Purpose: To answer 2 specific questions in relation to mandibular hypomobility after orthognathic surgery (OGS): 1) Is hypomobility after OGS permanent? 2) Is there any underlying mechanism?
Materials and methods: A Medline and PubMed search was performed to locate relevant articles. To meet inclusion in this review, articles were required to include patients with no pre-existing temporomandibular joint (TMJ) disorders who had been treated by the commonly performed OGS procedures. Case reports, pilot studies, and review articles were excluded. Twelve electronic search articles were identified. Manual search of the reference lists of these articles added another 11 articles.
Results: Of the 23 potentially relevant articles, 7 were considered eligible for inclusion. Five articles were retrospective and 2 were prospective. Vertical maxillary excess, Class II malocclusion, and Class III malocclusion were addressed in 344 patients who underwent Le Fort I maxillary osteotomy, sagittal split mandibular ramus osteotomy, or intraoral or extraoral vertical mandibular ramus osteotomy. Mandibular ramus surgeries were performed alone or in combination with Le Fort I osteotomy. Mandibular hypomobility, in terms of incisal range of motion, was measured with a ruler in 5 studies, with a Perspex triangular trismus gauge in 1 study, and with a jaw motion analyzer system in 1 study. Two studies reported permanent decreases in all ranges of mandibular motion 2 years after surgery and 5 studies did not support the notion that OGS affects mandibular mobility permanently. No mechanism for hypomobility after OGS was identified.
Conclusion: Mandibular hypomobility after OGS is still in need of long-term prospective studies with homogenous patient samples of dentofacial deformities and the same TMJ conditions treated by the same experienced surgeon with adequate follow-up, internal controls, and blinding of examiners.
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