Cytotoxicity evaluation of perforation repair materials on human periodontal ligament cells in vitro

Perforation of a tooth structure resulting in communication of the pulp space with periodontium occasionally occurs during endodontic therapy. For the best prognosis, the perforation area must be sealed as soon as possible. Because these materials will be in direct contact with periodontal tissues, their cytotoxic potential must be evaluated before clinical use. The purpose of this study was to determine the cytocompatibility of three perforation repair materials (amalgam, resin, and glass ionomer). Cultured human periodontal ligament (PDL) cells were used to evaluate the cellular response resulting from these materials by cell viability and proliferation assays. Twenty-seven 5 x 4 mm cylinders of each material were fabricated for this study. All tested materials were cytotoxic to human PDL cells. Both types of material and time affected cell viability and proliferation. Resin exhibited the most cytotoxic effects followed by glass ionomer and amalgam during a 14-day incubation period. Amalgam and glass ionomer slightly inhibited cell viability and growth in the first 24 hr, compared with the control. Amalgam or glass ionomer may initially react more favorably to PDL cells than resin. The present model of cultured human PDL cells is simple, relatively cheap, and easily established and propagated under standardized conditions in any laboratory. Furthermore, this method allows long-term observation of human cellular reactions and thus might be a preliminary screening test for initial biocompatibility of dental materials.