Initial biocompatibility of novel resins for 3D printed fixed dental prostheses

Several materials for 3D printing of fixed dental prostheses (FDP) have been recently introduced. This study aims to evaluate the initial biocompatibility of novel printable resins for manufacturing temporary and permanent FDP.Specimens of five printable resins (VarseoSmile Crown plus, NextDent C&B MFH, VarseoSmile Temp, Temp PRINT, P Pro Crown & Bridge), two types of resins for subtractive manufacturing (Tetric CAD, Telio CAD) and two types of resins with conventional curing processes (Tetric EvoCeram, Protemp 4) were produced and finished. Post-processing was strictly performed according to the manufacturer's protocol. Biocompatibility was evaluated by eluting specimens with cell culture medium and treating human gingival fibroblast cells with the eluates. A 72-hour continuous read cell viability assay measuring the reducing potential of the cells was performed. The cellular inflammatory response in terms of IL-6 and PGE2 levels was determined with specific ELISAs. Oxidative stress was determined by measuring oxidized glutathione concentrations after exposure to the resin eluates. A luminescence-based apoptosis assay was used to detect apoptosis.Tetric CAD and Telio CAD were slightly toxic. All other resins were moderately to severely cytotoxic. VarseoSmile Crown plus and P Pro Crown & Bridge significantly enhanced PGE2 levels. Higher concentrations of oxidized gluthatione were determined in the presence of Telio CAD, VarseoSmile Temp and P Pro Crown & Bridge. Tetric EvoCeram and Protemp 4 reduced intracellular gluthatione levels. All printable resins slightly induced apoptosis.Further post-processing steps such as additional curing and washing may improve the biocompatibility of printable materials.