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 interpositional 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 ISD: 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.
Arpornmaeklong
Premjit
P
Oral and Maxillofacial Surgery Unit, School of Dental Science, University of Melbourne and Royal Children's Hospital, Parkville, Melbourne, Victoria, Australia.
Shand
Jocelyn M
JM
Heggie
Andrew A
AA
D000293:Adolescent; D000328:Adult; D001860:Bone Plates; D016025:Bone Transplantation; D001864:Bone Wires; D002508:Cephalometry; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008313:Malocclusion, Angle Class III / Q000601:surgery; D008334:Mandible / Q000601:surgery*; D016555:Matched-Pair Analysis; D008437:Maxilla / Q000601:surgery*; D010027:Osteotomy / Q000379:methods*; D019340:Osteotomy, Le Fort; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012399:Rotation