Restorative Dentistry Department, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil.
Craniofacial Biology Department, University of Colorado, Aurora, CO, United States.
Dent Mater. 2019 Jun;35(6):928-936. doi: 10.1016/j.dental.2019.03.007. Epub 2019 Apr 16.
This study probes how modifiedapproaches for filler surface treatment in dental composites based on alternative silanes and functional nanogel additives affects physicochemical properties of these materials with a focus on polymerization stress development.
Nanogels were synthesized from isobornyl methacrylate, ethoxylated bisphenol-A dimethacrylate and isocyanatoethyl methacrylate followed by partial further reaction with 2-hydroxyethyl methacrylate to provide both isocyanate and methacrylate functionalization. A barium glass filler (˜1 μm particle size) was treated with either γ-methacryloxypropyltrimethoxysilane (MPS), N-methylaminopropyltrimethoxy (MAP) or N-allylaminopropyltrimethoxy (AAP) silanes. The reactive nanogels were then covalently attached to the aminosilane-treated fillers. Surface treatment was characterized by thermogravimetric analysis (TGA) and diffuse reflectance infrared spectroscopy (DR-IR). Composites were formulated with 60 wt% of the various functionalized fillers and the materials were evaluated for polymerization kinetics, polymerization stress (PS), volumetric shrinkage, mechanical properties and photorheology. Data were evaluated by one-way ANOVA and Tukey's test at 5% significance level.
Filler surface treatments were confirmed by TGA and DR-IR analyses. Nanogel-functionalized fillers significantly reduced PS up to 20%, while the degree of conversion and elastic modulus were not compromised. Similar storage modulus development during polymerization was observed among materials by photorheology although the rate of polymerization was significantly increased for nanogel-based treatments. A significant decrease in flexural strength was observed for amino functional silane groups; however, there was no statistical difference in strength for the MPS control group compared with the nanogel-modified composites.
Filler surface treatment modified with a reactive nanogel enables significant PS reduction, without compromise to degree of conversion or mechanical properties of dental composites.
本研究探讨了基于替代硅烷和功能性纳米凝胶添加剂的牙科复合材料中填料表面处理方法的改进，如何影响这些材料的物理化学性质，重点是聚合应力的发展。
纳米凝胶由异冰片甲基丙烯酸酯、乙氧基化双酚 A 二甲基丙烯酸酯和异氰酸酯乙基甲基丙烯酸酯合成，然后与 2-羟乙基甲基丙烯酸酯部分进一步反应，提供异氰酸酯和甲基丙烯酸酯官能化。钡玻璃填料（˜1μm 粒径）用γ-甲基丙烯酰氧基丙基三甲氧基硅烷（MPS）、N-甲基氨基丙基三甲氧基（MAP）或 N-烯丙基氨基丙基三甲氧基（AAP）硅烷处理。然后将反应性纳米凝胶共价键合到氨基硅烷处理的填料上。通过热重分析（TGA）和漫反射红外光谱（DR-IR）对表面处理进行了表征。复合材料由 60wt%的各种功能化填料组成，并对聚合动力学、聚合应力（PS）、体积收缩率、力学性能和光流变性能进行了评价。数据采用单向方差分析和 Tukey 检验，置信度为 5%。
TGA 和 DR-IR 分析证实了填料表面处理。纳米凝胶功能化填料可显著降低 PS 达 20%，而转化率和弹性模量不受影响。光流变学研究表明，聚合过程中材料的储能模量发展相似，但纳米凝胶处理的聚合速率显著提高。氨基官能化硅烷基团显著降低了弯曲强度；然而，与 MPS 对照组相比，纳米凝胶改性复合材料的强度没有统计学差异。
用反应性纳米凝胶对填料表面进行处理，可以显著降低 PS，而不会影响牙科复合材料的转化率或力学性能。
