Hereditary Dentin Defect

The hereditary dentin disorders, dentinogenesis imperfecta (DGI) and dentin dysplasia (DD), comprise a group of conditions characterized by abnormal dentin structure affecting either the primary or both the primary and secondary dentitions.

Epidemiology

DGI is reported to have an incidence of 1 in 6,000 to 1 in 8,000 births, whereas that of DD type 1 is 1 in 100,000.

Clinical description

Clinically, the teeth are discolored and show structural defects such as bulbous crowns and small pulp chambers on radiographs. The underlying defect of mineralization often results in shearing of the overlying enamel leaving exposed weakened dentin which is prone to wear. Currently, three subtypes of DGI and two subtypes of DD are recognized but this categorization may change when further causative mutations are identified.

Etiology

DGI type 1 is inherited with osteogenesis imperfecta and recent genetic studies have shown that mutations in the genes encoding collagen type 1, COL1A1 and COL1A2, underlie this condition. All other forms of DGI and DD, except DD type 1, appear to result from mutations in the gene encoding dentine sialophosphoprotein (DSPP).

Diagnostic methods

Diagnosis is based on family history, pedigree construction and detailed clinical examination, but genetic diagnosis may become useful in the future once a sufficient number of disease-causing mutations have been identified.

Differential diagnosis

Differential diagnoses include hypocalcified forms of amelogenesis imperfecta, congenital erythropoietic porphyria, conditions leading to early tooth loss (Kostmann syndrome, cyclic neutropenia, Chediak-Higashi syndrome, histiocytosis X and Papillon-Lefevre syndrome), permanent teeth discoloration due to tetracyclines, and Vitamin D-dependent and vitamin D-resistant rickets (see these terms).

Genetic counseling

Both DGI and DD are transmitted as autosomal dominant conditions.

Management and treatment

Treatment involves removal of sources of infection or pain, improvement of aesthetics and protection of the posterior teeth from wear. Beginning in infancy, treatment usually continues into adulthood with a number of options including the use of crowns, over-dentures and dental implants depending on the age of the patient and the condition of the dentition.

Prognosis

Where diagnosis occurs early in life and treatment follows the outlined recommendations, good esthetics and function can be obtained.