Evaluation of the effect of different pulp capping materials on the secretion of Interleukin-6 from human dental pulp stem cells: an in vitro study

Regenerative treatments in endodontics are biological treatments to manage immature teeth, remove inflamed and necrotic tissue, and create a suitable environment for tissue repair. In these treatments, substances with reparative properties of dental pulp and dentin are placed on the pulpal tissue. Interleukin-6 is one of the cytokines secreted in response to various immune activities of the body and studies have demonstrated its vital role in mineralization induction and hard tissue formation. Recently, calcium silicate-based materials have been widely implemented in dentistry due to their great biocompatibility and hard tissue formation induction. Considering the role of IL-6 in the regulation of stem cells, the purpose of this study is to compare the effect of CEM cement, Biodentine, TheraCal LC, and MTA on the level of IL-6 secretion by dental pulp stem cells.

In this laboratory study, 4 types of cement were used as the main groups, and 1 control group contained culture medium without cement. Discs were prepared under sterile conditions in six-well plates with a diameter of 35 mm and a height of 2 mm and they were given time to set for 48 hours. Human pulp stem cells were obtained from Iran's Center for Biological Resources and cultured in a culture medium containing DMEM with 15% FBS and 1% penicillin-streptomycin (10,000 units/ml) as antibiotics. Pulp stem cells at passages 3-5 were used for experiments. Discs of each cement were prepared under sterile conditions and according to the manufacturer's instructions. To prepare the extract of each cement, the DMEM cell culture medium was placed near these discs for 24 hours. Then, human dental pulp stem cells (hDPSCs) were cultured in the vicinity of the disc extract for 72 hours. After that, this extract was collected and the level of IL-6 secretion in it was measured by the ELISA method. The experiments were repeated 3 times. Then the obtained data were entered into SPSS 16 software and analyzed using analysis of variance and the Kruskal-Wallis test.

The results showed that the highest level of IL-6 secretion by cells was in the presence of TheraCal LC, Biodentine, and CEM, respectively; But there was no significant difference between the groups. The average level of IL-6 secretion in the presence of MTA was lower than in other groups and this difference was significant (P<0.01).

The results of the present study showed a lower level of IL-6 cytokine secretion by pulpal stem cells in the presence of MTA compared to TheraCal, CEM, and Biodentine types of cement. Considering the role that IL-6 can have in osteogenic and odontogenic activities, the results of this study can be useful in establishing information in the field of introducing the most suitable cements for clinical procedures.