Abstract Objectives The aim of this in vitro study was to evaluate the cytotoxicity of two direct-printed photopolymers, LuxCreo and Nylon, intended for orthodontic applications. Methods LuxCreo (LuxCreo Inc., Chicago, IL) and Nylon (EOS, Munich, Germany) direct-printed materials were compared to conventionally used orthodontic materials including polyethylene terephthalate glycol (PETG) and polymethyl methacrylate (PMMA). Human gingival fibroblasts (hGFB) were cultured in 12-well plates on sterilized material discs for 24-h, 72-h or 7-day intervals (n = 3). Following co-incubation of hGFB with the materials, an MTT assay was conducted to evaluate cell viability, an LDH assay was used to evaluate cell death, and ELISA was used to measure IL-6, IL-8, and IL-1β production. Results Nylon significantly reduced cell metabolic activity at 24 h, 72 h, and 7 days, while LuxCreo showed a reduction only at 72 h and 7 days, compared to conventional materials. None of the materials induced a significant increase in cell death in hGFB. Elevated levels of IL-6 and IL-8 were observed only in the Nylon group. IL-1β levels were not significantly different between groups. Conclusion Direct-printed materials reduced cell viability. While none of the materials induced cell death, Nylon did increase the pro-inflammatory cytokine response. Future studies should investigate the underlying mechanisms of cytotoxicity and pro-inflammatory responses to improve the safety and biocompatibility of orthodontic materials. Clinical relevance The elevated pro-inflammatory cytokine response observed with direct-printed photopolymers highlight the need for clinical studies to investigate the mechanisms underlying cytotoxic and inflammatory responses. Future research should also evaluate the effects of long-term intraoral exposure and monitor relevant biomarkers during orthodontic treatment to better assess the safety and biocompatibility of these materials.
T. et al. (Thu,) studied this question.