The aim of this study was to compare the bond strength of resin composites to dental structure photoactivated with a light emitting diode (LED) curing unit.
Methods and Materials
One hundred bovine incisors were selected and a conical cavity was prepared in the facial surface of each tooth. Clearfil SE Bond (Kuraray CO., LTD. Osaka, Japan) adhesive system was applied, and the cavities were filled with a single increment of Filtek™ Z250 (3M ESPE, St. Paul, MN, USA) or Esthet-X (Dentsply-Caulk – Mildford, DE, USA). The specimens were assigned to ten groups (n=10) according to the irradiance used: 100, 200, 300, 400, or 500 mW/cm2. Photoactivation was accomplished using an Ultrablue IS LED (DMC Equipamentos LTDA, São Carlos, SP, Brazil). The radiant exposure time was kept constant. A push-out test was conducted in a universal testing machine. Bond strength values were submitted to a two-way analysis of variance (ANOVA) and a Tukey's test at the 5% significance level.
The bond strength of the Z250 was higher than the Eshet-X (p<0.05). However, the modulation of irradiance adjusted to the same radiant exposure had no influence on Z250. The bond strength using an irradiance of 100mW/cm2 was higher than the other levels for Esthet-X. When composites were compared, no significant differences were detected between them for activation with irradiances of 100 and 200 mW/cm2.
The modulation of the luminous energy emitted by LED was almost unable to provide significant differences among the groups for both composites, except for a lower irradiance of Esthet-X.
Segreto D, Brandt WC, Correr-Sobrinho L, Sinhoreti MAC, Consani S. Influence of Irradiance on the Push-out Bond Strength of Composite Restorations Photoactivated by LED. J Contemp Dent Pract 2008 February;(9)2:089-096.