Abrasion, polishing, and stain removal characteristics of various commercial dentifrices in vitro.

OBJECTIVE: To evaluate, using conventional in vitro procedures, the abrasivity, enamel polishing properties, and stain removal effectiveness of various commercial dentifrices that have a variety of compositions and are marketed for cleaning, whitening, and/or polishing capabilities, and to examine their relationships between stain removal and abrasivity. METHODS: The Relative Dentin Abrasivity (RDA) method was used to measure abrasivity, and the Pellicle Cleaning Ratio (PCR) procedure was used to evaluate stain removal performance. A Cleaning Efficiency Index (CEI) was calculated using the RDA and PCR values. Enamel polish was determined on bovine enamel specimens using a reflectometer. All treatments were performed on a V-8 cross-brushing machine using aqueous dentifrice slurries and standard nylon-bristle toothbrushes. A total of 26 dentifrices, purchased at retail, were tested against the American Dental Association (ADA) calcium pyrophosphate reference standard. RESULTS: All dentifrices removed extrinsic stain and produced some dentin abrasion, but scores ranged widely between products (from 36 to 269 for RDA and from 25 to 138 for PCR). The majority of dentifrices contained hydrated silicas, and those with high PCR scores often, but not always, had higher RDA values. Products containing other abrasives (e.g., dicalcium phosphate, sodium bicarbonate, and calcium carbonate) generally had lower RDA values and usually lower PCR scores. There were exceptions (e.g., refined kaolin clay) that had high PCR scores and low RDA values, resulting in higher CEI values. Similarly, brushing with all dentifrices significantly increased reflectance readings of acid-dulled teeth, but polish scores also were highly variable among products (ranging from 38 to 97). The polish scores of dentifrices containing hydrated silica varied extensively (ranging from 38 to 80), and the scores of products containing other abrasives fell within this same range, except for dentifrices containing either Fuller's earth (86) or kaolin (97). CONCLUSION: With only a few exceptions, dentifrices marketed as "whitening" products were generally more abrasive to dentin, especially for those containing silicas. Similarly, aside from two non-silica products, those dentifrices advertised for polishing ability generally were no more effective than other products. The relationship between stain-removal ability and abrasivity of dentifrices was not necessarily direct.

Clinical validation and calibration of in vitro peroxide tooth whitening.

OBJECTIVE: The purpose of this study was to validate and calibrate an in vitro test method for screening the performance of peroxide-containing toothpastes against actual clinical whitening performance. An additional objective was to estimate the whitening performance of a new peroxide-additive gel using the in vitro methodology. METHODS: A one-month longitudinal clinical study was performed to provide a benchmark for the in vivo intrinsic whitening performance of a peroxide-containing fluoride toothpaste. An in vitro study was then conducted, using freshly prepared slurries of the same peroxide-containing toothpaste in artificial saliva, to repeatedly treat extracted human teeth with natural intrinsic stain. The effect of cumulative treatment time on whiteness was determined using objective chromometer whiteness measurements (L*, a*, and b*), and more subjective Vita Shade guide (Vitapan) comparisons, and the results were correlated. A non-peroxide fluoride toothpaste was used as a negative control. The peroxide gel additive, combined in a 1:1 ratio with each of two non-peroxide toothpastes and diluted in artificial saliva, was evaluated using the same instrumental and subjective measures for in vitro whitening efficacy. The previously evaluated peroxide toothpaste and one of the non-peroxide toothpastes were used as positive and negative controls, respectively. RESULTS: In the clinical study, the peroxide-containing toothpaste produced a linear increase in tooth whiteness with time, achieving an approximately two Vita Shade guide improvement in whiteness at the end of four weeks. The same peroxide toothpaste in vitro produced a curvilinear increase in tooth whiteness versus cumulative treatment time, with a two-shade increase being achieved in 116 minutes. The non-peroxide control toothpaste produced less than half a shade guide increase in whiteness within the first 30 minutes, and none thereafter. Both the clinical and in vitro studies indicated that further whitening can be obtained with longer use of the peroxide-containing toothpaste or peroxide-additive gel. CONCLUSION: Treatment of naturally stained teeth in vitro with the peroxide toothpaste for 116 cumulative minutes produced the same two-shade increase in whiteness as obtained with twice-daily brushing for four weeks in vivo. The peroxide-additive gel, combined with a non-peroxide toothpaste, is projected to provide a similar two-shade increase in whiteness when used twice daily for four weeks. There are indications that greater intrinsic whiteness increase would be achieved with the peroxide toothpaste or with the peroxide-additive gel plus non-peroxide toothpaste with more extended regular twice-daily use in vivo.

Laboratory investigation of Colgate 360 degrees toothbrush and Oral-B indicator toothbrush for the removal of dental stains.

The objective of this in vitro study was to evaluate the stain-removal efficacy of a newly designed manual toothbrush, the Colgate 360 degrees, relative to a commercially available toothbrush, the Oral-B Indicator. A modification of Stookey et al was used to evaluate the stain-removal effects of toothbrushes instead of dentifrice on bovine teeth. A V.8 mechanical cross-brushing machine equipped with the test toothbrushes and adjusted to 500g to enamel surfaces evaluated stain removal using a dentifrice slurry and water after 800 double strokes. The overall results of this laboratory investigation indicate that the Colgate 360 degrees toothbrush is more effective, P < .05, than the commercial Oral-B Indicator toothbrush in removing dental stain and brightening teeth using a standard toothpaste or water.