title: Interaction of LED light with coinitiator-containing composite resins: effect of dual peaks.
abstract: OBJECTIVE
  Recently the colour stability of composite resins has been an issue due to the emphasis on the aesthetics of restored teeth. The purpose of the present study was to investigate how dual-peak LED units affect the polymerization of coinitiator-containing composite resins.
  
  
  METHODS
  Five composite resins [coinitiator-containing: Aelite LS Posterior (AL), Tetric EvoCeram (TE), and Vit-l-escence (VI); only CQ-containing: Grandio (GD) and Filtek Z350 (Z3)] were light cured using four different light-curing units (LCUs). Among them, Bluephase G2 (BP) and G-light (GL) were dual-peak LED LCUs. Microhardness, polymerization shrinkage, flexural, and compressive properties were measured.
  
  
  RESULTS
  BP and GL had no consistent effect on the microhardness of AL, TE, and VI on the top and bottom surfaces of resin specimens. Among the specimens, AL and VI showed the least (9.86-10.41 μm) and greatest (17.58-19.21 μm) polymerization shrinkage, respectively. However, the effect of BP and GL on the shrinkage of specimens was not consistent. Among the specimens, GD showed the greatest flexural properties [strength (FS) and modulus (FM)] and TE showed the lowest flexural and compressive properties [strength (CS) and modulus (CM)]. In same resin product, maximum FS and CS differences due to the different LCUs were 10.3-21.0% and 3.6-9.2%, respectively. Furthermore, the influences of BP and GL on FS and CS were not consistent.
  
  
  CONCLUSIONS
  The tested dual-peak LED LCUs had no consistent synergic effect on the polymerization of coinitiator-containing composite resins as compared with QTH and single-peak LED LCUs.
  
  
  CONCLUSIONS
  The dual-peak LED LCUs achieve a similar degree of polymerization in coinitiator-composite resins as QTH and single-peak LED LCUs did. Choice of LCU does not appear to be a determinant of the light curing of coinitiator-composite resins.
authors: Department of Dental Materials, School of Dentistry, Medical Research Institute, Pusan National University, Yangsan 626-870, Republic of Korea.
authors: Jae-Seong
authors: JS
authors: Sim
authors: Hyo-Joung
authors: HJ
authors: Seol
authors: Jeong-Kil
authors: JK
authors: Park
authors: Franklin
authors: F
authors: Garcia-Godoy
authors: Hyung-Il
authors: HI
authors: Kim
authors: Yong Hoon
authors: YH
authors: Kwon
mesh_terms: D000465:Algorithms; D001713:Biphenyl Compounds / Q000737:chemistry / Q000528:radiation effects; D002164:Camphor / Q000031:analogs & derivatives / Q000737:chemistry / Q000528:radiation effects; D047188:Chalcones / Q000737:chemistry / Q000528:radiation effects; D003116:Color; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D055117:Curing Lights, Dental / Q000145:classification*; D003764:Dental Materials / Q000737:chemistry* / Q000528:radiation effects; D055119:Elastic Modulus; D006244:Hardness; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D010720:Phosphines / Q000737:chemistry / Q000528:radiation effects; D058567:Photoinitiators, Dental / Q000737:chemistry* / Q000528:radiation effects; D018583:Pliability; D058105:Polymerization; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: C520678:(2,4,6-trimethylbenzoyl) diphenylphosphine oxide; C401765:2,2-dimethoxy(1,2)diphenyletanone; C485363:Aelite LS; D001713:Biphenyl Compounds; D047188:Chalcones; D003188:Composite Resins; D003764:Dental Materials; C509998:Grandio; D010720:Phosphines; D058567:Photoinitiators, Dental; C501891:Tetric EvoCeram; C515948:Vit-l-escence Trans Ice; C533204:filtek Z350; D002164:Camphor; C553149:camphorquinone; C100349:1-phenyl-1,2-propanedione