Achieving, Maintaining, and Recovering Successful Tooth Bleaching

J O U R N A I . OF F S T H E T I C D E N T I S T R Y

Achieving, Maintaining, and Recovering Successful Tooth Bleaching

VAN B. HAYWOOD. D M D ‘

00th bleaching may involve T internal bleaching of nonvital teeth, external bleaching of vital teeth in the office, or external bleaching of teeth using a prosthesis at home.’.-O All three options may be permanent in some situations, but color change is generally of a limited duration. Nightguard vital bleaching is a procedure in which vital teeth are bleached with a 10% carbamide peroxide applied daily or during the night in a custom-fitted nightguard (prosthesis).’ This procedure is also called matrix-bleaching or dentist-prescribed, home-applied blea~hing.~.’ Nightguard vital bleaching has proved to be highly successful, with nine of ten patients expericnc- ing a lightening of their teeth in 2 to 6 weeks application time.x Questions remain, however, about the rate, extent, and duration of the color change and methods of maintenance and recovery of the initial bleaching r e ~ u l t . ~ Also unknown is the effect of varying amounts of carbamide peroxide.

K A T E A N D EXTENT OF L I G H T E N I N G

The rate at which teeth lighten during bleaching varies consider- ably among patients. In general, there is a gradual lightening in color that eventually reaches a plateau of maximum lightening for that patient. Beyond this point, further treatment makes no change. Where this color plateau is located and how long it takes to get there varies from patient to patient. Some patients’ teeth lighten quickly and progress to a very light shade, whereas other patients’ teeth take a longer time to obtain either the same or a more moderate result. There are no predictors for rate or final outcome. Experienced practitioners develop a sense of prediction, but there are no absolutes. Only by attempting the procedure will patients learn how light their teeth can get and how quickly the lightening will occur.

Just as each patient responds differently, so do different tccth. This phenomenon allows the better matching of a single dark tooth with the adjacent teeth. Once the conventional prosthesis is fabri- cated, all the teeth begin to lighten. However, the normal teeth reach their color plateau and stop changing. Continued treatment applications allow the darker tooth to “catch-up” with the other teeth, resulting in an overall lightening of all teeth and a bettcr match with the single darker tooth.

Not only may some teeth respond differently, but also parts of a tooth may respond differently. Generally, the incisal edge begins to lighten first, with the necks of the teeth being the last area to lighten. This sequence is generally related to the physical thickness of the tooth from incisal to gingival, the longer availability of material in the prosthesis at the incisal por- tion of the prosthesis, and the ratio of dentin to enamel thickness.

*Assocrate Professor, Department of Oral Rehahrlrtatron, School of Dentrstty. Medrcul College of c;e<JrglU, Augusta. Grorgra

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Most of the tooth color comes from the dentin, so in places where the dentin is thicker, the color change will be slower.

Occasionally some teeth go through a “splotchy” stage, where certain isolated areas lighten faster than others. This variation may be due to alterations in enamel forma- tion that give varying responses to bleaching. Regardless of the etiol- ogy, continuation of treatment will result in a harmonization of color, as in the single discolored tooth scenario. Encouragement and reas- surance by the dentist during this awkward time are essential to the patient continuing to a successful result. The final outcome has always been better than the initial presenting conditions.

Once treatment has beeh terminated, there is often an initial subtle relapse in color in the first few days. This reversion may be due to the teeth returning to equi- librium in the mouth as the oxygen dissipates out of the tooth. The presence of additional oxygen in the tooth may alter the optical properties of the tooth. Because of the phenomenon,, as well as the inhibiting effects of oxygen on bond strengths of composite, shade selection for restorative materials and bonding is best delayed for 1 to 2 weeks after completion of bleaching. Following this initial reversion, the tooth color stabilizes.

STABILITY A N D RBCOVERY OF T H E INITIAL. BLEACHING RESULT

Previous reports have noted that at 1.5 years post treatment, 74% of teeth that have been bleached have retained their lightening without any additional treatment. At 3 years post treatment, 62% still retain a clinically acceptable lightening (Figures 1-3).x Some of the results, especially treatment of single darkened teeth (Figures 4-6) or removal of brown fluorosis (Figures 7-10), may be permanent. However, 1 to 3 years is the expected duration of the lightening. Teeth that lose the lightening effect tend to discolor slowly. Patients often describe their teeth as getting “dingy” or “losing their brightness.” In these instances, a touch-up treatment generally will restore the lightening in 1 to 4 days of treatment. I t is not considered necessary to treat the teeth monthly but, rather, better to wait until there is some obvious relapse in color before applying a re-treatment.

One challenge in rendering touch- up treatment is maintaining an acceptable prosthesis. The original prosthesis must still be available and must still fit the patient. Otherwise, re-treatment costs approach initial treatment costs. Some dentists prefer to retain the cast and/or prosthesis after completion of the initial treatment. However, patients are not generally in favor of this approach. More importantly, the dentist is charged with the responsibility of maintaining the materials in serviceable condition for a significant amount of time, with the inferred responsibility of replacement if the prosthesis is lost or damaged. It may be more prudent to give the patient the cast and prosthesis with instructions to store the two in a refrigerator or cool placc. If patients should experience. any concern about the color of their teeth, they should return to the office with the prosthesis. This recall visit allows the dentist to determine if the discoloration is a

Figure 1 . Pre-bleaching example of discolored teeth from genetics or aging.

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Figure 2. in a custom-fitted tray there is noticeable lightening vf central incisors. Mandibular arch is untreated, and laterals are too translucent to respond well to bleaching.

Immediately following bleaching with 10% carbamide peroxide

bleaching matter or requires some other treatment and to evaluate the fit and condition of the prosthesis. Occasionally the discoloration reported by the patient is related to a different problem for which bleaching is not indicated. Should bleaching be appropriate and the prosthesis still fits, the dentist can dispense a small amount of material for 1 to 4 nights of treatment. The bleaching material used by the dentist should be available in small doses or packages to facilitate minor treatment times or extended treatment times. The office should consider whether to charge a fee, and, if so, the fee should be estab- lished in advance. The amount of time since the termination of initial therapy and the amount used by the patient to achieve the original result may influence this decision. The patient should understand that if significant dentistry has occurred and the prosthesis is lost or no longer usable, a new impression

and prosthesis will be required. The fee for this procedure should be determined prior to treatnicnt as well.

Another trcatment option for the patient who is unablc to use the original prosthesis may be to employ in-office bleaching with a rubber dam and 35% hydrogen peroxide. However, onc in-office bleaching treatment can seldom

match results attainable with extended wear and use of nightguard vital bleaching, so the cost for the two options should be weighed carefully. If cost is less important than obtaining quick results, then the patient should consider a combination approach consisting of an in-office bleaching treatment, followed up with a matrix treatment for 3 weeks. Generally, fabrication of a new prosthesis a t full fee may be less costly than one to two officc visits for in-office bleaching. Having the new prosthesis would prepare the patient for any subsequent relapsc and treatment nceds. However, time constraints or patient prefer- ences may prcclude nightguard vital bleaching and favor in-office treatment. Often, if the initial bleaching was obtained by in-office techniques. thc touch-up may still be done using the matrix-bleaching approach.

Figure 3 . treatment.

Three-year post nightguard vital-bleaching with no touch-up

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than gel toothpaste. However, overzealous use of an abrasive toothpaste removes enamel along with stain, resulting in an eventual yellowing of the tooth as the dentin-to-enamel ratio is changed. The use of abrasive toothpastes and hard brushes has long been recognized as creating more problems than it potentially can solve.

Figure 4. Pre-bleaching single tootb discolored from trauma, but vital.

M A I N T E N A N C E

If the original discoloration was a result of chromogenic food or drink, smoking, or other stains, it is reasonable to advise the patient that the bleaching result will last longer with cessation of the use of these materials. However, quality of lifestyle issues generally do not result in changing patient behavior, especially since re-treatment is so simple. Discolorations that are genetic or from aging cannot be avoided. In previous years, the in- office bleaching technique recommended acid-etching the teeth prior to each treatment. Although the teeth were polished at the conclusion of each appoint- ment, patients were cautioned a bout staining from chromogenic materials between appointments. More recent research has indicated that acid-etching prior to in-office bleaching is not required.ln

ORAL HYGIENE A N D TOOTHPASTES

Whitening toothpastes have been suggested to help maintain the bleach. Whitening toothpastes can be divided into several groups based on mechanism of action, One group is those toothpastes that are more abrasive than normal toothpastes. The abrasive toothpaste attempts to remove surface staining by sanding. Generally, paste toothpaste is more abrasive

Another class of toothpaste acts to chemically remove the surface pellicle that houses the stain, much in the same manner as tartar-con- trol toothpastes prevent the build-up of tartar. These toothpastes may be effective in reducing surface stains, but do not alter the internal color of the teeth. Occasionally teeth are sensitive to chemical means of stain and tartar removal, and their use must be terminated due to sensitivity.

Figure 5. Immediately following bleaching with nightguard vital bleaching and treating all the teeth with a custom-fitted prosthesis.

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Many of the whitening toothpastes contain titanium dioxide, a white pigment designed to enter the surface irregularities of the tooth." This white pigment is proposed to give the illusion of whitened teeth, much as adding white characteriza- tion to ceramic crowns can. Again, this is only a surface phenomenon, not internal color modification.

Finally, there are those whitening toothpastes that contain peroxides. Some toothpastes contain the same concentration as the original bleaching materials. However, the mechanism of application does not seem to be sufficient to make significant alterations on internal color. Initial over-the-counter whitening systems applied peroxides with a brush or cotton swab, but the contact time was insufficient to produce a favorable result. On the other hand, long- term use has the potential to make some changes, but raises the ques- tion of safety. Peroxide certainly has the possibility to remove the discoloration of surface staining, so there may be some chemical surface effects on the surface stain as well.

The effectiveness of whitening toothpastes has not been demon- strated scientifically. Brushing with anything that patients believe will work generally makes them more conscientious about their oral care. Regular oral prophylaxis to remove surface staining and maintenance of healthy gingival tissues

Figure 6. darkening has occurred, but not to the point that the patient wants to touch- up. Composite has been placed on the other central.

Three years after bleaching with no touch-up treatment slight

with appropriate brushing and flossing are important to a pleasing smile. Patients should be instructed in proper brushing techniques that not only clean the teeth but also keep the gingival tissue healthy. Instructions should include selection of a soft toothbrush with the appropriately sized head for their arch form, and avoidance of ovcr-

brushing thc same location. Overly aggressive brushing may result in gingival recession and tooth abra- sion with normal toothpaste. Often the affected area is the opposite maxillary arch from the dominant hand. Hence, a right-handed person often over-brushes the maxillary left incisors and premolars, while missing the maxillary right

Figure 7. to primary tooth during development o f permanent tooth.

Pre-bleaching of brown isolated defect, possibly related to trauma

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Figure 8. touch-up treatment since initial treatment. All the teeth were treated during nightguard vital bleaching.

Three years after bleaching by nightguard vital bleaching with no

side. The change in length of exposed tooth, health and color of tissue, and amount of surface stain makes the teeth unattractive, even if the inherent color is stable. Instructing the patient to start on the same side as their dominant hand and increasing their aware- ness of their personal habits can help avoid these problems.

DETRACT I N C FA <:TORS

Generally, persons who have light- ened their teeth have more confidence and become more out- going.I2 They may even change their dressing habits or expand their wardrobe as they enjoy their new-found confidence in their smile. Wearing an inappropriate lipstick shade or make-up may give the illusion of discoloration of the teeth. The most extreme example of this phenomenon is the apparent yellow color of a clown’s teeth when the face is whitened. Removal of the clown make-up results in a “whitening” of the

teeth. Patients may need to be counseled on the effect of lipstick, cosmetics, and clothing color on teeth and encouraged to maximize their tooth color. Having a color consultant available to the practice for determining appropriate colors of clothing or cosmetics is beneficial. l3

SENSITIVITY

Another area related to maintenance of bleaching is the prevention of tooth sensitivity to obtain a successful bleaching. First and foremost, the dentist should explain to the patient that two thirds of patients undergoing tooth bleaching using nightguard vital bleaching experience some sensitivity during treatment. This sensitivity is usually 1 to 4 days in duration, but may occur throughout the experience. Patients need assurance that the sensitivity will stop with cessation of treatment and will not return.

Although there are no predictors for whether or not the patient will have sensitivity, generally a history of sensitive teeth or an exaggerated response to an air blast during examination may indicate the predilection for sensitivity. Reports have indicated that the frequency and duration of application may be the only controlling factor.8 This observation has lead some practitioners to choose treatment regimes that start with less fre- quent application times, or less duration of application, then increase weekly. Although the treatment time is extended, the patient is able gradually to achieve a satisfactory lightening.

If sensitivity occurs that is severe enough to interrupt treatment, then stopping treatment either tem- porarily or permanently, or reducing treatment time, can allevi- ate the problem. These treatment options are considered “passive” treatments. Some practitioners prefer some “active” treatment options, such as placing fluoride or desensitizing toothpastes in the guard. Whether these options are effective is unknown, but their use may acquire some time for the “passive” results to take place. Generally, an understanding, informed attitude, coupled with titration of wear time and frequency of application, will allow the patient to successfully complete the bleaching procedure.

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Figure 9. child.

Pre-bleaching o f generalized brown fluorosis on 1 0-year-old

A 111 I1 N C T I V E R EST 0 R AT I V E

Veneers Often teeth are bleached prior to initiating porcelain veneers, in an effort either to eliminate the need for veneers or to reduce the need for masking discolored teeth.14 After the veneers are cemented, the color of the natural tooth may relapse over time as with normal bleaching situations. If this color relapse is evident clinically through the veneers, the teeth can he re- bleached as previously described. A new prosthesis will be required, since the previous bleaching was done prior to the veneers. The carbamide peroxide can enter the tooth through the lingual and proximal surfaces. Several reports

Occasionally, porcelain vencers stain around the margins as well. If this stain is in a decp crevice, it may he desirahlc to remove the stain by bleaching, then sea] the crevice with acid-etching and a dentin bonding agent. This

T R E A T M 1:. N T S

approach avoids replacement of the veneer or more aggressive repair using Class V composite preparations.

N O N V I ' I A L. TEETH

Research has resulted in changes in treatment of nonvital teeth. All posterior teeth that have been endodontically treated still generally require a full-coverage casting. This is due to the multirooted anatomy of the teeth with natural vertical cleavage lines; the mutually protected dental articulation of natural teeth that has all teeth contacting in maximum intercus- pation position, with the posterior teeth contacting more heavily than the anterior teeth; the multicusp anatomy o f the crown; and occlusal function, predisposing the tooth to fracture. However, antc- r i o r teeth have been shown not to

Figure 10. touch-up treatment has been given, although orthodontics has been completed. Mandibular teeth were not treated.

Three years after bleaching with nightguard vital bleaching. N o have noted the easy passage of carbamide peroxide through the enamel and dentin, allowing the teeth to be bleached from the lingual.1s-lY

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require a crown unless they are an abutment for a prosthesis or would have needed a crown for other rea- sons. If there is reasonable remaining tooth structure for a single anterior tooth, closure of the endodontic access opening with an acid-etched composite is indicated. The longevity of this restorative approach equals that of a crown with post and core, and the failure is generally not catastrophic. Posted teeth fracture vertically, requiring extraction, whereas non- posted anterior teeth tend to fracture horizontally, allowing re- treatment with a post and core. Anterior teeth that have been treated endodontically and now are discolored are bleached internally, and the access opening is restored with acid-etch composite. Generally, this composite is bonded to enamel and dentin and has good color stability.

Should the tooth discolor subse- quently, it is desirable not to have to remove the acceptable composite to re-bleach internally, since removal generally involves additional loss of tooth structure and further weakens the tooth. In these instances, re-bleaching is best accomplished externally with either in-office bleaching or nightguard vital bleaching.


CONCLUSIONS

Bleaching permits a successful esthetic outcome while conserving tooth structure at minimal expense. The beauty of nightguard vital bleaching has been not only the relative ease and low cost of initially bleaching the teeth, but also the minimal maintenance or lifestyle changes needed to enjoy a long-lasting result. The ease, versa- tility, and quickness of re-treatment have made nightguard vital bleaching one of the most popular treatment options in the profession.

R E F E R E N C E S

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Haywood VB. Bleaching o f vital and nonvital teeth. Cuw Opin Dent 1992;

Coldstein CE, Goldstein RE, Feinman RA, Garber DA. Bleaching vital teeth: state of the art. Quintessence lnt 1989;

Coldstein RE, Garber DA. Complete dental bleaching. Chicago: Quintessence, 1995.

Heymann HO, Sockwell CL, Haywood VB. Additional conservative esthetic procedures. In: Sturdevant CM, ed. The art and science of operative dentistry. 3rd Ed. St. Louis: Mosby, 1995:643-647.

Haywood VB, Heymann HO. Nightguard vital bleaching. Quintessence

Haywood VB. Considerations and variations of dentist- rescribed, home- applied vital tooth btaching techniques. Compend Cont Educ Dent 1994; 15 (Suppl 1 7):S6 I 6 S 6 2 I .

Garber DA, Coldstein CE, Goldstein RE, Schwartz CG. Dentist monitored bleaching: a combined approach. Pract Perio Aesthet Dent 1991; 3(2):22-26.

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9. Haywood YE. Commonly asked uestions about nightguard vital B leaching. I n d i o ~ Dent Assoc J 1993;

10. Hall DA. Should etching be performed as a part of a vital bleaching technique? Quintessence lnt 1991; 22A79-686.

11 . Havwood VB. Advice to batients on over

72(5):28-33.

_ _ th&ounter bleaching a g k . Esther Dent Update 1995;6(3):73-74.

12. Goldstein RE. Change your smile. Chicago: Quintessence, 1988:53.

13. Goldstein RE. Esthetics in dentistry. Philadelphia: J B Lippincott, 1976445.

14. Haywood VB, Williams HA. Status and restorative options for dentist-prescribed home-applied bleaching. Esthet Dent Up&te 1994; 5(3):65-67.

Penetration of the ulp chamber by

Endod 1992; 18(7):315-317.

penetration by rdrogen peroxide following vital bleaching procedures. J Endod 1987; 8:375-377.

15. Cooper JS , Bokmeyer TJ, Bowles WH.

carbamide peroxi C P e bleaching agents. J

16. Bowles WH, U uneri 2. Pulp chamber

17. Anuill T, Myreberg N, Soremark R. Penetration of radioactive isoto es through enamel and dentin. Od!ntol Revy 1969; 20:47-54.

18. Atkinson HR An investigation into the permeability of human enamel using osmotic methods. Br Dent J 1947;

19. Wainwright WW, Lemoine FA. Rapid

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diffuse enetration of intact enamel and dentin !y carbon 14-labeled urea. J Am

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Reprint requests: Van B. Haywood, DMD, Associate Professor, Department of Oral Rehabilitation, Room AD3144, School of Dentistry, Medical College of Georgia, Atlanta, G A 30912-1260 81 996 Decker Periodicals

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Achieving, Maintaining, and Recovering Successful Tooth Bleaching