[The effect of different etching time on enamel lesions of deciduous teeth]

To study the effect of etching time on the demineralization of deciduous teeth enamel using confocal laser scanning microscope.

Twenty-eight primary incisors were used in this experiment. Each incisor was created 4 rectangular windows in the labial surface. The 4 windows of each tooth were randomly divided into 4 treatment groups with different etching time of 30s(A), 60s(B), 90s(C) and 120s(D). All the treatment groups were applied with 32% phosphoric acid gel. After staining by 0.1 mmol/L rhodamine B, the examination of the demineralization regions were performed by a confocal laser scanning microscope (CLSM). The data was analyzed by test of normality and S-N-K analysis with SPSS 11.0 software package.

As the etching time increased, the CLSM band was thickening,but the scales-liked structure was becoming unsharp.All the three parameters, area of the fluorescent lesion(FLA), average lesion fluorescence(AF) and total lesion fluorescence(TF) were increasing. The FLA value of A,B,C,D were (5.5 + or - 1.6) x 10(2) microm(2), (7.4 + or - 2.7) x 10(2) microm(2), (9.2 + or - 3.0) x 10(2)microm(2), (9.6 + or - 2.9) x 10(2) microm(2); The TF value of A,B,C,D were (3.5 + or - 1.3) x 10(4), (5.7 + or - 2.9) x 10(4), (8.3 + or - 3.6) x 10(4), (9.7 + or - 3.4) x 10(4); The AF value of A,B,C,D were 128.4 + or - 35.3,166.6 + or - 21.1, 200.8 + or - 19.4 and 219.1 + or - 12.8,respectively. The pairwise comparison of AF showed significant difference between the four groups, while there was no significant difference between group C(90s) and group D(120s) in both FLA and TF.

The degree of demineralization increases with the etching time. Etching time has a large effect on the profile of demineralization.Supported by Research Fund of Science and Technology Commission of Shanghai Municipality(Grant No.074119644 and 08DZ2271100) and Shanghai Leading Academic Discipline Project (Grant No.S30206).