Effect of CPP–ACP paste on mechanical properties of bovine enamel as determined by an ultrasonic device

Objective The purpose of this study was to determine the effect of Casein Phosphopeptide—Amorphous Calcium Phosphate (CPP–ACP) paste on demineralization of bovine enamel by measuring changes in the ultrasound transmission velocity. Methods The enamel specimens were prepared by cutting bovine teeth into blocks. The specimens were stored in 0.1 M lactic acid buffer solution (pH 4.75, Ca 0.75 mM, P 0.45 mM) for 10 min twice a day, and then stored in the artificial saliva (pH 7.0). Other specimens were stored in a 10-times diluted solution of CPP–ACP paste and a placebo paste without CPP–ACP for 10 min, followed by 10 min immersion into a demineralization solution twice a day before storage in the artificial saliva. The propagation time of longitudinal ultrasonic waves was measured by a Pulser-Receiver (Model 5900, Panametrics) with a transducer (V112, Panametrics). Six specimens were used for each condition, and one-way ANOVAs followed by the Tukey HSD tests (α=0.05) were done. Results The sonic velocity was found to decrease with time for specimens stored in the demineralization solution. On the other hand, a significant increase in sonic velocity was found for specimens stored in the CPP–ACP solution. Conclusions From the result of this study, it was suggested that the conditions of de- and remineralization of the enamel structure could be measured non-destructively by using an ultrasonic pulse method. It could be concluded that the inorganic components contained in high concentrations in CPP–ACP acted to enhance remineralization of the enamel structure.