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>

The positive effect of transforming growth factor beta on ectomesenchymal stem cells of embryonic facial processes differentiating to smooth muscle cells / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of transforming growth factor beta (TGF-beta) on ectomesenchymal stem cells differentiating to smooth muscle cells.</p><p><b>METHODS</b>60 pmol/L TGF-beta was added to the ectomesenchymal stem cells of embryonic facial processes. Immunohistochemistry assay and image analysis were used to value the expression extent of a smooth muscle actin (alpha-SMA) and quantitative RT-PCR was used to value the quantity of alpha-SMA.</p><p><b>RESULTS</b>2 days later, about 95% cells in TGF-beta group and 65% cells in control group without differentiation inhibitor expressed alpha-SMA. Expression of alpha-SMA in TGF-beta group was stronger than that of control group after one and two days. Quantitative RT-PCR showed the quantity of alpha-SMA mRNA in treated group cells was more than that of in control group.</p><p><b>CONCLUSION</b>Quantity of alpha-SMA in TGF-beta group is more than that of spontaneous differentiation group. TGF-beta has positive effect on ectomesenchymal stem cells differentiating to smooth muscle cells.</p>