Department of Orthodontics, M A Rangoonwala Dental College, Pune, Maharashtra, India
*Address for Correspondence: Dr. Maryam Maniyar, Department of Orthodontics, M A Rangoonwala Dental College, Pune, Maharashtra, India. E-mail: maryam.maniyar87@gmail.com
Online published on 21 February, 2015.
The aim was to study and compare lower incisor dentoalveolar compensation and mandibular symphysis morphology of patients with Class II and Class III malocclusion.
Lower incisor inclination (incisor mandibular plane angle [IMPA]), as well as buccal (LA) and lingual (LP) cortex depth, and mandibular symphysis height (LH) were measured in 60 lateral cephalometric X-rays of adult patients without prior orthodontic treatment. The subjects were divided into three groups based on antero-posterior skeletal malocclusions -Class I (control group), Class II and Class III groups.
IMPA and symphysis dimensions showed significant differences between the sagittal malocclusion groups. In Class III subjects, the lower incisor apex was closer to the buccal cortex, therefore, value of LA was decreased and LH was increased. In Class II subjects, the lower incisor apex was near to the lingual cortex, there value of LP was reduced and LH increased.
Narrow alveolus was observed in Class II and III subjects compared to the Class I subjects. Natural compensation elongates the symphysis and influences the lower incisor position. Thus limiting the pre-surgical decompensation and increasing the risk of damage to periodontal tissues.
Buccal cortex, lingual cortex, lower incisor apex, occlusal plane, vertical growth pattern
