Evaluation of a quadwave curing light compared to a dual-peak LED curing light

Abstract

Objective

To determine if the PinkWave (PW) light-curing unit (LCU) that emits red and infrared (IR) light as well as violet and blue light improves the depth of cure and degree of conversion (DC) of resin-based composites (RBCs).

Methods

The DC of RBCs at various distances was calculated from data collected at a rate of 13 Hz using attenuated total reflectance Fourier-transform infrared spectroscopy. To assess the contributions of the different wavelengths of light, optical filters were used to block the red and IR light from the PW. The depth of cure was also evaluated by photocuring RBC samples in both metal and plastic molds for 20 s at a 0 mm distance. The length of resin remaining was then measured and divided by 2. Starting from a baseline of 32 °C, the temperature rise during photocuring was measured in the plastic and metal rings reproducing the conditions used to measure the depth of cure and the DC respectively.

Results

In general, the PW produced greater depth of cure, however the use of metal molds greatly reduced this effect because the temperature increase was reduced. Increasing the distance by up to 4 mm from the light tip produced a significant increase in the DC for the RBCs photocured with the PW, but not for the G4. The wavelength of the blue peak (peaking at 473 nm) from the PW was longer compared to the control LCU (peaking at 448 nm). This 25 nm difference negatively affected the photocuring efficiency of some resins.

Significance

The internal optics and the additional red and IR wavelengths from the PW significantly increased the temperature in the RBCs and increased both depth of cure and the DC.