Odontohypophosphatasia

Odontohypophosphatasia is the mildest form of hypophosphatasia that manifests as tooth dysplasia and/or early loss of deciduous or permanent teeth.

Pathology

As with all forms of hypophosphatasia, the underlying abnormality is a mutation in the ALPL gene that encodes for tissue non-specific alkaline phosphatase. Genetic testing combined with low serum alkaline phosphatase activity make the diagnosis since the radiological appearances alone are not specific.

Radiographic features

Although the imaging appearances are non-specific, plain radiographs of these patients can show:

• short tooth roots
• dysplasia of the dentin or cementum
• alveolar bone height reduction
• expanding root or pulp chamber

Treatment and prognosis

Severe forms of hypophosphatasia can now be treated with recombinant enzyme replacement therapy, but the milder forms of the disease have not yet been licensed for this. Dental complications are managed accordingly with appropriate surgery such as root canal therapy or dental implantation.