A study on the skeletal changes in maxillary protraction of the skeletal Class III malocclusion patients

Lee, Young Ji; Cha, Kyung Suk; Lee, Jin Woo

Abstract

A Skeletal Class III malocclusion may be the result of a large mandible, a small maxilla, or combination of the two. Prot_action devices for the maxilla are used to promote the growth of a deficient maxilla by applying extraoral force to actively growing patients. This study has been performed to determine whether there are significant differences in skeletal and dental changes between FR/Pal 1 and FH/Pal 2 group, SNA 1 and SNA 2 group, SNB I and SNB 2 group, and LFH 1 and LFH 2- group after RME and facial mask therapy. The results of this study can be summarized and concluded as follows; 1. In all patients after maxillary protraction, the maxilla and maxillary dentition moved forward, and the mandible rotated backward and downward. In most of them, palatal plane is tends to have an upward inclination. 2. The FH/Pal group 1, having an upward inclination of the palatal plane as a result of Facial mask, showed statistically significant maxillary forward movement compared to the FH/Pal group 2. 3. The SNA group 1 showed significantly less mandibular backward movement and there was a tendency for the palatal plane to upward inclination compared to SNA group 2. 4. The SNB group 1 showed significantly less maxillary forward movement, but the vertical dimension, especially the lower facial height increased by mandibular downward rotation compared to SNB group 2. 5. LFH group 1, which had large saddle angle and posterior positioned mandible in the pre-treatment stage, showed maxillary protraction effect without significant increase in lower facial height compared to LFH group 2.