Sagittal changes after maxillary protraction with expansion in class III patients in the primary, mixed, and late mixed dentitions: a longitudinal retrospective study.Am J Orthod Dentofacial Orthop 2000; 117(6):669-80AJ
The purpose of this study was to determine the sagittal response of Class III patients in the primary, mixed, and late mixed dentition phases fitted with a protraction mask and expansion. The before-and-after cephalometric records of 112 patients divided by gender were analyzed at age groups 3 to 6, 6 to 9, and 9 to 12 years to assess the maxillary, mandibular, and intermaxillary sagittal changes. Data were correlated by means of paired t tests and Scheff¿e multiple contrasts. The study showed: (1) descriptive statistics and the before-and-after results in males and females in the different age groups; (2) the changes in males and females, disregarding age; and (3) the changes at the different ages, disregarding gender. Results show no significant differences between males and females in most of the angular and linear measurements at different ages. Greater significant changes were seen in patients treated in the primary and mixed dentition phases. Females showed highly significant changes in most linear and angular measurements between the ages of 3 and 6 years (P <.0001) compared with males (P <.05) at the same age. Significant changes were seen in the angle between the anterior part of the maxilla and the base of the skull (SNA), the maxillary depth, and the facial convexity angles, being more active in females than males. In contrast, the angle between the anterior part of the mandible and the base of the skull (SNB) showed no significant changes in all age groups, with the exception of males between 3 and 6 years. Even if correction can be achieved in all age groups, we recommend that treatment be started as soon as the diagnosis is made and cooperation allows for it. Young patients show greater and faster results in less time. Esthetics are greatly enhanced, compliance is improved, and the possible psycho-social scars can be greatly reduced.