A comparison of Class II open bite correction by maxillary or mandibular surgery

The purpose of this study was to compare treatment outcomes for anterior occlusion and vertical skeletal stability after maxillary or mandibular surgery for correction of Class II malocclusion with a mild to moderate open bite.

The records of 57 consecutive patients were retrieved; 30 had undergone 1-piece Le Fort I osteotomy, and 27 had undergone a bilateral sagittal split osteotomy (BSSO), without additional surgery. Lateral cephalograms at 6 stages were available (pretreatment to 3 years postsurgery).

After the surgery, 87% of the Le Fort I patients and 63% of the BSSO patients had a positive overbite, and at the 6-month follow-up, the percentages were 90% and 74%, respectively. At 3 years after surgery, 74% of the Le Fort I patients and 42% of the BSSO patients had a positive overbite. The anterior facial height decreased in the Le Fort I subsample and increased in the BSSO subsample, and the mandibular plane angle decreased in both. The Le Fort I subsample generally remained stable, whereas clinically significant relapse of the mandibular plane angle (≥2°) occurred in 80% of the BSSO subsample.

When taking into account the limitations of retrospective clinical studies, several conclusions can be drawn. A significant improvement of the anterior occlusion can be expected in most patients when either maxillary or mandibular surgery is used for correction of Class II open bite. However, there will be individual patients in whom considerable posttreatment changes occur in both the anteroposterior and vertical dimensions. Although individual morphology needs to be taken into account, it seems that both short- and long-term stability are likely to be greater after Le Fort I surgery compared with BSSO.