Eric Habib1, Ruili Wang1, X X Zhu2. 1. Department of Chemistry, Université de Montréal, CP 6128, Succ. Centre-Ville, Montreal, QC, H3C 3J7, Canada. 2. Department of Chemistry, Université de Montréal, CP 6128, Succ. Centre-Ville, Montreal, QC, H3C 3J7, Canada. Electronic address: julian.zhu@umontreal.ca.
Abstract
OBJECTIVE: The viscosity of dental resin composites is important in their formulation and clinical use; it depends on the filler particle size and loading. We intend to study the viscosity and conversion of composites made of low dispersity spherical silica fillers. METHODS: Experimental dental resin composites were formulated using low dispersity spherical silica particles of graded sizes (75, 150, 500, 350, 500, 1000nm) at several loading levels with resins based on Bis-GMA and UDMA. Their rheological properties and double bond conversion were measured with a rheometer and differential scanning calorimeter, respectively. RESULTS: The complex viscosity of the unpolymerized pastes can be fit to an extended Krieger-Dougherty equation that includes an adjustment factor to account for filler particle surface area. This relationship is also extended to estimate the degree of conversion, where the calculated or experimental viscosity is used to predict the resulting conversion. SIGNIFICANCE: The enhanced understanding of the relationship of filler size, composite viscosity, and monomer conversion will allow improved accuracy in the prediction of the properties of dental resin composite formulations to obtain ideal viscosity for their clinical use and a high degree of conversion.
OBJECTIVE: The viscosity of dental resin composites is important in their formulation and clinical use; it depends on the filler particle size and loading. We intend to study the viscosity and conversion of composites made of low dispersity spherical silica fillers. METHODS: Experimental dental resin composites were formulated using low dispersity spherical silica particles of graded sizes (75, 150, 500, 350, 500, 1000nm) at several loading levels with resins based on Bis-GMA and UDMA. Their rheological properties and double bond conversion were measured with a rheometer and differential scanning calorimeter, respectively. RESULTS: The complex viscosity of the unpolymerized pastes can be fit to an extended Krieger-Dougherty equation that includes an adjustment factor to account for filler particle surface area. This relationship is also extended to estimate the degree of conversion, where the calculated or experimental viscosity is used to predict the resulting conversion. SIGNIFICANCE: The enhanced understanding of the relationship of filler size, composite viscosity, and monomer conversion will allow improved accuracy in the prediction of the properties of dental resin composite formulations to obtain ideal viscosity for their clinical use and a high degree of conversion.
Authors: Saad Saeed AlShahrani; Mana'a Saleh AlAbbas; Isadora Martini Garcia; Maha Ibrahim AlGhannam; Muath Abdulrahman AlRuwaili; Fabrício Mezzomo Collares; Maria Salem Ibrahim Journal: Materials (Basel) Date: 2021-01-15 Impact factor: 3.623
Authors: Aurealice Rosa Maria Martins; Luciana Machado-Santos; Regis Cleo Fernandes Grassia; Rafael Pino Vitti; Mário Alexandre Coelho Sinhoreti; William Cunha Brandt Journal: Eur J Dent Date: 2021-01-07