Mandibular Size and Position in 8-13 Year Old Iranian Children with Class II Division 1 Malocclusion

Statement of problem: assessment of mandibular size and position is essential when planning a treatment strategy for patients with class ii malocclusion. purpose: this study was carried out to evaluate the mandibular size and position of 8- 13 year-old children with class ii division 1 malocclusion whom were referred to the faculty of dentistry, shiraz university of medical sciences, iran. materials and methods: 935 lateral cephalograms of children with normal occlusion (425 films) and class ii division 1 patients (510 films) referred to the department of orthodontics, school of dentistry, shiraz university of medical sciences, during 2002 to 2004 were evaluated. the control and class ii division 1 subjects were each divided into three groups according to age (8-9, 10-11 and 12-13 years), and were further divided into two subgroups according to gender. the radiographs were converted to computer-readable x and y coordinate and data obtained from 29 linear and angular measurements in the cranial base, mandible and dentition, were compared. results: the cranial base angle was significantly larger in class ii division 1 patients as compared to the control subjects. a smaller mandible along with a protrusive dentition was observed in the test group. the form and position of the mandible was also different in comparison to normal cases. all class ii patients showed a vertical growth pattern and an increased facial height. conclusion: the main factors responsible for class ii division 1 malocclusion in 8-13 year-old children in present study were retropositioning of the lower jaw and a short mandibular length.