Positional Changes of the Maxillary Permanent Canines After Treatment with Facemask and Hyrax: A retrospective cohort study.

Background: Early treatment of Class III malocclusion in growing patients remains a significant orthodontic challenge due to unfavorable growth patterns. This study evaluates the positional changes of the maxillary permanent canines (Mx3) and the first maxillary permanent molars (Mx6) after early treatment of Class III malocclusion with maxillary expansion and protraction (MEP).

Material and methods: A retrospective cohort study was conducted, including a longitudinal and panoramic radiographic (panorex) analysis. Forty-one Class III patients with maxillary hypoplasia (25 females, 16 males) treated in mixed dentition with MEP were compared to an untreated control group of 41 patients (23 females, 18 males). Positional changes of Mx3 were assessed using panorex. Angulation and sectional location of Mx3 were classified according to Power & Short (PS), the Lindauer modification of Ericson & Kurol (L), and Warford (W).

Results: No statistically significant differences were found in the PS and W analyses or in the height of Mx3 between the initial and final evaluations. The L analysis indicated that most Mx3 were located in sectors I and II. Some Mx3 in sector II progressed toward sector I. No Mx3 in the treated group had a poor prognosis, compared to only 3.7% in the control group. Most Mx3 maintained their L prognosis, with improvement observed in 22% of the control group and 29.3% of the treated group. The majority of Mx3 in the final evaluation had a favorable prognosis.

Conclusions: The results indicate that MEP treatment does not cause unfavorable positional changes in Mx3 or Mx6 in these patients. Key words:Malocclusion, Angle Class III, Palatal Expansion Technique, Extraoral Traction Appliances, Child, Maxillary Permanent Canine, Diagnosis.