Angle class II correction : stepwise mandibular advancement or bite jumping?: A systematic review and meta-analysis of skeletal, dental and condylar effects

Abstract

Introduction: There is no consensus regarding which mode of activation or mandibular advancement (stepwise [SW] or maximum bite-jumping [BJ]) of fixed or removable functional appliances (FFA; RFA) for correction of Angle class II malocclusion is advantageous to produce dental, skeletal or condylar effects and has the lowest rate of undesired dental or technical side-effects. Methods: A systematic search was conducted up to Oct. 20, 2019 in the MEDLINE, EMBASE, Scopus, Central Cochrane Library, and BBO databases. Included were preadolescent, adolescent, and adult humans with initial (pretreatment) Angle class II malocclusion, without further restriction. The intervention group was composed of subjects treated with FFA or RFA in SW mandibular advancement; the control group received BJ advancement. Search terms included prospective randomized and nonrandomized trials in English, German, Spanish, and Portuguese with the primary outcomes of skeletal and dental class II correction, effects on condylar growth, lower incisor proclination, overjet and overbite reduction. The risk of bias (ROB) was assessed using the Cochrane Collaboration’s ROB2 tool. Mean differences were calculated and pooled by a meta-analysis using a random effects model. Results: Data from five randomized controlled trials (RCT) with 401 participants (mean age 13.84 years; SD 1.53) were included; 331 derived from four studies were included in the meta-analysis. The ROB in the selected articles was high. We detected a slightly increased reduction of the ANB (mean difference [MD] −0.95°, 95% confidence interval [CI] −1.80 to −0.10°; I2 = 72%) that may be attributed to a slightly more pronounced increase of the SNB angle in SW-advanced mandibles (MD 0.27°; 95% CI −0.47 to 1.00°; I2 = 38%). SW advancement tended to reduce the undesired side effect of lower incisor proclination (MD = −1.59°; 95% CI −3.98 to 0.8°; I2 = 0%), indicating more pronounced mandibular incisor changes with bite-jumping advancement. Conclusion: There is weak evidence indicating a slightly increased reduction of the ANB and less lower incisor proclination with SW advancement compared to BJ, but the clinical relevance is debatable due to the small overall magnitude and small number of high-quality papers. Registration: Prospero #CRD42017075469 (www.crd.york.ac.uk/prospero).