Bioactivity of Endodontic Cements in Human Dental Follicle Cells

Objective: The dental follicle is a connective tissue harboring stem cells and committed progenitor cells for cementoblasts, periodontal ligament cells and osteoblasts. The main purpose of this study was to isolate cells from dental follicle tissue to test the bioactivity of endodontic cements. Methods: The Dental follicle tissue was removed from extracted third molars and was chopped up into small segments. To harvest the cells, segments were submitted to enzyme digestion for 15 min followed by the enzyme inactivation in culture media. One week after cell isolation, colonies were easily identified in the Petri dishes, where the cells have a fibroblast-like spindle shape. The human dental follicle cells (hDFCs) were subcultured in culture vessels. Before the hDFCs become 100% confluent they were seeded in 24 well culture plates at 10⁴cells/well and exposed for 1, 2, 3 and 7 days to Portland cement (PC) and MTA. The cements were prepared and inserted into plastic rings adapted inside transwell inserts (n=3/group). After being incubated with the cements, the cell viability was assessed by 3-(4,5-dimethyl-thiazoyl)-2,5-diphenyl-tetrazolium-bromide assay (MTT) and the bioactivity of endodontic cements was evaluated by alkaline phosphatase activity. After one week of exposure, the morphology of hDFCs was analyzed by transmission electronic microscopy (n=30cells/group). The results were statistically analyzed (ANOVA, Bonferroni, p<0.01). Results: MTT demonstrated a significant viability cell rate after 1 and 2 days for both endodontic cements (>100%). Microscope images showed morphology of differentiated cells such as secretion vesicles, uncountable mitochondria located near Golgi-complex, defined nucleus and nucleoli, typical aspects of intense protein synthesis. Alkaline phosphatase activity data demonstrated that PC promoted significant enhancement of this osteogenic marker expression. Conclusions: The hDFCs were of easy isolation and very suitable for dental material bioactivity tests. In addition of being biocompatible, PC and MTA are also bioactive materials.