An In Vitro Study Of Interproximal Enamel Reduction And Reminaralization On Enamel

Objective To investigate the validity of method of using the confocal laser scanning microscope(CLSM) to assess the effect of reminaralization after interproximal enamel reduction(IER), and to compare the effect of remineralization among different remineralizing agent after IER.Method 120 human premolars extracted for orthodontic treatment were collected and randomly divided into 6 groups with different managements, 20 teeth in each group. There was no management in group A. Samples in group B, C, D, E and F were treated with IER and polishing, and the group C, D, E and F were respectively applied with different remineralizing agent of 0.1% fluoride varnish, Durophat, Flor-Opal Varnish White and GC tooth mousse plus. The microhardness of all samples was measured by microhardness tester. All data were analyzed by SPSS17.0 statistical software. Mono factor analysis of variance was used to analysis, and LSD-t statistical test was used to compare the data among groups. There was a significantly statistical difference when P<0.05. The samples were also observed by CLSM, and the Mean Optical Density(MOD) was measured by using Image J software and made comparison to the result of microhardness test.Results ①Results of microhardness(kg/mm2): Group A: 258.68±7.91, group B: 205.65±8.88, group C: 223.68±4.10, group D: 225.43±7.38, group E: 226.57±6.68, group F: 240.57±5.79. The microhardness of group A was the highest and group B was the lowest. The microhardness of group C, D, E and F were all lower than that of group A, but higher than group B. The microhardness of group F was higher than that of group C, D and E. There were significantly statistical differences in all above(P=0.000, P<0.05). There was no statistical difference between group C and D(P=0.360, P>0.05), group C and E(P=0.108, P>0.05), group D and E(P=0.613, P>0.05). ②Results of CLSM: The red fluorescence area was the least in group A, and the most in group B. The red fluorescence area in group C, D, E and F were less than that in group B, but more than group A. The red fluorescence area in group C, D and E were more than that in group F. ③Results of MOD: Group A: 0.01045 ± 0.00201, group B: 0.02955±0.00588, group C: 0.02150±0.00330, group D: 0.02035±0.00184, group E: 0.01965±0.00176, F: 0.01455±0.00132. MOD of group B was the highest and group A was the lowest. The MOD of group C, D, E and F were higher than that of group A, lower than group B. The MOD of group F was lower than that of group C, D and E. There were significant statistical differences in all above(P=0.000, P<0.05). There was no statistical difference between group C and D(P=0.244, P>0.05), group C and E(P=0.062, P>0.05) group D and E(P=0.477, P>0.05).Conclusions ①GC tooth mousse plus, Durophat, 0.1% fluoride varnish and Flor-Opal Varnish White can promote the remineralization after IRE. The effect of GC tooth mousse plus is the best, but there is no significant difference among other groups. ②CLSM is an effective method to assess enamel remineralizing after IRE.