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Aim: To evaluate the ability of two experimental toothpastes containing 0.1%w/w o-cymen-5-ol, 0.6%w/w ZnCl(2) and 0.320%w/w NaF to reduce demineralisation of sound human enamel compared with control toothpastes. Methods: Study 1: Specimens were treated with toothpaste slurries, followed by alternating periods in demineralising and neutral solutions. Demineralisation was assessed using surface microhardness (SMH). Study 2: Specimens were subjected to a 14 day cycling regime of alternating demineralisation / remineralisation with two toothpaste treatments per day, before and after demineralisation. Demineralisation was assessed by cross-sectional microhardness and mineral loss (ΔZ) was calculated. Test toothpastes were a) 0%w/w or 0.002%w/w NaF placebo, b) 0.055%w/w or 0.149%w/w NaF (dose response), c) 0.320%w/w NaF marketed product, d & e) 0.1%w/w o-cymen-5-ol, 0.6%w/w ZnCl(2) and 0.320%w/w NaF (experimental toothpastes). Results: Study 1: Mean ± SE % of baseline hardness values were a) 48.0 ± 2.1(a), b) 66.7 ± 1.7(b), c) 82.9 ± 1.9(c), d) 91.7 ± 1.4(d) and e) 94.6 ± 2.1(d). Study 2: Mean ± SE ΔZ values were a) 2114 ± 187(a), b) 1206 ± 132(b), c) 303 ± 89(c), d) 19 ± 73(c), and e) −10 ± 55(c). Letters represent different statistical groupings (P < 0.05). Conclusion: In study 1, both experimental toothpastes were statistically superior to the marketed product and in study 2; they were at least as effective as the marketed product at reducing caries lesion development.

OBJECTIVES We have previously reported on progress toward the refinement of profilometry-based abrasivity testing of dentifrices using a V8 brushing machine and tactile or optical measurement of dentin wear. The general application of this technique may be advanced by demonstration of successful inter-laboratory confirmation of the method. The objective of this study was to explore the capability of different laboratories in the assessment of dentifrice abrasivity using a profilometry-based evaluation technique developed in our Mason laboratories. In addition, we wanted to assess the interchangeability of human and bovine specimens. METHODS Participating laboratories were instructed in methods associated with Radioactive Dentin Abrasivity-Profilometry Equivalent (RDA-PE) evaluation, including site visits to discuss critical elements of specimen preparation, masking, profilometry scanning, and procedures. Laboratories were likewise instructed on the requirement for demonstration of proportional linearity as a key condition for validation of the technique. Laboratories were provided with four test dentifrices, blinded for testing, with a broad range of abrasivity. In each laboratory, a calibration curve was developed for varying V8 brushing strokes (0, 4,000, and 10,000 strokes) with the ISO abrasive standard. Proportional linearity was determined as the ratio of standard abrasion mean depths created with 4,000 and 10,000 strokes (2.5 fold differences). Criteria for successful calibration within the method (established in our Mason laboratory) was set at proportional linearity = 2.5 ± 0.3. RDA-PE was compared to Radiotracer RDA for the four test dentifrices, with the latter obtained by averages from three independent Radiotracer RDA sites. Individual laboratories and their results were compared by 1) proportional linearity and 2) acquired RDA-PE values for test pastes. RESULTS Five sites participated in the study. One site did not pass proportional linearity objectives. Data for this site are not reported at the request of the researchers. Three of the remaining four sites reported herein tested human dentin and all three met proportional linearity objectives for human dentin. Three of four sites participated in testing bovine dentin and all three met the proportional linearity objectives for bovine dentin. RDA-PE values for test dentifrices were similar between sites. All four sites that met proportional linearity requirement successfully identified the dentifrice formulated above the industry standard 250 RDA (as RDA-PE). The profilometry method showed at least as good reproducibility and differentiation as Radiotracer assessments. It was demonstrated that human and bovine specimens could be used interchangeably. CONCLUSIONS The standardized RDA-PE method was reproduced in multiple laboratories in this inter-laboratory study. Evidence supports that this method is a suitable technique for ISO method 11609 Annex B.

To demonstrate the robustness of the Featherstone pH cycling model when tested in three independent laboratories and to evaluate the use of "non-inferiority" testing at those laboratories.The fundamental principles for the Featherstone laboratory pH cycling model to be an appropriate alternative to animal testing is that it must demonstrate equivalent accuracy to the "Gold Standard" (rat caries model) by: (1) providing a meaningful representation of the caries process; (2) demonstrating a proportionate response to fluoride dose (or concentration); (3) being able to show that clinically proven formulations perform similarly relative to the controls; and (4) differentiating products that have attenuated fluoride activity.This cross-validation study confirmed the ability of the three independent laboratories to discriminate between various concentrations of fluoride-containing dentifrice formulations, demonstrated that clinically proven formulas perform as expected and identified an attenuated fluoride formulation (NaF/CaCO3 dentifrice - 1100 ppm NaF) as inferior compared to the 1100 ppm F (NaF/silica) positive control.

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.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.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).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.

The aim of the present study was to investigate the anticaries potential of a new sodium fluoride dentifrice in comparison to two commercial dentifrices containing different fluoride compounds by determining enamel fluoride uptake (EFU) and early caries lesion remineralization (REM) in an established in vitro caries remineralization/demineralization pH cycling model.Test products were: new dentifrice formulation in a fluoride dose-response (0; 675; 1426 ppm F as sodium fluoride [NaF-0; NaF-675; NaF]); Elmex Kariesschutz (1400 ppm F as amine fluoride [AmF]); and Oral-B Pro-Expert (1450 ppm F-1100 ppm F as stannous fluoride and 350 ppm F as sodium fluoride [SnNaF]). Artificial caries-like lesions were formed in human enamel specimens by immersion in lactic acid buffer (LA). Specimens were then subjected to a daily cycling regime for 20 days comprising four one-minute dentifrice slurry treatments (prepared in pooled human saliva), and one four-hour LA challenge and remineralization in pooled human saliva. After 20 days, REM was evaluated as the change in surface Vickers microhardness from lesion baseline and EFU using the microdrill technique. The data were analyzed using ANOVA.A good fluoride dose-response was established for EFU and REM, with NaF delivering greater EFU and REM than NaF-675, which was superior to NaF-0 (p0.05). The new dentifrice NaF also showed greater EFU and REM than AmF and SnNaF (p0.05). In EFU, AmF and SnNaF were as efficacious as NaF-675 and superior to NaF-0 (p0.05). AmF and NaF-675 were also comparable in REM, whereas both products exhibited superior REM vs. SnNaF (p0.05), which was superior to NaF-0 (p0.05).The present study has demonstrated that fluoride dentifrices vary in their capability of enhancing anticaries potential as determined using an established in vitro caries cycling model. The new dentifrice NaF showed superior predicted anticaries potential compared to the two commercial dentifrices AmF and SnNaF in this model, which demonstrates the importance of fluoride compound and formulation excipients on driving anticaries potential in vitro.

This in vitro study examined the ability of Forté, based upon co-catalyzed calcium peroxide and carbamide peroxide (CaCP), to remineralize and recalcify pre-existing incipient lesions in tooth enamel, renewing the teeth while they are being whitened.Artificial lesions to 70-100 micrometers depth were created, simulating in vivo conditions. Calcium concentrations were determined by micro drill, and surface hardness was determined using a Leco Indenter. Remineralization and calcium uptake were determined by comparing the surface hardness and calcium concentration of subsurface incipient lesions in extracted human teeth before and after a whitening treatment, and also comparing to a non-whitening control (saliva).Specimens treated with the CaCP whitening gels had a significant calcium uptake of 33,000 micrograms of calcium/gram of enamel measured to a depth of 100 micrometers, and had corresponding increases in surface hardness, from a Vickers Hardness Number of 40 VHN to a value of 83 VHN.Recalcifying incipient lesions to clinically significant depths, and improving the surface hardness of enamel while performing a popular cosmetic bleaching service, compares favorably with losses of calcium and decreased enamel surface hardness, as reported in studies of many conventional whitening agents.

The aim of the present study was to evaluate the ability of a new fluoride-containing dentifrice to protect surface-softened enamel against further erosive challenges in an in vitro cycling model, and to relate any effects to enamel fluoride uptake (EFU) and free fluoride.Human enamel specimens were subjected to a daily cycling regimen comprising: three two-minute treatments; five two-minute challenges using 1% citric acid pH 3.8; and remineralization in a mixture of human saliva and mucin-containing artificial saliva. Surface microhardness (SMH) was measured at baseline, 10, and 20 days, and the fluoride content of biopsied specimens determined at 20 days. EFU studies were based on method #40 described in the United States Food and Drug Administration (FDA) testing procedures. Free-fluoride availability was determined from slurries of one part toothpaste plus three parts deionized water.SMH showed that a 1150 ppm NaF test dentifrice protected enamel specimens greater than Crest Cavity Protection (1100 ppm NaF) and a fluoride-free placebo at both 10 days and 20 days (p0.05). The fluoride content of specimens treated with this prototype was higher than either Crest or the placebo. SMH for a 1450 ppm NaF test dentifrice was greater than for Elmex Sensitive (1450 ppm amine F) and placebo at 10 days, while both products were greater than the placebo at 20 days. The fluoride content of specimens treated with this test dentifrice was higher than Elmex Sensitive, which was higher than placebo. The fluoride uptake seen in the cycling model correlated for the NaF dentifrices with a standard EFU procedure. Different EFU results for a series of commercial dentifrices demonstrated that EFU is not necessarily a function of free-fluoride availability.This study demonstrated that fluoride dentifrices can increase the protection of enamel against an erosive challenge in vitro, and that the increased protection correlated with fluoride uptake. The fluoride uptake seen in the cycling model correlated with a standard FDA EFU procedure for the NaF dentifrices. The present studies demonstrate the importance of formulation effects on driving performance in in vitro models.