Remineralization of caries-like lesions of enamel with acidulated calcifying fluids: a polarized light microscopic study.

The purpose of this in vitro study was to evaluate the effects of acidulated calcifying fluids (CF) on remineralization of caries-like lesions of enamel. Lesions were created in sound enamel using an acidified gel. Central longitudinal sections were taken from each tooth (N = 20) following lesion formation to serve as control lesions (CL). Each tooth was sectioned into quarters and each quarter was assigned to one of four groups: 1) 1 mM calcium CF at pH 7.0 (CF1); 2) 1 mM calcium CF at pH 5.0 (ACF1); 3) 3 mM calcium CF at pH 7.0 (CF3); 4) 3 mM calcium CF at pH 5.0 (ACF3). Tooth quarters were treated with assigned CFs (HAP [Ca/P = 1.63], pH 7.0 or 5.0, 0.05 mM Fl) for ten 60-sec periods. Longitudinal sections were prepared and imbibed in water for polarized light study. Mean lesion depths were determined and compared (ANOVA and DMR). With 1 mM calcium CFs, mean lesion depths were 187 microns for CL, 154 microns for CF1 and 133 microns for ACF1. With 3 mM calcium CFs, mean lesion depths were 192 microns for CL, 172 for CF3 and 149 for ACF3. Acidulated (22%, 29%) and nonacidulated (10%, 18%) CFs resulted in significant reductions (P < 0.05) in lesion depths when compared with control lesions. Acidulated CFs (13%, 14%) resulted in significant lesion depth reductions (P < 0.05) when compared with nonacidulated CFs. The acidulated 1 mM calcium CF produced the greatest degree of remineralization. Acidulation of CFs enhanced the degree of remineralization over that attained by nonacidulated CFs. This improvement in remineralizing ability of acidulated calcifying fluids may be due to creation of a more reactive enamel surface.