Objectives:

This cephalometric study intended to evaluate pre-surgical changes in cephalometric variables on the lower third of the face produced by the orthodontic treatment, in patients with severe Class III malocclusions.

Methods:

The sample included 40 adults, divided into three groups: no-extractions (N), extractions for orthodontic reasons (E), and previous extractions for non-orthodontic reasons (E-NO). Student t-tests were used to evaluate the influence of orthodontic treatment on the cephalometric variables. An ANOVA was used for group comparisons before treatment and to compare the changes produced by the orthodontic treatment in the three groups. The significance level was established at 5%.

Results:

In Group E, significant (p<0.05) retraction and retroclination of the upper incisors were observed. The lower incisors proclined in all the three groups and protracted in Groups N and E-NO. The upper incisor remained proclined in Group N, and the lower incisor retroclined in Group E-NO. There was a clockwise rotation of the mandible, with an increase in total and inferior facial heights, in both the extraction groups. The upper molars advanced in all groups.

Conclusions:

1) The SNA angle decreased due to point A retraction in Group E. 2) Mandibular clockwise rotation led to increased total and inferior facial heights, in both the extraction groups. 3) Extractions facilitated incisor decompensation in Group E. 4) After treatment, the lower incisors remained retroclined in Group E-NO, due to an exaggerated initial retroclination.

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