Several studies have described the craniofacial morphological characteristics of DS, from prenatal to postnatal periods ( Gosman, 1951 Austin et al., 1969 Cohen et al., 1970 Jensen et al., 1973 Fink et al., 1975 Westerman et al., 1975 Jara et al., 1993 Farkas et al., 2001 Guihard-Costa et al., 2006). Although a wide spectrum of phenotypes can be expressed, typical craniofacial features make DS distinct and easily recognizable. The complex genetic disorder is clinically characterized by a combination of mental and physical features ( Frostad et al., 1971 Fink et al., 1975 Silva et al., 1997). The 21 regular trisomy is the most common (94.1 per cent), while translocations (3.6 per cent) and mosaics (2.3 per cent) occur in a smaller proportion ( Stoll et al., 1998). DS has three genetic etiologies that are expressed in phenotypes with greater or lesser syndrome characteristics. identified a chromosomal numerical change, with karyotypes characterized by trisomy 21 ( Lejeune et al., 1959). Maxillary deficiency was not so expressive in the face of DS subjects because of the overall reduction in craniofacial dimensions.ĭown syndrome (DS) is the most prevalent genetic malformation (1 in 750–800 live births) and was first described in 1866 by the English physician Langdon Down ( Frostad et al., 1971 Fink et al., 1975 Silva et al., 1997). Subjects with DS differed from Class III with maxillary deficiency with respect to the flatter cranial base and reduced maxillary length. The group with maxillary deficiency showed a more unfavourable maxillomandibular relationship (MMD, P < 0.001) and a mandibular protrusion (SNB, P < 0.001). A flattened cranial base (BaSN, P < 0.001) also contributed to differentiating DS from nonsyndromic groups. Maxillary length (Co–A, P < 0.001) and facial convexity (NAP, P < 0.005) were reduced when compared with the control group, although maxillary position to cranial base (SNA, P < 0.005) was within the normal range. The DS group showed reduced anterior cranial base (S–N, P 0.005). The differences among the three groups were compared with analysis of variance and Tukey’s tests. This study compared the craniofacial differences of white male children from Central–Western Brazil with DS ( n = 30, mean age: 8 years 3 months), skeletal Class III profile with maxillary deficiency ( n = 30, mean age: 7 years 9 months), and skeletal Class I profile ( n = 30, mean age: 8 years 2 months), using lateral cephalometric radiographs. Differences in craniofacial morphology between DS and nonsyndromic skeletal Class III malocclusion with maxillary deficiency remain unclear. Maxillary deficiency is one of the facial features of Down syndrome (DS).
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