Stability of large maxillary advancements using a combination of prebent and conventional plates for fixation

Objective The purpose of this study was to determine the stability of one and two jaw maxillary advancements fixed with prebent plates and “L”-shaped plates. Study Design Twenty-six patients met the inclusion criteria (group 1: one jaw [14]; group 2: two jaws [12]). Radiographs were digitized before surgery (T1), immediately after surgery (T2), at 6 weeks (T3), and at 6 months (T4). Stability was assessed comparing A-point movement and change in palatal plane. t tests were used for comparisons between groups, and linear regression analysis was used to assess the stability of A-point T2-T4 versus A-point movement T1-T2 and changes in the palatal plane T1-T2. Results Initial A-point movement between the two groups was significant (group 1 = 7.61 ± 1.73; group 2 = 5.22 ± 1.67) (P = .0002). Both showed relapse (group 1 = 0.78 ± 0.95; group 2 = 0.04 ± 0.49). Although there was no significant relationship between initial A-point movement and relapse, there was a significant negative relationship between change in palatal plane and relapse in group 1. When initial A-point movement and change in palatal plane were combined, as both increased, relapse also increase (P = .007; R2 = 0.41). Conclusions Prebent plates used with “L” plates are a stable fixation technique. Relapse increases with large advancements and change in palatal plane (posterior impaction).