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- Title
Nanogel-Based Filler-Matrix Interphase for Polymerization Stress Reduction.
- Authors
Fronza, B.M.; Rad, I.Y.; Shah, P.K.; Barros, M.D.; Giannini, M.; Stansbury, J.W.
- Abstract
A novel filler-resin matrix interphase structure was developed and evaluated for dental composite restoratives. Nanogel additives were chemically attached to the filler surface to use this created interphase as a potential source of compliance to minimize stress development during polymerization. In addition, we evaluated the effects of free nanogel dispersion into the resin matrix, combined or not with nanogel-modified fillers. Nanogels with varied characteristics were synthesized (i.e., size, 5 and 11 nm; glass transition temperature, 28 °C to 65 °C). Glass fillers were treated with trimethoxyvinylsilane and further reacted with thiol-functionalized nanogels via a free radical thiol-ene reaction. γ-Methacryloxypropyltrimethoxysilane-surface treated fillers were used as a control. Composites were formulated with BisGMA/TEGDMA resin blend with 60 wt% fillers with nanogel-modified fillers and/or free nanogel additives at 15 wt% in the resin phase. Polymerization kinetics, polymerization stress, volumetric shrinkage, and rheological and mechanical properties were evaluated to provide comprehensive characterization. Nanogel-modified fillers significantly reduced the polymerization stress from 2.2 MPa to 1.7 to 1.4 MPa, resulting in 20% stress reduction. A significantly greater nanogel content was required to generate the same magnitude stress reduction when the nanogels were dispersed only in the resin phase. When the nanogel-modified filler surface treatment and resin-dispersed nanogel strategies were combined, there was a stress reduction of 50% (values of 1.2 to 1.1 MPa). Polymerization rate and volumetric shrinkage were significantly reduced for systems with nanogel additives into the resin. Notably, the flexural modulus of the materials was not compromised, although a slight reduction in flexural strength associated with the nanogel-modified interphase was observed. Overall, modest amounts of free nanogel additives in the resin phase can be effectively combined with a limited nanogel content filler-resin interphase to lower volumetric shrinkage and dramatically reduce overall polymerization stress of composites.
- Subjects
NANOGELS; POLYMERIZATION; DENTAL fillings; MECHANICAL behavior of materials; ADDITIVES; STRESS relieving (Materials); DISPERSION (Chemistry); STRETCH (Physiology); RESEARCH; DENTAL resins; DENTAL materials; RESEARCH methodology; PHYSIOLOGIC strain; EVALUATION research; MEDICAL cooperation; COMPARATIVE studies; MATERIALS testing; RESEARCH funding; ACYCLIC acids; SURFACE properties; POLYMETHACRYLIC acids
- Publication
Journal of Dental Research, 2019, Vol 98, Issue 7, p779
- ISSN
0022-0345
- Publication type
journal article
- DOI
10.1177/0022034519845843