Effect of a Syndromic Diagnosis on Mandibular Size and Sagittal Position in Robin Sequence

Purpose: Despite its pathogenic heterogeneity, it is often assumed that the small mandible in a neonate with Robin sequence will not grow normally The purpose of this study was to determine mandibular length and position in patients with nonsyndromic versus syndrome Robin sequence. Patients and Methods: Lateral cephalograms of 51 children with Robin sequence were analyzed Group I consisted of nonsyndromic (NS) subjects and group 11 consisted of subjects with the 4 most common syndromic (S) diagnoses Cephalometric measurements included sella-nasion-A point (SNA), sella-nasion-B point (SNB). sella-nasion-pogonion (SNPg), articulate-gonion-pogonion (ArGoPg), temporo-mandibular joint-pogonion (TmPg), articulare-gonion (ArGo), and gonion-pogonion (GoPg) Differences between groups and subgroups were compared using t test. Results: There were 26 NS patients (mean age, 6.8 yrs and 25 S patients (mean age, 8.7 yrs), mean age was statistically different between groups (P = 04), therefore, cephalometric measurements were compared with age-matched normal values. Syndromes included Stickler (n = 10), bilateral facial microsomia (n = 8), velocardiofacial (n = 4), and Treacher Collins (n = 3) SNA was statistically different from normal in both groups (NS, P = .017), S, P = 007), however, SNB was not different from normal for either group (NS, P = 175; S, P = .537). SNPg (0.007) was significantly greater than normal in NS (P = .007) but not in S (P = .702) patients, SNA, SNB and SNPg were not significantly different between groups. In both groups, mandibular length was short (P = .00), especially in S patients (P = 049), mandibular body was small (NS, P = .00; S, P = 00), and the gonial angle more obruse (NS, P = 019) Mandibular length (TmPg) was smaller than normal in all S subgroups with respect to mandibular sagittal position (SNB, P = .00; SNPg, P = 00) and mandibular length (TmPg, P = 008) There were no differences in S subgroups with respect to age, SNA, ArGo, GoPg, and ArGoPg Conclusion: Mandibular morphology and position are variable in Robin sequence, based on the presence and type of associated syndromic diagnosis. (C) Americal Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 67 2323-2331, 2009