Stability of combined Le Fort I maxillary advancement and mandibular reduction

Background: There have been reports that correction of severe Class III abnormality by single jaw surgery may invite relapse in the long-term. The purpose of this study was to retrospectively evaluate the stability of combined Le Fort I maxillary advancement and bilateral sagittal split osteotomies for mandibular reduction.

Methods: Thirty patients with a skeletal Class III malocclusion underwent bimaxillary surgery using rigid fixation and inter-positional bone grafting of the maxilla. The average age was 24.4 years, and the mean follow-up period was 20 months (Range: 12–63 months). Post-operative changes were measured on lateral cephalometric radiographs using an anatomical best-fit technique.

Results: The maxilla was advanced, on average, 6.1 mm (SD: 1.8 mm) and repositioned superiorly at PNS 1.9 mm (SD: 2.1 mm). The mandible was repositioned posteriorly 5.6 mm (SD: 4.2 mm) at menton, which also auto-rotated superiorly. At follow-up, the maxilla relapsed horizontally 0.6 mm (SD: 1.1 mm, p < 0.01) with no significant vertical change. The maxillary central incisors were proclined and the interincisal angle was reduced. Menton relapsed anteriorly 1.4 mm (SD: 2.7 mm, p < 0.01), and gonion rotated superiorly 1.5 mm (SD: 2.3 mm, p < 0.001). In 67 per cent of cases menton moved anteriorly less than 2.5 mm. The overjet and overbite did not change significantly.

Conclusions: The data show that 12-months post-operatively, maxillary advancement combined with mandibular setback was relatively stable in the horizontal and vertical planes.