Poster N13 - Development of a Self-Assembling Combination Peptide System for Regenerative Endodontic Therapy (RET)

Introduction: Dental caries and traumatic injuries are common problems in young children with immature permanent teeth with open apex, often leading to irreversible pulpitis, necrosis, and eventually dental pulp death. An immature permanent tooth is a young, erupted tooth with incomplete root apex formation, making it difficult to treat with conventional root canal fillings. Regenerative endodontic therapy (RET) is a promising approach aimed at repairing and rejuvenating the dental pulp by encouraging the growth of new tissue and restoring the natural function of the tooth's inner pulp. While blood clot-based RET (e.g., over-instrumentation) is a simple method that does not induce immunogenicity, it has limitations including the uncontrolled generation of disorganized and mineralized tissue and a lack of odontoblasts, nerves, and endothelial cells. Achieving consistent and predictable regeneration and maintaining a sterile environment remains a challenge for generating new tissue. Various treatments are being explored to enhance RET outcomes, including autologous stem cells, collagen scaffolds, and various antibiotic regimens. However, these methods face challenges such as invasive procedures, variable quality, biocompatibility issues, high costs, and antibiotic resistance. We have developed a combinatorial peptide platform consisting of antimicrobial self-assembling peptide (SAP) and angiogenic SAP. This system serves as an injectable acellular regenerative scaffold that is intrinsically antimicrobial and instructive. Previously, efficacy has been demonstrated in a canine model using angiogenic SAP. Our objective is to assess whether a combination of SAP hydrogel can effectively combat infection while simultaneously promoting the regeneration of the pulp-dentin complex and facilitating root maturation.

Materials and

Methods: Pulpectomy will be performed on the molars of maxilla and mandible in a sex-balanced Wistar rat model using a dental round burr with a high-speed handpiece. After pulp exposure, the pulp tissues were extirpated using an endodontic file (#6). . Following the pulpectomy, treatment consisting of the angiogenic/structural hydrogels and a PBS control will be administered to the vacated canal space. Following 7, 14, 28 days, animals will be anesthetized with ketamine/xylazine injection and sacrificed. Molars will be isolated, cleaned and sterilized. To measure root maturation, lengthening, thickening and apical closure teeth including the jaws will be scanned and analyzed by using vivoquant at each terminal time point. Analysis will be blinded to the observer. Regenerated tissue in the root canal space and surrounding area was evaluated using histological analysis.

Results, Conclusions, and Discussions: We expect that the angiogenic hydrogel will stimulate microvasculature growth, with consequential increases in granulated tissue observed through hemotoxin and eosin-stained cross-sections. Consistent with previous studies, we expect to see decreases in inflammatory cells observed and an increase in odontoblasts starting at Day 7 post treatment. Previous studies with the angiogenic hydrogel alone have shown decreases in inflammatory cell count and increased granulated tissue relative to a vehicle control starting 7 days post treatment. It is hypothesized the antimicrobial hydrogel will mitigate inflammation and infection from the pulpectomy procedure, further enhancing the improvements in inflammation modulation and dental pulp regeneration. The combination antimicrobial and angiogenic SAP system could be used in treatment of immature permanent teeth with open apex in order to prevent infection of the vital tooth pulp and facilitate root maturation. The scope of the work described herein serves as a proof of concept for combining different bioactive peptides to form a multi-faceted hydrogel system that addresses multiple root causes for complex pathologies. Future directions include refinement of the bioactive domains and translational work involving higher order animal models.

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