Inhibition of dentine demineralization by zinc oxide: In vitro and in situ studies

OBJECTIVE: The objective of this study was to evaluate the inhibitory effect of zinc oxide on dentine demineralization in vitro and in situ. METHODS: In the in vitro study, dentine specimens treated with a zinc oxide suspension were demineralized in a pH 5 solution. In the in situ study, subjects wore dentine specimens on their teeth and instructed to rinse with zinc-containing toothpaste slurry three times a day for 14 days. The design of study was a crossover one. RESULTS: Microradiography employed in the in vitro study revealed the dentine surfaces treated with distilled water had a lower mineral content than those treated by zinc. Toothpaste with zinc had a statistically significant, 49% greater inhibitory efficacy on dentine demineralization over the control. In the in situ study, zinc-containing toothpaste was also confirmed to have an inhibitory effect on dentine demineralization when compared to the zinc-free toothpaste. These in vitro and in situ studies revealed that zinc oxide can have a significant effect on the inhibition of dentine demineralization, even when the zinc oxide is blended into toothpaste. SIGNIFICANCE: This suggests that zinc oxide may be effective in the prevention of root caries.