OBJECTIVEThe purpose of this study was to study the changes of available spaces of posterior arch segments in mandible dentitions (ASPAS) from ages of 11 to 20 years, which would provide information on normal growth and development of the dental arches in teenagers in Chengdu area.

METHODSThe data were derived from systematically collected preorthodontic lateral cephalograms of 526 patients, including 232 males and 294 females from the Orthodontic Department of West China College of Stomatology, Sichuan University during the period of 1999-2000 (aged 11-20 years). The values of ANB angle, FH-MP, ASPAS were obtained using the cephalometric analysis. Afterwards, the growth changes of ASPAS from the subjects and their correlations with age, gender, angle malocclusion types and vertical skeletal patterns were analyzed.

RESULTSASPAS was related to age and class II angle malocclusion. Though gender was not associated with ASPAS, significant differences in curves of ASPAS were found between males and females. The growth changes of ASPAS in the patients with skeletal Class III malocclusion were more obvious than in patients with Class I and II malocclusion.

CONCLUSIONOur results reveal that significant differences were demonstrated in growth change values in posterior available spaces of patients with different races and angle malocclusion types.