HOME TRAY BLEACHING

When professional vital tooth bleaching using trays for athome use was first introduced to the profession, there were concerns over adverse reactions and patient complaints. The adverse reactions and patient complaints included: taste of bleaching gel, gingival irritation, uneven tooth bleaching, splotchy appearance of the teeth during the initial stages of bleaching, and tooth hypersensitivity while bleaching. These issues have been investigated and research has provided a better understanding. Manufacturers of tooth bleaching products have made changes in technique recommendations and product components to address these issues. Clinician and patient complaints concerning issues of taste have been addressed with an expanded selection of better flavors for improved patient acceptance. 

Gingival irritation has occurred with trays that were poorly fabricated either because of inaccuracy of casts or the need for scalloping the tray for higher concentrations of hydrogen and carbamide peroxide bleaching gels (22). During the initial bleaching, especially with higher concentrations of tray bleaching gels, patients have reported a splotchy appearance of the teeth during the first week (22). This uneven coloration of the teeth being bleached disappears after the first week of bleaching. Tooth sensitivity during bleaching has been the highest reported adverse reaction. In clinical research studies, tooth sensitivity during bleaching has been reported in a

range of 18%–78% of patients, either with at-home tray delivery or in-office procedures (23–25). The sensitivity due to tooth bleaching in clinical observations suggests that it

is transient, with no long-term effects (26). Some clinicians believed that this transient sensitivity was due to gingival recession. However, it has been shown that gingival recession is not a factor in the occurrence of tooth hypersensitivity when bleaching (27). There was no significant difference in reported sensitivity while bleaching based on the presence or absence of gingival recession. To minimize tooth sensitivity during vital tooth bleaching, the clinician can recommend that the patient decrease the time the tray is worn the first week, to no more than 1 hour a day for carbamide peroxide products or for higher concentration hydrogen peroxides, as little as 15 minutes a day or use lower concentrations of peroxide. Five Percent potassium nitrate (KNO3) formulation has been shown to be an effective desensitizer in toothpastes (FF, use three others). Noting this effectiveness, a number of manufacturers have added a 5% KNO3 desensitizing agents to their bleaching gels. The addition of KNO3 to bleaching gels does not provide the sensitivity relief that is seen with KNO3 in extended use with desensitizing toothpastes (23, 28). Two effect strategies using a KNO3- desensitizing toothpaste that have been clinically evaluated are brushing with the desensitizing toothpaste for 2 weeks before

initiating bleaching (23) and having the patient place a sensitivity toothpaste containing a 5% KNO3 1 week before initiating bleaching in the tray that will be used for bleaching for 30 minutes a day (29). Both strategies take into account the mechanism for desensitizing that KNO3 provides. Another strategy is to have a patient use a professionally dispensed desensitizing gel with 5% KNO3 for use with bleaching (30). Amorphous calcium phosphate (ACP) has been shown to be an effective desensitizer (31, 32). Recent research has shown that a paste (Prospec MI Paste, GC America) containing Recaldent®, a casein phosphopeptide- amorphous calcium phosphate (CPP-ACP), has been effective in reducing tooth sensitivity due to bleaching (29,33). One manufacturer, Discus Dental, has introduced bleaching products that contain ACP. A research study evaluating these ACP-containing bleaching gels demonstrated that ACP could be added to a 16% carbamide peroxide bleaching gel with significant reduction in clinical measures of dentinal hypersensitivity both during and after treatment (34). Over the years, there has been controversy about what

tray is best. When tray bleaching was introduced, the trays

were fabricated from thin and thick flexible vacuum-forming materials and thin rigid plastic materials. Some manufacturers created a foam-lined tray, believing it would hold the bleach on the teeth more effectively. From the current research that has evaluated a wide variety of tray configurations and types, and duration of wearing the tray, one can conclude the following:

• Thin flexible vacuum-formed materials are the standard

• Spacers on the stone model to create reservoirs is not

necessary, but using reservoirs results in the patient swallowing less bleaching gel (35, 36)

• Scalloping the tray to follow the gingival contours is not

necessary when using a 10% carbamide peroxide, but should be done for higher concentrations of carbamide peroxide or hydrogen peroxide equivalents. Overtrimming the tray leaving a portion of the tooth uncovered is not a problem because the bleach will penetrate beyond the tray (37)

• Custom-fitted trays provide improved bleaching geltooth 
contact (36)

• Most companies provide bleaching gel for a 2-week

application

• Higher concentrations of carbamide peroxide bleach

worn in a tray show faster initial improvements, but over a 6 week period comparing 10% carbamide peroxide to higher concentrations, there is no difference in the final result (38, 39)

• The concept of teeth lightening to a final certain level

has been termed as the “inherent lightness potential” of a tooth; there is an endpoint to how much lighter teeth will get (39)

• In most cases, moderate and dark tetracycline staining

can be treated with bleaching over an extended time of 3–6 months (40, 41)

• Concern over the effectiveness of the bleaching potential with overnight wearing of a tray has been addressed; wearing a tray overnight with a bleaching gel has demonstrated a degradation in peroxide concentration over time, but the bleaching agent is still effective. Hydrogen peroxide has a greater than 50% degradation within 30 minutes, whereas carbamide peroxide bleaching gels can be used overnight (21)

• 10% at-home carbamide peroxide bleaching gels are clinically safe when exposed to enamel, dentin, root surfaces, ceramics, cast metal, and composite resins (10); there is one case report of greening of amalgam during bleaching. At-home tray bleaching requires a number of steps to achieve success, which include accurate study casts that need to be trimmed to allow for a vacuum-down, thin, flexible mouthguard to be fabricated. The mouthguard can be trimmed to be scalloped (for the higher concentrations of bleaching peroxides) or with a 0.5–1 mm extension from the free gingival margin. The patient should be instructed on the how to place the bleaching gel in the trays and how to remove any excess gel after insertion. Although there are variations in the duration for wearing the tray, for most patients 2 weeks at least 1 hour a day will provide up to 90% of the whitening effect. Research has shown that a bleaching endpoint will be reached at 6 weeks independent of the concentration and type of peroxide used (Figure 2). Table 1 has a partial listing of at-home professionally