Objective: The aim of the study was to assess, in vitro, the influence on cytotoxicity of heat treatment applied before photopolymerization, while mixing three self-adhesive resin cements, in an NIH/3T3 fibroblast cell culture, based on cell viability measures. Methods: Samples were divided into three groups: (1) no heat treatment while mixing (control), (2) 37°C, and (3) 60°C heat treatment while mixing. Cements were light-cured immediately after mixing and immersed in Dulbecco's Modified Eagle Media for the extraction of possibly uncured products after 24 h and 7 days. Cultures contained 0.5 mL of NIH/3T3 fibroblasts per well at a concentration of 0.4 × 10⁵ cells/mL and specific extracts for each sample. Statistical Analysis Used: Data were statistically analyzed with ANOVA and post hoc Student–Newman–Keuls (significance of 5%). Results: Cement cytotoxicity increased with time, as shown by the higher values observed at 7 days. There was a slight difference in intragroup cytotoxicity levels between 24 h and 7 days. Heat treatment at 60°C was associated with a major decrease in cytotoxicity levels in all three groups, both at 24 h and at 7 days, with no differences among the cements. Conclusions: Heat treatment at 60°C should be considered as a strategy to reduce cytotoxicity of self-adhesive resin cements, as evidenced by the results observed at 24 h and 7 days of analysis.

Background. Direct pulp capping is a method designed to preserve the exposed dental pulp. Due to good biological, physical, and mechanical properties, new versions of calcium silicate-based materials have been developed as pulp capping materials. The present study aimed to evaluate the cytotoxic effects of four calcium silicate-based pulp capping materials, of which the Bio-C Repair Íon+ is still in an experimental phase. Methods. Biodentine, MTA Repair HP, Bio-C Repair, and Bio-C Repair Íon+ cements were dispensed in a metallic matrix to produce 125-mm3 specimens, which were immersed in Dulbecco’s Modified Eagle Medium (DMEM) to obtain extracts. NIH 3T3 cells were cultured and exposed to the extracts for 24 hours and seven days. Cell viability was assessed by the methyl tetrazolium test (MTT). The mean values for the experimental and control groups (without treatment) were compared by analysis of variance (ANOVA) and post hoc Tukey tests, considering a significance level of 5%. Results. All the tested materials demonstrated a reduction in cell viability (P<0.05). According to ISO 10993-5: 2009 (E), Bio-C Repair Íon+ exhibited mild and moderate cytotoxicity in the 24- hour and 7-day analyses, respectively. Bio-C Repair and Biodentine showed mild cytotoxicity, and MTA Repair HP exhibited moderate cytotoxicity at both intervals. Conclusion. The highest cell viability was demonstrated by Biodentine, MTA, and Repair HP, in descending order. Bio-C Repair and Bio-C Repair Íon+ showed moderate cytotoxicity, similar to MTA Repair HP in the 7-day analysis.

Additive manufacturing resins used in dental prosthetics may retain uncured monomers post-polymerization, posing potential long-term patient exposure risks. Understanding the biological safety of these materials is crucial, particularly for 3D-printed acrylic-based prosthodontic devices such as occlusal nightguards, complete and partial dentures, and temporary fixed prostheses. This paper reviews the literature evaluating the cytotoxicity of such materials. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, we conducted a scoping review using the MESH keywords related to population (P), intervention (I), comparison (C), and outcome (O) across databases, including OVID Medline, EMBASE, and SCOPUS. Our search, limited to peer-reviewed English language articles from 2015 to 2023, resulted in 22 papers. These studies, utilizing digital light processing (DLP) or stereolithography (SLA) printing methods, varied in examining different 3D-printed materials, as well as washing and post-curing protocols. The primary experimental cells used were human gingival fibroblasts (HGF) and mouse fibroblasts (L929). There are no statistical differences in biocompatibility regarding different commercially available resins, washing solutions, or methods. Improvements in cell viability were related to an increase in washing time, as well as post-curing time. After the polishing procedure, 3D resin-based printed occlusal devices perform similarly to milled and conventionally processed ones. Our findings underline the importance of appropriate washing and post-curing protocols in minimizing the cytotoxic risks associated with these 3D-printed resin-based devices.