Effect of electronic cigarettes on optical properties of long-lasting composites for CAD/CAM systems

This study evaluated the influence of electronic cigarettes on the color stability and translucency of ceramic-filled resin composites indicated for long-term dental rehabilitation and fabricated by additive or subtractive manufacturing techniques. A ceramic-filled hybrid material for 3D printing (VarseoSmile Crown Plus, BEGO) and a nano-ceramic resin hybrid CAD/CAM block (Grandio® Blocs, VOCO) were investigated. Circular specimens (10 mm × 1.5 mm) were manufactured according to each manufacturer's recommendations and polished with a sequence of #400, #600, #800, #1200, and #2000 grit sandpaper to standardize surface texture. Samples were exposed to 1500 puffs of electronic cigarette aerosol and evaluated at baseline, 500, 1000, and 1500 puffs. Color was analyzed using a CM-2600 spectrophotometer (Konica Minolta, Tokyo, Japan) based on the CIELab color system, and translucency was calculated using TP00 values. Baseline translucency differed significantly between groups (milled ≈ 12.7; printed ≈ 4.67). TP00 values showed no significant change for printed specimens (p = 0.402), whereas milled specimens exhibited significant reductions (p < 0.001). All milled ∆TP00 values exceeded the perceptibility threshold (∆TP00 > 0.62) but remained below the acceptability threshold (∆TP00 > 2.62). Both groups presented ∆E00 values above perceptibility (0.81), with significantly higher values for milled specimens (p < 0.001), exceeding the clinical acceptability threshold (≤ 1.77). Within the limitations of this in vitro study, milled resin exhibited clinically perceptible translucency changes and unacceptable color differences, while printed resin maintained clinically acceptable optical stability.