Bio-fillings to Treat Dental Caries and Prevent Dental Materials-associated Toxicity

Objectives: Dental caries is the most common health problem in humans and cause breakdown of the enamel and dentin, chronic infection, and pain. The current artificial dental filling materials to treat dental caries are limited to amalgam and dental composites which are highly toxic due to the presence of mercury and Bisphenol A (BPA). Alternative approaches are still a challenge in dentistry. Our aim is to develop bio-fillings produced in vitro that are similar to native enamel and dentin in terms of function, structure and composition. Bio-fillings are produced by inducing ameloblast differentiation in dental epithelial stem cells (DESCs) through gene delivery of the key ameloblast inducer (TBX1) using non-toxic gemini-surtactant (GS) nanoparticles (NPs) and co-culture with human dental pulp stem cells (hDPSCs) within dual compartment bio-scaffolds.
Methods: Delivery of TBX1 gene was optimized initially into rat DESCs (HAT-7) using different N/P ratios of GS- and clinically developed DOTAP-based NPs. Cells were transfected with lipoplexes and then were cultured for 48 hours and analyzed by MTT assay, qRT-PCR and western blot. Afterwards, DESCs were transfected with the optimum formulation and/or co-cultured with DPSCs. After 2-4 weeks, differentiation and bio-enamel quality were analyzed by alkaline phosphatase and von Kossa staining, SEM, microCT, immunocytochemistry and qRT-PCR.
Results: After optimization of transfection and co-culture conditions, DESCs were able to express ameloblast markers and secrete enamel-like matrix in vitro. The whole system is also being adapted into dual-compartment scaffolds for enamel and dentin regeneration.
Conclusions: Combination of TBX1 gene delivery and co-culture with DPSCs into 3D-printed dual compartment scaffolds guides DESCs amelobast differentiation and results in bio-enamel formation in vitro. These scaffolds may include a light-curable envelope that is used to attach the 3D-bioengineered enamel into defective teeth surfaces. This strategy may reduce material-induced toxicity and provide enhanced options for dental caries treatments.