Effect of different acid etchants on the remineralization process of white-spot lesions: An in vitro study

Purpose: To investigate the effect of acid etchants with different low concentrations on remineralization of white spot lesion (WSL).

Methods: WSL were prepared on buccal surfaces of 100 intact premolars using the methyl cellulose gel/lactic acid method. The samples were then placed in a remineralizing solution in addition to fluoride application twice daily for 5 minutes. The changes were quantified weekly using the Quantitative Light-induced Fluorescence (QLF) system. When changes in fluorescence radiance approached zero, each sample was etched with one of the following acids; 5% phosphoric acid, 10% phosphoric acid, 5% polyacrylic acid or 10% polyacrylic acid for 15 seconds, washed, dried, and placed again in the remineralizing solution. Two samples were randomly selected from each group for transverse microradiography (TMR) and scanning electron microscopy (SEM) analysis.

Results: The 10% polyacrylic acid group showed the most significant improvement in fluorescence gain over the second phase of remineralization. It also showed partial loss of surface minerals without affecting enamel thickness as the phosphoric acid did. Additionally, 10% polyacrylic acid created the largest number of pores and smallest in size when compared to phosphoric acid, thus enhancing remineralization more efficiently than phosphoric acid without compromising the enamel outermost layer.

Clinical significance: The findings of this study may improve the remineralization of WSL from the bottom of the lesion instead of precipitation on the outermost layer of the lesion leaving a better quality of enamel. 10% polyacrylic acid enhanced remineralization more efficiently than phosphoric acid without compromising the enamel outermost layer.