Stability of midface augmentation: an experimental study of musculoskeletal interaction and fixation methods

This study examined stability of vertical midface augmentation when different methods to alleviate potentially distracting muscles were used. Eighteen adult monkeys underwent Le Fort I osteotomy with interpositional bone grafts. One group had wire fixation of the maxilla and bone graft. A second group underwent a similar procedure with the addition of myotomies of the masseter and temporalis muscles. A third group wore a bite-opening appliance before downgrafting. A fourth group underwent downgrafting with rigid internal fixation. Serial cephalograms with the aid of bone markers were used to assess postsurgical change. The results showed that the animals who underwent rigid fixation had the most stable results, followed by the myotomy and bite-opening appliance groups. The animals who underwent wire fixation with no supplemental procedures had gross relapse, resulting in an average retention of only 15% of the surgical change by 12 weeks.