title: Comparative efficiency of plasma and halogen light sources on composite micro-hardness in different curing conditions.
abstract: OBJECTIVE
  Recent developments have led to the introduction of high power curing lights, which are claimed to greatly reduce the total curing time. This study evaluated the effectiveness of a plasma-curing device (Apollo 95 E) and a halogen device (Heliolux DLX), in different curing conditions.
  
  
  METHODS
  Vicker's micro-hardness values were performed on 1 and 2 mm thick composite discs cured in a natural tooth mold by direct irradiation or indirect irradiation through composite material (2 or 4 mm) and dental tissues (1 mm enamel or 2 mm enamel-dentin). Measures were, respectively, performed after a 1, 3, 6 s (SC, step curing mode) or 18 s (3xSC) exposure to the plasma light, and a 5, 10, 20 or 40 s exposure to the halogen light.
  
  
  RESULTS
  With the PAC light used, a 3 s irradiation in the direct curing condition was necessary to reach hardness values similar to those obtained after a 40 s exposure to the halogen light. Using the indirect curing condition, hardness values reached after an 18 s exposure (3xSC mode) with the plasma light were either equivalent or inferior to those obtained with 40 s halogen irradiation.
  
  
  CONCLUSIONS
  Direct polymerization with the plasma light used requires longer exposure times than those initially proposed by the manufacturer. The effectiveness of plasma generated light was lowered by composite or natural tissues, and therefore requires an important increase in the irradiation time when applied to indirect polymerization. The practical advantage of this polymerization method is less than expected, when compared to traditional halogen curing.
authors.affiliation: Division de Cariologie, d'Endodontie et de Pédodontie, Section de Médecine Dentaire, Faculté de Médecine, Université de Genève, 19 Rue Barthélémy Menn, 1205 Geneva, Switzerland. ddietschi@medecine.unige.ch
authors.forename: D
authors.initials: D
authors.lastname: Dietschi
authors.forename: N
authors.initials: N
authors.lastname: Marret
authors.forename: I
authors.initials: I
authors.lastname: Krejci
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000528:radiation effects*; D003748:Dental Equipment; D003799:Dental Stress Analysis; D006219:Halogens; D006244:Hardness / Q000528:radiation effects; D006801:Humans; D008027:Light; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry; D012822:Silicon Dioxide / Q000528:radiation effects; D013499:Surface Properties; D013674:Technology, Dental / Q000379:methods; D013997:Time Factors; D014978:Xenon; D015040:Zirconium / Q000528:radiation effects
chemical_list: D003188:Composite Resins; D006219:Halogens; D011108:Polymers; C121818:Tetric ceram; C083568:Z100 composite resin; D014978:Xenon; D012822:Silicon Dioxide; D015040:Zirconium