Title Mandibular Setback Orthognathic Surgery Has the Potential to Lead to Similarly Stable Surgical Outcomes as Bimaxillary Surgery
Clinical Question For patients skeletal Class III malocclusion does mandibular setback orthognathic surgery lead to a more stable outcome compared to bimaxillary surgery?
Clinical Bottom Line In the short term and long term, mandibular setback surgery could potentially be as stable as bimaxillary surgery in patients with skeletal class III surgery patients, but additional clinical evidence is needed, especially prospective studies, to validate the results.
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
33305502Rizk/20219 studies/582 participants aged 17-40 years Systematic review of non-randomized trials
Key resultsBased on cephalometric analysis of skeletal measurements, both mandibular setback (one-jaw surgery) and bimaxillary surgery (two-jaw surgery) lead to comparable results in terms of stability of short-term and long-term outcomes. Sagittal skeletal landmarks such as A point (MD: 0.44 mm; 95% CI −0.03 to 0.92), B point (MD: 0.14 mm; 95% CI −0.55 to 0.84), and ANB angle (MD: 0.12 degrees; 95% CI −0.44 to 0.69) all showed no statistical difference in terms of stability outcomes. Greater overjet relapse was observed in the patients receiving only mandibular setback in the short term (MD: -0.40 mm; 95% CI -0.77 to -0.04), but no significant difference was found in the long term (MD: 0.18 mm; 95% CI −0.44 to 0.80).
Evidence Search Orthognathic Surgical Procedures AND malocclusion AND Stability AND (Mandibular Setback OR 1 Jaw) AND (Bimaxillary or 2 Jaw) AND Cephalometry AND Orthodontics
Comments on
The Evidence
This study is the most recent systematic review addressing the topic and includes the most updated publications. Study selection was carried out by two reviewers with a third acting as a mediator to the selection process. Searches were made across six electronic databases (Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Scopus, LILACS and Web of Science) until October 2020 with no limitations on publication date, language utilized, or study design. Articles were assessed for risk of bias with Downs and Black Quality Assessment Checklist which contains 5 domains: power, confounding and selection bias, internal validity, external validity, and reporting bias. The domains were scored, and articles were assessed into categories excellent (26-28), good (20-25), fair (14-19) and poor (less than 14). For this systematic review, articles were determined to range from very low to moderate quality, scoring between 11 and 19 points, signifying an increased chance of bias within the studies that could potentially affect the conclusion. Additionally, only 2 of the studies reported a sample size calculation. The low quality of the studies is attributed to the study designs (retrospective cohort studies). Moderate to substantial heterogeneity was observed between studies assessing the short-term stability of sagittal skeletal measurements of ANB angle (Chi squared=P value 0.09 and I2=53%) and A point (Chi squared=P value 0.02 and I2=71%). Additionally, 8 of the 9 studies included in this systematic review were retrospective cohorts. Retrospective studies often don’t have data or don’t control for confounding factors. In this case some confounding factors could be cephalometric tracing variability/errors. More extensive research designs such as randomized controlled trials for these procedures lead to ethical consideration based on individualized patient needs. Further prospective cohort studies should be evaluated. Based on the heterogeneity of the data used in this study and the risk of bias, the clear answer to the question seems uncertain.
Applicability The general hierarchy of stability established by William Proffit states that mandibular setback surgery alone leads to a less stable outcome for surgical correction of skeletal class III malocclusion than a two-jaw surgery. All orthognathic surgery patients will likely experience some degree as relapse in the short-term following surgery as the osteotomy site heals, but this is dependent on direction of movement, the distance of the movement, technique, and the fixation used. The results of this systematic review imply that patients receiving mandibular setback will have the same stability as patients who underwent a two-jaw surgery. Undergoing orthognathic surgery is an invasive and intense procedure that can lead to numerous benefits. For patients knowing that they will be able to correct their skeletal malocclusion without the need of involving an additional jaw could affect patient’s perceptions pre-surgery and post-surgery, and thus their quality of life.
Specialty (Oral Surgery) (Orthodontics)
Keywords Le Fort Osteotomy; class III malocclusion; mandibular osteotomy; orthognathic surgical procedures; relapse; stability; systematic review.
ID# 3487
Date of submission 12/02/2021
E-mail glesener@live.unc.edu
Author Tim Glesener
Co-author(s) Anne-Isabelle Foucher
Co-author(s) e-mail foucher@livemail.uthscsa.edu
Faculty mentor Dr. Ravi Anthony
Faculty mentor e-mail ANTHONYR@uthscsa.edu
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
None available
Comments and Evidence-Based Updates on the CAT
None available