[Laboratory evaluation of the effectiveness and safety of the Chairside Light Whitening System fläsh]. / Laboratornaya otsenka effektivnosti i bezopasnosti otbelivayushchei sistemy Chairside Light Whitening System fläsh.

THE AIM OF THE STUDY: Optimization of methods for treating dental discoloration using whitening systems based on hydrogen peroxide by laboratory studying their chemical properties. MATERIAL AND METHODS: The effectiveness of the bleaching system was assessed by quantitatively assessing the color change of model samples of hydroxyapatite (HAP) in the CIE L*a*b* system on a Spectron-M color analyzer after exposure to coloring food media. Safety assessment was carried out on samples made from teeth removed according to indications. RESULTS: The results of laboratory tests allow us to conclude that the Chairside Light Whitening System professional teeth whitening system fläsh. (WHITEsmile GmbH, Germany) has high whitening efficiency with a whitening degree of ~84%, which significantly exceeds the norm of GOST R 702.3.004-2021. the microhardness of the enamel of samples exposed to the whitening gel for 15 minutes changes extremely little. After exposure of the studied samples to the Chairside Light Whitening System fläsh whitening system for 45 minutes, an increase in digital microhardness indicators is observed, which indicates the dynamics of processes demineralizing the hard tooth structure. CONCLUSIONS: Chairside Light Whitening System fläsh professional teeth whitening system has high whitening efficiency with minimal impact on the teeth structure and high safety.

[Laboratory methods for measuring adhesive bond strength between restoration materials and hard tooth tissues]. / Laboratornye metody ispytaniya adgezionnoi prochnosti soedinenii restavratsionnykh materialov s tverdymi tkanyami zuba.

THE AIM OF THE STUDY: Was to review laboratory methods measuring the bond strength of adhesive dental materials to hard tooth tissues. The paper points out the impact of test conditions on the measured strength of adhesive bond to dentine and enamel. Various in vitro studies are discussed, including the analyses of fracture surfaces and test-induced stresses. These studies are found to be helpful to identify particularities, advantages, and limitations of each approach. We present a systematic picture of available bond-strength data aimed at revealing general trends in adhesive performance. No clear superiority of any particular method for determining the bond strength between restoration materials and tooth tissues can be identified on the basis of reviewed literature. Therefore, no single universal approach can be at present proposed for determining the strength of adhesive bond.

[Reinforcement of photosensitive material for bases of orthodontic appliances]. / Armirovanie svetootverzhdaemogo polimera dlya bazisov ortodonticheskikh apparatov.

OBJECTIVE: The objective of the study was to improve the strength properties polymer by modifying its basis with various materials. MATERIAL AND METHODS: A polymer in the form of a pink-colored plasticine mass with veins was studied, a quartz mesh «Quartz splint mesh¼ manufactured by RTD (France) and two metal gold-plated wire mesh (0.1 mm and 0.15 mm in diameter) manufactured by Renfert (Germany). Modified test specimens, 65×40×3.5 mm in size were covered with a lavsan film and at a slight pressure the material was rolled out with a glass cylinder flush with the frame. Curing was carried out in Fhotopress photopolymer (Aveyron, RF) under the 460-470 nm wavelength light for 6 minutes on each side. The plates were sawn with a mill in the form of strips 64×10×3.3 mm and kept in distilled water at 37 °C for 50 h before testing. The test of the reinforced samples was carried out with a middle and lower location of quartz and metal grids pre-treated with adhesive and subjected to a 4-point bending test. Bending strength, bending modulus, and fracture deformation were determined using a Zwick/Roell Z010 testing machine with a constant crosshead speed under loading (5±1) mm/min. The statistical significance of the influence of reinforcing elements on the performance of the basic physical and mechanical properties of the base material was determined using Student's t-test. RESULTS: The value of fracture toughness index K1 at the lower location of the quartz mesh was 3.72±0.43 MN/m1.5, which was 4.9 times significantly higher than K1 for the non-reinforced material (p=0.0001). CONCLUSION: The ability to achieve maximum material strength with the lower reinforcement method increases the functional usefulness of removable orthodontic and orthopedic structures with a basis of «Nolatek¼ light-cured material.

[Color measurements of composite materials for tooth restoration in standardized in vitro conditions]. / Izmerenie tsveta kompozitnykh materialov dlia restavratsii zubov v standartizovannykh usloviiakh in vitro.

A national standard GOST R 58165-2018 (ISO/TR 28642:2016) 'Dentistry - Guidance on colour measurement' has been developed based on the international document which establishes standardized conditions for carrying out laboratory methods of measuring color by visual and instrumental methods. In vitro tests of samples of FiltekTM Ultimate, FiltekTMZ250 and Premise on the acoustooptic color analyzer SPEKTRON-M (FGUP 'VNIIOFI', Russia) in accordance with the recommendations of the standard GOST R 58165-2018 (ISO/TR 28642:2016) allowed to determine the effect of the shelf life of paste composite materials on the aesthetic indicators: colour compatibility, colour stability after aging and degree of transparency. The greatest changes in color characteristics in the CIELAB system during the storage of pastes were noted for the Premise Kerr A2 Enamel and A3 dentin composites. The greatest color change after exposure in water at 37 ° C was established for FiltekTMZ250 A4 samples with a long shelf life of the composite resin, ΔE=3.92>2.7 (p=0.001), but the color resistance of samples of the same composite from a new batch after exposure in water corresponds to the requirements of the standard, ΔE=2,18<2,7 (p=0,001).

[Study of the film thickness of dental composite resins after preheating]. / Izuchenie tolshchiny plenki kompozitov posle ikh nagrevaniia.

PURPOSE: To compare film thickness of adhesive resin cement and dental composite resins after they are preheated with hot air. MATERIAL AND METHODS: The film thickness was measured using adhesive resin cement Variolink esthetic (Ivoclar-Vivadent, Liechtenstein), micro-hybrid composite Enamel (Micerium, Germany) and nanofilled composite Estelite sigma quick (Tokuyama Dental, Japan) at different temperatures. RESULTS: The film thickness of the Variolink esthetic at room temperature was 23 µm, and the dental composites after preheating them with hot air and applying adhesive on both surfaces to be joined produced the following results: Estelite 62 µm and Enamel 25 µm. CONCLUSION: As a result of the study, it was found that the proposed method allows one to achieve a film thickness for high-viscosity composites comparable to the film thickness of composite cements.

[Laboratory evaluation of retraction cords properties].

The aim of the study was the investigation of the effect of two factors on the diameter changings of different types of retraction cords. Using an optical microscope MBS-10 (x10) the diameter of the different retraction cords was measured. The measurement also was performed after tension and after wetting cords with distilled water. The cords diameter decreased after their tension and increased after wetting. The degree of diameter changes depends on the kind of cords weaving. Braided cords "00" and "1" sizes diameter after it tension decreased at 31% and 37%, knitted cords under tension changed the diameter at 53% and 48%, correspondingly. Cords features after wetting also varied. Wetting of the braided cords with distilled water did not lead to significant diameter changes while wetting of knitted cords increases their diameter at 13% (00) and 15% (1).

[Comparative in vitro evaluation of modern glass ionomer cements for adhesion strength and fluoride release].

The study proved similar adhesion strength and fluoride release level in aqueous extracts of glass ionomer cements Cemion (VladMiVa, Russia), Glassin Rest (Omega-Dent, Russia), Cemfil 10 (StomaDent, Russia) and Fuji VIII (GC Corporation, Japan). Despite of close concentrations of fluoride in glasses, the rate of fluoride release in water from calcium and calcium-barium glasses is much higher than that of strontium glasses.

[Adhesion as criterion of choice of materials for dental restorations of defects in cervical area]. / Adgeziia kak kriterii vybora materiala dlia restavratsii zubov s defektami v prisheechnoi oblasti.

The paper presents the results of comparative in vitro evaluation of classical and flow consistency restorative polymeric materials (Japan and Russia) adhesion to dentin in cervical area. The adhesive properties of these materials were compared with the experimental systems of "sandwich" type, combining layers of classic and flow consistency, glass-ionomer cement Fuji 8 (Japan) and material SMARTCEM 2 (Switzerland). The highest dentin adhesion strength showed Fuji 8, restoration materials of classical consistency proved to have advantage in adhesion properties.

The use of acoustic microscopy to study the mechanical properties of glass-ionomer cement.

OBJECTIVES: The aim of the study was to investigate the relationship between microstructure, acoustic and mechanical properties of hardened dental cement samples, prepared with different powder/water ratios. METHODS: Glass-ionomer dental cement samples, prepared with a standard amount of cement powder and different amounts of water have been examined after being hardened. Surface microstructure and ultrasound, longitudinal and shear velocities were obtained with a scanning acoustic microscope. Conditional effective elastic modulus and Poisson's ratio have been calculated using longitudinal and shear sound velocity values. Then on the same samples elastic modulus and microhardness have been determined by standard tests. Additional samples have been used to determine compressive strength. RESULTS: Density; conditionally instantaneous elastic modulus; high-elasticity modulus and compression strength of the samples decrease when large amounts of water were used for their preparation. At the same time porosity and microhardness of the cement matrix increase. Acoustic parameters and parameters of elasticity, calculated on the basis of sound velocity, demonstrated changes, similar to those obtained in standard mechanical tests. SIGNIFICANCE: The established relation between microstructure, acoustic and mechanical parameters demonstrated a high capacity of acoustic microscopy application for non-destructive characterization of dental materials. A particular advantage of the acoustic microscopy is the opportunity to evaluate microstructure and mechanical properties on the same sample.