The effect of retraction of anterior teeth on the point A in patients submitted to corrective orthodontic treatment

Tien LI AN, Osmar Aparecido CUOGHI, Marcos Rogério de MENDONÇA, Francisco Antonio BERTOZ

Objective: it was aimed to evaluate the effect of retraction of anterior teeth on the point A sagittally and vertically, as well as the correlation and the predictability of the behavior of these structures. Methods: sixty lateral cephalograms were used, which were taken at the beginning and at the end of fixed appliance orthodontic treatment, from thirty patients (22 female and 8 male) aging from 10 to 17 years at baseline, with Class II, Division 1 or Class I malocclusion, who underwent four first premolars extractions or maxillary first premolars extractions only. Besides the variables 1.NA, 1-NA, U1/PP and U1 AVERT, horizontal and vertical linear measurements were made in relation to a horizontal reference line constructed from the S-N plane minus 7o and its perpendicular. As distributed normally, all the data were measured twice, and the mean values were submitted to paired t test, linear correlation and regression tests. Results: in average, point A retracted 0.71mm and moved 2.38mm downwardly, following 1.03mm of root apex and 4.13mm of incisal edge retraction, and 2.35mm of tooth extrusion. The retraction of point A was positively correlated with root apex (r = 0.75; p < 0.0001) and with incisal edge retraction (r = 0.70; p < 0.0001), showing a predictable sagittal behavior. Conclusions: it was concluded that point A retracted and moved downwardly following the tooth, and the retraction of point A in relation to the incisors was predictable.

Keywords: Cephalometrics. Tooth extractions. Tooth movement.

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