Biocompatibility effects of indirect exposure of base-metal dental casting alloys to a human-derived three-dimensional oral mucosal model

Abstract Objectives The study employed a three-dimensional (3D) human-derived oral mucosal model to assess the biocompatibility of base-metal dental casting alloys ubiquitous in fixed prosthodontic and orthodontic dentistry. Methods Oral mucosal models were generated using primary human oral keratinocyte and gingival fibroblast cells seeded onto human de-epidermidised dermal scaffolds. Nickel–chromium (Ni–Cr) and cobalt–chromium (Co–Cr) base-metal alloy immersion solutions were exposed to oral mucosal models for increasing time periods (2–72 h). Analysis methodologies (histology, viable cell counts, oxidative stress, cytokine expression and toxicity) were performed following exposure. Results Ni-based alloy immersion solutions elicited significantly decreased cell viability ( P < 0.0004) with increased oxidative stress ( P < 0.0053), inflammatory cytokine expression ( P < 0.0077) and cellular toxicity levels ( P < 0.0001) compared with the controls. However, the Ni-free Co–Cr-based alloy immersion solutions did not elicit adverse oxidative stress ( P > 0.4755) or cellular toxicity ( P < 0.2339) responses compared with controls. Conclusions Although the multiple analyses highlighted Ni–Cr base-metal alloy immersion solutions elicited significantly detrimental effects to the oral mucosal models, it was possible to distinguish between Ni–Cr alloys using the approach employed. The study employed a 3D human-derived full-thickness differentiated oral mucosal model suitable for biocompatibility assessment of base-metal dental casting alloys through discriminatory experimental parameters. Clinical significance Increasing incidences of Ni hypersensitivity in the general population warrants serious consideration from dental practitioners and patients alike where fixed prosthodontic/orthodontic dental treatments are the treatment modality involved. The novel and analytical oral mucosal model has the potential to significantly contribute to the advancement of reproducible dental medical device and dental material appraisals.