Non-autologous endodontic pulp regeneration approach in molar teeth of the rat

Abstract

The dental pulp is an important soft connective tissue which is able to produce dentin over time as a reaction on external stimuli. It also maintains the biological and physiological vitality of the dentin. Due to this the pulp is essential for teeth homeostasis. However, dental caries is still one of the most prevalent health problems in dentistry and therefore, one major cause for early loss of the dental pulp vitality and subsequent tooth extractions. Meanwhile the potential for successful pulp regeneration therapy is increasing due to advances in the field of regenerative endodontics. Thus, adequate experimental animal models are required for testing and validating these new regenerative therapies. Rodents and rats in particular, are relevant models for experimental periodontal research. The breeding and housing costs of rats are relatively low facilitating studies with sufficient numbers for statistical analysis in comparison to bigger sized mammals like beagle dogs, miniature pigs or monkeys. Additionally, rat molar teeth and pulps are characterized by similar anatomical, histological, biological and physiological features to human teeth. Essential biological reactions of the pulp tissue and the interaction during the different stages of wound healing of rat molar teeth are comparable to that of other mammals. However, despite of the multiple research activities in the field of regenerative endodontics and the above mentioned advantages of the rat model only rare in vivo studies are published. Therefore, the presented study aimed to introduce the rat molar teeth as a valid model for studying dental pulp stem cell based endodontic tissue regeneration. Human dental pulp stem cells were implanted into the pulp of immunodeficient rats (RNU rats). Cell growth was supported by a collagenous membrane, which was applied on top of the cells after implantation. After closing the pulpal cavity with a light-polymerisable resin human dental pulp stem cells were able to maintain cell viability in the rat molar pulp niche for at least three weeks. This demonstrated the suitability of immunodeficient RNU rats for non-autologous dental stem cell based endodontic tissue engineering approaches.