| Objective Experimental on the effect on enamel microstructure after the fluid remineralization and Beyond cold whitening technologys combineal application,to the influence of the fluid remineralization on enamel surface, structure, composition, microhardness and roughness of healthy permanent tooth, providing the necessary basic science information to guide clinical tooth whitening operation.Materials and Methods 1.Preparation of samples, 60 premolars collected recently from patient’s which need orthodontic teeatment with informed content obtained.All the collected teeth was sound, no caries and crack, should be observed.Further inclusion criterior including tooth integral and tooth color uniformity should be achieved no dental fluorosis and not tetracycline. The pulled teeth were placed in 0.9% saline water at 4 ℃. Before the experiment calculus and residual soft tissue was removed with dental scalers. Root was removed and discarded. The control part of the tooth was sliced into four parts longitudinally along the middle buccolingual and mesiodistal line. The above sectioned tooth blocks was embeded by using self-curing resin to escape only the targeted enamel surface.2. The 60 premolars were randomly divided into three groups, respectively to group 1, group 2, and group 3, n = 20, group 1 was observed by SEM and XRD, microhardness was measured to the groupe2, roughness was measured to the groupe 3. Each teeth was preparaed to 4 samples, randomly selected one of the four samples to do the baseline detection, results was no abnormal. The remained three sample from the same tooth were randomly assigned to group A、B and C. Group A was the control group; group B was cold light whitening group, referred to as whitening group; group C was remineralization solution and cold light whitening, refered to as mineralized group. In the group of one, two and three, respectively receiving the corresponding experimental intervention. After the experimental intervention, in the time of immediately, one day, one week and two weeks did the experimental detection. There are five samples at each time corresponding to the intervention group.Each immediate group, observed at the end of the experiment immediately; each 1day group was immersed in artificial saliva at 37℃ water bath and observed after 24 hours. One week groups were immersed in artificial saliva at 37℃ water bath inside a week to observe. Two week groups were immersed in saliva at 37 ℃ water bath and observed after two weeks. In groupe one, samples in each group immediately were observed after the experiment, 1 day, 1 week and 2 weeks after using a scanning electron microscope(SEM) to observed morphology changes after whitening, combined with the spectrum analyzer enamel surface phase changes in the structure, namely the amount of enamel surface of calcium and phosphorus. Enamel samples in experiment two before and after whitening in immediately, 1 day, 1 week and 2 weeks used the microhardness tester measured the microhardness of enamel, and compared the differences between the groups. Enamel samples in group three before and after whitening immediately, 1day, 1 week and two week used a synthesis measuring profilometer observed the enamel surface roughness. The data obtained were analyzed by SPSS17.0 software.Results1. Scanning electron microscope(SEM) to observe the results of the enamel surface morphology: group A enamel surface is smooth, no special changes to normal morphology of the enamel surface, the surface has superficial scratches. Samples in Group B at high magnification enamel surface rough, loose-like structure was porous, irregularly shaped pores, visible shallow scratches. Group C after whitening enamel surface morphology is rough, irregular pores visible shape, but relatively shallow compared to whitening group B. With the extension of time after whitening, demineralization radually reduced, two weeks after whitening, enamel surface morphology returned to normal on the whale.2. Combined with X-ray diffraction analysis showed that the mineral content of the enamel surface between each group immediately after whitening were displayed downward trend in Ca and P content aspect, A group> Group B> C group, with statistical significance between groups. There was statistically significant between the 24 hours after the whitening after group A and group B, A group with group C, no significant between B, C two groups. After whitening 1 week, 2 weeks the content of each group were similar, and no statistically significant difference.3. Synthesis measuring profilometer measured microhardness results: after whitening immediately each whitening group compared with the control group that the hardness was reduced, but no significant difference. After whitening 24 h, 1 week, 2 weeks, the hardness gradually with the time of the extension and restored to the normal. No significant difference between the groups in terms of hardness before and after whitening, no statistical difference.4.Roughness measurement results : The results showed that the roughness of each group were increased whitening after whitening, after whitening in immediately, were statistically significant between each of the groups; after whitening one day, group A and group C did not significant difference and was no statistically significant, A group and group B exist significant difference, with a statistically significant; one week and two weeks whitening later, the roughness between the groups have no statistically significant. In the calcium/phosphorus ratio, after the whitening immediately the calcium/phosphorus ratio is significantly decreased, group B and group A has statistical significance; However,have no significant difference with group C,and between group A and C, also has no statistical significance.Conclusion 1. By SEM observation and results showed that: the enamel surface demineralization after whitening treatment immediately, at the end of the treat immediately, using of remineralization can promote e mineralization deposite on the enamel surfac, so that relieve demineralization degree.2. XRD diffraction analysis: after whitening immediately,on the enamel sueface showed calcium and phosphorus reduction, use mineral solution can be reduced to reduce the amount of calcium and phosphorus on enamel surface.3. Before and after whitening the microhardness of enamel did not change significantly, the use of liquid remineralization did not change the microhardness of enamel significantly.4. After whitening immediately can change the surface roughness of enamel, enamel surface roughness increases, immediately use remineral solution for improved surface roughness of enamel after whitening. Reducing roughness can reduce adsorption of pigment molecules, help to maintain whitening effect. |
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