From Organoids to Enamel: Investigating Ameloblast Differentiation and Functional Modulation

Objectives: Nearly half of the global population is affected by some form of oral disease, such as tooth decay or tooth loss, presenting a major public health challenge. These conditions largely stem from the breakdown of enamel, the protective outer layer of teeth. During tooth development, the dental epithelium generates ameloblasts, responsible for enamel production. After amelogenesis, these cells undergo apoptosis, and dental epithelial stem cells significantly decline during adulthood, posing challenges for their study.
Methods: Our research group specialises in generating epithelial tooth organoids (ETO) from the epithelial cell rests of Malassez within the dental follicle of extracted human wisdom teeth. These organoids closely mimic the structure and function of the dental epithelium, including differentiation into ameloblasts. Hence, they provide a valuable platform for investigating the intricate process of amelogenesis.
Results: Molar Incisor Hypomineralization (MIH) is a developmental defect of the dental enamel that predominantly affects the permanent first molars and incisors in young children. It is characterised by a qualitative enamel defect, manifesting as reduced mineral content and discoloured plaques. We subjected the ETO during ameloblast differentiation to various factors correlated to MIH, such as bisphenol A (BPA) and the antibiotic amoxicillin. Both BPA and amoxicillin significantly reduce gene expression levels of ameloblast markers AMTN and ODAM compared to control conditions in a dose-dependent manner.

Additionally, chemotherapy can negatively impact the developing teeth. To explore this further, we utilised ETO to study the effects of two commonly used chemotherapeutic agents in young children: vinblastine and vincristine. Both drugs demonstrated a significant dose-dependent reduction in the expression of maturation-stage markers, AMTN and ODAM.
Conclusions: In conclusion, our study deepens our understanding of amelogenesis and the direct influence of external factors on this critical process. In addition, this study supports the reliability of ETO as a suitable in vitro model for studying enamel regeneration.