In vitro biocompatibility testing of 3D printing and conventional resins for occlusal devices

•3D printing resins have shown similar biological effects to conventional ones.•Freeprint Splint was the most cytotoxic on human gingival fibroblasts of the four dental resin studied.•The results obtained in this study suggest that hGFs showed better in vitro biocompatibility after exposition to Keysplint Soft, being the most eligible dental resin for occlusal devices. : To assess and compare the in vitro biocompatibility of new resins (Keysplint Soft (Keystone Industries), NextDent Ortho Rigid (3D System), and Freeprint Splint (Detax)) and traditional resins (Orthocryl (Dentaurum)) for dental splint. : Standardized discs (n=40) and 1:1, 1:2, and 1:4 extracts of the tested materials were prepared. Human gingival fibroblasts (hGFs) were isolated from gingival tissues. Different biological tests were carried out, including MTT assays to assess cell metabolic activity, cell migration assays, cell cytoskeleton staining, cell apoptosis, generation of intracellular reactive oxygen species (ROS), and scanning electron microscopy (SEM). Statistical analyses were performed using one-way ANOVA and Tukey's post hoc test (p