title: A comparative study of the properties of dental resin composites polymerized with plasma and halogen light.
abstract: OBJECTIVE
  Newly developed curing units utilizing plasma arc methodology have been advocated for rapid curing of dental composites. This study was conducted to investigate the effect of plasma light using a 3 s and a step cure regime on the properties of four dental restorative materials and compare it with properties resulting from halogen light curing of the same materials.
  
  
  METHODS
  Composites Quadrant, Filtek and two polyacid modified composites (compomers) Dyract AP and Compoglass F were cured, using a conventional halogen light, a plasma light for 3 s (Apollo95E) and a plasma step cure (Apollo 95E) method. The parameters studied for characterization of the restorative materials were polymerization exotherm, surface hardness and their interactions with saline.
  
  
  RESULTS
  Irradiation with plasma light for 3 s or step cure produced an order of hardness: Filtek>Compoglass F>Dyract AP>Quadrant (p<0.001), however, halogen cure yielded an order of hardness: Filtek>Quadrant>Dyract AP>Compoglass F. No significant differences in hardness were observed on the exposed and non-exposed surfaces of the materials cured by plasma step cure whereas a 3 s cure yielded a significant difference in the cases of Quadrant, Compoglass F and Dyract AP (p<0.001). Mass losses were also found to be greater in the specimens cured by plasma light for 3 s in comparison with plasma step cure and halogen cure.
  
  
  CONCLUSIONS
  Plasma step and halogen curing were found to yield composites with superior properties in comparison to a 3 s plasma cure, suggesting, that a step cure regime is a preferred method, when a plasma light unit is used. A 3 s curing with a plasma light may lead to less than optimum properties of the composite cements.
authors.affiliation: Department of Biomaterials, Guy's, King's and St Thomas' Dental Institute, King's College London, Floor 17, Guy's Tower, London Bridge, London SE1 9RT, UK. sanjukta.deb@kcl.ac.uk
authors.forename: Sanjukta
authors.initials: S
authors.lastname: Deb
authors.forename: Harminder
authors.initials: H
authors.lastname: Sehmi
mesh_terms: D000042:Absorption; D020770:Compomers / Q000737:chemistry / Q000528:radiation effects*; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D004356:Drug Storage; D006219:Halogens; D006244:Hardness; D008027:Light; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry; D012965:Sodium Chloride; D012995:Solubility; D013674:Technology, Dental / Q000379:methods; D014867:Water; D014978:Xenon
chemical_list: D020770:Compomers; D003188:Composite Resins; D006219:Halogens; D011108:Polymers; D014867:Water; D014978:Xenon; D012965:Sodium Chloride