The results agree with those obtained in similar populations and are considered representative of this ethnic group. The hypothesis of a genetically determined higher prevalence of numerical and morphological variations in the study population was not verified.

No abstract

The aim of the study was to establish the prevalence and incidence of amelogenesis imperfecta (AI) in the county of Västerbotten, northern Sweden using the criteria of Witkop & Sauk (1976). The diagnoses were based upon clinical and radiographic evidence. The study-population consisted of all 3-19-yr-olds born in the county from 1963 to 1979. AI was diagnosed in 79 children, 41 girls and 38 boys, giving a prevalence of 1.4:1000. The mean incidence 1963-79 was 1.3:1000. Half of the children with AI had brothers or sisters in the group. The hypoplastic form was the most common (58 children) followed by the hypomaturation form (16 children). Only five children had the hypomineralization form.

Amelogenesis imperfecta (AI) is an inherited tooth disorder affecting tooth enamel formation only. A gene for autosomal dominant AI, the local hypoplastic form, has been localized to a 4 Mb region on chromosome 4q (AIH2). The enamelin gene (ENAM ), has been mapped to chromosome 4q21, to the same region as AIH2, and was recently shown to be mutated in patients with smooth and thin hypoplastic autosomal dominant AI (ADAI). In this study, we describe an ENAM mutation causing the local hypoplastic form of ADAI, a phenotype that accounts for 27% of the autosomally inherited cases in Northern Sweden. This nonsense mutation in the enamelin gene results in a truncated peptide of 52 amino acids as compared with 1142 amino acids of the normal protein. Our results show that while a splice site mutation is associated with smooth and thin hypoplastic AI, a base substitution resulting in a shorter peptide causes local hypoplasia of the enamel, a milder form of AI. These findings support ENAM as a disease gene, and shed new light on the molecular mechanism of the disease and to the function of the enamelin protein in enamel formation.

Visual pedagogy is a useful tool in helping people with autism to improve their oral hygiene.