Some features of the bioceramic materials and the mouthrinse solutions were presented in
Table 1 and
Table 2, respectively. For the control group, the rinsing solution was replaced by distilled water. Ten samples for each group were chosen to perform statistical analysis: α = 0.05, β = 0.10 (1-β) = 0.90 and it was found that
P = .90467.
The ceramic specimens were prepared by cutting at 300 rpm using a minitom (Struers, Pederstrupvej 84, DK-2750 Ballerup, Denmark) and IPS e.max CAD (Ivoclar Vivadent, Schaan, Liechtenstein) specimens were crystallized by sintering for 30 minutes at 850℃ in an electric furnace (Programator P300, Ivoclar Vivadent, Liechtenstein). The ramp rate was 10 ℃/min for crystallization. All samples were cut into 2.0 × 12.0 × 14.0 mm dimensions and measured to 0.1 mm accuracy using electronic calipers (Mitutoyo, Kawasaki, Japan). Surfaces were ground using pre-wetted silicon carbide grinding paper (Grids 800, 1,000, and 1,200 Buehler-Meter II, Lake Bluff, IL, USA) prior to experiments. The samples were then rinsed with distilled water, ethanol, and finally acetone to remove the organic residues.
Mouth rinsing was simulated in a turbula shaker at 60 rpm by using a home-made agitation instrument, made up of five glass compartments (
Fig. 1). The specimen groups and control samples were placed into these compartments, filled with 120 mL mouthrinse solutions or distilled water. To simulated the time, it has been reported20 (
link)21 (
link) that each of test materials was exposed to mouthrinse for 12 hrs, which is equivalent time to 1 year of 2 min daily mouthrinse use. Therefore, in the present study, for about 10 years exposure to mouthrinse solution, dental bioceramic samples were immersed for 120 h. Every 12 hrs, the solutions were replenished and immersion was continued up to 120 hrs.
Following the incubation, the specimens were rinsed in distilled water. Reflectance was read by spectrophotometry (Vita Easyshade; VITA Zahnfabrik) and white-black (ΔL
*), red-green (Δa
*), and blue-yellow (Δb
*) values were obtained in a CIELAB system.22 Colour shift values, ΔE, were then calculated using the Eq.1. Before measurement of the reflectance, the spectrophotometre was calibrated on white colour.
Polished surfaces (Ra; in µm) of the specimens were analyzed by profilometry (MitutoyoSurftest SJ-301, Kanagawa, Japan) over a transverse length of 4 mm and with a cutoff value of 0.8 mm. The instrument was calibrated at 3.05 µm. Measurements were repeated three times and their mean values were taken as the average surface roughness value.
Representative twelve specimens were picked, and 10 × 10 µm areas were scanned by atomic force microscopy (AFM; Veeco Multimode 8, Santa Barbara, CA, USA) at 256 × 256 pixel resolutions at 1.6 Hz. The vibration frequency was 10 kHz. Average surface roughness value, Ra, was determined. Another twelve samples were analyzed by scanning electron microscopy (SEM, LEO 440, Cambridge, UK). The specimens were made conductive by coating with Au-Pd in a sputter coater device (Polaron SC7620) for 15 s at 3 Å per second under a vacuum of 4 × 10
-2 mbar before SEM investigations. Post process on SEM-SE image to analyze the surface roughness were made The linear histograms was extracted from the post processing software of Mira3 XMU SEM (Tescan, Brno - Kohoutovice, Czech Republic) and moving average for background was applied to analyze the relative peak to deep surface levels. The relatively high surfaces are seen whiter in SEM-SE whilst the darker regions indicate valleys with relatively lower surfaces. In histograms, 16 pixels are equal to 1 micron real distance of the surface at 10 kX magnification.
The mean ΔE and surface roughness values and standard deviations were calculated by using SPSS Statistical Software (SPSS version 22.0 software, SPSS Inc., Chicago, IL, USA). ΔE data were then analyzed by Generalized linear model. Surface roughness data were analyzed by Repeated measures. In both analyzes, ceramic and mouthrinse solutions interactions were tested. Significance values were adopted for cases where the differences were smaller than 0.05.
Soygun K., Varol O., Ozer A, & Bolayir G. (2017). Investigations on the effects of mouthrinses on the colour stability and surface roughness of different dental bioceramics. The Journal of Advanced Prosthodontics, 9(3), 200-207.