Ivanna V. Kozlova

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.

AIM: To determine the qualitative structure of dental diseases and pathological conditions of the maxillofacial region and the level of their prevalence among young individuals entering higher military educational institutions in Russia. MATERIALS AND METHODS: Data obtained during the dental examination of applicants to the Military Medical Academy named after S.M. Kirov as part of a military medical examination to provide admission to a higher educational institution was comprehensively analyzed. RESULTS: The results showed a moderately high level of prevalence of diseases and pathological conditions of the oral cavity in the surveyed population. Among 589 applicants aged 16–25 years who arrived from different regions in Russia, the percentage of those in need of oral sanitation was 51.95%. The most common nosological form among the examined young people was dental caries, including recurrent and secondary forms, which ranged from 19 to 44% in various groups of examined people. Additionally, a low level of oral hygiene was identified, noted in more than 45% of applicants. CONCLUSION: The peculiarities of the obtained research results should be explained by unsatisfactory knowledge and skills in matters of individual oral hygiene (hereinafter referred to as IHPR), insufficient medical education, low level of compliance, and readiness to carry out activities to maintain dental health among young people.

BACKGROUND: According to Russian and foreign literature, the probability of iatrogenic perforation of the wall of the tooth root canal is high (9.712.5%) during endodontic dental treatment. This is a poor prognostic sign and may subsequently result in tooth extraction. Moreover, cases without curing of mineral trioxide aggregate (MTA) cement with pronounced exudation were reported. Сurrently, the modification of domestically produced MTA cement is relevant for closing teeth root canal perforation. AIM: This study aimed to conduct a comparative experimental microscopic study of the preservation of the marginal fit to the tooth tissues in perforation areas filled with MTA cement mixed conventionally with distilled water and a colloidal silver dioxide solution. MATERIALS AND METHODS: Sixty teeth previously removed for medical reasons were endodontically treated after iatrogenic perforation formation in the furcation area of the roots. Two groups were formed. In the first group, MTA cement mixed with distilled water was used to close dental perforations. In the second group, MTA cement mixed with a colloidal silver dioxide solution was utilized. The groups were divided into subgroups depending on the MTA cement brand used. The teeth were placed in an automatic incubator HHD 7 LED, in which an optimal mode was created, simulating the conditions of the oral cavity (t = 37 C, humidity 99%). The samples were placed in artificial saliva. After two months of exposing the teeth to a humid environment, the preservation and damage to the marginal fit in the perforation area of the fillings were determined under a Levenhuk 720B binocular microscope. RESULTS: In the perforations of the 30 teeth sealed with various MTA cement types mixed with distilled water, damage of the marginal fit was found in seven (23.3 7.9%) cases. Similar damage in 30 teeth with colloidal silver dioxide solution used to prepare MTA cements was detected in two (6.7 4.6%) cases (p 0.050, t = 1.82). CONCLUSION: The use of MTA cement mixed in a colloidal silver dioxide solution, in comparison with distilled water, contributes to a greater preservation of the marginal fit of the material to the walls of the root canal in an in vitro experiment.