Evaluation of post-surgical relapse after mandibular setback surgery with minimal orthodontic preparation

BackgroundThe aim of this study was to evaluate of the patterns of post-surgical relapse after mandibular setback surgery with minimal orthodontic preparation (MS-MO).Materials and methodsThe subjects consisted of 15 patients with minimal pre-surgical orthodontic preparation (1.37 ± 1.69 months). Lateral cephalograms were taken in pre-surgical (T0), post-surgical 1 month (T1) and immediately after debonding (T2) stages. To evaluate the surgical changes (T1–T0) and the relapse (T2–T1), the linear and angular measurements were analyzed using paired t-test. Pearson's correlation coefficients of the horizontal and vertical relapses of Pog and Me to other measurements were calculated. Pog or Me in T1 were displaced rotationally on Ar-Pog or Ar-Me lines in T2 to evaluate the remaining surgical relapse except the rotational relapse from total relapse.ResultsThe mandible relapsed anteriorly 3.53 mm (Pog) and 4.00 mm (Me) and superiorly 2.72 mm (Pog) and 2.44 mm (Me). FH to Ar-Pog and FH to Ar-Me decreased by about 2°. Pure surgical relapses at Pog and Me, except rotational relapses, were about 0.5 mm anteriorly and inferiorly 0.8 mm.ConclusionThe vertical relapse might induce mandibular rotation with the horizontal relapse. For an accurate prediction after MS-MO, the rotational relapse might be considered.