Spray-drying-assisted fabrication of CaF_2/SiO_2 nanoclusters for dental restorative composites

摘要

Objective: The objective of this study is to develop novel CaF2/SiO2 nanoclusters (NCs) fillers, which can endow the dental resin composites (DRCs) with excellent mechanical properties, stable and sustained fluoride ion release, and good antibacterial activity.& nbsp;Methods: The CaF2/SiO2 NCs were efficiently fabricated by assembling CaF2/SiO2 nanoparticles (NPs) as building blocks with a spray-drying technology. CaF2/SiO2 NCs with different SiO2 coating amounts (20 wt%, 50 wt% and 80 wt%) were incorporated into the DRCs at the filler content of 55 wt% for the measurement of mechanical properties including flexural strength, flexural modulus, compressive strength, and hardness. The effect of the filling amount of CaF2/50SiO(2) NCs (50 represents 50 wt% SiO2 coating amount) in the DRCs was investigated, while CaF2/50SiO(2) NPs were adopted as comparison group. The fluoride ion release and antibacterial activity of the DRCs with the optimal mechanical performances were evaluated. Furthermore, the statistical analyses were performed for mechanical properties.& nbsp;Results: Spherical CaF2/50SiO(2) NCs with an average size of 2.4 mu m were obtained at the feed rate of 7.4 mL/min and the CaF2/50SiO(2) NPs solid content of 2 wt% in the suspension. The optimum comprehensive performances of the DRCs can be achieved by filling 55 wt% CaF2/50SiO(2) NCs. Compared with CaF2/50SiO(2) NPs, the filling amount of CaF2/50SiO(2) NCs was increased by 5 wt% (50-55 wt%), and under the same filling amount of 50 wt%, the flexural strength, flexural modulus, compressive strength, and hardness of the DRCs containing CaF2/50SiO(2) NCs were improved by 9.8%, 17.7%, 7.5% and 69.8%, respectively. Furthermore, the DRCs filled with 50 wt% CaF2/50SiO(2) NCs exhibited more cumulative F-release by 126% and more stable F-release rate than the counterpart filled with 50 wt% CaF2/50SiO(2) NPs after immersed for 1800 h. And 55 wt% CaF2/50SiO(2) NCs filled DRCs could inhibit the growth of S. mutans, reaching an antibacterial ratio of 93%.& nbsp;Significance: The spray-dried CaF2/50SiO(2) NCs are promising fillers for the development of high-performance multifunctional DRCs. (C) 2022 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.