Effect of Toothbrushing on Surface Color of Ceramic-polymer Materials: An In Vitro Study
F.L. Pouranfar, C.A. Salmon, R.R. Sheridan, K.S. Vandewalle
New CAD/CAM ceramic-polymer materials have been introduced with claims of convenient placement of visible-light-cured extrinsic stains. No research has been published on the longevity of these stains on these newer ceramic-polymer materials.
The purpose of this study was to examine the effects of toothbrushing on the change in color (Delta E*) of extrinsic characterization of ceramic-polymer materials.
Methods and Materials
Two ceramic-polymer materials (Cerasmart, GC; Enamic, Vita) and one lithium-disilicate material (IPS e-max CAD; Ivoclar Vivadent) were tested. The blocks were polished in a polishing machine (Ecomet 6, Buehler) using 320-grit through 420-grit silicon-carbide paper to simulate a milled surface. Each block’s thickness was measured with a digital caliper and then covered with 0.12mm thick masking tape (3M) with a window cut in the area to be stained and glazed. Each block material was stained and glazed per manufacturers’ instructions. After staining and glazing the blocks were re-measured with the digital caliper to assure a 100μm(+/- 30μm) thickness. Specimens were then brushed in a toothbrush machine (Sabri Dental Enterprises) under a load of 3N at 1 Hz with a soft toothbrush (GUM). A 3D printed index was utilized to standardize and record CIE - L*a*b* values with a spectrophotometer (Easyshade, Vita) at baseline and at 3, 6, 9, and 12-year simulated years of brushing (7,300 strokes/yr). A mean change in color (delta E*) and standard deviation were determined for each group and brushing interval. Data were analyzed with a repeated-measures ANOVA and one way ANOVA/Tukey’s (alpha = 0.05)
Cerasmart and Enamic had a significantly greater delta E* compared to IPS e.max at each time interval. The delta E* was not significantly different between Cerasmart and Enamic except at 3 years. Cerasmart and Enamic had a significant increase in delta E* between each time interval, whereas for IPS e.max, the increase in delta E* was only significant at 9 and 12 years of brushing.
The extrinsic stains on the ceramic-polymer materials may be more susceptible to change from toothbrushing compared to the lithium-disilicate material. However, the change may only be clinically perceptible to the naked eye (delta E* > 2.3) after 12 years of brushing the ceramic-polymer materials.