Edeinton Arumugam Department of Orthodontics and Dentofacial Orthopedics, SRM Dental College, Ramapuram India
Aim: To study the relationship between the amount of incisor retraction and the changes in soft tissue profile during orthodontic treatment involving extraction of first premolars in south Indian female orthodontic patients .
Materials and methods : Pre- and Post-treatment Lateral Cephalograms of30 female orthodontic patients with class I or class II division 1 malocclusion treated with premolar extraction in maxillary and mandibular archwere analysed and compared.
Results: Significant positive correlations were found between retraction of the maxillary and mandibular incisors with that of upper and lower lip soft tissue retraction. On an average 2.9 ± 2.8 mm maxillary incisor retraction resulted in 0.9 ± 1.7mm upper lip retraction. Similarly 1.6 ± 2.0 mm mandibular incisor retraction caused 1.1 ± 2.7 mm lower lip retraction. The ratio of maxillary incisor retraction to upper lip soft tissue retraction was 3:1 and mandibular incisor retraction to lower lip retraction was 1.5: 1.A significant increase in upper and lower lip thickness and length occurred with incisor retraction. The lower anterior face height and lower soft tissue component also increased following maxillary incisor retraction. The ratio between the increase in soft and hard tissue lower facial height was 0.7:1. Maxillary incisor retraction also produced an average increase in nasolabial angle.
Conclusion: In south Indian females, a strong correlation exists between anterior tooth retraction and the position and configuration of both lips.