Plaque formation and removal assessed in vivo in a novel repeated measures imaging methodology.

OBJECTIVE: A repeated measures digital imaging technique (Digital Plaque Image Analysis) was used to assess variations in plaque formation, including levels of plaque developed following evening and morning tooth brushing with a standard dentifrice, to establish a baseline for future assessments of antimicrobial formulations. METHODOLOGY: Following a rigorous oral hygiene period, subjects were provided with a standard commercial (non-antibacterial) dentifrice and manual toothbrush and instructed to brush b.i.d., as normal. On six separate days over two weeks, subjects reported at three times for a daily plaque assessment: in the morning before oral hygiene, post-brushing, and in the afternoon post-brushing. RESULTS: Morning plaque levels covered approximately 10% of the measured dentition, and plaque was removed by 75% with morning tooth brushing. Plaque underwent rapid regrowth during the day, and averaged approximately 7% coverage by the afternoon. CONCLUSION: These results support the value of Digital Plaque Image Analysis in recording diurnal plaque variations and treatment effects, and suggest that assessment of oral hygiene efficacy (either mechanical or chemopreventive) accounts for diurnal variations in plaque formation. In addition, the results suggest that plaque regrowth and virulence activity overnight is a significant target for oral hygiene interventions.

A 24-hour dental plaque prevention study with a stannous fluoride dentifrice containing hexametaphosphate.

Recently, a novel antibacterial fluoride dentifrice containing stannous fluoride and sodium hexametaphosphate (CrestPRO-HEALTH) was introduced. A digital plaque image analysis (DPIA) technique was used to quantify in situ plaque formation in a population carrying out a phased intervention protocol that included: (1) an initial treatment regimen including toothbrushing with standard sodium fluoride dentifrice in conventional bid brushing, (2) a second treatment regimen where a modified hygiene regimen was applied using standard sodium fluoride dentifrice including a period of 24 hours of non-brushing, and (3) a third treatment regimen where the 24-hour non-brushing regimen was continued using the antimicrobial stannous fluoride/sodium hexametaphosphate dentifrice. The quantitative evaluation of plaque formation was assessed in morning measurements following either standard evening hygiene (treatment period 1) or 24 hours since brushing (treatment periods 2 and 3). Post-brushing plaque measurements were also taken in each treatment regimen. Sixteen subjects completed all three treatment regimens with no side effects or oral complaints. Morning plaque coverage in treatment period 1 was 13.3%. Plaque coverage significantly increased in treatment period 2 when pre-bedtime brushing was discontinued, with 24-hour growth covering 18.4% of the dentition. Intervention of the antimicrobial stannous fluoride/hexametaphosphate dentifrice in treatment period 3 provided significant inhibition of plaque regrowth over 24 hours (15.2% coverage, a 17% reduction vs. sodium fluoride dentifrice control). These results support the strong retention and lasting antimicrobial efficacy of high stabilized stannous fluoride/sodium hexametaphosphate dentifrices.

Efficacy of a high bioavailable cetylpyridinium chloride mouthrinse over a 24-hour period: a plaque imaging study.

PURPOSE: To evaluate the antiplaque benefits of a 0.07% high bioavailable, alcohol-free cetylpyridium chloride (CPC) rinse used after toothbrushing versus toothbrushing alone. METHODS: A digital plaque image analysis technique was used to quantify in situ plaque formation in a subject population carrying out modified hygiene using standard fluoridated dentifrice or standard dentifrice augmented with 30 seconds mouthrinsing with an alcohol-free mouthrinse containing 700 ppm CPC. RESULTS: Comparison of plaque formation 24 hours following "last hygiene" revealed that brushing followed by CPC mouthrinse use provided a statistically significant decrease in plaque coverage on teeth averaging 42% as compared with brushing only. Moreover, toothbrushing with a standard dentifrice in the morning resulted in 34% less plaque when subjects used the CPC mouthrinse 24 hours prior to examination. CLINICAL SIGNIFICANCE: These results support the strong retention and lasting antiplaque efficacy of high bioavailable CPC mouthrinse and suggest that the plaque biofilms formed during CPC use are susceptible to more efficient debridement.

Peroxide interactions with hard tissues: effects on surface hardness and surface/subsurface ultrastructural properties.

Laboratory studies were performed to assess the impact of peroxide bleaching on enamel surface and subsurface physical and ultrastructural properties. Human enamel blocks were prepared, polished, and measured for native color. Cyclic bleaching treatments were carried out with soaks in whole stimulated saliva interspersed with bleaching treatments using bulk bleaching gels from commercial bleaching systems including Opalescence (20% and 10% carbamide peroxide systems) and Crest Whitestrips, a hydrogen peroxide gel formula, at doses of 5.3% and 6.5% hydrogen peroxide. Treatments ranged from conditions of normal use (14 hours as recommended for Crest Whitestrips) to excessive bleaching (70 hours). Controls included nontreated as well as treatments with placebo (not containing peroxide) gels. Surface hardness and confocal laser scanning microscopy (CLSM) techniques were used to characterize the effects of bleaching on the physical properties and ultrastructure of the teeth. Tooth color measurements revealed dose-response bleaching in vitro with the increases in L* and decreases in b* normally expected with effective bleaching. Placebo control treatments did not bleach. Surface hardness measurements showed no decreases associated with tooth bleaching. CLSM measurements also showed no effects from tooth bleaches on the surface or subsurface prism architecture of enamel. This was opposed to significant changes seen with even moderate levels of demineralization associated with the caries process. These studies support: (1) the safety of Crest Whitestrips formulas for enamel surfaces and tooth subsurfaces; and (2) the generic safety of peroxide bleaching of hard tissues associated with conditions of both recommended use and overuse.

Laboratory studies on the chemical whitening effects of a sodium hexametaphosphate dentifrice.

Laboratory studies were developed to permit the evaluation of chemical actions of toothpaste components in the non-abrasive prevention and removal of tea stains. Powdered hydroxyapatites were used as substrates for adsorption of tea chromogens. Pre-treatment with a sodium hexametaphosphate dentifrice (Crest Dual Action Whitening) reduced tea adsorption to powdered apatite, while post-treatments of pre-stained powder resulted in desorption of tea components. These results exemplified the chemical actions of condensed calcium phosphate surface active builders toward dental stain removal and prevention. A cycling synamel chip model permitted the study of stain prevention, including salivary pellicle formation and chlorhexidine enhancement of dental staining by tea chromogens. Staining was evaluated by image analysis of color development. Under these conditions, condensed phosphate dentifrices were observed to produce superior prevention of stain accumulations, with Crest Dual Action Whitening dentifrice providing stain prevention superior to a variety of commercial dentifrices, including Colgate Total, Aquafresh Whitening, Colgate Tartar Control Whitening, Mentadent Baking Soda and Peroxide Whitening, Close-Up Whitening, Crest Tartar Control and Crest Regular Cavity Protection.

Hexametaphosphate effects on tooth surface conditioning film chemistry--in vitro and in vivo studies.

These studies compared the effects of Crest Dual Action Whitening dentifrice with sodium hexametaphosphate and control commercial dentifrices on the surface chemistry of conditioning film-coated dental enamel in vitro and in vivo. Conditioning film chemistry was studied by measurements of film thickness, ability to wet the surface/surface energy, conditioning film chemical composition and zeta potential. Laboratory and in vivo studies demonstrated that brushing and chemical-only treatment of pellicle-coated enamel surfaces produced marked changes in surface chemistry. Brushing of surfaces with all commercial dentifrices significantly reduced pellicle film quantity. Effects on non-brushed areas, of significance in the clinical situation, were different for different dentifrices. For dentifrice chemical treatments, calcium phosphate surface active builders, such as pyrophosphate and hexametaphosphate, produced stronger effects than standard (non-tartar control) dentifrices, peroxide baking soda dentifrices and dentifrices formulated with carboxylate polymers, viz. Colgate Total with copolymer. Crest Dual Action Whitening hexametaphosphate dentifrice removed more pellicle conditioning film, produced a lower zeta potential, produced the largest changes in film composition and had the greatest impact on surface free energies of the tested dentifrices. Crest Dual Action Whitening dentifrice also produced lasting changes in the reacquisition of pellicle conditioning film, as established by in vitro cycling immersion studies. Crest Dual Action Whitening dentifrice produced stronger and more lasting effects on surface film chemistry than low molecular weight pyrophosphate (Crest Tartar Control) or other polymeric-based dentifrice systems (Colgate Total). These surface chemistries may contribute to the unique clinical actions of hexametaphosphate established in recently reported, randomized clinical studies of tartar control, stain prevention and stain removal effects.