2008 Volume 21 Issue 1 Pages 31-35
This study determined the ultimate micro-tensile strength (μUTS) of three dental adhesives cured with three different light sources; blue light-emitting diode (LED), violet LED, and quartz-tungsten-halogen (QTH). Three dental adhesives, Clearfil SE Bond (SE), Unifil Bond (UB), and D/E Resin (DE), were examined. 0.7 mm-thick dental adhesive discs were prepared, trimmed into an hourglass shape, and the μUTS was then measured at a cross-head speed of 1.0 mm/min (N=10). Additionally, the spectrum of each light source and the transmission spectrum of each adhesive were measured using a spectrometer. In SE, QTH showed the highest μUTS among the different light sources, and no significant difference was found between blue LED and violet LED. While no significant difference was found in μUTS between QTH and blue LED, violet LED indicated significantly lower μUTS value in both UB and DE. The spectrometric analysis of blue LED, violet LED and QTH light sources showed peaks at 471 nm (range: 440-510 nm), 404 nm (390-430 nm), and 492 nm (390-510 nm), respectively. In both UB and DE, transmittance was slightly decreased at the range of 390-510 nm, the same peak/range as seen for camphorquinone which is included as a photoinitiator. On the other hand, in SE, a significant reverse peak at 360-420 nm was additionally observed. It was concluded that light wavelength affects the μUTS of adhesive due to the differences in the photoinitiator.
