Morphological Characterization of Deciduous Enamel and Dentin in Patients Affected by Osteogenesis Imperfecta

Uros Josic,Federica Florenzano,Tatjana Maravic,Antonella Polimeni,Gaetano Ierardo,Maurizio Bossù,Lorenzo Breschi,Annalisa Mazzoni,Milena Cadenaro,Allegra Comba

doi:10.3390/app10217835

Abstract

The purpose of this study was to clarify the structural and ultrastructural alterations of the enamel and dentin collagen network in the deciduous teeth of children affected by osteogenesis imperfecta (OI) using field-emission in-lens scanning electron microscopy (FEI-SEM) and transmission electron microscopy (TEM) analyses. Exfoliated primary teeth were collected from children with a diagnosis of OI and from healthy individuals (N = 24). Tooth slices containing both dentin and enamel were fixed, dehydrated and dried, gold sputtered, and observed using FEI-SEM. Additional dentin fragments were decalcified, dehydrated, embedded in resin, cut, and processed for TEM analysis. Under FEI-SEM, the enamel in OI-affected children showed an irregular prism distribution with the enamel hydroxyapatite crystals unpacked. Ultrastructural correlative analysis of the dentin in patients affected by OI showed an altered collagen pattern with a low density. In some areas, teeth in OI patients showed a reduction in the number of dentinal tubules, with odontoblastic process missing in most of the tubules. The presence of altered dentine and enamel organization in OI children was firmly established at an ultrastructural level, but additional biochemical studies are necessary in order to clarify quantitatively and qualitatively the collagenic and non-collagenic proteins in this disorder.

Highlights

Type I collagen is the most abundant collagen of the human body and constitutes 85–90% of the dentin organic matrix
The aim of the present study was to clarify the structural and ultrastructural alterations of enamel in the deciduous teeth of patients affected by osteogenesis imperfecta (OI) by means of field-emission in-lens scanning electron microscopy (FEI-SEM) analysis and to evaluate the dentin collagen network organization by means of correlative FEI-SEM and transmission electron microscopy (TEM) analyses
The structural and ultrastructural features of the enamel and dentin in sound primary teeth and teeth from patients affected by OI were assayed

Summary

Introduction

Type I collagen is the most abundant collagen of the human body and constitutes 85–90% of the dentin organic matrix. It possesses a triple helix containing two alpha 1 and one alpha 2 polypeptides, which are expressed from COL1A1 and COL1A2 [1]. Mutations in these genes cause osteogenesis imperfecta (OI), an autosomal genetic disorder that affects connective tissues and, the proteins involved in the organization of the extracellular matrix. The main symptoms of this disease are attributable to fragile bones, blue sclerae, hearing loss, scoliosis, and dentinogenesis imperfecta (DGI) [2].

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