Dentoalveolar morphology and developmental changes in Down's syndrome (trisomy 21)

Abstract

T risomy 21, better known as Down’s syndrome or Mongolism, was reported by Lejeune and associates,l using cytogenetic techniques, as being caused by the presence of an additional autosomal chromosome at site No. 21. This disorder is characterized by a central growth deficiency which is evidenced by delayed physical and mental development. Oster” states that “Down’s syndrome is a symptom complex of features comprising several physical abnormalities, chiefly developmental defects, in association with mental deficiency.” He lists “cardinal signs” found in subjects with Down’s syndrome as follows: (1) fourfinger line; (2) short, crooked fifth finger; (3) short, broad hands; (4) hypernexibility; (5) oblique eyes; (6) epicanthus; (7) furrowed tongue; (8) irregular, a’bnormal teeth; and (9) brachycephalia. The incidence of Down’s syndrome is estimated to be between 1.6 to 2.5 per 1,000 live births.3 Persons with Down’s syndrome comprise about 5 to 10 per cent of all retarded children. The incidence of Down’s syndrome increases with increases in maternal age. The literature suggests that these persons exhibit asymmetric micrognathic jaws, tooth malformations, and congenital absence of teeth. However, the reported data are insufficient to permit an accurate assessment of the extent of these abnormalities. Furthermore, there is no agreement as to whether these abnormaliti.es exist in all persons with trisomy 21.