Hierarchy of surgical stability in orthognathic surgery: overview of systematic reviews

The purpose was to perform an overview of systematic reviews in order to create a hierarchical scale of stability in orthognathic surgery with the aid of the highest level of scientific evidence. The systematic search was conducted in the PubMed, Embase, and Cochrane Library databases. The grey literature was investigated in Google Scholar and a manual search was done of the references lists of included studies. Fifteen studies were included in the final sample, of which eight were systematic reviews and seven were meta-analyses. These were assessed for methodological quality using the AMSTAR 2 tool and all were considered to be of medium to high methodological quality. The clinical studies included in the 15 reviews and meta-analyses were classified by the review authors as having a moderate to high potential for risk of bias. The hierarchical pyramid of stability in orthognathic surgery was established, with two surgical procedures considered highly unstable: (1) maxillary expansion with semi-rigid internal fixation evaluated at the dental level in the posterior region, and (2) clockwise rotation of the mandible with rigid internal fixation of bicortical screws in the sagittal direction.