An in vitro comparative study of the effects of soy milk and coconut milk on the microhardness of primary molar enamel after an acidic challenge

Abstract Objectives This in vitro study aimed to compare the effects of soy milk and coconut milk on primary molar enamel microhardness after an acidic challenge. Materials and methods Microhardness of 30 primary molar enamel blocks was measured using a Vickers tester. For the acidic challenge, they were immersed in citric acid with a pH of 3 for 25 h, and then their microhardness was measured again. The specimens were then randomly assigned to 3 groups ( n = 10) for immersion in either soy milk, coconut milk, or artificial saliva (control) 3 times a day, each time for 5 min, for 7 days. Subsequently, they underwent microhardness test again. Data were analyzed by ANOVA, independent t-test, and LSD test (alpha = 0.05). Results The enamel microhardness significantly increased after immersion in coconut milk compared with the value after acidic challenge within the same group ( P = 0.035). However, the difference in microhardness was not significant between the coconut milk and artificial saliva groups after the intervention ( P = 0.178). No significant microhardness change occurred after soy milk immersion ( P = 0.121), and no difference was found between soy milk and artificial saliva groups ( P = 0.289). Conclusion Under in vitro conditions, coconut milk significantly increased enamel microhardness after an acidic challenge, while soy milk showed a non-significant increase. Neither plant milk demonstrated a significant effect on microhardness compared with artificial saliva.