title: Polymerization kinetics of pre-heated composite.
abstract: Temperature affects the polymerization behavior of dimethacrylate-based materials. This study describes the influence of pre-polymerization temperature and exposure duration on polymerization kinetics of a commercial dental photo-activated composite at the top and at 2-mm depth. We used the temperature-controlled stage of a diamond-attenuated-total-reflectance unit to pre-set composite temperature between 3 degrees and 60 degrees C. Composite was light-exposed by a conventional quartz-tungsten-halogen curing unit for 5, 10, 20, or 40 sec. Real-time conversion, maximum conversion rate (R(p)(max)), time to achieve R(p)(max), and conversion at R(p)(max) were calculated from infrared spectra. Composite pre-warming enhanced maximal polymerization rate and overall monomer conversion (top significantly greater than 2 mm). Time when R(p)(max) occurred did not change with temperature, but occurred sooner at the top than at 2-mm depth. Conversion at R(p)(max) increased with temperature, allowing more of the reaction to occur prior to vitrification than at room temperature.
authors.affiliation: Department of Dental Materials, School of Dentistry, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Daronch
authors.forename: F A
authors.initials: FA
authors.lastname: Rueggeberg
authors.forename: M F
authors.initials: MF
authors.lastname: De Goes
authors.forename: R
authors.initials: R
authors.lastname: Giudici
mesh_terms: D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D003764:Dental Materials / Q000737:chemistry* / Q000528:radiation effects; D006358:Hot Temperature; D006801:Humans; D007700:Kinetics; D008027:Light; D008029:Lighting / Q000295:instrumentation; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C466112:Esthet-X; D011108:Polymers