Light-curing of dental resins with GaN violet laser diode: The effect of photoinitiator on mechanical strength

Abstract

The purpose of this study was to evaluate whether a Gallium Nitride (GaN) -based violet laser diode (VLM500) could be used as a light source for light-cured dental resins. Three experimental unfilled resins containing different photoinitiators (camphorquinone, CQ; phenyl propanedione, PPD; or mono acylphosphineoxide, MAPO) were evaluated. These resins were lightcured with a VLM500 laser diode, and their ultimate micro-tensile strengths (μTS) were compared to those cured with three different LED light sources (Curenos, G-Light Prima-normal mode and G-Light Prima-PL mode). The VLM500 produced high µTS values in all three resins, and we concluded that this violet laser diode can be used as a light source for light-cured dental resin materials.

Origin and Function of Myofibroblasts in the Liver

“…Signaling pathways that include both portal fibroblasts and cholangiocytes as participants may include polarity, TGFβ, Hedgehog, and Notch signaling pathways; these may involve mature cells or peribiliary stem cells. [48][49][50][51][52] Jhandier et al have shown that portal fibroblasts and myofibroblasts, acting via extracellular nucleotides, regulate cholangiocyte proliferation. 53 This function may be particularly important in intrahepatic cholangiocarcinoma, a highly desmoplastic tumor with accumulation of myofibroblasts.…”

Light-curing efficiency of dental adhesives by gallium nitride violet-laser diode determined in terms of ultimate micro-tensile strength

“…Regardless of the difference in absorption, the µTS of both FL-Bond II and Tokuso Mac Bond II when cured using the VLM 500 unit was almost similar as when the adhesives were cured with the LED Curenos and G-light Prima light-curing units. In our previous study, the µTS of a 1% CQ-containing unfilled resin that was cured with the LED G-Light Prima unit used in 'PL mode' (only emission by the violet LED with an output of 52 mW/cm 2 ), was significantly lower than when the resin was cured with the LED Curenos unit and the LED G-Light Prima unit used in 'Normal mode' [42]. However, the µTS did not differ when the resin was cured either using the VLM 500 unit, the LED Curenos unit or the LED G-Light Prima unit used in 'Normal mode' [42].…”

“…In our previous study, the µTS of a 1% CQ-containing unfilled resin that was cured with the LED G-Light Prima unit used in 'PL mode' (only emission by the violet LED with an output of 52 mW/cm 2 ), was significantly lower than when the resin was cured with the LED Curenos unit and the LED G-Light Prima unit used in 'Normal mode' [42]. However, the µTS did not differ when the resin was cured either using the VLM 500 unit, the LED Curenos unit or the LED G-Light Prima unit used in 'Normal mode' [42]. These data therefore suggested that the lower absorption coefficient of CQ for violet light can be compensated by increasing the power density.…”

Effect of Emitted Wavelength and Light Guide Type on Irradiance Discrepancies in Hand‐Held Dental Curing Radiometers

“…Their emission range is from 390 to 500 nm, with a peak wavelength of 470–480 nm. Because the absorbance wavelength of camphorquinone (CQ), which is added to most light-cured restorative materials, has been reported as 430–490 nm with a peak at 468 nm, the emission ranges of these LCUs are likely to be optimal for CQ [25, 26]. D-Lux 2000 can be selected with either a turbo light guide or a conventional straight guide.…”

“…In contrast, the G-Light Prima and the Bluephase G2 are “dual-wave” LCUs that contain not only blue LEDs but also supplementary violet LED(s) to polymerize 1-phenyl-1,2-propanedione (PPD) and 2,4,6-trimethylbenzoyl diphenyl-phosphine oxide (Lucirin TPO) effectively [25, 26]. For the Pencure and the G-Light Prima, the displayed power densities in the Bluephase Meter and the Cure Rite were approximately 30% and 25% lower, respectively, than those of the USR-45 spectroradiometer.…”