Evaluation of the Efficacy of a Dentifrice Tablet to Prevent Dental Caries: A Microbial Study

Background/Objectives: Dentifrice tablets are a new over-the-counter dentifrice form that are gaining global interest. The aim of this microbial study was to investigate the effectiveness of a dentifrice tablet (DT) containing nanohydroxyapatite (nHAP) to prevent tooth demineralization. Methods: 120 bovine tooth blocks were randomly assigned to four treatment groups (30/group): Nanohydroxyapatite DT (5% nHAP), placebo DT (Placebo), NaF toothpaste (1100 ppm Fluoride) and no-treatment (Control). Blocks were subjected to 7-day demineralization by plaque growth in a mixed-organism Microbial Caries Model. Toothpaste was made into slurry (1 toothpaste:3 water), while DT was thoroughly crushed and homogenized with water (1 tablet:3 water) to slurry. Both slurries were applied twice daily for 2 min on each occasion. Demineralization was assessed using Surface Microhardness (SMH) testing before and after plaque exposure. Change (ΔSMH) and percentage change (%∆SMH) in SMH (percentage demineralization [%Dem]), and % demineralization inhibition (%Dem-Inhibition) in each group were calculated. Intra-group (SMH) comparison (paired t-test) and intergroup (%∆SMH) comparison (ANOVA/Tukey's test) were conducted (α = 0.05). Results: The paired t-test indicated a significant difference (p < 0.001) between pre-treatment and post-treatment SMH in all groups. The intergroup comparison based on their %Dem using ANOVA/Tukey's test showed that Control (29.93 ± 5.58) had significantly (p < 0.05) higher %Dem than Placebo (22.81 ± 7.47, p < 0.05), nHAP (13.93 ± 11.31, p < 0.001) and Fluoride (14.44 ± 10.65, p < 0.001). The Placebo had significantly (p < 0.01) higher %Dem than nHAP and Fluoride. No significant difference between nHAP and Fluoride. Intergroup comparison based on their %Dem-Inhibition (calculated relative to the control) using ANOVA/Tukey's test, nHAP (51.74 ± 40.05, p < 0.01) and Fluoride (50.56 ± 37.21, p < 0.05) had significantly higher %Dem-Inhibition than Placebo tablet (21.86 ± 5.55). No significant difference in %Dem-Inhibition between nHAP and Fluoride. Conclusions: The present study demonstrated that dentifrice tablets containing 5% nanohydroxyapatite are as effective as NaF toothpastes containing 1100 ppm fluoride in preventing tooth demineralization.