Influence of Irradiance on the Push-out Bond Strength of Composite Restorations Photoactivated by LED
Mário Alexandre Coelho Sinhoreti, Simonides Consani, Lourenço Correr-Sobrinho, Dario Segreto, William Cunha Brandt
Citation Information :
Sinhoreti MA, Consani S, Correr-Sobrinho L, Segreto D, Brandt WC. Influence of Irradiance on the Push-out Bond Strength of Composite Restorations Photoactivated by LED. J Contemp Dent Pract 2008; 9 (2):89-96.
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.
Results
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.
Conclusion
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.
Citation
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.
Light-emitting diode (LED) polymerisation of dental composites: flexural properties and polymerisation potential. Biomaterials. 2000; 21:1379-85.
Post-gel shrinkage with pulse activation and soft-start polymerization. Oper Dent. 2002; 27:81-7.
Polymerization shrinkage and polymerization shrinkage stress in polymerbased restoratives. J Dent. 1997; 25:435-40.
Relaxation of polymerization contraction stresses by flow in dental composites. J Dent Res. 1984; 63:146-8.
Comparison of polymerization contraction stresses between self- and light-curing composites. J Dent. 1999; 27:383-9.
Developing a more complete understanding of stresses produced in dental composites during polymerization. Dent Mater. 2005; 21:36-42.
Degree of conversion of composites measured by DTA and FTIR. Dent Mater. 2001; 17:178-83.
Relationship between bond strength and marginal and internal adaptation of composite restorations photocured by different methods. Acta Odontol Scand. 2006 64:306-13.
Effect of Photoactivation Systems and Resin Composites on the Microleakage of Esthetic Restorations. J Contemp Dent Pract. 2007;February;(8)2:70-9.
Effect of composite type, light intensity, configuration factor and laser polymerization on polymerization contraction forces. Am J Dent. 1997,10:88-96.
How filler properties, filler fraction, sample thickness and light source affect light attenuation in particulate filled resin composites. Dent Mater. 2005; 21:721-30.
Flowable resin composites as “filled adhesives”: literature review and clinical recommendations. Quintessence Int. 1999; 30:249-57.
Push-out bond strengths of tooth-colored posts bonded with different adhesive systems. Am J Dent. 2004; 17:422-6.
Effect of different photoactivation methods on the bond strength of composite restorations by push-out test. Quintessence Int. in press.
Stress reduction in resin-based composites cured with a two-step light-curing unit. Am J Dent. 2000; 13:69-72.
Degree of conversion and knoop hardness of Z250 composite using different photo-activation methods. Polymer Testing. 2005; 24:814-8.
Bond strengths of tooth-colored posts, effect of sealer, dentin adhesive, and root region. Am J Dent. 2003;16 Spec No:31A-36A.
Determination of polymerization shrinkage stress by means of a photoelastic investigation. Dent Mater. 2004; 20:313-21.
Shear bond strength with increasing light-guide distance from dentin. J Esthet Restor Dent. 2006;18:19-27; discussion 28.
Influence of the power density on the kinetics of photopolymerization and properties of dental composites. J Biomed Mater Res B Appl Biomater. 2005;72:393-400.
