[Preliminary study of Simplant software in mandibular molar implantation].

PURPOSE: The purpose of the study was to investigate the clinical effect and implementation method of mandibular molar implantation using a CT machine combined with Simplant software so as to provide a safer and more reliable method for preoperative preparation of mandibular molar implantation. METHODS: CT/cone-beam CT (CBCT) examinations were applied among 10 cases selected into the study. The Simplant software was used to measure the distances between implantation point center and superior wall of inferior alveolar nerve canal (H1), buccolingual diameter (H2), mesiodistal diameter (H3), ginginal thickness(H4) and occlusal distance (H5). Simplant software was also applied to calculate the bone mineral density of implantation areas and trace the inferior alveolar nerve canal. RESULTS: H1 was between 10.7 mm-17.6 mm, H3 was between 5.4mm-8.3mm.The 10 selected cases undertook implantations according to the results of simulation and all of them succeed after a one year's clinical follow-up. CONCLUSIONS: According to its accuracy in measuring data of the implantation area, Simplant software can be routinely used in preoperative preparation of mandibular molar implantation, which will make the process safer and more controllable.

[Cyclic strain promotes migration of human periodontal ligament cell via extracellular signal-regulated kinase (ERK) signaling pathway].

OBJECTIVE: To study the effect of cyclic strain on migration of human periodontal ligament cell(hPDLC) and underlying mechanism. METHODS: The cultured hPDLC were subjected to 10% or 20%-elongation magnitude cyclic strain at frequency of 0.1 Hz by FX-4000T system for 6 or 24 hours-duration respectively, while the static group serves as control. hPDLC migration was assayed by wound healing method. The expressions of matrix metalloproteinases-9 (MMP-9) and p-ERK1/2 in hPDLC without or with cyclic strain were analyzed by Western blotting. To investigate the effect of ERK signaling pathway and MMP-9 on migration of hPDLC, the cells were incubated with PD98059, a specific extracellular signal-regulated kinase (ERK) kinase inhibitor, or doxycycline, a MMP inhibitor. Then the expressions of p-ERK1/2 and MMP-9 and hPDLC migration were analyzed. RESULTS: In wound healing tests, the migration of hPDLC exposed to 10% or 20%-cyclic strain at 0.1 Hz-frequency for 6 hours was not apparent but became significantly different for 24 hours (P < 0.05) compared to control. Furthermore, the 20%-elongation magnitude of cyclic strain had more remarkable effect on migration of hPDLC than 10%-elongation magnitude at 24 hours-duration (P < 0.05). Cyclic strain obviously increased the expression of MMP-9 in hPDLC (P < 0.05). PD98059 could repress not only the activation of p-ERK1/2 but also the expression of MMP-9 induced by cyclic strain in hPDLC. The migration of hPDLC enhanced by cyclic strain was repressed by DOX or PD98059 in wound healing tests. CONCLUSIONS: Cyclic strain promotes the migration of hPDLC through activating ERK signaling pathway and inducing the expression of MMP-9.