background and aims. the aim of this study was to compare the biocompatibility of calcium-enriched mixture ce-ment (cem), composite resin and nano-particled mineral trioxide aggregate (np-mta) using human gingival fibroblasts. materials and methods. a comparative in vitro cell culture study was carried out using 60 single-rooted teeth which were assigned to the following four groups: 1) untreat...