Peters, S. B. | Search bioRxiv

bioRxiv2025

Comparative Evaluation of Three Calcium Silicate-Based Materials for Direct Pulp Capping: An In Vivo Study in Mice.

IntroductionVital pulp treatments (VPT) aim to conservatively manage deep caries and/or damage to preserve the vitality and function of the pulp. This minimally invasive approach is still debated when performing direct pulp capping (DPC), a treatment in which a protective biocompatible material is directly placed over the dental pulp, due to microbial risks inherent with pulp exposure and difficulties in sealing the exposure to protect the pulp from subsequent bacterial ingress. Several limitations associated with Mineral Trioxide Aggregate (MTA) such as long setting time and discoloration have promoted the development of next-generation MTA derivatives with enhanced physical, chemical, and biological properties. As these materials are relatively new, existing studies are limited in scope, lacking a comprehensive assessment of both reparative dentin formation and the sealing ability, which are critical parameters for determining long-term clinical success. These assessments require preclinical models, and while the mouse model offers the opportunity to explore the molecular mechanisms guiding reparative dentinogenesis, the materials and techniques optimized for human dentition present technical challenges in mice due to their small size. AimWe aimed to optimize a DPC technique to use in mice by comparing the tissue responses and the sealing ability of three calcium silicate capping agents: Bioceramic putty (BC), Biodentine (BD), and Theracal-LC (TLC) to a control material known to seal well but cause desiccation that would lead to tissue damage; Cavit-G (CG). Material and methodsDPC was performed on the maxillary first molar of C57BL/6 female mice. Reparative dentin was assessed with micro-computed tomography (micro-CT) and histological assessment of dentin bridge formation at 21 days. The sealing ability of the capping materials was evaluated using micro-CT. ResultsAll three calcium silicate materials showed good biocompatibility and the ability to form a dentin bridge. Micro-CT quantifications of material voids demonstrated superior seals with bioceramic putty and Theracal-LC groups as compared to Biodentine. ConclusionsReady-to-use, premixed capping agents exhibit better sealing ability in mice, while promoting dentin bridge formation to protect the dental pulp.

bioengineering↗

bioRxiv2020

Tgfbr2 in dental pulp cells guides sensory innervation in developing teeth

Transforming growth factor {beta} (TGF{beta}) plays an important role in tooth morphogenesis and mineralization. Our laboratory established a mouse model in which Tgfbr2 was conditionally deleted in the dental pulp (DP) mesenchyme using an Osterix promoter-driven Cre recombinase (Tgfbr2cko). These mice survived postnatally, but had significant defects in bones and teeth, including reduced mineralization and short roots. H&E staining revealed reduced axon-like structures in the mutant mice. Reporter imaging demonstrated that Osterix-Cre activity was localized within the tooth and was active in the DP and derivatives, but not in neurons. Previous research has established that paracrine signals from the dental pulp attract trigeminal axons toward and into the tooth during postnatal development, yet very little is known about the signals that regulate tooth innervation. Immunofluorescent staining for a neuronal marker, {beta}3 tubulin, was performed on serial cryosections from control and mutant molars at two different postnatal stages. Confocal imaging and pixel quantification of {beta}3 tubulin demonstrated reduced innervation in P7 and P24 Tgfbr2cko first molars compared to controls, indicating that the signals necessary to promote neurite outgrowth were disrupted by Tgfbr2 deletion. Quantitative real time PCR showed that the mRNA expression levels of several neuronal genes were reduced. Lastly, trigeminal neurons were co-cultured atop Transwell filters overlying primary Tgfbr2f/f DP cells. Tgfbr2 in the DP was deleted with an adenovirus expressing Cre recombinase. Confocal imaging of axons through the filter pores showed increased axonal sprouting from neurons cultured in the presence of Tgfbr2-positive DP cells compared to neurons cultured alone. Further, axon sprouting was reduced when Tgfbr2 was knocked down in the DP cells. These results indicate that Tgfbr2 in the DP mesenchyme regulates paracrine signals that guide sensory innervation of the tooth. Note: A list of abbreviations is included in the appendix.

neuroscience↗