Amelogenesis Imperfecta is a clinically and genetically heterogeneous group of disorders of Enamel formation that affect both dentitions (Primary Dentition & Permanent Dentition). Most cases of amelogenesis imperfecta fall into one of three clinical types: hypoplastic (disturbance in formation) or hypocalcified (disturbance in mineralization process) or hypomaturation. These are based on different inheritance patterns, clinical appearances, and radiographic features (Figure 1,2 & 3).
Several genes that are involved in enamel formation (amelogenin, enamelin, kallikrein 4, MMP20, others) are mutated in various forms of this condition. Mutations in the enamelin gene are believed to be responsible for the phenotypic change (Phenotype is the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment).
Amelogenesis imperfecta manifests itself differently in males and females. Affected males may have a very thin, smooth enamel layer, whereas females may have thicker enamel with vertical grooves.
In hypoplastic type of amelogenesis imperfecta, teeth erupt with insufficient amounts of enamel, ranging from pits and grooves in one patient to complete abscence (aplasia) in another. Becuase of the reduced enamel thickness in some cases, abnormal contour and absent interproximal contact points may be evident. In the hypocalcified type, the quantity of enamel is normal, but it is soft and friable, so that it fractures and wear readily. The color of the teeth varies from tooth to tooth and from patient to patient – from white opaque to yellow or brown. Teeth also tend to darken with age as a result of exogenous staining. Radiographically, Enamel appears reduced in bulk, often showing a thin layer over occlusal and interproximal surfaces. Dentin and pulp chambers appear normal. Although the enamel is soft and irregular, teeth are not caries prone. Treatment focuses on esthetics and protection of tooth tissue. Restorative dental procedures at an early age not only preserve teeth but have a significant effect on the patient’s self-esteem.
- Amelogenesis imperfecta is a congenital disorder affecting all teeth and both dentitions.
- Tooth color may be yellow.
- Teeth may appear smaller & pitted.
- X-ray findings show normal pulps/dentin; but reduced enamel.
- No systemic manifestations.
- Treatment involve full crowns.
Reference: Oral Pathology, sixth edition. By Regezi, Sciubba, & Jordan.
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