the patient's inability to return for follow-upvisits in a timely manner. Another factor in this decisionwas that the other endüdonticaily treated tooth (23) wasslightly ycilowcr than adjacent teeth and had alreadybeen scaled with an acid-etched composite restoration.The treatment plan was to lighten buth teeth 22 and 23with the single procedure of nightguard bleaching.

A conventional scalloped, reservoired tray was fab-ricated to eover all the teeth but not to extend to tis-sue. ^ The 10% CP material was applied nightly. Afterabout 30 nights of treatment, the shade of tooth 23was harmonious with the rest of the dentition (Fig 2b).At this time, the patient's availabihty had improved, sothe bleaching of tooth 22 was completed in about 2months with the inside-outside bleaching techniquedescribed in case 1.

After the bleaching was completed, the remainingcomposite restoration was removed. Because the toothdid not completely match the adjacent teeth, a shadeBl composite was placed in the pulp chamher tolighten the tooth further. Then the mesioincisal por-tion of the tooth was restored with shade D2 compos-ite restoration (Hercuhte XRV) (Fig 2c). This conserv-ative approach still leaves all other treatment optionsopen.

Case 3

A 37-year-old man eomplained that his maxillary rightcentral incisor (tooth 11[8]) was too dark and hisprosthetic maxillary left central incisor (tooth 21[91)was too light compared to all of his other teeth (Fig3a). The patient had been accidentally struck in themouth 24 years ago, resulting in avulsion of tooth 21

Fig 2c Posttreatmenf condition of tooth 22, which has beerrestored wilh resin com pos i le tc match the new enamei shade.

and apparent subluxation of tooth 11. The missingtooth 21 was replaced with an acrylic resin toothattached to a metal-based removable partial denture(RPD). No treatment was rendered for tooth 11because of a lack of symptoms.

The clinical examination confirmed tooth 11 to beseveral Vita shade tabs darker than the other naturalanterior teeth. A radiograph showed that the canalsystem was almost totally calcified, and the appear-ance of the periapical region was within normal limits.Electric puip testing of this tooth elicited no response.The mobility of this tooth was normal, and there wereno periodontal probings deeper than 3 mm.

The prosthetic tooth replacing 21 was overcon-toured and appeared to be one to two shade tabslighter than the adjacent natural teeth. This discrep-ancy further exaggerated the color mismatch withtooth 11. The maxillary RPD was in good conditionand possessed adequate retention.

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\

i à O.Fig 3a initiai appearance ot toolti 11. iliustrating its shade mis-match with the prosthetic tooth (21) and ttie otnernaturai teeth.

Fig 3b Midtreatment condition oí tooth 11 toiicwing 2 months ofnightguard bieaching. The shade of this tooth is simiiar to Iheotlner natural leeth. which are noi as iight as prosthetic tooth 21.

Fig 3c Appearance of the patient foiiowing an additionai 6weeks of nightguard bleaching in addition to recontourjng andpolisining ot tooth 21

Finances limited the patient's treatment options.Therefore, a treatment plan that included nightguardbleaching of tooth 11 along with esthetic recontour-ing and polishing of the acrylic resin prosthetic re-placement for tooth 21 was accepted. A nonscal-ioped, nonreservoired maxiiiary bleaching tray wasfabricated for the patient on a cast tbat did not in-clude tbe RPD. because carbamide peroxide has beenshown to discolor dental acrylic resin. ^ Because thetray could not be worn with the RPD in place,bleaching was performed only at nighttime. A reser-voir was omitted from tooth 11 in an attempt to en-hance the adaptation of the bleaching tray and tolimit the voiume of bleach in the area of tooth 11 toavoid inadvertent lightening of the maxillary right lat-eral incisor {tooth 12[7]). An alternative techniquewould include preparing a tray witb a facial windowon tooth 12. If tooth 11 did not respond to treatment,any lightening of tooth 12 would accentuate the color

mismatch. The patient was instructed to use the trayat night while sleeping and was given a 2-month sup-ply of 10% CR

After 2 months of nighttime bleaebing, the shade oftooth 11 was nearly equivalent to that of the adjacentnatural teeth (Fig 3b). The acrylic resin tooth replac-ing tooth 21 was recontourcd and polished to mirrortooth 11 in size and shape. The patient was verypleased with the results of the bleacbing treatmentat this time. However, there was some concern abouttbe appearance of tooth 21, which was still lighterthan all his natural teeth. Therefore, it was suggestedto the patient that he try bleaching his entire maxillaryarch in an attempt to match the shade of the acrylicresin tooth on the partial denture. This bleachingtreatment was initiated at this appointment and wascompleted in 6 weeks, providing the patient with adramatically improved appearance in an economicmanner (Fig 3c).

DISCUSSION

Two points arising from these case reports deserve dis-cussion. One is the duration of treatment with thenightguard technique using 10% carbamide peroxide.Most manufacturers' instructions suggest 2 weeks or¡ess. The implication is that all teeth should respond totreatment in that time frame. However, many pub-lished articles on clinical research trials and case re-ports have shown otherwise.

The first article in the literature on nightguard vitalbleaching, by Haywood and Heymann,' reported atreatment time of 5 weeks and recommended 6 weeks,although the authors mentioned that some patientsmay respond in only 2 weeks. The largest clinical trialon nightguard vital bleaching used 6 weeks as the

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treatment time because matiy patients do not respondadequately in 2 weeks.'" The guidelines for the Amer-ican Dentai Association Seal of Acceptance for perox-ide-containing whitening products specify that treat-ment opfions can range from 2 to 6 weeks.^'

However, in this era of instant gratification, boththe dentist and patient are interested in the shortestpossible treatment time. Marketing claitns stress rapidtreatment rather than optimum color change. Mostcompanies choose to advertise the shortest reason-able time, which may work for some patients.However, dentists should be aware that certain pa-tients or discolorations often require times that ex-tend beyond 2 weeks. Normal or slightly stubbornteeth may require 4 to 6 weeks, as previously de-scribed."'^*" Nicotine-stained teeth may require 3months.'^ Tetracycline-stained teeth may require 2 to6 months of nightly treatment.""^'' One report on ex-fended treatment time for tetracycline-stained teethindicated that 12 months was required io obtain asuccessful outcome.^- This type of treatment timevariation also exists for the single dark tooth. If thetreatment time is limited to 2 weeks, the best coloroutcome will not always be achieved.

The opportunity for extended treatment is one ofthe primary advantages of the inside-outside bleachingtechnique. The patient can receive treatment for alonger period of fime without having to return to theoffice. Pafients are usually willing to treat for longertimes if the dentist initially prepares thern for thatpossibility. Typically, teeth take 2 to 6 weeks oftreatment with 10% CP, and tetracyciine-stained teethtake 2 to 6 months. However, the best advice is to"bleach until they are white," because there have beenno documented negative consequences from thisphilosophy.

The other point of discussion is regarding the typeof tray design employed for bleaching. There is no uni-versal style of bleaching tray. Instead the design isrelated to the type of material being used, the tjipe ofdiscoloration being treated, and the specific patientbeing served. Bleaching trays can be designed with orwithout facial or lingual scalloping, and with or with-out reservoirs.'' Materials that are more viscous andsticky work best in reservoir trays to allow completeseating of the tray. However, neither reservoirs norfoam inserts are necessary for bleaching.'^ Also,scalloping (trimming the tray to approximate the freegingival margins) allows the dentist to eliminate mostsoft tissue contact, which may prevent tissue irritation.Conversely, bleaching material is more likely to leakfrom a scalloped tray and may irritate fhe tongue andlips. More viscous gels stay in the tray more readily.

When the discoloration is located at the gingivalarea, the authors use nonscalloped tray designs to

ensure proper application of the material to the discol-ored site. In the two cases presented where nonscal-loped trays were used, one involved an edentulousspace adjacent to the primary treatment site. This situ-afion precluded the use of a scalloped tray. The othersituafion involved the need for lingual appiication ofthe bleaching material, and it was thought that a non-scalloped tray would provide a better seal and be tol-erated better by the patient.

If a more fluid bleaching material is used, a non-reservoired tray design retains the materiai in the traybetter and is more comfortable for the pafient. If tissueirritation occurs, the tray can then be scalloped. Theoriginal trays used for nightguard bleaching did nothave reservoirs and were not scalloped. The gingivalirritafion resulted partiy frotn the rigidity of the traymaterial used and partly from the chemical nature ofthe material that came into contact with the soft fis-sue.'* With the newer, more flexible tray materials,there is less potential for gingival irritation.

Sficky bleaching rnaterials adhere to gingival tissuesmore easily and can cause contact irritation. Morewater-soluble materials do not seem to cause thisproblem. The bleaching material used in these casereports, a viscous, sticky gel, is generally used with ascalloped, reservoired tray, but such a design is notessential. Certainly if other materials are used, anappropriate tray design must be used.

These variations in patient response, tnaterialtype, and discoloration situation are just a few of thereasons why nightguard bleaching should always besupervised by the dentist.^'' The proper selection oftray design and material, as well as the monitoring ofside effects, is essential for tnaximum bleachingbenefit. Also, the acquisition of preoperative radio-graphs to verify the absence of periapical pathosis iscrucial for nonvifal feeth and always important forvital teeth.

CONCLUSION

Several conservative treatment opfions involving thenightguard bleaching of single, dark, nonvital teethwith 10% carbamide peroxide have been presented. Ifthese conservative approaches are used first, other,more traditional treatment options are still available ifneeded. The cost-benefit ratio of this procedure is veryattractive to pafients, and treatment does not involvesignificant office time for the dentist. Addifionaily, thesafety concerns associated with the use of 35% hydro-gen peroxide are eliminated. Bleaching often providesa more natural esthetic result than do crowns or ve-neers, and bleaching can itnprove the results of previ-ous restorafive treatment.

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