Outcome study of computer-aided surgical simulation in the treatment of patients with craniomaxillofacial deformities.

PURPOSE: The purpose of this study was to determine whether the surgical outcomes achieved with computer-aided surgical simulation (CASS) are better than those achieved with traditional methods. MATERIALS AND METHODS: Twelve consecutive patients with craniomaxillofacial (CMF) deformities were enrolled. According to the CASS clinical protocol, a 3-dimensional computer composite skull model for each patient was generated and reoriented to the neutral head posture. These models underwent 2 virtual surgeries: 1 was based on CASS (experimental group) and the other was based on traditional methods 1 year later (control group). Once the 2 virtual surgeries were completed, 2 experienced oral and maxillofacial surgeons at 2 different settings evaluated the 2 surgical outcomes. They were blinded to the planning method used on the virtual models and each other's evaluation results. The primary outcome was overall CMF skeletal harmony. The secondary outcomes were individual maxillary, mandibular, and chin harmonies. Statistical analyses were performed. RESULTS: Overall CMF skeletal harmony achieved with CASS was statistically significantly better than that achieved with traditional methods. In addition, the maxillary and mandibular surgical outcomes achieved with CASS were significantly better. Furthermore, although not included in the statistical model, the chin symmetry achieved by CASS tended to be better. A regression model was established between mandibular symmetry and overall CMF skeletal harmony. CONCLUSION: The surgical outcomes achieved with CASS are significantly better than those achieved with traditional planning methods. In addition, CASS enables the surgeon to better correct maxillary yaw deformity, better place proximal/distal segments, and better restore mandibular symmetry. The critical step in achieving better overall CMF skeletal harmony is to restore mandibular symmetry.

A novel occlusographic analysis for assessment of mandibular narrowing.

Accurate evaluation of transverse mandibular dimension is a controversial and rarely addressed topic. Although mandibular narrowing via symphyseal osteotomy and bilateral ramus sagittal split was initially described more than 30 years ago, the development of a simple and effective clinical tool to assess the outcome of such procedures remains elusive. Although many quantitative modalities, such as frontal cephalogram, tomography, and interdental distance measurement, are in current use, each possesses significant liabilities. Prompted by a need for improved accuracy, simplicity, and reliability in the clinical setting, we developed and used a novel occlusographic analysis. The Madjidi occlusographic analysis does not rely on the position or tilt of moveable teeth; therefore, orthodontic changes do not influence quantification of mandibular position. Contours and mandibular relationships of interest are seen clearly, radiation is unnecessary, and occlusographic analysis can be quickly reproduced in the clinical setting using widely available materials. Although the evaluation of transverse mandibular dimension after surgical narrowing is frequently more controversial than accurate, the Madjidi occlusographic analysis is a reliably simple solution to an often complex problem.

Distraction rate and latency: factors in the outcome of pediatric mandibular distraction.

BACKGROUND: Distraction osteogenesis was initially devised as a way to lengthen the lower extremity. All the basic tenets of the technique were developed based on this use. This includes both the supposed need for a latency period before distraction begins (3 to 5 days) and the ideal rate of distraction (1 mm/day). There is no evidence that these values apply to craniofacial distraction osteogenesis, particularly in children. Indeed, with the markedly improved blood supply in the face when compared with the lower extremity and the use of the technique in children versus adults, one might assume that a shorter latency period and a more rapid rate of distraction are possible. METHODS: This study is a retrospective review of 22 pediatric patients with mandibular hypoplasia undergoing mandibular distraction osteogenesis. All patients were operated on by a team consisting of an oral surgeon and a plastic surgeon. All the distraction devices used were external. All patients had a latency period, before activation, of less than 24 hours and a distraction rate of 2 mm/day. RESULTS: Two patients developed cellulitis at the pin sites, one patient developed premature healing, one patient developed a nonunion that required further surgery. This was the only patient in the series who had distraction of a previous bone graft. No patient undergoing distraction of native mandible developed a nonunion. CONCLUSIONS: Eliminating the latency period and rapidly distracting the mandible in pediatric cases has an acceptably low complication rate. This benefits the patient in terms of an overall reduction in the amount of time that the child needs to remain in the distraction device. The patient spends less time with the distraction device, thus reducing the potential morbidity and increased cost of the treatment. Potential explanations for why this variation in distraction technique is successful include the improved blood supply in the face of children and the failure of external devices to translate all the distracted movements to the bone interface. Some of this force is translated into both bending of the pins and migration of the pins through bone. Although a latency period might be necessary in the distraction of the lower extremities, the application of this concept to the craniofacial skeleton in children is erroneous.