Human Tooth Developmental Anomaly: Odontoblastic Differentiation in Hamartomatous Calcifying Hyperplastic Dental Follicles Presenting DSP, Nestin, and HES1

Abstract

Hyperplastic dental follicles (HDFs) represent odontogenic hamartomatous lesions originating from pericoronal tissues and are often associated with impacted or embedded teeth. These lesions may occasionally feature unique calcifying bodies, known as calcifying whorled nodules (CWN), characterized by stromal cells arranged in a whorled or spiral fashion. CWNs are typically observed in multiple calcifying hyperplastic dental follicles or regional odontodysplasia. In our study, we examined 40 cases of HDFs, including nine instances with characteristics of CWNs, which were infrequently accompanied by odontodysplasia. Histological examination was conducted on all 40 cases, with immunohistochemical analysis performed on 21 of them. Among the cases with CWN, nine affected a single embedded tooth, with one exception. CWNs exhibited diverse calcifications featuring sparse or entirely deposited psammoma bodies, and some displayed dentinoid formation. Immunohistochemically, stromal cells of HDFs were frequently positive for CD56 and nestin. In contrast, CWNs were negative for CD56 but positive for nestin and HES1, with a few DSP-positive calcified bodies. Our results revealed that hamartomatous calcifying HFDs can impact multiple and single-embedded teeth. CWNs composed of nestin and HES1-positive ectomesenchymal cells demonstrated the potential to differentiate into odontoblasts and contribute to dentin matrix formation under the influence of HES1. This study is the first report documenting odontoblastic differentiation in HDFs.