In vitro safety evaluation of a hydrogen peroxide whitening emulsion technology on human enamel and dentin.

PURPOSE: To assess effects of a novel hydrogen peroxide leave-on whitening emulsion on surface hardness, fracture susceptibility, surface erosion, and surface morphology of enamel and dentin. METHODS: Human enamel and root dentin sections embedded in resin were leveled and polished for uniformity. A cycling treatment simulating overuse conditions (60 hours over 10 days), coupled with incubation in pooled human saliva at 37°C and two daily toothpaste treatments were used to evaluate the safety of a 3% hydrogen peroxide whitening emulsion treatment (Crest Whitening Emulsions). Controls included a no treatment group, three erosion controls (water, 0.25% citric acid pH 3.6, 1% citric acid pH 3.6), and a bleaching control (8.25% sodium hypochlorite). Color measurements (b*) were taken on select post-treated specimens to confirm bleaching activity. Effects on enamel and dentin physical properties were determined by surface microhardness, fracture toughness, erosion depth, and surface morphology by light and scanning electron microscopy. RESULTS: The hydrogen peroxide emulsion b* value was significantly different versus water control (P< 0.05), confirming bleaching activity. Microhardness and fracture toughness results for hydrogen peroxide emulsions were not significantly different versus baseline (P> 0.2) and no treatment (P= 1.0), respectively. Erosion loss for the hydrogen peroxide emulsion was not observed on enamel (comparable to water) and significantly less than 0.25% citric acid (P< 0.05) on dentin which was verified by microscopic visualization. CLINICAL SIGNIFICANCE: The hydrogen peroxide emulsion had no significant negative effects on enamel and dentin properties after 60 hours of bleaching over 10 days, confirming safety under simulated overuse conditions.

Sustained antibacterial actions of a new stabilized stannous fluoride dentifrice containing sodium hexametaphosphate.

Stannous fluoride has been used as a chemotherapeutic agent for years to improve oral health. The benefits of stannous fluoride in controlling caries, plaque, and gingivitis are directly associated with its antimicrobial actions. Recently, a novel dentifrice was developed that combines stannous fluoride with an anticalculus agent, sodium hexa. metaphosphate. A series of independent evaluations were conducted to assess the long-lasting antimicrobial activity of stannous fluoride in the new stannous fluoride/sodium hexametaphosphate dentifrice: an in vitro Live/Dead assay; an in vivo Plaque Glycolysis and Regrowth Model study; a rapid in vitro salivary bacteria metabolic activity study; and a 12-hour in vivo tin-retention study. In the Live/Dead study, the new stannous fluoride/sodium hexametaphosphate dentifrice killed approximately 90% to 99% of the salivary microbes 16 hours after a single exposure. Similarly, the stannous fluoride dentifrice produced statistically significant reductions in plaque acid production and plaque regrowth activity compared to plaque treated with a standard fluoride dentifrice at all time intervals measured after product exposure (15 and 45 minutes). Results from the final two studies collectively demonstrated the presence of total soluble tin, which serves as a marker for the active stannous fluoride, at levels above the minimum concentration for inhibition of salivary bacteria metabolic activity 12 hours posttreatment. These findings confirm the long-lasting antibacterial action of the new stannous fluoride dentifrice, which serves as a basis for its therapeutic benefits.

Extrinsic whitening effects of sodium hexametaphosphate--a review including a dentifrice with stabilized stannous fluoride.

The number of tooth whitening products available to patients has grown dramatically during recent years. While peroxide is the primary agent found in products that bleach and remove intrinsic sources of discoloration, various ingredients are incorporated in formulations to remove and inhibit extrinsic sources of tooth discoloration, ie, tooth stain. Recently, an advanced antitartar ingredient with extrinsic-stain-inhibiting benefits was introduced: sodium hexametaphosphate. This long-chain condensed phosphate, also known as polypyrophosphate, chemically removes existing stains and provides long-lasting inhibition of new-stain chromogen adsorption. Sodium hexametaphosphate was originally introduced in a sodium fluoride dentifrice formulation and was later marketed in a chewing gum delivery system. Recently, sodium hexametaphosphate was launched in another dentifrice formulation containing stabilized stannous fluoride (Crest Pro-Health). This article reviews published clinical and laboratory data demonstrating sodium hexametaphosphate's extrinsic whitening benefits in all three formulations.