Stability of transverse maxillary dental arch dimensions following orthodontic-surgical correction of anterior open bites.

A sample of 130 patients with vertical maxillary hyperplasia; mandibular hypoplasia with a high mandibular plane angle; narrow, tapered maxillary dental arch form; and anterior vertical open bite were collected from three different institutions to evaluate the stability of transverse maxillary arch dimensions after correction of the open bite. Surgical treatment consisted of Le Fort I or bimaxillary osteotomies. Intermolar, interpremolar, and anterior arch widths were measured three-dimensionally on dental casts using a Reflex microscope, and transverse stability after orthodontic or surgical maxillary expansion was analyzed. Orthodontic expansion followed by a one-piece Le Fort I intrusion osteotomy was performed in 77 patients, and surgical maxillary expansion by a multisegment Le Fort I intrusion osteotomy was performed in 53 patients. The increase of transverse arch width and the relapse after orthodontic or surgical expansion were not significantly different. The transverse arch width in these two groups did not relapse in 20% of the patients after a mean follow-up of 69 months. An additional bilateral sagittal split osteotomy had no detectable effect on stability. Patients who underwent a multisegment Le Fort I osteotomy stabilized with rigid internal fixation showed better transverse stability than those with intraosseous wire fixation and maxillomandibular fixation. Maxillary intermolar and interpremolar arch width relapses were not correlated with tongue interposition or loss of interdigitation. The relapse of these arch widths showed significant correlations with clockwise rotation of the mandible but not with changes of overbite or overjet.