Caries and MIH Structural Changes in Hard Dental Tissues

Objectives: Molar-Incisor Hypomineralization (MIH) results from disruptions in the mineralization of hydroxyapatite crystals during the tooth maturation phase, leading to compromised enamel integrity. The objective of this study is to investigate and compare the organic and inorganic enamel structures of healthy, carious, and MIH-affected teeth in children aged 6-18 years using Raman microscopy and Scanning Electron Microscopy (SEM).
Methods: Four extracted permanent molars were examined: one with MIH, two with carious lesions, and one healthy control. The crowns were sectioned from the roots and sliced in the vestibular-lingual direction using a diamond disk to obtain 1 mm thick slices. After polishing, the samples were cleaned with distilled water and treated in an ultrasonic bath before observation under SEM and confocal Raman microscopy.
Results: SEM images revealed significant mineral loss and structural disorganization in carious enamel, characterized by fragmented surfaces and cavities resulting from hydroxyapatite prisms dissolution. Carious areas exhibited complete mineral degradation, marked by decreased PO₄ peak intensity in Raman spectra. In contrast, MIH samples retained structural characteristics closer to healthy enamel, though with altered mineralization and increased organic content. Structural changes in adjacent dentin were also observed near the enamel-dentin junction in MIH samples.
Conclusions: The combination of SEM and Raman microscopy provides valuable complementary insights into compositional and structural changes in hypomineralized teeth. This integrated approach offers a more comprehensive understanding of the joint alterations in enamel and dentin, contributing to improved preventive and therapeutic strategies.