Effect of thickness of CAD/CAM materials on light transmission and resin cement polymerization using a blue light-emitting diode light-curing unit

Author(s)

de Castro, Eduardo Fernandes ; Fronza, Bruna Marin ; Soto-Montero, Jorge ; Giannini, Marcelo ; dos-Santos-Dias, Carlos Tadeu ; Price, Richard Bengt

• Document type: Journal article
• Source: Journal of Esthetic and Restorative Dentistry; v. N/A, p. 13-pg., 2022-07-27.

Abstract

Objective Evaluate the effect of thickness of high-translucency (HT) CAD/CAM materials on irradiance and beam profile from a blue light-emitting diode light-curing unit (LCU) and on the degree of conversion (DC) and maximum polymerization rate (Rp(max)) of a light-cured resin cement (LCC). Material and methods The direct output from the LCU, the light transmission and irradiance ratio (IR) through one conventional composite and nine HT CAD/CAM materials (0.5, 1.0, 1.5, or 2.0-mm thick; n = 5) were measured with a integrating sphere coupled to a spectrometer. The light beam was assessed with a beam profiler camera. The DC at 600 s and the Rp(max) of one LCC was determined using a Fourier transform infrared spectrometer (n = 5). Data were analyzed by ANOVA followed by Tukey's tests, and Dunnett's test was also used for irradiance data (alpha = 0.05). Results A significant decrease in irradiance through all materials occurred as thickness increased. Thin CAD/CAM materials improved light homogeneity, which decreased with the increase in thickness. The DC of the LCC directly exposed to light was the same as when exposed to 45%, 25%, 15%, or 5% IRs. Rp(max) decreased with the decrease in IR. Conclusions Although the HT CAD/CAM materials reduced the irradiance from the LCU, minor effects were observed in the LCC's DC. Clinical significance Despite the light attenuation of blue light through different CAD/CAM materials that were up to 2-mm thick, the degree of conversion of one brand of light-cured resin cement was clinically acceptable when the LCU was used for 30 s. (AU)

• FAPESP's process: 17/50131-5 - Effect of argon plasma and primer application on the bond strength of resin cements to two yttrium-tetragonal zirconia polycrystal ceramics
• Grantee: Marcelo Giannini
• Support Opportunities: Regular Research Grants