Objective To improve the surgical treatment of square mandible deformity. Methods Based on cephalometric and facial feature, an integrated therapeutic project was designed. Through an oral approach the bilateral prominent mandibular angles were reseeted. Meanwhile, genioplasty was applied to correct chin deformity. Results From March 2000 to December 2006, 18 cases of square mandible with chin deformity were corrected with this procedure. The postoperative appearance was improved greatly after 3～6 months. Beautiful chin outline was reconstructed in esthetical standard. Mentolabial sulcus became natural and harmonious. Conclusion Mandible angle osteotomy combined with genioplasty is an ideal methods to recontour square mandible with chin deformity. It is beneficial to whole facial con-tour improvement.

Objective To investigate the effect of surgical treatment of adult mandibular condylar fractures (including intracapsular fracture). Methods Thirty-two patients (33 sides) with condylar fractures underwent open reduction and rigid fixation. Six patients with intracapsular condylar fractures were treated with two 18-mm positional screws through a preauricular approach. Six patients (7 sides) with condylar neck fractures were rigidly fixed by 1 mini-plate via a retromandibular transparotid approach. Twenty patients with subcondylar fractures were operated and fixed by two titanium plates using an angular approach. Results The mean follow-up period was 13.5 months, and the mean maximum mouth opening was 37.5 mm by the last visit. All patients acquired good occlusal relationship and mandibular symmetry. Seven patients (21.9%) experienced transient palsy of the branches of the facial nerve, and recovered completely after three months. One patient developed a salivary fistula, and healed after two weeks of gauze compression. No permanent deficit of any facial nerve branch was observed. No patient showed condylar head resorption. Conclusion Appropriate surgical approaches and fixation methods for different types of condylar fractures are the key factors to achieve reliable clinical results.

Objective To explore the location of the centre of resistance for the maxillary complex in cleft lip and palate by the use of finite element analysis. Methods Combining spiral CT scanning technology with the three-dimensional finite element method, a three-dimensional FEM model of LeFort Ⅰ , Ⅱ , and Ⅲ complex and soft tissue in cleft lip and palate was developed for analysis. Anteriorly and inferiorly directed forces of 9.8N were applied at five different levels parallel to the functional occlusal plane and four different levels perpendicular to the functional occlusal plane, respectively.For each loading condition, horizontal and vertical displacements of different anatomic points in the complex and on the maxillary dentition were analysed. Location of the centre of resistance in different osteotomy complex were studied. Results The resistant center of the LeFort Ⅱ complex in cleft lip and palate was located on intersection between basis nasi and medium of apertura piriforms vertically,apex of the canine and posterior point of the first bicuspid horizontally. The resistant center of the LeFort Ⅲ complex in cleft lip and palate was located on intersection between anterior of the nasion and medium of apertura piriforms vertically, posterior point of the first molar and first bicuspid horizontally. Conclusion Knowledge of the resistant center of different osteotomy complex could establish a basis for biomechanical studies of craniofacial complex distraction osteogenesis in cleft lip and palate.