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).