Postsurgical growth changes in the mandible of adolescents with vertical maxillary excess growth pattern.

This case-control study investigates the effects of superior maxillary repositioning by LeFort I osteotomy on adolescent mandibular growth. A total of 15 growing patients (average age, 12.8 years) with vertical maxillary excess who had undergone maxillary surgery were compared with matched untreated control subjects. Lateral cephalograms were evaluated and superimposed to describe the presurgical (1.6 years), surgical, and postsurgical (4.0 years) changes. During the presurgical period, comparisons of traditional measures and mandibular modeling changes showed no significant differences between the 2 groups. During surgery, the maxilla was impacted approximately 3 mm anteriorly and 1 mm posteriorly, which caused a 3.2 degrees autorotation of the mandible. During the postsurgical period, there was no change in the vertical growth pattern of the surgical patients, with the vertical facial heights increasing the same as the control subjects and the mandible rotating backwards. Although there was no inhibition of mandibular growth in the patients postsurgically, there was a decrease in horizontal maxillary growth compared with control subjects. There were clear postsurgical changes in the mandibular modeling and condylar growth, which were indicative of adaptive compensations for surgical mandibular repositioning and autorotation. It is concluded that early maxillary impaction does not normalize or inhibit the vertical maxillary excess growth pattern; mandibular modeling and condylar growth undergo adaptive changes in response to repositioning.