Fluoride preconditioning attenuates sensitivity induced by tooth bleaching: a scanning electron microscopy study / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effects of fluorid on morphology change in enamel and dentin during tooth bleaching.</p><p><b>METHODS</b>The study population consisted of twelve patients who required the extraction of first premolars for orthodontic reasons. Twelve participants were divided into three groups: bleaching with NaF-treated group, bleaching-treated group and control group. Immediately after bleaching treatment, all teeth were extracted and prepared for scanning electron microscope (SEM). Morphologic observations were carried out with SEM.</p><p><b>RESULTS</b>In the bleaching-treated group, mild demineralization was observed on the surface of enamel and collapse of collagen scaffold was also observed on the longitudinal section of dentine. The diameter of dentinal tubule was not uniform due to peritubular dentine was demineralized. In the bleaching with NaF-treated group, the demineralization of enamel and dentin were reduced and some diameter of dentinal tubule were smaller than bleaching-treated group.</p><p><b>CONCLUSION</b>Fluoride can reduced the demineralization of enamel and dentine obviously, which may be applied as a therapeutic tool for sensitivity induced by tooth bleaching.</p>

In vitro effect of pulse Nd: YAG laser plus NaF on ultrastructure and fluoride distribution of enamel / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of pulse Nd: YAG laser combined with NaF on caries resistance of human enamel in vitro.</p><p><b>METHODS</b>24 caries-free, constant premolares were cut into enamel mass. Surface ultrastructure and fluoride distribution of enamel in laser-NaF treated group, laser treated group, NaF treated group and control group were observed by scanning electron microscope (SEM) and electron probe microanalyzer.</p><p><b>RESULTS</b>(1) SEM observation: In laser-NaF treated group, the smear layer was almost removed, the enamel surface showed partially melted-like and bubble-like appearance, diffuse white-small particles distributed on enamel surface, and melted position, microcrack and microhole appeared whitely blocking-reflection. (2) Electron probe microanalyzer analysis: In enamel samples, the highest average Ci of F- and the hightest depth which F- entered in enamel were recorded in the laser-NaF treated group. The average Ci of F- in laser-NaF treated group was significantly increased compared with that in NaF-treated group or laser-treated group or control group (P < 0.001).</p><p><b>CONCLUSION</b>The pulsed Nd:YAG laser combined with sodium fluoride could make the enamel surface partially melt, change the structure of the crystal, enhance the absorption of fluoride, and clear smear layer. This technology may resist the caries.</p>