Enamel and Dentin Defects From Dentinogenesis Imperfecta in the Secondary Dentition

Objectives: Dentinogenesis imperfecta (DI) and dentin dysplasia (DD) arise from DSPP mutations. Affected individuals exhibit a spectrum of mild to severe disorders of dentin organization and mineralization. We previously identified a family with a DD/DI presentation in the young male proband, his older sister, and their mother. The proband exhibited the most severe phenotype of the family in his primary dentition, consistent with DI type III. His primary teeth displayed thin dentin, widened pulp chambers, abnormal or absent dentinal tubules, and disorganized and trapped odontoblasts. Unusually, he also had dramatically reduced enamel thickness and density. Severity of defects in DD/DI can vary between primary and secondary teeth. We aimed to determine if dentin and enamel defects were recapitulated in the secondary dentition of the proband.
Methods: The proband underwent extraction of several secondary teeth due to susceptibility to pulp necrosis and abscesses. Extracted secondary teeth of the male proband (n= 7) and healthy controls (n=6) were analyzed by high-resolution micro-computed tomography (micro-CT) and histology. Teeth underwent rapidly decalcification and were paraffin processed for histology.
Results: Micro-CT revealed that the proband's secondary teeth had thin dentin and severely defective enamel that was barely visible. Enamel thickness was reduced 95% and enamel density was reduced more than 50% in DI vs. control teeth (both p<0.0001). Dentin thickness was reduced about 70% in DI vs. control teeth (p<0.0001), though dentin density was not diminished. Dentin matrix organization was severely disrupted in DI teeth compared to controls.
Conclusions: This family presents a combination of dentin and enamel phenotypes that is unusual for DD/DI. Severity of defects did not appear to diminish in secondary vs. primary dentition and several teeth required extraction. Additional studies are required to identify mechanisms underlying enamel and dentin defects.