451 - Demarcated developmental enamel defects in cleft-adjacent tooth

Abstract:

Purpose: Developmental enamel defects are frequently found in children affected with a cleft palate. Cleft- adjacent teeth may be delayed in their formation and may display demarcated enamel opacities, phenotypically similar to molar-incisor hypomineralization. This study aimed to characterize and visualize the mineral content and enamel matrix proteins in opacities.

Methods: An extracted premolar adjacent to a cleft was collected from a pediatric patient. A premolar removed for orthodontic reasons served as control. Teeth were imaged with microcomputed tomography (microCT) and stereomicroscopy to identify and visualize opacities. Next, teeth were processed and sections mounted onto glass slides. Tissues were stained with Masson’s trichrome, and immunohistochemistry for the protein ameloblastin (AMBN) was performed. Staining patterns were evaluated by light microscopy.

Results: MicroCT imaging demonstrated demarcated regions of low mineral density on the cleft adjacent premolar. Masson’s trichrome staining revealed staining within hypomineralized enamel, consistent with increased retention of organic matrix. Immunohistochemical analysis revealed localization of AMBN within enamel rods, rod sheath and along the dentinoenamel junction (DEJ). Within hypomineralized zones, the trajectory of rods alternated, consistent with Hunter-Schreger bands. Scalloping at the DEJ appeared more pronounced in the cleft-affected tooth.

Conclusions: Enamel opacities of teeth adjacent to a cleft are hypomineralized and contain a high organic content. The accumulation of enamel matrix proteins in hypomineralized enamel suggests that clearance of organic content may be halted during the maturation stage of amelogenesis, resulting in localized, incomplete enamel maturation. Ameloblast function may be suppressed by the altered, local morphology of a cleft.

Identify Supporting Agency and Grant Number: Research supported by the National Institutes of Health R01DE026769.