BACKGROUND:Obturation with warm gutta-percha can achieve perfect three-dimensional root canal obturation effect. Due to specific structure of oval canal, particularly in the bypass preparation process, excessive cutting of local tooth tissue may lead to tooth tissue thinning and irregular shape. The separation equipment is the metal with good heat conduction, so the heat caused by the bypassing warm gutta-percha obturation would burn periodontal tissue remains controversial. OBJECTIVE:To investigate the changes of root surface temperature produced by two bypassing warm gutta-percha obturation for the separation instrument in oval canalin vitro by using infrared thermography. METHODS:Forty mandibular first premolars were harvested from oval canals, and were separated using stainless steel 15# K file at apical 3 mm, with the length of 3 mm. The root canal bypassing was prepared using TF nickel-titanium file under operating microscope. The teeth were randomly divided into two groups, with 20 teeth in each group, and were obturated with the Thermafil warm gutter-percha and E&Q plus warm gutta-percha vertical compaction, respectively. An infrared thermoviewer was used to measure the external root surface temperature before and after the obturation. RESULTS AND CONCLUSION:Two warm gutta-percha obturation methods used for separating instruments bypassing in the oval root canal, had both caused the rise of root surface temperature, which was less than 10℃. In the Thermafil group, the temperature changes were 3.2-8.1℃ and the average change was 4.97℃. In the vertical condensation group, the temperature changes were 5.5-9.8℃ and the average change was 7.35℃. There were significant differences in the change of root surface temperature between the two groups (P < 0.05). Thermafil warm gutter-percha obturation would increase the root surface temperature, but cannot damage periodontal tissues. It is more secure than warm gutta-percha vertical condensation.

BACKGROUND:Due to the complexity and irregularity of bypass obturation of oval root canal and the particular stress of the post and core to the tooth, we have not yet found a reasonable post crown for dental restoration after bypass obturation of the oval root canal.
OBJECTIVE:To compare the flexural capacity of the three kinds of post-and-core repair systems (cobalt-chromium cast post and core, zirconium oxide post and core, and CAD/CAM-fabricated glass fiber post and core) after bypass obturation of the oval root canal warm gutta.
METHODS: Ninety mandibular first premolars were selected for bypass obturation of the root canal with Obtura II & System B, and then randomized into three groups that were respectively restored with cobalt-chromium cast post and core, zirconium oxide post and core and CAD/CAM-fabricated glass fiber post and core. After that, cobalt-chromium metal crown was used for ful-crown restoration. Fracture strength and fracture type were recorded in different groups.
RESULTS AND CONCLUSION: The fracture resistance was higher in the cobalt-chromium cast post and core group and zirconium oxide post and core group than the glass fiber post and core group (P < 0.05), and the former two groups had no significant difference. Cobalt-chromium cast post and core was fractured at the root of tooth, and could not be repaired; the zirconium oxide post and core was fractured at the root neck and root of tooth, which was confirmed as reparative fracture; the glass fiber post and core was fractured at the tooth neck, which could be restored. These findings indicate that the cobalt-chromium cast post and core can bear greater occlusal force, but has a higher probability of root fracture; the CAD/CAM-fabricated glass fiber post and core exhibits a lower probability of root fracture

Objective To investigate the protective effects of Wnt-7a protein on renal interstitial fibrosis in mice of unilateral ureteral obstruction (UUO)model.Methods Eighteen male C57BL/6 mice were randomly divided into 3 groups:sham-operation group,the UUO model group and Wnt-7a treatment group.The body weight of mice was measured everyday.All the mice were sacrificed at thc seventh day after the operation.The left kidney was taken for histology evaluation and molecular biology assay.Masson's stain was performed as a main indicator of interstitial fibrosis.The expression of vimentin,α-smooth muscle actin,and E-adherin in renal tissue was detected by immunohistochemistry staining and the expression of α-smooth muscle actin and E-cadhe(nn) in renal tissue was detected by Western blotting.Results Compared with sham-operation group,body weight of the (,)odel group was significantly lower (P＜0.05),and the relative area of interstitial fibrosis was significantly larger (P＜0.05).Furthermore,the expression of vimentin and α-SMA was significantly up-regulated (P＜0.05),and the expression of E-cadherin was significantly down-regulated (P＜0.05).Compared with model group,all the above-mentioned abnormalities were restored to some extent and showed significant differences (P＜0.05) in Wnt-7a treatment group.Conclusion Wnt-7a protein can decrease the interstitial fibrosis by inhibiting epithelial to mesenchymal transition in UUO mice.

Objective To investigate whether the mucosal surface volume can be an alternative to the oral cavity volume for predicting grade 3/4 acute oral mucosal toxicity in patients with locally advanced nasopharyngeal carcinoma(LANPC). Methods A total of 92 patients with LANPC who underwent intensity-modulated radiotherapy(IMRT)and concurrent chemotherapy were enrolled in this study. The delineation of the oral mucosa was performed using oral cavity contours(OCC)or mucosal surface contours(MSC). Dosimetric comparisons of toxicity were performed based on the obtained dose-volume histograms(DVHs). The receiver operating characteristic(ROC)curve and logistic regression analysis were used to do statistical analysis of the data obtained from the two different contour methods. Results Both contouring methods showed a significant dose-volume association between oral mucosal exposure and acute oral mucosal toxicity. Logistic regression analysis showed that body weight loss was the independent associated factor for grade 3/4 toxicity in both OCC group and MSC group(P=0.017 and 0.005). And the independent correlation factors for dosimetric parameters in OCC group and MSC group were V30(P=0.003)and V50(P=0.003),respectively. The area under the ROC curve(AUC)of OCC at V30was 0.753(P=0.001)and the AUC of MSC at V50was 0.714(P=0.004). Conclusions DVH analysis of mucosal surface volume can accurately predict grade≥3 oral mucosal toxicity in patients with LANPC who receive IMRT and concurrent chemotherapy. However, OCC is superior to MSC in clinical application.