The basis of modern teeth whitening systems is the use of a whitening gel, usually containing hydrogen peroxide or carbamide peroxide. The purpose of our study was to evaluate the effect of chemical and modified office teeth whitening systems on the mineral metabolism of oral fluid and to determine a safer method. The study covered 81 patients aged 22 to 35 years of both sexes with teeth color A2 and darker on the Vita Classic scale. Determination of the concentration of calcium and phosphates in the oral fluid was carried out on a spectrophotometer using ready-made Human kits. Chemical tooth whitening was performed using a gel based on 40% hydrogen peroxide. After the procedure, remineralization therapy with enamel-sealing liquid was performed for 14 days. The obtained results indicate that the most pronounced changes in the content of calcium (+74.4%, p <0.001) and рhosphates (phosphorus) (-23.07%, p <0.001) were observed when using a chemical bleaching system. After the teeth whitening procedure using a modified technique, less pronounced changes in the concentrations of calcium (+29.07, p <0.001) and phosphorus (-14%, p <0.001) were observed. The use of remineralizing agents led to a faster recovery of the initial levels of calcium and phosphates in the oral fluid. Both bleaching systems caused similar changes in the chemical composition of the oral fluid.

The aim was to evaluate the effect of different whitening toothpastes on the enamel surface roughness and color variation. Twenty-four molars were sectioned and divided into eight groups (n = 3), considering the two factors under study: toothpaste type (Colgate® Total Original, Oral B® 3D White Luxe Perfection, Curaprox® Black is White, and Signal® White Now) and brushing protocol (short-term and a long-term). Surface roughness was examined by atomic force microscopy (AFM), and color change (ΔE) was measured using the CIE L*a*b* system. Data were statistically analyzed using comparative parametric tests at a 5% significance level. In the short-term protocol, only the Signal® White Now toothpaste increased surface roughness (p = 0.038) compared to the Colgate® Total Original group. No significant differences (p > 0.05) were observed in surface roughness in the long-term protocol. Regarding color variation, no statistically significant differences (p > 0.05) were observed in either protocol. Overall, the whitening toothpastes did not affect enamel surface roughness or color, except for Signal® White Now causing increased roughness in the short-term protocol. However, all toothpastes induced a visual change in color.

In the era of digital information consumption, YouTube has emerged as a prominent platform for disseminating knowledge across various domains. One such area that has gathered significant attention is teeth whitening, with a plethora of videos offering insights into professional proce-dures, home remedies, and personal experiences. This study delves into the vast landscape of teeth whitening content on YouTube, meticulously categorizing videos into professional and amateur domains. The aim is to critically analyze the information presented, considering its accuracy, re-liability, and potential impact on public perceptions and oral health choices. A total of 100 videos in Greek (n1= 73) and in English (n2= 27) were studied. The analysis was based on views, likes, publication year, duration, presence of background music, and the presence of a description. The completion date of the search was October 7, 2023. Professional videos predominantly present whitening as a painless, conservative, and economical procedure, emphasizing safety measures. Bleaching mechanisms involving hydrogen peroxide and carbamide are explored, with various application techniques discussed, including whitening strips, splints, and in-office procedures. Contradictory findings on the efficacy of home versus in-office treatments are highlighted. In-ternal and external discoloration factors are delineated, with contraindications specified. Amateur videos, garnering greater public appeal, present personal experiences, product promotions, and homemade remedies, reflecting a concerning trend of misinformation. The analysis incorporates viewer engagement metrics, emphasizing the impact of non-professional content. As social media platforms play an increasingly influential role in shaping healthcare narratives, understanding the nuances of dental discourse on YouTube becomes crucial for both practitioners and the public. This exploration encompasses a spectrum of topics, ranging from the chemical intricacies of bleaching agents to the societal dynamics influencing viewer preferences. By unraveling the complexities of online dental information, this study seeks to contribute valuable insights to the evolving land-scape of oral health education in the digital age. Future research should adopt a multi-platform approach and explore the dynamic interaction between content creators and viewers for a more holistic comprehension of online dental information.

In this study, ozone oxidation experiment was carried out for the removal of fluorescent whitening agent which is widely used in textile dyeing and paper industry. The stilbene fluorescent whitening agent has been industrialized since the earliest, and the amount of current production is the highest. Due to the characteristics of the fluorescent whitening agent that cannot be removed by conventional wastewater treatment methods, the fluorescent whitening agent in wastewater treatment has difficulty in using as recycled water in the process. Pre-treatment ozone oxidation experiment was conducted prior to the introduction of Membrane Bio Reactor (MBR) treatment process by converting biodegradable materials into biodegradable materials. The removal efficiencies of fluorescent whitening agents, a diaminostilbene disulfonic acid derivative by ozone oxidation were evaluated by UV254 Scan, COD, T-N and color using a synthetic wastewater sample (COD=433.0 mg/ℓ) and paper and paper mill wastewater (COD=157.2 mg/ℓ).

In this study, effluent water was produced through Submerged Membrane Bio-Reactor (SMBR) process, which is a simple system and decomposes organic matter contained in wastewater with biological treatment process and performs solid-liquid separation, Especially, ozone oxidation treatment process is applied to effluent water containing fluorescent whitening agent, which is a trace pollutant which is not removed by biological treatment, and influences the quality of reused water. The concentration of COD in the SMBR was 449.3 mg/ℓ-COD, and the concentration of permeate water was 100.3 mg/ℓ-COD. The removal efficiency was about 70.1%. The amount of ozone re- quired for the removal of the fluorescent whitening agent in the permeated water in SMBR was 6.67 g-O3/min, and the amount of ozone required to remove COD relative to the permeate water was calculated to remove 0.997 mg-COD for 1 mg of O3.

The inaccurate estimates of linear prediction coefficient (LPC) and noise variance introduce bias in Kalman filter (KF) gain and degrades speech enhancement performance. The existing methods proposed a tuning of the biased Kalman gain particularly in stationary noise condition. This paper introduces a tuning of the KF gain for speech enhancement in real-life noise conditions. First, we estimate noise from each noisy speech frame using a speech presence probability (SPP) method to compute the noise variance. Then construct a whitening filter (with its coefficients computed from the estimated noise) and employed to the noisy speech, yielding a pre-whitened speech, from where the speech LPC parameters are computed. Then construct KF with the estimated parameters, where the robustness metric offsets the bias in Kalman gain during speech absence to that of the sensitivity metric during speech presence to achieve better noise reduction. Where the noise variance and the speech model parameters are adopted as a speech activity detector. The reduced-biased Kalman gain enables the KF to minimize the noise effect significantly, yielding the enhanced speech. Objective and subjective scores on NOIZEUS corpus demonstrates that the enhanced speech produced by the proposed method exhibits higher quality and intelligibility than some benchmark methods.