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Indian J Dent Res. 2017 Sep-Oct;28(5):530-537. doi: 10.4103/ijdr.IJDR_549_15.

Profile changes following orthodontic treatment of class I bimaxillary protrusion in adult patients of Dravidian ethnicity: A prospective study.

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Department of Orthodontics, Government Dental College, Kozhikode, Kerala, India.



To prospectively evaluate soft and hard tissue responses to orthodontic treatment of bimaxillary protrusion (BMP) in Dravidian population using McLaughlin, Bennett, and Trevisi (MBT) mechanics of the preadjusted edgewise appliance.


Thirty-one adult (18-30 years) Class I BMP patients were treated using the above mechanics after extraction of four first premolars. Forty-five pre- and post-treatment variables on lateral cephalograms were compared using paired t-test and Pearson's correlation coefficient.


All linear and angular parameters pertaining to hard and soft tissues showed significant changes, indicating retraction of incisors, upper and lower lips; increase in nasolabial angle; and decrease in circumoral convexity, interlabial gap, and lip thickness. Various correlations established were (1) upper lip to upper incisor retraction 1:2.01, (2) lower lip to upper incisor retraction 1:1.5, (3) lower lip to lower incisor retraction 1:1, and (4) upper incisor retraction to nasolabial angle 1:2.02.


Orthodontic therapy using MBT mechanics is very useful in achieving favorable hard and soft tissue changes, following four first premolar extractions in BMP. The various correlations established between incisor retraction and soft tissue parameters could prove useful to the discerning clinician.

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