[Comparison of condylar position between Angle Class I and Class II malocclusion in teenagers].

Purpose: To analyze and compare the difference of condylar position between Angle Class I and Class II malocclusion patients using cone-beam CT (CBCT).

Methods: Thirty Class I patients, 30 Class II division 1 patients and 30 Class II division 2 patients were selected in this study. Each patient underwent CBCT.

[Morphological characteristics of upper alveolar bone around central incisor in Class II division 1 and division 2 malocclusion on cone-beam CT].

Purpose: During orthodontic treatment, the incisors in patients with Class II division 1 and division 2 malocclusion showed different clinical features, which determine the different ways to move the teeth to the suitable position. This study analyzed the morphology of alveolar bone around upper central incisor with cone-beam CT (CBCT).

Methods: The sample consisted of 20 normal malocclusion and 40 patients with Class II malocclusion （division 1 20 cases and division 2 20 cases）.

[Clinical effect of premolar extraction with high torque self-locking appliances].

Purpose: To analyze the clinical effect of extraction correction of patients with maxillary protrusion by using Damon high torque appliances.

Methods: Forty patients with extraction of four first premolars due to orthodontic treatment were selected. They had protrusion of maxilla and were randomly divided into two groups.

[A study on the thickness of buccal bone in the mandible of different vertical facial type in adults using cone-beam CT].

Purpose: To provide some references of using micro-implant anchorage in clinical orthodontic treatment, the thickness of buccal bone of mandible of different vertical facial type in adults with cone-beam CT (CBCT) were measured.

Methods: Initial 3-dimensional images of 45 adult patients (15 men, 30 women)were reoriented by using a standardized protocol, and divided into 3 groups by angle of mandibular plane (G1: high angle, 15 patients; G2: average angle, 15 patients; G3: low angle, 15 patients). After signing the informed consent form, three measurement points were defined at 4, 6, and 8mm from the alveolar crest in each measurement area.

[Comparative evaluation of two kinds of micro-implant system with different size].

Objective: To offer some reference for micro-implant's development and population by analyzing clinical application of two kinds of micro-implant systems.

Methods: 38 patients treated with MIA (micro-implant anchorage) and 28 patients treated with SDIA (self-driven titanium implant for orthodontic anchorage) were included. Analyzing the rate of lost implants, the gum's reactivity and the efficiency of moving teeth summarized the excellences and shortcomings of two systems.

[Finite element analysis of mechanical characteristics during retracting mandibular incisors through sliding mechanics].

Purpose: To analyze the mechanical characteristic changes of teeth and arch under different loading direction during retracting mandibular incisors through implant, simulating clinical loading system.

Methods: Three- dimensional finite element model, including brackets, archwire, crampable hooks and implants, was reconstructed. The force direction was determined by connecting the points in crampable hook and the center point of implant, and the force point and force direction were changed with the adjustment of the height of crampable hook and the height of implant.

[Comparison between J-hook and micro-implant anchorage in the treatment of patients with bimaxillary protrusion].

Objective: To compare the difference between J-hook and micro-implant anchorage in the treatment of patient with bimaxillary protrusion.

Methods: Thirty patients with bimaxillary protrusion were divided into two groups (J-hook and micro-implant groups) and treated with MBT appliance. Four first premolars were extracted in all patients.