[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.

[Bond strength of metal brackets to enamel with a Russian adhesive complex: an in vitro study]. / Sila adgezionnogo soedineniya emali zuba i metallicheskogo breketa, poluchennogo s pomoshch'yu otechestvennogo adgezivnogo kompleksa in vitro.

BACKGROUND: The era of using adhesives to fix brackets began in the 70s of the last century. There are eight generations of foreign-made adhesive systems for the restoration of teeth. However, until now, in orthodontics, the development of domestic adhesive systems with improved properties of adhesion of brackets to tooth enamel still important, especially in the posterior teeth. OBJECTIVE: The purpose of this work was to study the shear strength of fifth generation domestic adhesive between metal brackets and the enamel of molar teeth in laboratory conditions. MATERIAL AND METHODS: The study included 17 specimens of extracted maxillary molars embedded in acrylic resin blocks. Brackets from G&H Orthodontics (G&H Wire Company, USA) were fixed to the tooth enamel using the domestic Compofix (ortho) set. The enamel was treated with etching gel (37% phosphoric acid) for 30 seconds. Then the gel was washed off with water and the surface of the enamel was thoroughly dried. A primer was applied to the prepared surface with an applicator, inflated with a weak air flow for 5-10 seconds and photopolymerized for 20 seconds. The surface of the bracket was treated with degreaser, then a thin layer of adhesive was applied, and the sample was fixed to the enamel. Excess material was removed with an applicator. The samples were photopolymerized for 20 sec. Then, the shear bond strength of the adhesive was determined according to the method of GOST 31574-2012 on a (Zwick/Roell Z010 testing machine, Zwick, Germany). RESULTS: The shear strength of the adhesive joint obtained during the test is 13.54±1.01 MPa, the average value of the index of adhesive residues on the surface of the bracket was 23%±4%, which corresponds to the standard average values according to GOST. CONCLUSION: The tested domestic adhesive system of the fifth generation can be recommended for the practical work of an orthodontist.

[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.

[The experimental study of a Russian orthodontic mini-screw]. / Eksperimental'noe issledovanie otechestvennogo ortodonticheskogo minivinta.

BACKGROUND: The aim of this research is the experimental study measuring stability of the orthodontic miniscrews «Turbo¼ designed in Russia in comparison with its foreign analogues, namely, «Vector Tas¼ (USA) and «BioRay¼ (Taiwan). MATERIAL AND METHODS: Four self-drilling orthodontic miniscrews of each manufacturer, i.e. «Vector Tas¼, USA, (10-mm length, 2-mm diameter), «BioRay¼, Taiwan, (10-mm length, 2-mm diameter), «Turbo¼, Russia, (9-mm length, 2-mm diameter), a total of 12 items, were inserted into native pig mandible sample. Their stability was estimated by torques using a dynamometer (Zahoransky AG, Germany) and «Periotest¼ device («Periotest M¼, Germany). This experiment was conducted in native pig mandible sample immediately after the screws' placement and in 7 days after loading at an angle 70°. RESULTS: After application of a load, the decreased torque values and increased Periotest values were registered in all orthodontic miniscrews. CONCLUSION: Orthodontic miniscrews «Turbo¼ designed in Russia are slightly inferior to «VectorTas¼ miniscrews and superior to «BioRay¼ miniscrews in primary stability and stability after 7 days under loading.

Expression of Metalloproteinases and Type I and III Collagens during Healing of Excisional Skin Wound on the Abdomen and Back in Rats.

The study was carried out using a novel rat model developed in our laboratory, namely16 mm diameter circular excisional wounds were generated on the abdomen which resulted in minimal scarring. Restoration of the skin integrity was completed by day 60 after the wounding surgery. By this time, regenerates on the abdomen were stronger than on the back (at, respectively, 58 and 17.4 % of the tensile strength of the intact skin at corresponding location) and the ratio of type I and type III collagens in regenerates on the abdomen reached the level of intact skin at the same location. On days 3 to 14, the ratio of Mmp9/Timp1 expression levels on the abdomen was higher than on the back. On days 20 and 30, the Mmp9/Timp1 ratio on the abdomen was identical to the level of intact skin, whereas the increased MMPs expression levels on the back were maintained until day 30. It has been shown for the first time that according to functional and molecular characteristics, wound healing on the abdomen of an adult rat is more similar to complete regeneration than scarring repair of the back skin.

[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).

[Mantle dentin as biomodel of materials for structural teeth restoration]. / Plashchevoi dentin kak biomodel' materialov dlia strukturnoi restavratsii zubov.

The article describes a structural element of natural teeth - mantle dentin. It has been shown that the presence of this element in the structure of a natural tooth largely ensures its strength under the influence of repeated loads in a functional oral environment and arrests crack growth at the enamel/dentine interface. This later effect is explained by the influence of a thin layer of mantle dentine, which has physical and mechanical characteristics different from that of the main dentin.

[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.

[A comparative study of mechanical properties of materials for custom-made impression trays used by implant-fixed restorations].

Materials for custom-made impression trays used for impression by implant fixed restorations were compared in the study. The analysis included such values as flexural strength and elasticity modulus, impression material adhesion strength with the use of adhesive and without it. Light-cured plastic Elite LC Tray had the best rates of bending strength and elasticity modulus and the Protakril M had the highest adhesion strength both with and without adhesive.

[Non-destructive ultrasonic technique of enamel thickness measurement].

An ultrasonic technique of enamel thickness measurement has been proposed. In this technique, a thin tray with a hole is placed on the surface of the tooth and the tip of the ultrasonic probe is inserted in this hole to prevent lateral shift of the tip during adjustment of angular position of the probe. Results of the ultrasonic measurements carried out on the extracted teeth with the enamel layer thickness in a range of 1-0.3 mm and the inclination angle up to 0.1 show that the relative thickness measurement error does not exceed ± 2-3%. Typical deviation between the ultrasonic data and the results of the destructive evaluation of the specimens is about ± 0.05 mm.

[Study of physical-mechanic characteristics of prosthetic construction after their adjustment with the use of laser welding and hot metal adding].

Study of physical-mechanic characteristics of connecting joints of beam construction after laser welding and hot metal adding was performed. Increase of microhardness of joints as well as small reduction of bending strength of prosthetic constructions was established.

[Study of physical-chemical properties ot endodontic sealant Acroseal when different methods of root canal obturation].

Results of the study of physical-chemical properties of new endodontic sealant Acrosil (Septodent, France) were presented. The results of all used in the experiment tests corresponded with the existing standards. The received data were compared with the corresponding tests of endodontic sealant AH-Plus (Dentsply, DeTrey, Germany) and were analyzed statistically. The comparison showed higher adhesion properties of Acrosil.

[Acoustic microscopy application for the evaluation of restorative materials bonding quality. Experimental investigation].

Ultrasound transmission and reflection at the interface between restorative material and tooth tissue have been investigated using experimental flat-parallel models and whole extracted human teeth with restorations. It has been found that in the case of good bonding the ultrasound wave energy practically does not reflect at the cement/dentin interface and propagates into dentin layer. If any microscopic cavity had been formed between cement and dentin, the most part of the acoustic energy would be reflected from the interface between cement and gaseous or liquid contents of that cavity. The results acquired have been used for the interpretation of morphological peculiarities of the adhesive bonding area in visual images, non-destructively obtained in acoustic microscope ultrasound frequency - 50 MHz. The differences discovered could be used as a base for the design and development of new ultrasound methods for the restorative materials bonding evaluation as well as for secondary caries revealing.