Effect of Propolis on Dentin Regeneration and the Potential Role of Dental Pulp Stem Cell in Guinea Pigs

Objective: Evaluation of the effect of Propolis as a bioactive material on quality of dentinand presence of dental pulp stem cells.Materials and Methods: For conducting this experimental split-mouth study,a total of48 maxillary and mandibular incisors of male guinea pigs were randomly divided into anexperimental Propolis group and a control calcium hydroxide group. Cutting the crownsand using Propolis or calcium hydroxide to cap the pulp, all of the cavities were sealed.Sections of the teeth were obtained after sacrificing 4 guinea pigs from each group on the10th, 15th and 30th day. After they had been stained by hematoxylin and eosin (H&E),specimens underwent a histological evaluation under a light microscope for identificationof the presence of odontoblast-like cells, pulp vitality, congestion, inflammation of the pulpand the presence of remnants of the material used. The immunohistochemistry (IHC)method using CD29 and CD146 was performed to evaluate the presence of stem cells andthe results were statistically evaluated by Kruskal-Wallis, Chi Square and Fisher tests.Results: In H&E stained specimens, there was no difference between the two groups inthe presence of odontoblast-like cells, pulp vitality, congestion, inflammation of the pulpand the presence of remnants of used material(p>0.05). There was a significant differencebetween the quality of regenerative dentin on the 15th and 30th days (p<0.05): all of thePropolis cases presented tubular dentin while 14% of the calcium hydroxide cases producedporous dentin. There was no significant difference between Propolis and calciumhydroxide in stimulation of dental pulp stem cells (DPSCs).Conclusion: This study which is the first one that documented the stimulation of stem cellsby Propolis, provides evidence that this material has advantages over calcium hydroxideas a capping agent in vital pulp therapy. In addition to producing no pulpal inflammation,infection or necrosis this material induces the production of high quality tubular dentin.