Stain removal, abrasion and anticaries properties of a novel low abrasion dentifrice containing micro-fibrillated cellulose: in vitro assessments.

OBJECTIVES: This laboratory study assessed the performance of a novel fluoride dentifrice containing micro-fibrillated cellulose (MFC) and entrapped silica. METHODS: Removal of extrinsic stains was assessed using the pellicle cleaning ratio (PCR) method, and radioactive dentin abrasivity (RDA) was measured, to calculate a cleaning efficiency index (CEI). Fluoride efficacy was evaluated using widely used remineralization and fluoride uptake methods. The test product (Protegera™) was compared to common dentifrices (Crest - Cavity Protection™ and ProHealth™, Sensodyne Pronamel™, Arm & Hammer™ Advanced Whitening, Crest ProHealth™, and Colgate Optic White™). RESULTS: The PCR for the MFC dentifrice (141) was comparable to three known marketed stain-removing dentifrices (Arm & Hammer™ Advanced Whitening, Crest ProHealth™, and Colgate Optic White™) but it had a significantly lower RDA (88 ± 6) than 5 other products. This gave it the highest CEI of the tested products (2.0). In a 10-day pH cycling study, the fluoride efficacy of the MFC product was comparable to Sensodyne Pronamel and Crest Cavity Protection. The MFC dentifrice was superior for promoting fluoride uptake into incipient enamel lesions compared to the USP reference dentifrice. CONCLUSION: The MFC dentifrice has low abrasion, but despite this, it is highly effective in removing stained pellicle. It also is an efficacious fluoride source when compared to relevant commercially available fluoride dentifrices with high dentin abrasivity. CLINICAL SIGNIFICANCE: The addition of micro-fibrillated cellulose to a fluoride dentifrice gives a low abrasive product that can effectively remove external stains, and serve as an effective fluoride source. This combination of benefits seems well suited to enamel protection and caries prevention.

A Comparative Study of Laboratory Dentifrice Abrasion Measuring Methods.

OBJECTIVES: Recently, a profilometry-based method for measuring toothpaste dentin abrasivity has been proposed to be equivalent to the traditional radiotracer RDA (relative dentin abrasion) procedure. This review outlines the findings and comparative assessment of laboratory studies used to measure the abrasivity of commercially available whitening dentifrices on human dentin. Traditional radiotracer and profilometry RDA-PE (Profilometry Equivalent) methods were assessed, with the objective of determining how they compare, and also to learn if the two techniques yield RDA values that are consistent with each other, specifically in ranking and potential for discrimination of three commercially available silica-based products. Chosen were regular toothpaste and two whitening dentifrices having abrasive properties against dentin ranging from medium to high. METHODS: Dentin specimens underwent standard preparation, preconditioning, and abrasivity testing according to the ISO 11609 requirements for radiotracer method and RDA-PE. Three test dentifrices were used, each product containing various abrasive and polyphosphate agents, namely: Whitening Product A: Hydrated silica with disodium pyrophosphate (Crest® 3D Luxe); Product B: Hydrated silica (Crest® Cavity Protection); and Whitening Product C: Hydrated silica with tetrasodium pyrophosphate (Colgate® Ultrabrite Advanced Whitening). The products were chosen since they gave a range of RDA values from mid to high when compared with an ADA reference material that is given a value of 100. RESULTS: The data were subjected to statistical and SNK (Student-Newman-Keuls) analyses. Both procedures yielded numerical RDA values that permitted a ranking of the three test dentifrices. However, there was no direct correlation of the RDA values obtained by profilometry with those from the conventional radiotracer method. Significantly, one dentifrice rated as most abrasive using the radiotracer method was rated as moderately abrasive using profilometry. Additionally, there was loss of statistical significance and discrimination between products with RDA-PE. CONCLUSIONS: Given the lack of agreement between radiotracer and profilometry for the products tested in this study,it would appear that the RDA-PE method may not be equivalent to the traditional RDA radiotracer method, specifically in the higher abrasivity range.

Impact of an anticaries mouthrinse on in vitro remineralization and microbial control.

Objective. The objective of this research was to evaluate the caries control potential of a new fluoride mouthrinse that also contained antimicrobial agents and a biofilm disrupting agent using different in vitro models. Methods. Four in vitro studies were conducted to assess the performance of this three pronged approach to caries control: (1) traditional enamel fluoride uptake, (2) surface microhardness study using pH cycling model and subsequent fluoride uptake, (3) a salivary biofilm flow-through study to determine the anti-microbial activity, and (4) a single species biofilm model measuring effect on biofilm matrix disruption. Results. The data showed that a LISTERINE rinse with fluoride, essential oils and xylitol was superior in promoting enamel fluoride uptake and in enhancing antimicrobial activity over traditional commercially available fluoridated products. An increase of the surface microhardness was observed when the LISTERINE rinse was used in combination with fluoridated toothpaste versus the fluoridated toothpaste alone. Finally, it was demonstrated that xylitol solutions disrupted and reduced the biovolume of biofilm matrix of mature Streptococcus mutans. Conclusion. These in vitro studies demonstrated that a fluoride mouthrinse with antimicrobial agent and biofilm matrix disrupting agent provided multifaceted and enhanced anti-caries efficacy by promoting remineralization, reducing acidogenic bacteria and disrupting biofilm matrix.

In vitro assessment of a toothpaste range specifically designed for children.

OBJECTIVE: To evaluate the ability of a range of low abrasivity experimental toothpastes designed for use by children at different stages of their development (typically ages 0-2 years, 3-5 years and 6+ years) to promote fluoride uptake and remineralisation of artificial caries lesions. METHODS: pH cycling study: demineralised human permanent enamel specimens were subjected to a daily pH cycling regime consisting of four 1-minute treatments with toothpaste slurries, a 4-hour acid challenge and remineralisation in pooled whole human saliva. Surface microhardness (SMH) was measured at baseline, 10 days and 20 days, and the fluoride content determined at 20 days. Enamel Fluoride Uptake (EFU): these studies were based on Method #40 described in the US Food and Drug Administration (FDA) testing procedures. Abrasivity: relative enamel abrasivity (REA) and relative dentine abrasivity (RDA) were measured using the Hefferren abrasivity test. Bioavailable fluoride: the bioavailable fluoride was determined for all experimental toothpastes from slurries of one part toothpaste plus 10 parts deionised water. RESULTS: Enamel remineralisation measured by changes in SMH correlated with enamel fluoride content. A statistically significant fluoride dose response was observed for all toothpastes tested across all age groups (P < 0.05). The fluoride content of specimens in the pH cycling model correlated with the EFU testing results. The enamel and dentine abrasivities were low and the level of bioavailable fluoride was high for all experimental toothpastes. CONCLUSION: A series of low abrasivity experimental toothpastes were developed which were effective at promoting fluoride uptake and remineralisation of artificial caries lesions.

The Featherstone laboratory pH cycling model: a prospective, multi-site validation exercise.

PURPOSE: 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. METHODS: 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. RESULTS: 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.

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.

Laboratory assessment of the anticaries potential of a new dentifrice.

OBJECTIVE: 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. METHODS: 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. RESULTS: 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 (p < 0.05). The new dentifrice NaF also showed greater EFU and REM than AmF and SnNaF (p < 0.05). In EFU, AmF and SnNaF were as efficacious as NaF-675 and superior to NaF-0 (p < 0.05). AmF and NaF-675 were also comparable in REM, whereas both products exhibited superior REM vs. SnNaF (p < 0.05), which was superior to NaF-0 (p < 0.05). CONCLUSION: 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.

Use of a calcium peroxide whitening agent for remineralization and recalcification of incipient lesions.

OBJECTIVE: 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. METHODOLOGY: 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). RESULTS: 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. CONCLUSION: 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.

Surface microhardness changes, enamel fluoride uptake, and fluoride availability from commercial toothpastes.

OBJECTIVE: 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. METHODOLOGY: 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. RESULTS: 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 (p < 0.05). 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. CONCLUSION: 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.

Estudio "in vitro" sobre remineralización y desmineralización de lesiones incipientes, al comparar dentífricos de diferente formulación y procedencia / An in vitro study on remineralization and demineralization of incipient lesions, comparing dentifrices of different formulation and origin

Usando elmodelo de pH cíclico se midió la eficacia de cuatro dentífricos de procedencia y formulación diferentes, para remineralizar "in vitro" caries incipientes y determinar posteriormente su resistencia a la desmineralización. Cuarenta y ocho muestras de esmalte con lesiones artificiales fueron divididas al azar en cuatro grupos experimentales: a) 0,243 por ciento FNa (USA); b) 0,243 por ciento FNa (Chile); c) 0,76 por ciento Na2FPO3 (USA) y d) 0,0 por ciento FNa (placebo). Los cambios en la dureza superficial (VHN) se determinaron antes y después de los períodos de remineralización y después de diferentes períodos de desmineralización. En remineralizar, los resultados no muestran difefencias significativas en los A VHN entre los grupos a) y b) o c) y d). No obstante, todos los dentífricos con flúor fueron más efectivos que el placebo (p > 0,05) en remineralizar. En cuanto a prevenir la desmineralización subsecuente (4 y 36 horas), los grupos a) y b) fueron significativamente superiores a los grupos c) y d). Los resultados en base a FNa de USA y Chile son similares en promover la remineralización de lesiones incipientes del esmalte y significativamente superiores a los formulados en base a Na2FPO3 en prevenir su posterior desmineralización