Objective: To analyze the microstructure of retained HIES primary teeth and identify possible irregularities in root resorption patterns.
Methods: Scanning electron microscopy was performed on 4 extracted retained primary incisors from 2 HIES patients (2 females, age 7-8 years) with confirmed STAT3 mutations. Root surface and cross-sectional morphologies of HIES teeth were compared to 4 non-retained primary teeth (exfoliated normally or extracted for orthodontics) from 3 unaffected controls (1 male, 2 females, age 6-8 years).
Results: The root surfaces of HIES teeth showed some normal accellular extrinsic fiber cementum but mostly hyperplastic appearing cementum, with minimized resorption lacunae at resorption areas and/or retention of dentinal peritubular matrix, indicative of an altered resorption pattern. This contrasted with the polycyclic resorption lacunae and demineralization patterns seen through the normal cementum of control teeth. Cross-sectionally, intact HIES roots manifested thicker, more irregular cemental layers compared to controls. A macroscopically non-resorbed control root demonstrated microscopic evidence of resorption around its apex, compared with a pristine HIES root apex. Cementicles- cemental developmental anomalies of calcified spherical bodies attached to or embedded within cementum- were a common finding along HIES root surfaces but were not seen in controls.
Conclusion: Microstructural morphological variations were observed on HIES root surfaces. Altered resorption morphology, rougher cementum layer, and cementicles on HIES roots indicate either a more regenerative cementum or less active resorption, and may be directly associated with the delayed or absent deciduation of primary teeth in HIES. These findings provide novel insight into the pathogenesis of this complex syndrome.