The raman spectroscopy method for evaluation of structural changes in hard tissues of teeth after in-office whitening

Start The experiments in evaluation of hard tissues using the Raman spectroscopy method have been made. Spectral differences between the tooth enamel and dentin before and after the in-office whitening procedure were found as a result of the work. It was shown with the use of the Raman spectroscopy method that the whitening process causes changes of tooth enamel and dentin related to the changes of organic and mineral components.

Comparative In Vitro Studies on the Effect of Bleaching Agents on Dental Structures in Healthy and Predialysis Patients

(1) Background: What is the effect of 16% and 40% concentration bleaching agents on dental structures in healthy patients compared to predialysis patients? (2) Methods: Forty teeth were included in the study (20 from healthy patients and 20 from predialysis patients). Each group was randomly divided into another two subgroups (n-10), depending on the bleaching agent concentration (16% and 40% gels). Color parameters were registered before and after the whitening process using a spectrophotometer. To determine enamel ultramicroscopic modifications, SEM and AFM analysis were performed before and after bleaching. (3) Results: An increasing trend was identified in the average values of ∆E and ∆L within the groups of predialysis teeth between teeth whitened with 40% concentration gel and those whitened with 16% concentration gel, while for the enamel samples from healthy patients the trend was reversed. The average values for roughness in the case of the two bleaching agents in healthy and predialysis teeth presented statistically significant differences (p < 0.05). (4) Conclusions: The effects of bleaching agents are less significant on teeth from predialysis compared to healthy patients. A direct link exists in terms of the clinical effect between the concentration of the whitening gel and color modifications.

In vitro influence of amazonian substances on the dental bleaching

Due to the wide scientific divergence of results among in vitro investigations about the influence of food pigmentation on teeth staining during bleaching, this study aims to evaluate in the laboratory the effectiveness of at-home bleaching using carbamide peroxide (CP), and in-office bleaching using hydrogen peroxide (HP) applied to bovine teeth exposed to açaí and guarana energy drink during the dental whitening process. Extracted bovine incisors were randomly separated into six groups as follows: two control groups (at-home bleaching [HB] and in-office bleaching [OB] and immersed in artificial saliva), two groups following the immersion in açaí (HBa and OBa), and two groups following the immersion in guarana (HBg and OBg). The immersion cycle was conducted three times a day for five minutes. After the initial reading, the color was registered subsequently to the third (and last) week of whitening process. This procedure was carried out using Easyshade spectrophotometer and Vita shade guide. The data were submitted to a two-way ANOVA test (p<0.05). The results showed that after three weeks of bleaching, the whitening rate for the OBa group decreased significantly when compared to the other groups, also those submitted to at-home bleaching. After the third week of the whitening process, it was observed that the groups submitted to at-home bleaching presented higher whitening rates than the ones submitted to in-office bleaching. Therefore, the contact with açaí during whitening period may reduce the in-office bleaching efficacy.

MODERN VIEWS ON TOOTH WHITENING

Resume. In the modern world, the appearance of teeth is of great importance. Beautiful white teeth are not only a sign of good health, but also an element of culture and well-being. Definition, the individual natural color of the teeth is mainly determined by dentin, however, the color, transparency, thickness and degree of mineralization of the enamel affect the color of dentin. Any changes in dentin and enamel during the formation, development and after teething can cause changes in light guide properties, and accordingly, changes in color. Purpose. Analysis of the sources of scientific and medical information about the features of tooth whitening by various methods and their effectiveness with the presentation of their own clinical examples. Methods. An analytical review of the literature on various methods of teeth whitening and indications and contraindications to these methods. Results. There are different options for coloring teeth and they call as external and internal. A separate category of discolors is such as internalized staining, when external chromogens penetrate into the hard tissues of the tooth. Treatment of diseases and conditions accompanied by discoloration of the teeth is complex and may include therapeutic (occupational hygiene, whitening, restoration) and orthopedic measures. Teeth whitening is a chemical oxidation process in which the color of enamel and dentin changes from dark to light. Modern bleaching systems are based on the use of preparations of hydrogen peroxide or urea peroxide in combination with activating factors. Currently, the following main types of whitening systems are widely used in dental practice: for professional use in the clinic, for home use under the supervision of a doctor, for home use without a doctor's supervision, for example, whitening toothpastes, strips, pencils and standardized caps with gel inside. The work presents various options for teeth whitening from home to clinical and professional. Indications and contraindications to the teeth whitening procedure and its protocol are given. The analysis of the results of modern scientific research in dentistry shows that now it is possible to consider that professional whitening is effective. That is why the use of high-intensity blue diode light (LED) is quite promising, especially when eliminating deep tooth pigmentation. One of the most popular brands in the world of whitening is Philips Zoom system. The Philips Zoom WhiteSpeed lamp is a fundamentally new technology in which the manufacturer has used LEDs as a light source, which has made the teeth whitening process more comfortable and safe for the patient. Conclusion. To date, researchers and manufacturers have created various well-functioning, safe and comfortable systems for whitening teeth. It is important to find various aspects of tooth whitening and possible hazards. Understanding the operation of various systems and awareness of their advantages and disadvantages will allow you to choose the most optimal system. A professional approach to teeth whitening guarantee success.

Perbandingan Penggunaan Natrium Perkarbonat, Hidrogen Peroksida, Hipoklorit, dan Xilanase terhadap Sifat Optik Deinked Pulp

Penggunaan bahan baku dari jenis kertas SWL (sorted white ledger) yang berasal dari proses mekanikal dan jenis kertas bekas yang mengandung banyak tinta memiliki dampak negatif karena menyebabkan sifat optik dari deinked pulp yang dihasilkan tidak optimal. Penyebab dari masalah tersebut adalah tingginya kandungan logam dan lignin pada SWL dan kertas bekas. Untuk mengatasi masalah tersebut, pada penlitian ini dilakukan penambahkan DTPA (Diethylene Triamine Pentaacetic Acid) sebagai penghilang kandungan logam dan bahan pemutih untuk menghilangkan lignin. Bahan pemutih yang digunakan adalah natrium perkarbonat, hidrogen peroksida, hipoklorit, dan xilanase. Dilakukan variasi dosis (1%; 1,5%; dan 2%) dan suhu pemutih (50°C, 70°C, dan 90°C) untuk menentukan titik optimal. Hasil penelitian menunjukkan bahwa bahan pemutih yang digunakan mampu meningkatkan derajat cerah dan derajat putih dari deinked pulp. Nilai sifat optik yang paling optimal didapat pada proses pemutihan menggunakan 2% natrium perkarbonat pada suhu 70°C, dengan nilai derajat cerah sebesar 85,30% ISO dan derajat putih sebesar 112,27% ISO. The Comparison of Sodium Percarbonate, Hydrogen Peroxide, Hypochlorite, and Xylanaseon Optical Properties of Deinked PulpAbstract The use of raw materials from SWL (sorted white ledger) paper originating from mechanical processes as well as used paper types that contain a lot of ink has a negative impact because it causes no optimal value for the optical properties of deinked pulp. The cause of these problems is the high content of metals and lignin. To overcome this problem, it is necessary to add DTPA (Diethylene Triamine Pentaacetic Acid) as a remover for metals and bleaching agents to remove lignin. The bleaching agents used in this study were sodium percarbonate, hydrogen peroxide, hypochlorite, and xylanase. Variation of bleach dose (1%, 1,5%, and 2%) and temperature (50°C, 70°C, and 90°C) is performed to determine the optimal point. The results showed that the whitening material used was able to increase the bright and white degrees of deinked pulp. The most optimal optical properties values obtained in the whitening process using 2% sodium percarbonate at 70°C, with a bright degree value of 85.30% ISO and a degree of white of 112.27% ISO. Keywords: SWL, waste paper, sodium percarbonate, hydrogen peroxide, hypochlorite, xylanase.

An Improved Second-Order Blind Identification (SOBI) Signal De-Noising Method for Dynamic Deflection Measurements of Bridges Using Ground-Based Synthetic Aperture Radar (GBSAR)

Ground-based synthetic aperture radar (GBSAR) technology has been widely used for bridge dynamic deflection measurements due to its advantages of non-contact measurements, high frequency, and high accuracy. To reduce the influence of noise in dynamic deflection measurements of bridges using GBSAR—especially for noise of the instantaneous vibrations of the instrument itself caused by passing vehicles—an improved second-order blind identification (SOBI) signal de-noising method is proposed to obtain the de-noised time-series displacement of bridges. First, the obtained time-series displacements of three adjacent monitoring points in the same time domain are selected as observation signals, and the second-order correlations among the three time-series displacements are removed using a whitening process. Second, a mixing matrix is calculated using the joint approximation diagonalization technique for covariance matrices and to further obtain three separate signal components. Finally, the three separate signal components are converted in the frequency domain using the fast Fourier transform (FFT) algorithm, and the noise signal components are identified using a spectrum analysis. A new, independent, separated signal component matrix is generated using a zeroing process for the noise signal components. This process is inversely reconstructed using a mixing matrix to recover the original amplitude of the de-noised time-series displacement of the middle monitoring point among three adjacent monitoring points. The results of both simulated and on-site experiments show that the improved SOBI method has a powerful signal de-noising ability.

Teeth re-whitening effect of strawberry juice on coffee stained teeth

Many people favor coffee. However, regarding health and aesthetic dentistry, coffee gives a negative effect. Tanin in coffee causes a brown stain on the tooth surface. Therefore, in aesthetic dental care, teeth whitening has become popular matter. One of the natural ingredients used for teeth whitening treatment is strawberry. The purpose of this study was to obtained data regarding the effect of strawberry juice on the re-whitening process of the coffee-stained tooth enamel surface. This study was a pure experimental in-vitro using Friedman and Wilcoxon Matched Pairs Tests for statistical analysis. The population of this study was anterior teeth. The samples were maxillary central incisors. The sampling technique using sample size determination based on the testing formulas of the difference of two average data pairs resulted in 11 specimens. The result of the research showed that all coffee-stained teeth sample had an increasing enamel colour index. The samples were then applied with strawberry juice resulted in a significant average difference colour index value indicated by p<0.001. The conclusion of this research indicated that there was an effect of strawberry juice on the coffee-stained teeth re-whitening process.

Whitening Revisited

This chapter examines the question of whitening as a process that required both family and nation to force ideological and behavioral commitments on individuals. Focusing on race-making behaviors in nineteenth-century Cuba, it interrogates the historical ambiguity of blanqueamiento, or whitening process, using a methodology that emphasizes the social construction of race. More specifically, it proposes the concept of “sexual economy of race” as a means to elucidate the conjunction between reproductive behavior and the social construction of race. It also explores the restriction of interracial marriages in Cuba as part of its whitening agenda, along with the ways in which racialized reproductive choices influenced the standard system of racial classification and fostered whitening in some cases and discouraged it in others. The chapter shows that whitening efforts in colonial Cuba were not as predictable or linear as previously theorized.

Isolasi Identifikasi Bakteri Penghasil Xilanase serta Karakterisasi Enzimnya

<p>Xylanase is an extracellular enzyme produced by<br />microorganisms. This enzyme is able to hydrolise xylane<br />(hemicellulose) to produce xylooligosaccharide and xylose.<br />Thermoalkaliphilic xylanase is an agent that can be used as<br />a substitute in the pulp whitening process instead of chlorine.<br />A study was done to isolate, identificate of bacteria and<br />characterize xylanase. The isolation of xylanase producing<br />bacteria has been done from soil and waste of starch industry.<br />Colonies which produced clearing zone were presumed<br />as xylanolytic bacteria and chosen for further screening.<br />Identification of potential isolate in xylanase production was<br />done using 16S ribosomal RNA sequencing. Isolate Bacillus<br />pumilus RXA-III5 originated from lime or alkaline soil was<br />more potential isolate in xylanase production than other 24<br />isolates. Precipitation of xylanase, that was done using<br />ammonium sulphate followed by dialyzes produced xylanase<br />of a higher specific activity (267.1 U.mg-1) than that using<br />acetone (131.1 U.mg-1) and ethanol (186.65 U.mg-1). Xylanase<br />was done at purification produced three fractions of xylanase.<br />Xylanase characteristics consist of pH and temperature<br />(9 and 50oC), Km and Vmaks value 6 mg.ml-1 and 0.2<br />mol.minute-1, respectively. The Fe2+ was the strongest activetor<br />and Mg2+ was the strongest inhibitor activity. This enzyme<br />was detected as a cellulose-free xylanase. Xylanase is a<br />prospective agent for bio-bleaching of paper.</p>