Aleka R. Latif

Background . Modern dental restoration relies on achieving reliable adhesion between dental fillings and hard tissues, which is largely determined by the quality of tooth preparation. Objective . To analyze the effect that the condition of working parts in Diatech and MANI diamond burs, as well as chemically different conditioners, can have on the quality of tooth surface preparation. Methods . A nonrandomized experimental controlled study was conducted using 64 intact molars that had been previously extracted for medical reasons; artificial Class I cavities of the same size were drilled in these teeth (as per G.V. Black’s classification). An air-turbine handpiece, Diatech diamond burs (with a grit size of 64–126 µ), and MANI burs (with a grit size of 106–126 µ) were used to prepare the teeth. These teeth were divided into four groups of 16 teeth each depending on the use of new or previously used diamond burs, as well as eight subgroups of eight teeth each; in half of them, the prepared surfaces were conditioned with Travex37 (Omega Dent, Russia) containing 37% orthophosphoric acid; the other half, with Multi Etchant gel containing an adhesive phosphate monomer (M-TEG-P) (Yamakin, Japan). The enamel and dentin were conditioned for 30 and 15 seconds, respectively, followed by rinsing with a jet of water and air for 60 seconds. The used burs and conditioned tooth surfaces were examined using a scanning electron microscope. The quality of conditioned tooth surfaces was comparatively analyzed through the study of electron diffraction patterns of five dentin areas obtained for each tooth; each examined surface was rated on a scale from 0 to 3. The obtained data were statistically processed using Statistica 12.0 (StatSoft, USA) and Microsoft Office Excel 2017 (Microsoft Corporation, USA). Differences were considered statistically significant at p < 0.05. Results . A comparative analysis of the electron diffraction patterns of tooth surfaces from four experimental groups revealed a relationship between the quality of a diamond bur (the presence of visually and microscopically detectable areas on the bur surface that lack the diamond abrasive layer) and the structural characteristics of a tooth surface after preparation and conditioning. The use of both new (in 62.5% of cases) and previously used (in 100% of cases) MANI burs to prepare the surfaces led to the detection of cracks in the dental hard tissues. According to the analysis of electron diffraction patterns with the use of to the developed scale, Multi Etchant gel was found to ensure better preparation of tooth surfaces for the next stage than 37.0% orthophosphoric acid as it provides a cleaner surface even in the case lower-quality diamond burs. For example, areas of dentin surface prepared with the Mani burs and conditioned with Multi Etchant scored 1 point in 72.5% of cases, while those conditioned with Travex were given a score of 1 in only 37.5% of cases. Conclusion . A microscopic examination of the previously used Diatech burs (ten cycles of use), revealed insignificant wear of the diamond coating, which manifested itself in a partial loss of the abrasive layer on the working surface. Therefore, the effect of bur wear on the quality of tooth surface preparation is insignificant, which contributes to the formation of a smooth surface during tooth preparation and a reduced frequency of crack formation.

BACKGROUND: It is known that the development of the carious process is promoted by microorganisms that secrete waste products that penetrate into the tooth tissue during the depressurization of the filling material. That is why high-quality restoration prevents the development of secondary caries. AIM: Based on the study of the edge fit of restorations made of various types of filling materials, when restoring the chewing surface of the tooth, to determine the most optimal method of filling, which reduces the likelihood of violation of the edge fit of the seal in cases of significant changes in atmospheric pressure. MATERIALS AND METHODS: The removed teeth were prepared and treated with the Single Bond Universal adhesive system, the samples were divided into 4 groups, the cavities were filled according to the classical method with traditional composite materials Estelite Sigma Quick (Tokuyama Dental), OptiShade (Kerr) and materials of the bulk fill Tetric N-Ceram (Ivoclar Vivadent), SonicFill (Kerr). After sealing, groups 3 and 4 were placed in a pressure chamber (the study was conducted at the Department of Aviation and Space Medicine) and exposed to low atmospheric pressure. Next, the restoration slots were made and the study was carried out using a scanning electron microscope JEOL JSM-6380LV. RESULTS: As a result of microscopic studies, a violation of the marginal fit along the filling-tooth border was determined in all samples sealed with traditional composite materials (Estelite Sigma Quick, OptiShade) 65 9.18% (p 0.05) and bulk fill group materials (Tetric N-Ceram, SonicFill) 98 2.69%, (p 0.05) in cases of exposure to low atmospheric pressure. In the samples that were not exposed to atmospheric pressure, the marginal depressurization was 12 6.25% (p 0.05) Estelite Sigma Quick, OptiShade and 21 7.84% (p 0.05) Tetric N-Ceram, SonicFill. CONCLUSION: It has been proved by laboratory method that traditional composite materials and bulk fill group materials are rational to use only in persons who are not associated with extreme effects on the body, since in cases of exposure to atmospheric pressure, there are violations of the marginal fit of the material along the sealtooth border.

BACKGROUND: Dental caries is the most common disease of the oral cavity, which can usually be treated by direct composite restoration. AIM: To assess the quality of the marginal fit of adhesive systems and photocomposites to the hard tissues of the tooth. MATERIALS AND METHODS: A scanning electron microscopic study was conducted with 30 restorations on teeth previously removed for medical reasons using a 7th-generation adhesive system from the universal group of various manufacturers and composite materials. The experiment included Tetric N-Bond Universal (Ivoclar Vivadent), PrimeBond Universal (Dentsply Sirona), OptiBond Universal (Kerr), and composite materials (OptiShade, сeram.х SphereTec, and Tetric N-Ceram). All of these adhesives can be used with any enamel and dentin conditioning technique or with dual-curing composites; thus, their use is relevant in orthopedic dentistry. Teeth sections were made with restorations and scanning electron microscopy was performed. RESULTS: The self-etching adhesives of the universal group produced different results after studying the electron diffraction patterns of the teeth sections with restorations. The OptiBond Universal (Kerr) adhesive system had the best marginal fit, followed by Tetric N-Bond Universal (Ivoclar Vivadent) and Prime Bond Universal (Dentsply Sirona). A clinical case of restoration with a combination of class 5 and 3 cavities according to Black was represented by the OptiShade material. CONCLUSION: A violation of the marginal fit of the material in the zone of contact with the hard tissues of the tooth was noted in 60% of the cases when using the composite material Ceram.x SphereTec (Dentsply Sirona) and the adhesive PrimeBond Universal; 20% Tetric N-Ceram (Ivoclar Vivadent) and PrimeBond Universal adhesive; in 10% composite OptiShade (Kerr) and adhesive OptiBond Universal (Kerr). The adhesive should be applied with a brush.