New Immunohistochemical Findings on Amelogenin and Dentin Sialophosphoprotein in Genetic Tooth Diseases.

OBJECTIVE: Diseases that affect teeth can change their structure and the distribution and expression of amelogenin (AMELX) and dentin-sialophosphoprotein (DSPP). This study aimed to conduct a histopathological, ultrastructural, and immunohistochemical comparison of AMELX and DSPP in teeth from patients with amelogenesis imperfecta (AI), dentinogenesis imperfecta (DI), osteogenesis imperfecta (OI), regional odontodysplasia (ROD), and control teeth. Additionally, a model of the structure of the affected primary teeth is proposed.

DESIGN: This case series study examined 27 affected teeth with various diseases and 14 control teeth. Some teeth were analysed using light microscopy, polarised light, and scanning electron microscopy, while others underwent decalcification for histological analysis and immunohistochemistry with AMELX and DSPP antibodies.

RESULTS: Teeth with hypoplastic AI exhibited thin enamel and abnormal or absent prismatic structure. In hypomineralised AI, the prismatic structure displayed minor alterations, while severe cases revealed remnants of enamel matrix and the presence of amelogenin. Teeth showing both types of AI and controls presented DSPP in peritubular dentin. DI and OI cases showed reduced dentinal tubule density, with loss of parallelism and varying diameters. The principal difference between DI and OI was seen with anti-DSPP antibody; in OI, a strong peritubular and intertubular immunolabeling was observed, while DI displayed minimal labeling in peritubular dentin. In ROD, enamel and dentin were thin with irregular prisms and tubules, with anti-AMELX and anti-DSPP demonstrating mild immunostaining.

CONCLUSION: The study of teeth with AI, DI, OI, and ROD contributes to differentiating these pathosis, with DSPP immunostaining particularly distinguishing DI from OI.