3D-printed Cu-bearing titanium alloy crowns for pediatric oral health: biocompatibility, antibacterial activity, and internal fit.

INTRODUCTION

Dental caries in primary teeth is a significant global health problem. Conventional stainless-steel crowns (SSCs), widely used in pediatric dentistry, lack inherent antimicrobial properties. This study investigates a novel Cu-bearing titanium alloy, Ti6Al4V6Cu, fabricated by laser powder-bed fusion (LPBF), which is anticipated to offer both mechanical robustness and antibacterial performance.

OBJECTIVES

This study aimed to comprehensively evaluate the suitability of 3D-printed Ti6Al4V6Cu alloy for pediatric crown applications by assessing its mechanical properties, corrosion resistance, biocompatibility, and antibacterial efficacy.

METHODS

The alloy's mechanical and corrosion properties were analyzed via microhardness, universal testing, and electrochemical tests. Biocompatibility was evaluated using human gingival fibroblasts (HGFs) through CCK-8, IF, FCM, phalloidin, SEM, and qRT-PCR assays. Antibacterial activity againstStreptococcus mutanswas assessed using growth curves, plate counts, live/dead staining, lactic-acid production, TEM, and qRT-PCR. Crown internal fit was compared with traditional SSCs using silica-gel weighing and 3Shape software.

RESULTS

Ti6Al4V6Cu exhibited significantly higher surface hardness and compressive strength than pure Ti6Al4V and 304 stainless steel (P < 0.05), alongside superior corrosion resistance. The material demonstrated excellent biocompatibility with no cytotoxicity and supported normal HGF adhesion and proliferation. Antibacterial assays showed significant reductions in bacterial growth, biofilm formation, and acid production. TEM revealed structural damage to bacterial cells and elevated ROS levels, while qRT-PCR indicated downregulation of key virulence genes. The internal adaptation of TC4-6Cu crowns was significantly better than that of prefabricated SSCs (P < 0.05).

CONCLUSION

The 3D-printed TC4-6Cu alloy exhibits superior mechanical properties, enhanced corrosion resistance, excellent biocompatibility, and potent antibacterial effects, demonstrating strong potential as a next-generation material for pediatric dental crowns.