The study aimed to evaluate the effect of Polyacrylic Acid (PAA) concentration on the remineralization of artificial enamel lesions in a pH cycling (pHc) model in vitro, as well as the effect of different durations to the pHc. Bovine enamel specimen were prepared and two artificial caries lesions were created with a demineralization solution (pH 4.95; 28 d) separated by varnish. Specimens were randomly assigned to three groups for different PAA concentrations (n = 40). One lesion in each specimen was etched (37% H3PO4, 5 s) and infiltrated with PAA (0.1, 1 or 10 mg/ml), the other lesion served as a non-treatment control (NTC). To obtain a baseline control (BL), specimens were cut perpendicularly to the lesions. The remaining halves (E) were exposed to pHc (21 h/d: pH = 7; 3 h/d: pH = 4.95) for either 28 d or 56 d (n = 20). The difference in integrated mineral loss between baseline and after pHc was analyzed using transverse microradiography (ΔΔZ = ΔZE—ΔZBL). After 28 days, lesions treated with 0.1 mg/ml and 1 mg/ml PAA showed significantly greater mineral gain than NTC (p 0.05). Prolonging pHc to 56 days did not yield significant differences between groups (p > 0.05, Kruskal–Wallis). Lower concentrations of PAA seem to promote remineralization in the chosen pHc model.
Vieweg et al. (Sat,) studied this question.