"Abnormalities of Teeth"
– 7 –
Charles Dunlap, DDS
Sept. 2004
Dentinogenesis Imperfecta (DI), also known as opalescent dentin)
This is an autosomal dominant condition affecting both deciduous and permanent teeth. Affected teeth are gray to yellow-
brown and have broad crowns with constriction of the cervical area resulting in a “tulip” shape. Radiographically, the teeth
appear solid, lacking pulp chambers and root canals. Enamel is easily broken leading to exposure of dentin that undergoes
accelerated attrition. Slides #49–52 are examples of DI. The gene maps to chromosome #4. It encodes a protein called
dentin sialophosphoprotein (DSPP). This protein constitutes about 50% of the noncollagenous component of dentin matrix.
It is not known how the mutant protein causes near obliteration of the pulp. A clinically and radiographically indistinguish-
able dental condition is seen sometimes in patients with osteogenesis imperfecta. The following classification has been pro-
posed.
A. Dentinogenesis imperfecta type I, with osteogenesis imperfecta
B. Dentinogenesis imperfecta type II, without osteogenesis imperfecta
C. Dentinogenesis imperfecta type III (see below)
DI type III is even more rare and paradoxically characterized by too little rather than too much dentin resulting in “shell
teeth”, Slide #53. Type III DI may be and allelic variant of type II DI, ( a different mutation in the same gene) both genes
map to the same region on chromosome #4. (Slide #53 was loaned to us by another pathologist and is not to be copied or
published. It is exclusively for the use of students at UMKC.)
Slide 49: dentinogenesis imperfecta Slide 50: dentinogenesis imperfecta Slide 51: dentinogenesis imperfecta
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