title: Effects of two amine reducing agents on the degree of conversion and physical properties of an unfilled light-cured resin.
abstract: The influence of varying concentrations of two amine reducing agents commonly used in commercial light-cured composites, N,N-dimethyl-p-toluidine (DMPT) and 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA), on the degree of conversion (DC), Knoop hardness, and compressive and transverse strengths of an unfilled light-cured resin was investigated. The DC obtained from employing two different internal standard peaks, carbonyl (C=O) at 1730 cm-1 and urethane (N-H) at 3350 cm-1, was compared. The resin consisted of 50 wt% triethyleneglycol dimethacrylate (TEGDMA) and 50 wt% 1,6-bis(methacryloxy-2-ethoxycarbonylamino)-2,4,4-trimeth ylhexane (UDMA) activated with 0.5 mol% camphorquinone (CQ) and varying concentrations of either DMPT or DMAEMA. The DC calculated by use of either C=O or N-H absorption peak as an internal reference showed similar values. For both amines, the physical properties were directly related to DC and appeared to reach maximal values at an amine/CQ molar ratio of 4.0. The DC, however, appeared to reach a maximum at an amine/CQ molar ratio of 3.0. Generally, for the same amine/CQ molar ratios, the polymers formulated with DMAEMA, had greater DCs and better physical properties than those formulated with DMPT.
authors.affiliation: Division of Biological Materials, Northwestern University Dental School, Chicago.
authors.forename: K
authors.initials: K
authors.lastname: Yoshida
authors.forename: E H
authors.initials: EH
authors.lastname: Greener
mesh_terms: D000588:Amines / Q000737:chemistry*; D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D006244:Hardness; D016014:Linear Models; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D013718:Tensile Strength; D014052:Toluidines / Q000737:chemistry
chemical_list: D000588:Amines; D003188:Composite Resins; D008689:Methacrylates; D011109:Polymethacrylic Acids; D011140:Polyurethanes; D014052:Toluidines; C029824:urethane dimethacrylate luting resin; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; C049840:2-(dimethylamino)ethyl methacrylate; C015835:dimethyl-4-toluidine