Amelogenesis imperfecta (AI) is a group of developmental conditions, which affect the enamel and may be associated with biochemical and morphological changes elsewhere in the body. The exact prevalence is unknown. However, its incidence is known to vary from 1:700 to 1:14,000 in some studies. Affected patients have yellowish- brown dental enamel, and a rough tooth surface. An anterior open bite, with or without increased sensitivity to thermal changes or tendency towards disintegration is seen in some patients. Four types of AI are recognized clinically. Of these, Type II or the Hypomaturation type is characterized by an open bite, creamy to yellow-brown roughly surfaced teeth that may be tender and sore, and thickened and unusually brittle enamel.
AI can occur in isolation or in association with other abnormalities as part of a syndrome. Diagnosis is based on the family history and clinical evaluation. The condition can be managed by early intervention. In infancy, this can be achieved by the use of metal crowns on posterior teeth. Longer-term care involves the use of crowns and plastic restorations.
Shahid et al., (2016) enrolled 21 Saudi Arabian families having 41 patients with non-syndromic forms of tooth agenesis. In addition, 100 healthy matched controls were also recruited into this study. These patients were referred to the dental clinic for dental treatment. Two of the participants fulfilled the definition of oligodontia and the mean number of missing permanent teeth was 7. Diagnosis of tooth agenesis was confirmed by clinical and radiographic examination. Sanger sequencing enabled the identification of a previously reported p.Lys18Thr mutation in exon 1 of PPM20 gene in five of the patients. Two of these patients were related (mother-daughter). This mutation was also found in 10% of controls. In all, 16 patients were found to carry bialllelic mutations or SNPs in the MMP20 gene.