Faculty Bibliography

BACKGROUND: This article aims to assess the spectrum of unfavorable events or incidents encountered during mandibular distraction and to evaluate the difference in the incident rates among the following treatment groups: (1) native bone distraction using an external device, (2) native bone distraction using an internal device, and (3) grafted bone distraction using an external device. METHODS: This retrospective study examined the records of 141 patients treated by mandibular distraction over a 16-year period. Of the total 141 patients, 56 underwent unilateral mandibular distraction and 85 underwent bilateral mandibular distraction, contributing to a total of 226 sided distraction procedures. The number of procedures performed on native bone using external devices was 149, versus 41 internal devices. There were 36 distractions performed on grafted bone with external devices. Incidents were broadly classified into three groups based on a severity index. A minor incident was one that resolved satisfactorily with minimal or no invasive intervention. A moderate incident was one that resolved satisfactorily with moderate clinical intervention. A major incident was one that did not resolve or could not be resolved with surgical intervention, and compromised treatment outcome. RESULTS: The major incident rate was 5.31 percent (total of 226 distraction procedures). A higher rate of major incidents was observed when distracting grafted bone. The overall minor incident rate was 26.99 percent and the moderate incident rate was 20.35 percent. CONCLUSION: Mandibular distraction can be considered a safe and predictable procedure for lengthening/augmenting the mandible in patients with lower jaw deficiencies

BACKGROUND: The application of distraction osteogenesis is an effective treatment for mandibular deficiencies. A priori, a horizontal vector of distraction was hypothesized to produce horizontal movement of the mandible and a vertical vector of distraction to produce primarily downward vertical elongation of the ramus. This study was designed to test this hypothesis. METHODS: A retrospective clinical and radiographic review was conducted of all patients who underwent bilateral, uniplanar distraction with an external device at the New York University Medical Center between October of 1990 and February of 2004 (n = 185). A subset of 15 patients was identified who satisfied inclusion criteria and had adequate predistraction and postdistraction lateral cephalograms. Cephalometric tracings were made and multiple landmarks were assessed before and after distraction. RESULTS: A strong correlation was noted between the vector of distraction and rotation of the symphyseal plane, movement of the mandibular symphysis, and change in interocclusal angle. A horizontal vector of distraction resulted in minimal counterclockwise rotation of the symphyseal plane, greater downward vertical translation of the mandibular symphysis, and minimal closure of an anterior open bite. In contrast, a vertical vector resulted in greater counterclockwise rotation of the symphyseal plane, greater horizontal projection of the mandibular symphysis, and greater closure of an anterior open bite. Mathematical formulas were derived to correlate the distraction vector and mandibular movements. CONCLUSIONS: Successful distraction is dependent on accurate prediction of outcomes. This study demonstrates that the vector of distraction predictably affects the mandibular response during bilateral distraction osteogenesis but contradicts the a priori hypothesis

BACKGROUND: Bilateral cleft lip-cleft palate is associated with nasal deformities typified by a short columella. The authors compared nasal outcomes of cleft patients treated with banked fork flaps to those of patients who underwent nasoalveolar molding and primary retrograde nasal reconstruction. METHODS: A retrospective review of 26 consecutive patients with bilateral cleft lip-cleft palate was performed. Group 1 patients (n = 13) had a cleft lip repair and nasal correction with banked fork flaps. Group 2 patients (n = 13) had nonsurgical columellar elongation with nasoalveolar molding followed by cleft lip closure and primary retrograde nasal correction. Group 3 patients (n = 13) were age-matched controls. Columellar length was measured at presentation and at 3 years of age. The number of nasal operations was recorded to 9 years. The Kruskal-Wallis and Tukey-Kramer tests were used for statistical analysis. RESULTS: Initial columellar length was 0.49 +/- 0.37 mm in group 1 and 0.42 +/- 0.62 mm in group 2. Post-nasoalveolar molding columellar length was 4.5 +/- 0.76 mm in group 2. By 3 years of age, columellar length was 3.03 +/- 1.47 mm in group 1, 5.98 +/- 1.09 mm in group 2, and 6.35 +/- 0.99 mm in group 3. Group 2 columellar length was significantly greater (p < 0.001) than that of group 1 and not statistically different from that of group 3 (p > 0.05). All group 1 patients (13 of 13) needed secondary nasal surgery. No nasoalveolar molding patients (zero of 13, group 2) required secondary nasal surgery. CONCLUSION: Nonsurgical columellar elongation with nasoalveolar molding followed by primary retrograde nasal reconstruction restored columellar length to normal by 3 years and significantly reduced the need for secondary nasal surgery.

BACKGROUND: Unilateral craniofacial microsomia is characterized by soft-tissue and bony deficiencies. Mandibular distraction osteogenesis can be used to augment the hypoplastic skeleton and improve facial symmetry. The aim of this study was to determine how the vector of unilateral mandibular distraction affects treatment outcomes. METHODS: A retrospective chart and radiographic review was conducted of all patients treated with external mandibular distraction osteogenesis between October of 1990 and February of 2004 (n = 185). A subset of 42 patients underwent primary unilateral, uniplanar, external distraction, and 13 patients were found to have satisfied inclusion criteria and had adequate predistraction and postdistraction lateral and posteroanterior cephalograms. Cephalometric tracings were made and multiple points and planes were assessed before and after distraction. RESULTS: A strong correlation was noted between the vector of distraction and the movement of the mandible. A horizontal vector of distraction resulted in minimal increase in ramal length but a marked shift in the mandibular midline (r = 0.68, p < 0.05). In contrast, a vertical vector of distraction resulted in marked mandibular ramus lengthening but minimal mandibular midline shift (r = 0.73, p < 0.05). Mathematical formulas were derived to correlate the distraction vector and mandibular movements to improve preoperative planning. CONCLUSIONS: Successful distraction is dependent on accurate preoperative planning and prediction of outcomes. This study demonstrates a predictable relationship between the vector of unilateral distraction and the mandibular response

BACKGROUND: The purpose of this study was to investigate the relationship between soft-tissue and underlying skeletal structures before and after unilateral mandibular distraction osteogenesis. METHODS: The sample consisted of 11 patients (three girls and eight boys) with an average age of 4.6 years at the time of treatment. All patients had unilateral craniofacial microsomia (four right-sided and seven left-sided unilateral craniofacial microsomia) and all underwent unilateral mandibular distraction osteogenesis. Measurements were performed on frontal medical photographs and posteroanterior cephalograms at predistraction (time 1) and postdistraction (time 2) periods. Left and right ramus heights, skeletal midline deviation, and transverse occlusal plane were measured on the posteroanterior cephalograms and compared with the linear distances between the lip commissures and the orbital plane, the circumference of both sides of the faces, and the angulation of the oral commissure plane as recorded on the medical photographs, respectively. To reduce magnification error, ratios of affected to less affected sides of the mandibles and soft-tissue facial structures were selected and studied. RESULTS: A similar relationship was observed between soft-tissue and skeletal components. However, there was no 1:1 relationship between the changes in ramus height and improvement in parallelism of lip commissures to the orbital plane. CONCLUSIONS: A significant improvement in soft- and hard-tissue anatomy has been observed following unilateral distraction osteogenesis of the mandible. The relationship between the soft-tissue and skeletal correction was different for all patients because of the large range in severity of the craniofacial malformation. Greater skeletal deficiency requires more correction to achieve symmetry of both hard and soft tissue

BACKGROUND: Gingivoperiosteoplasty has been shown to eliminate the need for secondary alveolar bone grafting in 60 percent of patients. The purpose of this study was to compare radiographic alveolar anatomy following infant gingivoperiosteoplasty, secondary alveolar bone grafting, and secondary alveolar bone grafting in patients who had prior infant gingivoperiosteoplasty with inadequate bone formation. METHODS: Seventy-four consecutive nonsyndromic patients (complete bilateral cleft lip-cleft palate, n = 12; complete unilateral cleft lip-cleft palate, n = 46; complete unilateral cleft lip and alveolus, n = 14) treated at New York University Medical Center were available for evaluation. Eighty-two complete alveolar cleft sites were assigned to three groups: gingivoperiosteoplasty (n = 30), secondary alveolar bone grafting (n = 41), and secondary alveolar bone grafting following gingivoperiosteoplasty (n = 11). All gingivoperiosteoplasties were performed at the time of primary lip surgery, and secondary alveolar bone grafting (cancellous iliac crest at 7 to 12.5 years of age) was performed before eruption of the permanent canine. Radiographs were measured according to the modified method of Long. RESULTS: Seventy-three percent of gingivoperiosteoplasty cases did not require secondary alveolar bone grafting and none had fistulas. The rate of missing teeth in the total sample, adjacent to the cleft, was within normal limits for the population. Group 1 alone and groups 1 and 3 combined had superior alveolar anatomy compared with group 2 (p < 0.01). No significant differences existed between groups 1 and 3 (p > 0.05). Crest height was best in group 1 (p < 0.01), followed by group 3 and then group 2, with no difference between the latter two groups. CONCLUSION: Gingivoperiosteoplasty alone or combined with secondary alveolar bone grafting results in superior bone levels when compared with conventional secondary alveolar bone grafting alone

BACKGROUND: The authors studied the effect of midface distraction on maxillary skeletal position and clinical appearance in patients with Crouzon, Pfeiffer, and Apert syndromes, and examined the stability of these changes at 1 year after distraction. METHODS: Fifteen consecutive patients (six male and nine female; average age, 5.9 years) underwent Le Fort III osteotomy with midface advancement using a rigid external distraction device. Six patients had Crouzon, five had Pfeiffer, and four had Apert syndrome. Midface advancement was initiated at the level of the occlusal splint and at the zygomatic/maxillary anchor screws. The device was activated 11 mm on average, at a rate of 1 mm per day. Twenty anatomical landmarks were identified and digitized at three time intervals, and displacement of each landmark was compared with its pretreatment position. RESULTS: By the time of device removal, point A had advanced sagittally along the x axis 15.85 mm and moved downward 1.06 mm along the y axis; the orbitale was moved sagittally along the x axis 12.72 mm and downward 1.99 mm along the y axis. Maximum mean advancement (17.16 mm) was observed at the upper incisal edge. Maxillary and mandibular skeletal discrepancy was significantly decreased, with the ANB angle changing from -5.87 to +13.17 degrees. At 1 year after distraction, point A had advanced an additional 0.81 mm, and the orbitale and upper incisal edge had moved posteriorly 0.07 mm and 1.34 mm, respectively. CONCLUSION: Significant midface advancement can be achieved and maintained with rigid external distraction of the Le Fort III osteotomy segment (up to 24 mm), with excellent stability of the advanced midfacial skeleton