Distraction Osteogenesis Normalizes Mandibular Body-Symphysis Morphology in Infants With Robin Sequence.

PURPOSE: To evaluate changes in mandibular morphology in infants with Robin sequence (RS) after mandibular distraction osteogenesis (MDO) and compare the post-distraction morphology with that in infants without RS and infants with RS who had not undergone MDO. MATERIALS AND METHODS: Infants with RS treated with MDO were retrospectively evaluated over a 12-year period. All patients had pre-distraction and end-consolidation maxillofacial computed tomograms. Morphologic features of the mandible were divided into ramus and condyle, body and symphysis, and composite measurements. Post-distraction RS mandibular morphology was compared with pre-distraction morphology, as well as to age-matched infants without RS and age-matched infants with RS who had not undergone MDO. Comparisons were done using nonparametric paired-samples analyses. RESULTS: During the study period, 17 patients with RS treated with MDO met the inclusion criteria for the study. The mean ages at distraction and end-consolidation were 1.95 ± 3.24 and 8.46 ± 5.99 months, respectively. The post-MDO mandible was significantly different from the pre-MDO mandible with regard to the ramps-condyle unit and body-symphysis measurements, including development of a more parabolic mandibular arch form (P ≤ .001). Compared with age-matched non-RS infant mandibles, the post-distraction RS mandibles had similar morphologies. Compared with age-matched non-MDO RS mandibles, the post-distraction mandibles had significantly different morphologies anterior to the gonial angle, including a more parabolic arch form (P ≤ .006). CONCLUSIONS: MDO normalized mandibular morphology in infants with RS, with the greatest effect on measurements anterior to the gonial angle.

Defining mandibular morphology in Robin sequence: A matched case-control study.

Robin Sequence (RS) is classically defined as the triad of micrognathia, glossoptosis, and airway obstruction. While there remains significant debate over diagnostic criteria for severity, there is consensus regarding micrognathia as a defining feature of the condition. The purpose of this study was to compare mandibular morphology among infants and children with RS to infants and children without RS using maxillofacial computed tomography. Our hypothesis was that there are discrete morphologic differences between RS and non-RS mandibles. Our goal was to determine if there are defined and measureable differences in RS mandible shape that can be used in defining the sequence. We identified 20 cases with RS and 20 age- and sex-matched controls without RS. Linear, angular, and composite measurements were obtained for each patient. Cases had shorter mandibular sagittal lengths (-27%, p = 0.001), shorter inferior border arc lengths (-11.5%, p = 0.002), steeper gonial angles (+10.5%, p < 0.001), and narrower symphyseal angles (-11.5%, p < 0.001). Mandibular shape in RS was more rounded/elliptical (p < 0.001) and infants with RS had a significantly smaller submental cross-sectional area (-29.4%, p < 0.001). These shape differences anterior to the gonial angle of the mandible appear to be a defining morphologic feature in RS.

Quantitative assessment of the effectiveness of phase 1 orthodontic treatment using the American Board of Orthodontics Discrepancy Index.

INTRODUCTION: This retrospective study included a sample of 300 randomly selected patients from the archived records of Saint Louis University's graduate orthodontic clinic, St. Louis, Mo, from 1990 to 2012. The objective of this study was to quantify the changes obtained in phase 1 of orthodontic treatment and determine how much improvement, if any, has occurred before the initiation of the second phase. METHODS: For the purpose of this study, prephase 1 and prephase 2 records of 300 subjects were gathered. All were measured using the American Board of Ortodontics Discrepancy Index (DI), and a score was given for each phase. The difference of the 2 scores indicated the quantitative change of the complexity of the treatment. Paired t tests were used to compare the scores. Additionally, the sample was categorized into 3 groups according to the Angle classifications, and the same statistics were used to identify significant changes between the 2 scores. Analysis of variance was applied to compare the 3 groups and determine which had the most change. Percentages of change were calculated for the significant scores. RESULTS: The total DI score overall and the scores of all 3 groups were significantly reduced from before to after phase 1. Overall, 42% improvement was observed. The Class I group showed 49.3% improvement, the Class II group 34.5% and the Class III group 58.5%. Most components of the DI improved significantly, but a few showed negative changes. CONCLUSIONS: Significant reductions of DI scores were observed in the total sample and in all Angle classification groups. This indicates that early treatment reduces the complexity of the malocclusions. Only 2 components of the DI showed statistically significant negative changes.