Evaluation of a possible protective effect of regenerating dentifrices in reducing erosive tooth wear and caries development in enamel and dentin under a microcosm biofilm model: an in vitro study

• Grant number: 25/10672-3
• Support Opportunities: Regular Research Grants
• Start date: October 01, 2025
• End date: September 30, 2026
• Field of knowledge: Health Sciences - Dentistry
• Principal Investigator: Ana Carolina Magalhães
• Grantee: Ana Carolina Magalhães
• Host Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil
• Associated research grant: 19/26070-1 - Modulation of acquired enamel pellicle to control dental mineral loss: unravelling mechanisms to make therapies possible, AP.TEM

Abstract

This in vitro study will be divided into two stages. The first study aims to compare self-styled regenerating/repairing commercial dentifrices with conventional dentifrices in terms of their protective effects on reducing erosive tooth wear (ETW) and the second study will analyze these same effects on the development of dental caries under a microcosm biofilm model. In the first stage, to evaluate the protective capacity against ETW, 120 bovine crowns and 120 bovine roots will be allocated according to the 10 treatment groups (n=12): G1 - Elmex Erosion Protection (GABA, Switzerland, 1400 ppm F-, SnCl2, AmF, NaF, Chitosan) (positive control); G2 - Dentalclean® Regenerador Sensitive (1450 ppm F-); G3 - Sensodyne® Repair & Protect toothpaste (1450 ppm F-); G4 - Sensodyne® Pro-enamel toothpaste (1425 ppm F-); G5 - Sensodyne® Clinical Repair (1100 ppm F-); G6 - Regenerate® Enamel Science - NR-5 (1450 ppm F-); G7 - Colgate® Mais Neutraçúcar (1450 ppm F-); G8 - Xerolacer® (2500 ppm F-); G9 - PRG Pro Care Gel Shofu® (5% de partículas S-PRG) ; G10 - erosion only (negative control). The samples will be subjected to erosive challenge (4 x 90s/day in 0.1% citric acid, pH: 2.5) and G1 to G9 will also be subjected to abrasive challenge (2 x 15s/day abrasion + 45s treatment) using dentifrice's suspension (1:3 water) and a brushing machine for 7 days. Between the erosive and abrasive challenges, the samples will be immersed in artificial saliva. The amount of wear will be quantified using a contact profilometer (um) to compare the initial and final profiles. In the second study, to evaluate the anticariogenic and remineralizing capacity, 120 bovine enamel samples and 120 bovine dentin samples (4x4mm) will be prepared and divided into the following groups: G1 - Elmex anticaries (GABA, Switzerland, 1400 ppm F-, AmF, positive control); G2 - Dentalclean® Regenerador Sensitive (1450 ppm F-); G3 - Sensodyne® Repair & Protect dentifrice (1450 ppm F-); G4 - Sensodyne® Pro-enamel dentifrice (1425 ppm F-); G5 - Sensodyne® Clinical Repair (1100 ppm F-); G6 - Regenerate® Enamel Science - NR-5 (1450 ppm F-); G7 - Colgate® Mais Neutraçúcar (1450 ppm F-); G8 - Xerolacer® (2500ppm F-); G9 - PRG Pro Care Gel Shofu® (5% de partículas S-PRG); G10 - PBS (Phosphate-Saline Buffer, negative control). In 24-well plates, each enamel sample and each dentin sample will be exposed to 1.5 ml of inoculum (human saliva-glycerol + McBain saliva, 1:50) for 8h. After the initial 8h, the inoculum will be removed, the samples will be washed with PBS (5s), and will receive 1.5 ml of fresh medium (McBain's artificial saliva) for 16h, completing the initial 24 h. From the 2nd to the 5th day, the sucrose medium will be changed 1x/day, the samples treated with the different suspensions of dentifrice 1:3 water (1 ml per well, 1 min) and the plates incubated at 5% CO2 and 37°C. Cultivation will be carried out in biological triplicate (n=4 for each repetition, final n=12). The antimicrobial effect will be assessed by counting the Colony Forming Units (Log10 CFU/mL) in culture media for Streptococcus mutans/sobrinus and total Lactobacillus. With regard to the anti-caries effect, transverse microradiography (TMR) will be used to measure demineralization. The data will be checked for normality and homogeneity (Kolmogorov-Smirnov test and Bartlett's test, respectively). If they pass these tests, the data of CFU (log 10 CFU/mL), integrated mineral loss (%vol.µm), average mineral loss (%vol), lesion depth (µm) and enamel and dentin wear (µm) will be submitted to ANOVA followed by the Tukey test (p<0.05). (AU)