[Effect of low magnitude tension on the inflammatory response of periodontal ligament cells induced by isoproterenol].

PURPOSE: To investigate the effect of tension on the inflammatory response of human periodontal ligament cells (PDLCs) induced by isoproterenol (ISO) and its molecular mechanism. METHODS: Human PDLCs were cultured in vitro and stimulated with a certain concentration of ISO(0.01, 0.1, 1 µmol/L) for 24 h. Cyclic tensile strain with different degrees of elongation (5%, 10% and 15%) were applied. The expression of IL-1ß and IL-6 mRNA in PDLCs was detected by real-time quantitative PCR(RT-qPCR). The protein expression of p-PERK, PERK, p-eIF2α, eIF2α and ATF4 related to ER stress was detected by Western blot. The expression of PERK gene in PDLCs was knocked down by cell transfection technique, and the expression of IL-1ß and IL-6 mRNA in PDLCs with low expression of PERK was detected by RT-qPCR under the stimulation of ISO and low magnitude tension. Statistical analysis was conducted with SPSS 22.0 software package. RESULTS: ISO induction could significantly up-regulate the IL-1ß and IL-6 mRNA expression in PDLCs(P＜0.05). Compared with the control group, the expression of IL-1ß and IL-6 mRNA in PDLCs induced by ISO was inhibited by low magnitude tension, and the difference was statistically significant(P＜0.05). Western blot results showed that low magnitude tension could inhibit the ISO-stimulated phosphorylation of PERK and eIF2α and the expression of ATF4（P＜0.05）. Compared with the negative control group, IL-1ß and IL-6 mRNA expression was decreased in the ISO-stimulated PDLCs silenced by PERK gene. CONCLUSIONS: Tension with 5% degrees of elongation may inhibit ISO-stimulated periodontal inflammatory response through endoplasmic reticulum stress pathway.

[Treatment of mandibular angle fracture through intraoral and extraoral approach: a comparative study].

PURPOSE: To compare the clinical effects of mandibular angle fracture surgery through intraoral and extraoral approach. METHODS: From January 2008 to December 2014, 46 patients with mandibular angle fracture were retrospectively recruited in this study. An intraoral approach was used in 22 cases as group 1 in whom the fractures were fixed by one titanium miniplate alone, the others through an extraoral approach as group 2 in whom the fractures were fixed by two plates. Intermaxillary traction was used in all patients for 3 weeks following the operation. The data was collected in MS Excel 2003 and further analyzed by SPSS13.0 software package. RESULTS: The wound healing was in uneventful group 1, no complication occurred 3 weeks later. On the contrary, 5 cases with postoperative infection and 3 cases with temporary weakness of facial nerve were observed in the group 2. Three months later, postoperative panoramic radiographs showed mandible fractures healed well in group 1; while in group 2, three cases complained of unhealed fractures and unsatisfactory occlusion. CONCLUSIONS: Compared with extraoral approach to manage mandibular angle fracture with 2 miniplates, one miniplate through intraoral approach can provide better outcomes.