Professional Tooth Whitening: a Minimally Invasive Esthetic Treatment
Today’s dental practice has many options for whitening
Tooth whitening is best performed under the care of a dental team. Not all patients will benefit from whitening or are appropriate candidates for the procedure and it is recommended the patient first have a clinical evaluation to understand why the teeth are discolored.
Clinical decisions regarding tooth whitening are based on the patient’s opinions about tooth whitening, a history of allergies (particularly in regard to bleaching materials), and information regarding tooth sensitivity. Important considerations for the cause for the discoloring may be diseases and conditions that require endodontic therapy, restorations, or dental surgery. When a dental team is deciding the best course of whitening treatment, it is best to understand patient expectations, limitations, and willingness to follow a course of treatment.
Dental office–dispensed or in-office tooth whitening can include a variety of concentrations of hydrogen and carbamide peroxide for use in trays or strips, or in-office techniques with and without light or heat enhancement that can be provided to the patient in a single appointment.
Research has demonstrated safety and effectiveness of tooth whitening with peroxide products.1-3 In all cases, the agents evaluated lightened the color of the teeth safely and effectively with minimal, transient adverse reactions reported. When the bleaching procedure was completed, these adverse reactions that were reported during treatment were no longer present. Based on a comprehensive literature review, the use of bleaching products containing hydrogen and carbamide peroxide does not appear to pose an increased risk of oral cancer in the general population, including those persons who are alcohol abusers and/or heavy cigarette smokers.4
Today the dental practice has many choices for whitening. These include different types of tray and trayless systems with peroxides in a wide range of concentrations. When comparing chemical concentrations, an approximate ratio to use is that 3% hydrogen peroxide is approximately equivalent to 10% carbamide peroxide. The addition of a carbopol to carbamide peroxide vital tooth bleaching gels extends the bleaching potential of the gel over as long as 8 hours, so that a recommendation can be made to wear a tray overnight.5 This is not true of hydrogen peroxide–based vital tooth bleaching products. Hydrogen peroxide will lose more than 50% of its bleaching potential within 30 minutes. Therefore the recommendation for hydrogen peroxide bleaching is that it be used for only 30 minutes at a time. Higher concentrations of hydrogen and carbamide peroxides allow the patient to decrease the total wear time in days/weeks of the tray and decrease the time necessary for a whitening result. Higher concentration hydrogen peroxides (25%-35%) are used for in-office bleaching with and without light and heat enhancement.
At-Home Bleaching
Predictable, effective tooth whitening with trays requires attention to detail in the fabrication of the tray and providing the patient with instructions that are easy to understand and follow. After evaluating the patient’s smile and desired outcome, the choice of both maxillary and mandibular arch whitening, or only maxillary arch whitening can be made.
Tray Fabrication
Critical to providing the patient with a problem-free tooth whitening experience is good tray fabrication technique:
1. Make impressions that are accurate and poured immediately with the impression of choice for diagnostic casts. It is easier to make a new intraoral impression than to try to duplicate an existing cast, and the new one will usually be more accurate
2. Pour a bubble-free cast from the impression. Many offices use fast setting stone so the tray can be fabricated in a single visit.
3. Trim the cast to a horseshoe shape with no tongue space or palate. This means trimming the cast so the base is very minimal. Also trim the cast to eliminate the buccal vestibule.
4. Before fabricating the trays, inspect the cast to remove any irregularities and blebs. Make sure the gingival margins of the cast are accurate. The use of spacers on the stone model to create reservoirs is not necessary, but the use of reservoirs will help the patient swallow less bleaching gel.6,7 For the use of spacers, follow the preferences of the clinician.
5. Use the thin, flexible tray material provided with the bleaching material, along with the vacuum device in the practice, following the specific instructions for its use.
6. Custom fitted, well-adapted trays provide improved bleaching gel–tooth contact.7 Once the tray is vacuumed over the cast, wait for the tray material to cool before removing from the cast for trimming. Another technique for trimming does not require tray removal from the cast. The tray can be easily trimmed on the cast using a Tray Magic™ (Premier Dental, www.premusa.com) electric soft tray trimmer, resulting in a scalloped tray that follows the free margin of the gingival on both the facial and lingual surfaces, leaving all the gingival tissues uncovered by the tray. By trimming the tray on the cast, there is less concern about distortion that occurs when trimming with a scissor.
7. Trim the tray with sharp scissors, being careful to have the tray extend to the free margin of the gingiva for the teeth being whitened. The final tray should have a horseshoe appearance. (Figure 1)
Once the tray(s) are fabricated, they can be delivered to the patient. Most companies provide bleaching gel for a 2-week period of application. Although higher concentrations of the whitening gel show faster initial improvements, over a 6-week period of time there is no difference in the final result, when comparing 10% carbamide peroxide to higher concentrations.8,9
Patient instruction is important. Patients often are not concentrating at the end of the dental visit. To be certain the patient understands how to use the whitening tray and gel, provide the patient with an instruction sheet that describes the procedure, reviews the instructions, and explains what to do if there is an adverse reaction.
Adverse reactions have been reported, including gingival irritation, uneven tooth bleaching, a uneven coloration during early stages of bleaching, and tooth hypersensitivity while bleaching. Most times gingival irritation is due to poor tray fabrication, or the need to scallop the tray for higher concentrations of hydrogen and carbamide peroxide bleaching gels.10 During the initial bleaching, especially with higher concentrations of tray bleaching gels, patients have reported uneven coloration or splotchy appearance, which disappears after the first week.10
Transient tooth sensitivity has been the highest reported adverse reaction, in a range of 18%-78% of patients during bleaching with at-home tray delivery and in-office procedures.11-14 It has been shown that gingival recession is not a factor in the occurrence of tooth hypersensitivity when bleaching.15 Tooth sensitivity is more often seen with higher concentrations of whitening gels and during the first week of whitening. A past history of sensitivity when whitening should alert the dental team to make recommendations to minimize sensitivity. To minimize tooth sensitivity during vital tooth bleaching, the clinician can recommend decreasing time the tray is worn the first week to no more than one hour a day for carbamide peroxide products, or for higher concentration hydrogen peroxides as little as 15 minutes a day, or to use lower concentrations of peroxide.
A 5% potassium nitrate (KNO3) formulation has been shown to be an effective desensitizer in toothpastes,16-18 and some bleaching gels have added a 5% KNO3 desensitizing agent. Two effective strategies using a KNO3 desensitizing toothpaste that have been clinically evaluated are brushing with the desensitizing toothpaste for two weeks prior to initiating bleaching11 or having the patient place a sensitivity toothpaste containing a 5% KNO3 one week prior to the initiation of bleaching in the tray that will be used for bleaching for 30 minutes a day.19 Another strategy is to have a patient use a professionally dispensed desensitizing gel with 5% KNO3 for use with bleaching.20 In addition, amorphous calcium phosphate (ACP) (MI Paste™, GC America, www.gcamerica.com) has been shown to be an effective desensitizer.21-23
In-Office One Hour Whitening
For patients who cannot find the time to apply trays or strips in their busy lives, in-office whitening offers the convenience of whitening their teeth in one or more dental appointments. The first in-office procedures required using the dental dam, painting the teeth with high concentrations of hydrogen peroxide, and employing heat lamps to activate the bleach. Patients were usually very uncomfortable, and three to four visits were required to achieve a favorable result.
There has been much improvement in the process. Currently the most popular systems for in-office bleaching use high concentration hydrogen peroxides (25%–35%) and are often referred to as “one-hour bleaching.” In-office bleaching can be provided to patients as either a one-visit 1–1.5 hour treatment or a multiple visit procedure.24-26 One can use one of the light enhanced bleaching techniques, a laser activated bleach, or a paint-on bleaching gel (Figure 2 and Figure 3).
In-office professional whitening can be a perfect complement to an at-home whitening system.27 In-office whitening can offer patients the convenience of whitening their teeth in one or more dental appointments without the need for wearing a tray for two weeks.
How effective is in-office bleaching? Studies have been done to compare in-office bleaching to at-home tray bleaching.28-30 Although all bleaching regimens provide for tooth whitening that pleases patients, the results of in-office bleaching with light enhancements have been controversial. Within the dental literature, there are conflicting studies as to whether or not high concentration hydrogen peroxide bleaching compounds are effective. Some studies have shown that the use of a light-activated/enhanced bleaching product provides better whitening,24,25 while other studies demonstrate that there is no benefit to using an accessory light.31,32 In-office tooth whitening may require multiple visits to get optimal results or in some cases in-office bleaching with one week at-home tray whitening is recommended after the in-office procedure.26,28,29
There have been reports of sensitivity during this chairside procedure.33,34 Using a protocol of administering preoperative ibuprofen prior to chairside bleaching has reduced the clinical symptoms of sensitivity, but not the postoperative sensitivity.35 Use of a desensitizing gel prior to tooth bleaching has also been effective.36
The techniques for one hour whitening vary from product to product. In most cases, the in-office vital tooth bleaching products are 25%–35% hydrogen peroxide gels. The use of high concentration hydrogen peroxide gels intraorally requires that specific safety protocols be used. First, the patient and practitioner must be wearing eye protection, and a barrier placed on the gingival soft tissues adjacent to the procedure. Some lights generate heat and/or UV rays, so a rubber dam napkin can be used to shield the face from the light source. In some cases, the manufacturers provide moisturizers for the lips or sunscreen as protection from the UV rays. While a dental dam would be ideal, as seen with other bleaching techniques, the placement of a dental dam will inhibit the bleaching of the cervical areas of the teeth, which may cause dissatisfaction in patients, who want their entire visible tooth surface to become whiter. Manufacturers have responded by providing barrier protection in the form of a light cured resin (similar to flowable composite resin) that is painted over the gingival tissues and light cured (Figure 4 and Figure 5).
As noted earlier, concerns have been expressed that one-hour whitening with light enhancement is no different from whitening without the light. If this is the case, why use a light? Often, patients expect the use of a light to enhance vital tooth bleaching. They have read articles, viewed makeover television shows, and witnessed the procedure in the mall at whitening kiosks. Even though the research is not definitive on the use of light-enhanced bleaching, patients will wonder if they are getting the proper care or the best whitening without it, therefore it may be important for patient satisfaction.
Bleaching Relapse
From all clinical and research accounts, tooth whitening with the latest generation of vital bleaching products is effective, safe,24-26,37-39 and relatively long lasting. Bleaching relapse has been reported. With in-office bleaching, Clinical Research Associates reported relapse of 41% at 1 year.39 For tray bleaching, Haywood reports 26% relapse at 18 months.40 Others have reported varying degrees of bleaching relapse over time.41,42 The original concentration of the bleaching agent had no effect on bleaching relapse.43 To prevent bleaching relapse, a patient would have better success with a power toothbrush and a whitening toothpaste over manual toothbrushing.40 Bleaching can be maintained through the use of whitening and bleaching toothpastes with yearly touch-up bleaching using a peroxide bleaching agent in the patient’s custom fitted tray.
Conclusion
Vital tooth bleaching is an effective treatment modality that can change the appearance of teeth. Patient satisfaction has been demonstrated after use of both professionally dispensed bleaching treatments and OTC products. Based upon the clinical results reported with professional vital tooth bleaching, it is a viable, esthetic treatment for the discolored dentition. Its conservative nature and little if any risk make it an important part of an esthetic dentistry treatment plan.
References
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About the Authors
Howard E. Strassler, DMD
Professor and Director of Operative Dentistry
Department of Endodontics, Prosthodontics and Operative Dentistry
University of Maryland Dental School
Baltimore, Maryland
Roseanna J. Morgan, CDA
Clinic Coordinator
Postgraduate Prosthodontics
University of Maryland Dental School
Baltimore, Maryland
