In vitro biocompatibility evaluation of three-dimensionally printed resin crowns for primary molars

This study aimed to assess the in vitro biocompatibility of two types of three-dimensionally (3D)-printed resin crowns (RCs) for primary molars. Three types of crowns were tested: (i) stainless steel crowns (SSCs), (ii) prefabricated zirconia crowns (PZCs), and (iii) 3D-printed RCs, which included two types: DIOnavi-P. MAX (RC1), and NextDent C&B Micro Filled Hybrid (RC2). Human gingival fibroblast (HGF) cells were exposed to extracts obtained from the crowns. Cell viability, proliferation, and migration were evaluated using the Cell Counting Kit-8 assay, flow cytometry, and a scratch wound healing assay. Oxidative stress levels were analyzed using a reactive oxygen species (ROS) assay. Expression of inflammatory biomarkers was assessed using a nitric oxide assay and reverse transcription quantitative polymerase chain reaction, and further confirmed by Western blotting. RC groups had a limited effect on HGF cell viability, proliferation, and migration. ROS levels were significantly lower in the RC groups than in the lipopolysaccharide group (p < 0.05). No significant upregulation of inflammatory biomarkers was observed in the RC groups compared to the other crown groups (p > 0.05). Within the limits of this study, 3D-printed RCs showed biocompatibility. These findings highlight the possibility of the clinical application of 3D-printed RCs for primary molars. Our results support that 3D-printed RCs for primary molars can offer an esthetic option with biocompatibility in gingival tissues, causing minimal inflammation.