Faculty Bibliography

BACKGROUND: It is essential to critically assess bone deposition in midface distraction. The aim of this study was to characterize the quality and volume of bone deposition at specific osteotomy sites following midface distraction. METHODS: At approximately 6 months after distraction, computed tomographic scans with three-dimensional reconstruction were obtained on 10 craniosynostosis syndromal patients who had undergone LeFort III osteotomy and midface distraction. Patient age ranged from 37 to 109 months (mean, 63.7 months) and the distractions ranged from 7 to 15 mm. Both the reconstructed scans and axial cuts were independently evaluated by four blinded observers (two plastic surgeons, an orthodontist, and a radiologist) and graded for bone deposition in predetermined anatomical sites correlated to the osteotomy. RESULTS: The authors found that variable bony bridging occurred at all sites along the osteotomy, but bone deposition was most reliably seen at the pterygomaxillary buttress and nasofrontal junction. In addition, the medial orbital walls tended to show greater consistency in bone deposition than the lateral orbital walls, and deposition at the zygomatic arches was shown to be least likely to occur. The technique of evaluation and the clinically significant findings are discussed. CONCLUSIONS: Bony deposition occurs more reliably in the medial facial skeleton following LeFort III osteotomy, and osteotomy through the zygomatic body was more likely to result in deposition than one through the arch

The purpose of this study was to examine mandibular morphology and growth in patients with Crouzon, Pfeiffer, and Apert syndromes using posteroanterior cephalograms. Fifteen patients with Apert (n = 2), Crouzon (n = 11), and Pfeiffer (n = 2) (11 female, 4 male) syndrome were included in this study. All patients had serial posteroanterior cephalograms at 5, 10, and 15 years of age. The bicondylar width, bigonial width, bicondylar/bigonial ratio, and ramus to intercondylar plane angle for each patient were measured on the cephalograms and compared with age-match controls. An analysis of variance analysis was carried out to detect differences between patients and controls and sex differences between patients. In both male and female patients, there was a statistically significant reduction in bicondylar width compared with age-matched controls. Male patients also had a statistically significant increase in bigonial width compared with controls and female patients at 10 and 15 years. The resulting bicondylar/bigonial ratios were significantly reduced, and the ramus to intercondylar plane angles were significantly increased in both male and female patients compared with controls. Unlike previous reports of patients with syndromic synostosis, this study demonstrates that the mandible has significant morphologic and growth abnormalities, including constriction of bicondylar width with near normal bigonial width in female patients. These findings suggest a narrowing at the cranial base with resulting restriction of normal transverse mandibular growth at the condyle. The secondary nature of the mandibular finding is suggested by the near normal or increased transverse growth at the gonion in females and males, respectively. Consequently, the ramus appears torqued inward, forming a greater angle with the cranial base.

BACKGROUND: The purpose of this study was to evaluate long-term mandibular skeletal stability and growth following unilateral mandibular distraction in growing children. METHODS: This retrospective longitudinal study of 12 consecutive patients with unilateral craniofacial microsomia who underwent mandibular distraction had a range of 5 years of postdistraction follow-up; five patients were followed for 10 years. Records included clinical photographs, dental study models, lateral and posteroanterior cephalograms, and panoramic radiographs obtained before distraction, at the time of device removal, and 1, 5, and 10 years after distraction. The mean patient age at the time of distraction was 48 months. The device was activated an average of 21.7 mm at the rate of 1 mm per day. The mean latency period was 6.1 days, and the mean consolidation period was 60.6 days. Fifty-two parameters were examined at each of the five time intervals. RESULTS: On average, the ramal length (condylion to gonion) increased 13.04 mm in the distracted rami. At 1 year after distraction, this dimension decreased by 3.46 mm. At 5 and 10 years after distraction, the average condylion-gonion dimension increased by 3.83 and 4 mm, respectively, with an average growth rate of 0.87 mm per year; during the same period, the unaffected ramus grew 1.15 mm per year. CONCLUSIONS: The distraction technique does not eliminate the inherent growth potential of the affected mandibular side. Facial asymmetry is significantly improved after distraction, and despite mild relapse observed during the first year, surgical correction is stable in the later years of follow-up

We present a 26-year-old patient with juvenile-onset arthritis, Alagille's syndrome, micrognathia, and progressive sleep apnea. Despite the presence of significant temporomandibular joint pathology, mandibular distraction was indicated to correct life-threatening sleep apnea. Before distraction, the patient had only 10 mm of maximal interincisal opening and bilateral temporomandibular joint symptomatology. After distraction, the patient's sleep apnea resolved. There was slight improvement in her maximal incisal opening (12 mm) with neither exacerbation nor improvement of her temporomandibular joint symptomatology

The purpose of this retrospective study was to evaluate the extent to which an early Le Fort III osteotomy affects the position and eruption of the permanent maxillary first and second molars. To test the null hypothesis that there are no changes in eruption patterns, 31 patients diagnosed with craniosynostoses (13 with Crouzon's syndrome, nine with Apert's syndrome, eight with Pfeiffer's syndrome, and one with Carpenter's syndrome) with a mean age at the time of surgery of 5.3 +/- 1.3 years were studied. All patients underwent a Le Fort III osteotomy performed by a single surgeon to correct the anatomical deformity for functional and psychosocial reasons. Eighteen patients with craniosynostoses who had not been operated on (11 with Crouzon's syndrome, four with Apert's syndrome, and three with Pfeiffer's syndrome) served as controls; they had a mean age of 21.2 +/- 9.5 years. First and second molar positions and eruption patterns were assessed separately on panoramic radiographs by three observers. For the patients who underwent surgery, long-term evaluation showed that although 79 percent of all first molars erupted compared with 100 percent for the control group (p < 0.001), only 18 percent of all second permanent molars erupted compared with 89 percent for the control group (p < 0.0001). The authors conclude that in a significant minority of cases, early Le Fort III osteotomy affects first molar eruption, whereas the probability of second molar eruption is significantly decreased in the majority of cases. Therefore, Le Fort III osteotomy sites should be positioned distal to the second molar tooth buds. If this is not possible, patients, parents, and dental professionals should be made aware of these early postosteotomy sequelae so that later treatment planning can be enhanced.

The mandibles of five patients who underwent unilateral or bilateral distraction osteogenesis were analyzed using computed tomography scans. The mandibles were reconstructed in three dimensions using General Electric computed tomography software. The total volume of each hemimandible was determined before and after distraction and compared. The mandibles were then segmented at 1-cm intervals, and the volumes of the segments were determined. The volumes of the mandibular segments before and after distraction were compared to determine the distribution of new bone through the mandible and the quantity of bone generated by distraction. The distracted hemimandibles increased in total volume by an average of 19.9% (statistically significant by the Student paired t test; P < 0.0001), whereas the nondistracted hemimandibles increased in total volume by an average of 5.2%. The segmental volumes of the distracted mandible were of similar or greater volume when compared to the preoperative mandibular segments. In addition, the distribution of regenerate bone mirrored the physiological distribution of the preoperative mandibular bone. This study indicates that distraction not only creates new bone but distributes that bone through the remodeled mandible in an anatomical pattern similar to that of the preoperative bone