title: Halogen lamp and LED activation of resin-modified glass ionomer restorative material. In vitro microhardness after long-term storage.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the activation of resin-modified glass ionomer restorative material (RMGI, Vitremer-3M-ESPE, A3) by halogen lamp (QTH) or light-emitting diode (LED) by Knoop microhardness (KHN) in two storage conditions: 24 hrs and 6 months and in two depths (0 and 2 mm).
  
  
  METHODS
  The specimens were randomly divided into 3 experimental groups (n = 10) according to activation form and evaluated in depth after 24 h and after 6 months of storage. Activation was performed with QTH for 40s (700 mW/cm) and for 40 or 20 s with LED (1,200 mW/cm2). After 24 hrs and 6 months of storage at 37 degrees C in relative humidity in light-proof container, the Knoop microhardness test was performed. Statistics Data were analysed by three-way ANOVA and Tukey post-tests (p < 0.05).
  
  
  RESULTS
  All evaluated factors showed significant differences (p < 0.05). After 24 hrs there were no differences within the experimental groups. KHN at 0 mm was significantly higher than 2 mm. After 6 months, there was an increase of microhardness values for all groups, being the ones activated by LED higher than the ones activated by QTH.
  
  
  CONCLUSIONS
  Light-activation with LED positively influenced the KHN for RMGI evaluated after 6 months.
authors.affiliation: Graduate Studies Division, Department of Restorative Dentistry, School of Dentistry, Guarulhos University, Brazil. acassoni@prof.ung.br
authors.forename: A
authors.initials: A
authors.lastname: Cassoni
authors.forename: P
authors.initials: P
authors.lastname: Macarini
authors.forename: E S
authors.initials: ES
authors.lastname: Leonetti
authors.forename: J A
authors.initials: JA
authors.lastname: Shibli
authors.forename: J A
authors.initials: JA
authors.lastname: Rodrigues
mesh_terms: D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects; D055117:Curing Lights, Dental / Q000145:classification*; D003624:Darkness; D005899:Glass Ionomer Cements / Q000737:chemistry / Q000528:radiation effects*; D006244:Hardness; D006801:Humans; D006813:Humidity; D008422:Materials Testing; D055668:Photochemical Processes; D019279:Resin Cements / Q000737:chemistry / Q000528:radiation effects*; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D003188:Composite Resins; D005899:Glass Ionomer Cements; D019279:Resin Cements; C084550:Vitremer