Stepwise versus single-step mandibular advancement with functional appliance in treating class II patients A meta-analysis

Background Difference in the functional orthopedic effect between stepwise mandibular advancement (SWA) and single-step mandibular advancement (SSA) in Angle class II patients remains unclarified. Objective To compare the treatment effects of SWA and SSA on skeletal and dentoalveolar changes in class II patients. Methods Randomized controlled trials (RCTs) and nonrandomized studies that compared differences in skeletal and dentoalveolar effects on class II patients between SWA and SSA were identified in PubMed, Embase, CENTRAL, and Web of Science. The grey literature was also searched. The primary outcomes were the mandibular length, L1-MP, and (ANB). Secondary outcomes included Pog sagittal, SNB, overjet, and mandibular plane angle. Results Seven studies, including three RCTs and four cohort studies, were retrieved. Meta-analyses revealed pooled mean differences (95% confidence interval) of 0.79 & x202f;mm (0.45 to 1.12 & x202f;mm) for Pog sagittal, 0.53 degrees (0.19 to 0.87 degrees) for SNB, -0.51 degrees (-0.83 to -0.20 degrees) for ANB, -0.17 degrees (-0.72 to 0.39 degrees) for the mandibular plane angle, -0.41 & x202f;mm (-0.90 to 0.09 & x202f;mm) for overjet, -1.87 degrees (-3.23 to -0.52 degrees) for L1-MP, and 1.03 & x202f;mm (0.63 to 1.42 & x202f;mm) for the mandibular length. Publication bias was not observed, except for Pog sagittal. The quality of evidence for each outcome was judged as low (mandibular length, SNB and overjet) and very low (Pog sagittal, ANB, L1-MP and mandibular plane angle). Conclusions Although the magnitude of differences in clinical practice was limited, SWA might be more appropriate because it produces a greater skeletal change and less dental compensation than SSA. As the level of current evidence is low, more high-quality RCTs are needed.