title: A novel light-cured glass-ionomer system for improved dental restoratives.
abstract: A novel light-cured glass-ionomer cement (LCGIC) system based on the 4-arm star-shape poly(acrylic acid) (AA) tethered with glycidyl methacrylate has been developed. The 4-arm poly(AA) polymer was synthesized using atom-transfer radical polymerization. The purified polymer was used to formulate with water and Fuji II LC filler to form LCGICs. Compressive strength (CS) was used as a screening tool for evaluation. The effects of grafting ratio, polymer/water (P/W) ratio, filler powder/polymer liquid (P/L) ratio and aging on strengths were investigated. All the specimens were conditioned in distilled water at 37 degrees C for 24 h prior to testing. The results show that the 4-arm poly(AA) polymer exhibited a lower viscosity as compared to its linear counterpart that was synthesized via conventional free-radical polymerization. This novel LCGIC system was 13% in CS, 86% in diametral tensile strength (DTS) and 123% in flexural strength higher but 93.6% in shrinkage lower than Fuji II LC. Increasing P/W ratio significantly increased both CS and DTS. Upon increasing grafting ratio, the CS was increased from 35% to 50% but not from 50% to 70%. Likewise, when P/L ratio was increased, the CS was increased from 2.2 to 2.7 but not from 2.7 to 3.0. During aging, the ultimate CS (MPa) was significantly increased from 209.2 at 1 h to 329.7 at 1 week. It appears that this novel LCGIC system will be a better dental restorative because it demonstrated improved mechanical strengths as well as little shrinkage and may eliminate cytotoxicity in current LCGICs caused by leached HEMA.
authors.affiliation: Department of Biomedical Engineering, Purdue School of Engineering and Technology, Indiana University-Purdue University at Indianapolis, Indianapolis, IN 46202, USA. dxie@iupui.edu
authors.forename: Dong
authors.initials: D
authors.lastname: Xie
authors.forename: Jun
authors.initials: J
authors.lastname: Zhao
authors.forename: Jong-Gu
authors.initials: JG
authors.lastname: Park
mesh_terms: D019245:Compressive Strength / Q000187:drug effects; D003793:Dental Restoration, Permanent; D005899:Glass Ionomer Cements / Q000138:chemical synthesis* / Q000737:chemistry*; D008027:Light; D008422:Materials Testing; D008954:Models, Biological; D011108:Polymers; D011208:Powders / Q000494:pharmacology; D012117:Resins, Synthetic / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; D011108:Polymers; D011208:Powders; D012117:Resins, Synthetic; D014867:Water