title: Influence of DPSS laser on polymerization shrinkage and mass change of resin composites.
abstract: OBJECTIVE
  This study evaluated the effectiveness of the diode-pumped solid state (DPSS) laser as a light source for light-curing dental resin composites.
  
  
  BACKGROUND
  A DPSS laser of 473  nm may be useful because of its match with the absorption peak of camphorquinone (CQ), the photoinitiator.
  
  
  METHODS
  A DPSS laser (LAS) of 473  nm and a quartz-tungsten-halogen (QTH) light-curing unit (OP) were used as the light sources for light curing six different resin composites (four nanocomposites and two hybrid composites). Polymerization shrinkage and mass change (water sorption and solubility) were measured during and after light curing to determine the degree of polymerization. Mass change was evaluated by following the ISO 4049 standard.
  
  
  RESULTS
  According to the evaluation, the specimens light cured using LAS showed similar maximum polymerization shrinkage (12.3∼18.1  μm for LAS; 13.2∼16.2  μm for OP) and water sorption (11.4∼24.1  μg/mm(3) for LAS; 11.3∼22.8  μg/ mm(3) for OP) to the cases light cured using OP. The specimens light cured using LAS showed a significantly higher solubility than the cases light cured using OP (2.4∼6.6  μg/ mm(3) for LAS; 0.8∼1.6  μg/ mm(3) for OP). However, the maximum water sorption and solubility obtained from the specimens were lower than the values permitted by the ISO 4049 standard.
  
  
  CONCLUSIONS
  The results may suggest that the DPSS laser with an emission wavelength of 473  nm can be used as a light source for light-curing dental resin composites.
authors.affiliation: Department of Dental Materials, College of Dentistry and Pusan National University Hospital Medical Research Institute, Pusan National University, Yangsan, Korea.
authors.forename: Dong-Hee
authors.initials: DH
authors.lastname: Shin
authors.forename: Dong-In
authors.initials: DI
authors.lastname: Yun
authors.forename: Mi-Gyong
authors.initials: MG
authors.lastname: Park
authors.forename: Ching-Chang
authors.initials: CC
authors.lastname: Ko
authors.forename: Franklin
authors.initials: F
authors.lastname: García-Godoy
authors.forename: Hyung-Il
authors.initials: HI
authors.lastname: Kim
authors.forename: Yong Hoon
authors.initials: YH
authors.lastname: Kwon
mesh_terms: D000042:Absorption; D000704:Analysis of Variance; D002164:Camphor / Q000031:analogs & derivatives / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects*; D055117:Curing Lights, Dental; D006244:Hardness; D053844:Lasers, Solid-State; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D053761:Nanocomposites; D058105:Polymerization; D012995:Solubility
chemical_list: D003188:Composite Resins; D002164:Camphor; C553149:camphorquinone