Influence of Monobloc/Lefort III Surgery on the Developing Posterior Maxillary Dentition and its Resultant Effect on Orthognathic Surgery.

BACKGROUND Timing of fronto-facial surgery for the syndromic craniosynostosis (SC) as it relates to various surgical risks has not been adequately studied. The purpose of this study was to investigate posterior dental complications of midface advancement in patients with SC undergoing surgery in different ages and the effects on subsequent orthognathic surgery. METHODS A retrospective chart review of patients with SC treated with midface advancement (mono-bloc or Lefort III) from 1999-2018 was carried. Patient demographics, records, imaging studies were reviewed. A sub-analysis of those patients who were also treated with OS in period 2014-2018 with imaging studies available for analysis was also performed. RESULTS 37 patients met the inclusion criteria. 64% of the patients had radiographic evidence of maxillary molar dental pathology. Older age at the time of surgery was significantly associated with a lower odds of sustaining dental injury (p=0.034, OR=0.55). The odds of damaging second or third maxillary molars was significantly higher with a younger age at the time of surgery (p=0.021 and p=0.034). The odds of sustaining dental injury increased moving posteriorly showing the risk of abnormal pattern of M3>M2>M1. Advanced age at time of surgery was significantly associated with decreased odds of dental injury (OR= 0.55, p = 0.034). CONCLUSION Damage to the developing permanent maxillary molars may affect orthodontic management, mastication, and potentially maxillary development. Delaying fronto-facial surgery till development of the permanent maxillary dentition should be considered if other indications do not mandate an earlier intervention.