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Background The aim of this study was to evaluate the effect of bioactive glass (BAG) 45S5 paste on colour change and tooth sensitivity (TS) when used in combination with 20% carbamide peroxide (CP) during at-home vital tooth bleaching. Methods Twenty-four patients were selected and assigned into two experimental groups (n = 12) in a double-blind study design. Each patient received 20% CP followed by the application of either BAG paste or non-active placebo paste. The shade evaluation was performed using a digital spectrophotometer based on the CIE L*a*b* colour space system at different time points and the overall colour changes ΔE were calculated. TS was evaluated using visual analogue scale (VAS). The values of ΔE and TS were statistically analysed using paired t-test. The level of statistical significance was established at p = 0.05. Results The overall colour changes (ΔE) between baseline and each time point showed no significant differences between BAG and placebo groups (p > 0.05). The use of BAG paste significantly decreased TS reported by the participants. Conclusions The association of BAG paste with at-home bleaching treatment presents a promising method as it decreased TS and did not deteriorate bleaching efficacy. Trial registration This study was approved and registered in the Australian New Zealand Clinical Trials Registry (ANZCTR) under Registration number: ACTRN12621001334897.

Three catalysts were prepared from copper oxide carried on a matrix of a mixture of Syrian, Jordanian natural zeolite, Syrian bentonite, and Al 2 O 3-CuO. As a simulation to the field motor car condition, a good quantity of macrosize granules of the catalyst was used, and the initial reacting agents were the car exhaust gases (C.E.G.). Catalytic experiments were conducted by means of a flow micro pulse-like reactor using the gases emitted from car exhaust. When the (Z J B-CuO, Al 2 O 3-CuO) catalyst was applied, the maximal de-CO conversion was as estimated as 60% at 250°C, and 90% for de-CH at 400°C, whereas the de-CH rate conversion of the (ZB-CuO, Al 2 O 3-MoO 3-CuO) catalyst was as much as 80% at 360°C and 78% for de-CO at 360°C. The catalytic data made it possible to suggest a mechanism for each of the ongoing reactions. A maximal de-CH, conversion rate on the (ZB-CuO, Al 2 O 3-CuO) catalyst was reached at 450°C. The N 2 adsorption-desorption measurements were carried out at (À196°C), thermal analysis, and X-ray diffraction for the catalysts were studied as well. A comparative study was conducted between the catalysts [(ZB-CuO, Al 2 O 3-MoO 3-CuO), and (Z J B-CuO, Al 2 O 3-CuO)] and a honeycomb structure commercial catalyst manufactured for use in gasoline vehicles.