Root contact with maxillomandibular fixation screws in orthognathic surgery: incidence and consequences

The use of maxillomandibular fixation (MMF) screws in orthognathic surgery has become common in recent years. The risk of injury to adjacent roots with their placement in this population has not been studied extensively. The aim of this study was to review the incidence and consequences of root contact/injury in patients undergoing orthognathic surgery. A retrospective analysis of the treatment and radiographic records of patients who underwent orthognathic surgery between January 2013 and September 2014 at a university in Kentucky, USA was performed. The mean number of screws used was correlated to the mean number of roots affected using Spearman's test, set to a level of significance of 5%. Of 125 patients who underwent orthognathic surgery, 15 (12%) had evidence of root contact. Subsequent radiographs showed resolution of the bone defects. There was no clinical evidence of pulpal necrosis or pain during follow-up. The average number of screws used was 3.14±0.35 per patient, with an average of 0.17±0.52 root contacts per patient. There was no correlation between the number of screws used and the number of roots injured (P=0.279). Based on these results, MMF screws can safely be used to establish interim fixation during orthognathic surgery. Caution should be taken during placement to avoid direct injury to the roots of teeth.