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Objective: To study the histological change of microscrew-bone interface, detect the relative cytokine of gingival crevicular fluid, and explore the impossible mechanism of peri-implantitis., Methods: Four male Beagles were collected. Randomly select one side of animals jaw as the experimental group to induce the peri-implantitis, and another side as the control group. Four microscrews were implanted on each side. In the 1st, 2nd, 3rd, 4th weeks after implantation, collect peri-implant sulcular fluid (PISF) and detect tumor necrosis factor-alpha (TNF-alpha) levels before sacrificed, and the harvest tissue were observed in histological ways., Results: According to the extension of time after implantation, the experimental group showed visible progress of interface destruction: 1st week after implantation showed large numbers inflammatory cells collected at the neck but did not undermine the cortical bone; 2nd week after implantation, cortical bone were observed angular absorption; Bone resorption continued to develop and at the 4th week, bone resorption were enlarged to the second thread of microscrew and the interface was filled with a large number of collagen fibers., Conclusion: The destruction of interface began at the neck of microscrew, and the further development was along the interface in depth. Both microscrews with peri-implantitis and the healthy controls showed the presence of TNF-alpha. Inflammation accumulation might trigger the up-regulation of TNF-alpha level, and the onset of inflammation would enhance the up-trend.

Objective: To evaluate the potential repairing effects of low-intensity pulsed ultrasound (LIPUS) irradiation on acute horizontal alveolar bone defects at the mandibular pre-molar areas in Beagle dogs., Methods: Horizontal alveolar bone defect models were established under enamelo-cemental junction 6 mm at the mandibular third and forth pre-molar buccal regions on both sides in 4 beagle dogs, and bilateral sides of each dog were randomly divided into two groups: Experimental groups with LIPUS irradiation (I(SATA) 30 mW X cm(-2), 20 min x d(-1)) and control groups without opening power source of LIPUS radiation. Dual energy X-ray bone densitometer was used to detect the bony density after an 8 weeks' irradiation. Meanwhile, decalcified bone tissue sections were used to assess the histological effects of new alveolar bone., Results: The results of new bony density detection in experimental group and control group were (0.6053 +/- 0.0566) g x cm(-2), (0.6047 +/- 0.0552) g x cm(-2), respectively, and there was no statistical significance between the differences of the two groups (P = 0.9839). Hematoxylin-eosin staining of decalcified bone tissue sections demonstrated that there were more osteoblasts lining at the edge of new alveolar bone in the experimental groups than that scattered in the control groups, and Masson staining revealed that collagens in new alveolar bone stained bright red indicating higher maturity in the experimental groups, while in the control groups mainly stained blue with some virescent areas indicating lower maturity., Conclusion: LIPUS irradiation on acute horizontal alveolar bone defects has potential repairing effects.

Objective: To guide the orthodontic diagnosis, treatment planning and prognosis by analyzing the craniofacial morphology and reimbursement mechanism of young patients with mandibular retrusion in Chongqing territory by Delaire cephalometric analysis., Methods: Both conventional cephalometric analysis and Delaire cephalometric analysis were conducted on the basis of the lateral cephalograms from 56 young mandibular retrusion patients and 40 teenagers with normal occlusion., Results: Decreases in angle SNB, Co-Go, Co-Pog, U1-L1 and increases in angle ANB, angle SN-MP, L1-MP were seen in mandibular retrusion group by conventional cephalometric analysis. Decreases in angle 1, angle 5, (Cp-Oi)/C2 and increases in angle 2, (M-Cp)/C2, angle 3, angle 4 were seen in mandibular retrusion group by Delaire cephalometric analysis. Me-F1 and Me-Met were -8.70 mm +/- 2.48 mm and 5.74 mm +/- 2.58 mm respectively., Conclusion: Delaire cephalometric analysis could evaluate cranio-maxillofacial architectural features of mandibular retrusion patients more visually and quantitatively, which suggests that mandibular retrusion is usually caused by the retrusion of mandibular position and the hypodevelopment of mandibule.

Objective: To investigate the biomechanical effects of micro-implant anchorage technique with sliding mechanics on maxillary anterior teeth retraction under different implant insertion heights and different retraction hook heights., Methods: The three dimensional finite element model of maxillary anterior teeth retraction force system was constructed with CT scanning and MIMICS software and the relationships between brackets, teeth, wire and micro-implant were simulating the clinical factions. Then the initial tooth displacement was calculated when the insertion heights were 4 mm and 8 mm and the retraction hook heights were 1, 4, 7, 10 mm respectively., Results: With retraction hook height added, the anterior teeth movement changed from lingual crown tipping to labial crown tipping and the intrusion movement was more apparent when the micro-implant was inserted in a higher location., Conclusion: The ideal teeth movement control could be achieved by different insertion heights of micro-implant and different retraction hook heights in straight wire retraction force system.

A facial asymmetry patient caused by temporomandibular joint ankylosis was operated by putting a distraction osteogenesis (DO)-appliance. One week after surgery, the right mandible was distracted. Twenty days after distraction, the height of right mandibular ramus and body increased obviously. Four months after retain of DO-appliance, the right maxilla down-grew automatically and the occluding relation recovered to normal. The DO-appliance was taken out. MEDPOR prosthesis was imbedded in new bone and genioplasty was operated. The facial asymmetry and abnormal occluding relation of the patient were improved obviously.

Objective: The purpose of this study was to establish the computer -assisted Delaire cephalometric analysis system with WinCeph8.0 in order to simplify the procedure of manual Delaire cephalometric analysis., Methods: On the basis of the theory of Delaire cephalometric analysis and the program module of WinCeph8.0, the landmark points and the auxiliary line were defined, the measurement and analysis program were written, then the computer-assisted Delaire cephalometric analysis system was established. Paired t-test and dispersion analysis of the computer-assisted and manual measurements were taken., Results: Computer-assisted Delaire cephalometric analysis system was convenient and accurate to trace the landmark points and the auxiliary line. It was able to proceed the measurement and calculation automatically and display the analysis results. Statistical analysis showed that computer-assisted analysis was more accurate than manual analysis., Conclusion: This study provided a convenient, simplified, accurate computer-assisted analysis platform for Delaire cephalometric analysis which facilitated its clinical application.

Objective: To explore a new method to construct the three-dimensional finite element model of micro-implant-maxilla using Materialise's interactive medical image control system (Mimics)., Methods: The maxilla with all teeth was scanned with Spiral CT and the images were transferred into the Mimics 9.0 software to obtain the three-dimensional images. The Abaqus 6.5 software was used to mesh the three-dimensional model and to establish the finite element model., Results: A detachable three-dimensional finite element model of micro-implant-maxilla based on Mimics was constructed rapidly, which can be flexibly re-assembled., Conclusion: The method of constructing the three-dimensional finite element model of micro-implant-maxilla is available and effective. The geometrical analogy of the model was greatly improved by using the Mimics system.

Objective: To investigate the effects of time varied stress on the shape-alteration of myoblast in rats and to provide a theoretic base to determine the mechanics of myoblast in orthodontic therapy., Methods: Based on the pulsatile mechanical system our group founded, this study loaded different strain (2.5 kPa, 5.0 kPa and 10.0 kPa) to the myoblast of lateral pterygoid muscle. The alterations in shape under time varied stress of 6 h and 12 h were assessed by phase-contrast microscopy, scanning electron microscope., Results: The orientation of myoblast seemed no obvious orderliness before loading. But after loading the lower time varied strain (2.5 kPa, 5.0 kPa), they were changed their orientation to paralel with the direction of strain along with the membrane. Meanwhile, there had one trend to set the shape of myoblast more upright along with the membrane after loading the higher time varied stress (10.0 kPa)., Conclusion: It was proved that the different time varied stress in vitro expressed the different influence on the remolding of myoblast.