Long-term stability of Class III treatment: rapid palatal expansion and protraction facemask vs LeFort I maxillary advancement osteotomy.Am J Orthod Dentofacial Orthop 2007; 131(1):7.e9-19AJ
The aim of this retrospective cephalometric study was 3-fold: (1) to compare the effects and long-term stability of protraction facemask treatment with untreated Class III controls, (2) to compare the long-term stability of early protraction facemask treatment with later surgical maxillary advancement with LeFort I osteotomy, and (3) to determine whether early intervention with protraction facemask is an effective treatment modality or whether surgical treatment after cessation of growth should be advocated.
The sample consisted of 34 consecutively treated white patients with Class III malocclusions characterized by maxillary deficiency. The protraction sample consisted of 17 children (8 boys, 9 girls). The surgical sample consisted of 17 adults (10 men, 7 women). The protraction group was also compared with a control group of white subjects with untreated Class III malocclusions. Lateral cephalograms were taken at T1 (initial records), T2 (end of functional appliance treatment or 2 weeks postsurgery), and T3 (7 years 6 months postprotraction or 1 year 5 months postsurgery). Means and standard deviations were calculated for descriptive cephalometric measurements. ANOVA was used to assess the differences between and within the protraction and surgery groups at T1, T2, and T3. The Tukey studentized range test was performed to determine the source of the difference. In addition, paired t tests were used to compare the differences between the protraction group and the matched controls as well as between the surgery group and the matched controls.
In the protraction group, there was continued favorable growth of the maxilla, even after the removal of the protraction facemask. From T2 to T3, the maxilla continued to move anteriorly in the protraction patients more so than in the control groups, which had decreases in the intermaxillary measurements (ANB angle and Wits appraisal) over time. The surgical group remained stable from T2 to T3 in all measurements studied.
The most striking findings of this study were the general similarity between the protraction and the surgical groups at T3 and the overall stability of both treatment modalities over time.