Stability of maxillary surgery in openbite versus nonopenbite malocclusions

Lateral cephalometric radiographs were evaluated to determine the posttreatment stability of 66 patients treated with LeFort I osteotomies to reposition their maxillae superiorly. The sample was divided into three groups based on the degree of pretreatment overbite: openbite subsample--no incisal overlap; overlap subsample--incisal overlap and no incisal contact; contact subsample--incisal overlap with incisal contact. The cephalograms were superimposed and linear measurements were made at each interval (pretreatment, posttreatment, and at least one year posttreatment). The results clearly show that the three subsamples reacted differently during the posttreatment interval. 42.9 percent of the subsample with pretreatment openbite showed a significant increase in facial height, significant eruption of maxillary molars, and a significant decrease in overbite. 28.6 percent of the openbite subsample and 16.7 percent of the overlap subsample showed a significant increase in facial height, significant eruption of maxillary incisors, and no change in overbite. The contact subsample had no significant posttreatment changes. Possible reasons for the posttreatment instability in the openbite subsample are proposed.