Skeletal and soft tissue point A and B changes following orthodontic treatment of Nepalese Class I bimaxillary protrusive patients.
OBJECTIVE
To test the hypothesis that there is no correlation in the interrelationships of skeletal and soft tissue points A and B with anterior teeth retraction.


METHODS
Thirty adult Class I bimaxillary protrusion patients treated with preadjusted appliances after first premolar extraction were included. Pretreatment and posttreatment variables were compared using paired t-test, and the relationship of soft and hard tissue variables was studied using Pearson correlation coefficient and linear regression equation.


RESULTS
Mean point A and soft tissue point A (sA) were retracted 2.7 mm (P < .001) and 1.7 mm (P < .001), and mean point B and soft tissue point B (sB) were retracted 2.1 mm (P < .001) and 1.2 mm (P < .001), respectively. Mean ratio of retraction of point A with sA and point B with sB was 1.5:1 and 1.7:1, respectively. A significant degree of correlation existed between retraction of point A and soft tissue point A (r = 0.648, P < .01) and point B and soft tissue point B (r = 0.806, P < .01). Linear regression analysis used to predict the changes in sA and sB showed significant relationship between point A and sA (r = 0.543, F = 11.7, R2 = 0.29, P < .001) and point B and sB (r = 0.825, F = 59.7, R2 = 0.68, P < .001). Decreases in hard and soft tissue convexity were due to the retraction of the skeletal and soft tissue points A and B in addition to the lips retraction.


CONCLUSIONS
The hypothesis is rejected. Retraction of skeletal point A and B lead to retraction of sA and sB under controlled root positions. Nearly proportionate changes existed in the skeletal points and overlying corresponding soft tissue points.
Department of Orthodontics, College of Dental Surgery, B.P. Koirala Institute of Health Sciences, Dharan, Nepal. dr.jnsharma@yahoo.com
Jagan Nath
JN
Sharma
D000293:Adolescent; D000328:Adult; D001641:Bicuspid / Q000601:surgery; D002508:Cephalometry; D002680:Chin / Q000473:pathology; D005145:Face; D005260:Female; D006801:Humans; D007180:Incisor / Q000473:pathology; D008046:Lip / Q000473:pathology; D008297:Male; D008311:Malocclusion, Angle Class I / Q000473:pathology / Q000628:therapy*; D008334:Mandible / Q000473:pathology*; D008437:Maxilla / Q000473:pathology*; D009295:Nasal Bone / Q000473:pathology; D009390:Nepal; D009967:Orthodontic Appliances; D012658:Sella Turcica / Q000473:pathology; D012690:Serial Extraction; D014087:Tooth Movement Techniques / Q000295:instrumentation; D055815:Young Adult