Objective:To evaluate the effect of segmental approach in the treatment of Angle class Ⅱ division 1 malocclusion.Methods:7 cases of classⅡ,division 1 maloclusion were treated.Upper first premolar and lower second premolars were extracted in all cases.Lower first molars were mesially moved by means of segmental arch. Cephalometric analysis was used to evaluate the effects of the treatment.Results:Facial profile improvement and lower anterior facial height maintenance were achieved.The occlusion plane angle,mandibular plane angle were well controlled with lower anterior teeth upright on the lower basal bone.All patients represented good mandible response.Conclusion:Segmental technique is a simple and effective approach in correcting class Ⅱ,division 1 maloclusion

Objective:To investigate the effects of different shapes of implant on stress distribution in implant-bone interface and to select the most appropriate shape for orthodontic anchorage. Method:3-dimesional finite element analysis method was used to analyze the stress and strain in implant-bone interface of knife-edged threaded, square threaded and smooth type implants.Results: The first,second and third main stress (MPa) of knife-edged threaded implant were 6.67, 1.47 and 0.52 respectively with 7.72 MPa of Von Mises stress;those of square threaded 13.00,2.51,0.57 and 11.8;smooth type 10.50,2.50,0.67 and 12.60,respectively. The variables of alveolar bone at the cervix of knife-edged threaded,square threaded and smooth type implants were (0.11×10-3), （0.13×10-3） and （0.94×10-4) mm respectively. Conclusion: The stress in knife-edged threaded implant-bone interface and alveolar bone deformation at the cervix of the implants is minimal,therefore the implants are more suitable for orthodontic anchorage.

Objective:To establish a 3-dimensional finite element model for implant in molar deprived region of mandible. And to lay basis for precise analysis for the biomechanic characteristics of implant anchorage system. Methods:The cross section outline drawn from the molar deprived region of mandible was input into a computer, and ANSYS 5.5 (Swanson Analysis Systems, Inc. Houston, USA) finite element analysis software was used to perform the finite element modeling of the mandible.Results:The cross section outline of the mandible,imitated by a spline curve was smooth and lifelike. This cross section outline was extruded into a three dimensional model. The three dimensional models of the implant and mandible could be smartly meshed to obtain the finite element model of mechanics. Conclusion: An effective 3-dimensional finite element biomechanical analysis model for implant as orthodontic anchorage was established.

Objective:To investigate the three-dimensional accuracy of four impression materials for fixed denture:silicone(OX),hydrocolloid(HT) and two kinds of alginate impression(FC and ZS).Methods:Ten plaster replication models for each impression materials were made on the same metal master cast respectively, vertical and horizontal dimensions between landmarks on the masters and plaster casts were measured with an optical microscope. ANOVA was used to compare the measurements among the materials.Results:The difference between the masters and casts in horizontal distances measured on ZS produced models was bigger than that on other impression material produced ones (P<0.01) and beyond clinical requirment.The difference between the masters and casts in all measured dimensions on OX produced models was the smallest.Conclusion:Alginate paste is not accurate enough for denture model,while silicone is.The hydrocolloid material is relatively accurate.

Objectives: To evaluate the effect of thickness and opaque resin on the light transmittance of Artglass. Methods: Samples of Artglass prepared in the thickness(mm) of 0.50,0.75,1.00,1.25,1.50,1.75 and 2.00 with or without opaque resin respectively.The light transmittance of the specimens was measured. The color values of the specimens on the CIE L*a*b* color system were determined by a digital chroma meter. Results: The light transmittance of Artglass decreased logarithmically with the increase of the thickness (R2=0.9834 in the group of samples without opaque and R2=0.9390 in those with opaque). The light transmittance of Artglass with opaque resin was lower than that without opaque resin. Conclusion: Thickness and opaque resin have significant effect on the light transmittance of Artglass.

Objective:To evaluate the effect of of twin block appliance in the early treatment of class Ⅱ malocclusion.Methods:20 cases with class Ⅱ malocclusion were treated with Twin block appliance.Cephalometric analysis was used to evaluate the effects.Results:The twin block appliance could stimulate the growth of mandible and lead to retrocline of the upper incisors and procline of the lower incisors.Conclusion:The twin block appliance can achieve remarkable effects of growth modification of dentognathic system.

Objective: To determine the distribution of Actinobacillus actinomycetemcomitans (Aa) in subgingival plaques in the patients with chronic periodontitis(CP). Methods: Samples of subgingival plaque were detected for Aa distribution by oligonucleotide probe from 60 sites of CP patients and 10 healthy sites of healthy people.Each sample was obtained from each site of each people. Results: Aa was detected in 19 out of 60 diseased sites(31.67%); Aa wasn't detected in healthy sites.The age(28.68±7.33) of Aa-positive patients was younger than that (44.48±12.48) of Aa-negative patients(P<0.05).Conclusion: Aa is possibly to cause chronic periodontal infection in younger people.

Objective: To view the characteristics and the primary treatment of civilian firearm wound in the maxillofacial region.Methods: 301 cases of the casualties admitted to our hospital were retrospectively investigated,the epidemic, etiology, wound characteristics, and treatments of the patients were viewed respectively. Results: Of all the cases, the ratio of male to female was 5.1∶1.0. 57% of the injuries were caused by gunshot, 66% were with multiple injuries.16% combination wound were craniocerebral injuries. In this group of patients, more than 900 wound tracks were found, 72% of the tracks were nonpenetrating and 67% of those were with foreign bodies lodged in. Burns with blast injuries were the main complex wounds, which mostly occurred in explosion. The treatments mainly included life maintaining, earlier debridement and infection control. Conclusions: The maxillofacial firearm injuries are complex and have their own characteristics depending on the firearms, the wound styles and the regional anatomy. All the factors must be considered when treatment is given.

Objective:To evaluate the effect of iliac bone graft and radial forearm flap in the reconstrucion of maxilla.Methods:Maxilla defects were reconstructed using iliac bone graft and radial forearm flap in 4 patients.The effects were evaluated clinicaly.Results:In all the 4 cases,palatal defects resulted from maxillectomy were optimally reconstructed with non-vascularized iliac graft and radial forearm flap.The masticatory function of the upper jaw,intelligible speech,swallow and natural facial appearance were recovered.As a result,quality of life of the patients was improved.Conclusion:Iliac bone graft and radial forearm are feasible in the reconstruction of maxilla defects.

Objective: To study the phenotype characteristic of mandibular condylar chondrocytes (MCCs) in vitro. Methods: MCCs of two-week-old New Zealand rabbits were isolated with enzyme digestion and cultured in DMEM. Phase contrast microscopy, image analysis system, MTT assay and immunocytochemistry method were used to compare MCCs of different passages in cellular shape and size, growth curve and expression of type I and type II collagen. Results: The majority of MCCs in earlier passages (1～3 passage) were polygonal, while more fusiform and spindle-shaped cells were found after 5～6 passages. MCCs in earlier passages were smaller than those in sixth passages. The proliferation rate of MCCs decreased with passaging. There were more type II collagen positive cells in 1 ～ 3 passages, while more type I collagen positive cells in 7th passage. Conclusion: The changing characters of MCCs in vitro such as cellular shape and size and expression of type I and II collagen are similar to those of MCCs in vivo from proliferating zone to hypertrophic zone. MCCs in later passages may be with dedifferentiation.