СOMPARATIVE SPECTROPHOTOMETRY ANALYSIS OF ZIRCONIUM DIOXIDE WITH THE CUBIC AND TETRAGONAL PHASE AFTER ARTIFICIAL AGING.

Aim - to evaluate optical features of the 3, 4 and 5Y-TZP zirconium dioxide with the spectrophotometry analysis under artificial aging procedure. For all experiments, identical standardized specimens of different types of zirconia with a diameter of 10 mm and a height of 1 mm were used. These types included Katana (Kuraray Noritake Dental, Tokyo, Japan) HTML (control) UTML, STML and ZirCAD Prime (Ivoclar Vivadent). Artificial aging (low-temperature degradation) was performed using the following autoclaving regime: 134 degrees Celsius, 2 atmospheres, 5 hours. A Shimadzu UV-3600 spectrophotometer was used to study the spectral characteristics of the provided samples. Since the samples have low bandwidth, it was decided to investigate the reflectance spectra. For this purpose, a Shimadzu SR-1503 integrating sphere was installed on the spectrophotometer. Results: All samples of Prime manufacturer show an increase in the reflected signal intensity in the range of 650-820 nm. This range corresponds to red and orange colors, which means that as a result of autoclaving the beige tint of the materials will become more pronounced. The intensity of scattered light of the sample UTML-glaze and STML-glaze has lower values in the whole visible wavelength range. However, the intensity decrease in this case is not uniform. In the range above 500nm the intensity decrease is more pronounced, which means that as a result of artificial aging the beige tint of the materials will become somewhat less pronounced. Zirconia restorations with a predominantly tetragonal phase with polished and glazed surfaces will not change reflectance during artificial aging.

EFFECT OF SURFACE TREATMENT PROTOCOLS OF ZIRCONIUM DIOXIDE MULTILAYER RESTORATIONS ON FUNCTIONAL PROPERTIES OF THE HUMAN ORAL MUCOSA STROMAL CELLS.

Aim - to study the effect of protocols of surface treatment of zirconium dioxide multilayer restorations on the functional properties of stromal cells of the human oral mucosa using molecular biological methods. For all experiments, identical standardized specimens of different types of zirconia with a diameter of 10 mm and a height of 1 mm were used. These types included Katana (Kuraray Noritake Dental, Tokyo, Japan) HTML (control) UTML, STML and ZirCAD Prime (Ivoclar Vivadent). DMEM/F12 growth medium (Paneco, Russian Federation) with addition of fetal calf serum (Gibco, USA) up to 10% and penicillin-streptomycin (Paneco, Russian Federation) up to 1% was used in the experiment. Cells were detached from the culture substrate with trypsin-EDTA solution (Paneco, RF) and their number and viability were assessed using an automatic counter TC-20 (Bio-Rad, USA). For repopulation, samples were transferred into wells of a 96-well culture plate (1 sample in 1 well) and cell suspension was layered at the rate of 12.5 thousand or 25 thousand live cells per well. After 48 hours, the cytotoxic properties of the tested samples were evaluated in vitro. According to the results of MTT test we can conclude that samples of ZirCad Prime and Katana UTML groups do not show cytotoxic properties (score "0" on the cytotoxicity scale according to GOST R ISO 10993-5-2009 "National Standard of the Russian Federation. Medical devices. Evaluation of biological effect of medical devices. Part 5. Studies on cytotoxicity: in vitro methods"). The samples of Katana STML group samples were slightly reduced compared to the control (about 12%), nevertheless, these samples can also be considered non-cytotoxic. Analyzing the direct contact with the material in all samples, a good occupancy of the material by cells was observed, in particular, the polished surface prevailed over the glazed one, however, this difference is not statistically significant. Analysis of human oral stromal cells to zirconium dioxide showed no statistically significant effect of different surface treatment protocols. However, the number of fibroblasts prevailed on the polished surface.

[The alveolar antral artery prevalence and topography according to literature review]. / Analiz vstrechaemosti i topograficheskikh dannykh al'veolo-antral'noi arterii na osnove obzora literatury.

INTRODUCTION: The lack of the available bone in the posterior maxilla is determined by the range of anatomical and topographical factors. Lateral sinus floor elevation is the procedure for vertical augmentation in this region. Several complications may occur while performing a lateral sinus lift and bleeding due to alveolar antral artery (AAA) damage is one of them.The aim of the study is to analysis the different literature on AAA topographical features on cadaver species and on radiographic methods. MATERIALS AND METHODS: A search of the English language literature was performed by three independent readers in the PubMed electronic database. Articles published between 2013 and 2018 on cadaver and radiographic studies were included. RESULTS: The analysis included 9 articles. AAA prevalence in cadavers was 100% but AAA bone signs in CBCT studies varied between 32% and 93%. The diameter varied from 0.91 mm to 3.6 mm, and the distances from AAA to the sinus floor and to the alveolar ridge crest were 7.38-9.97 and 14.6-18.66 mm respectively. CONCLUSION: Our literature analysis showed the difference between AAA prevalence in cadavers and in CBCT scans. The results show that even proper pre-operative planning of the lateral sinus lift with CBCT cannot guarantee avoiding AAA damage while performing the surgery.

[Morphology of mandibular lingual concavities]. / Morfologiia podnutrenii nizhnei cheliusti s iazychnoi storony.

AIM: The literature review on assessment of lingual concavities in posterior mandibula with CBCT to prevent complications such as perforations during dental implant placement. METHODS: The electronic search of full-text articles on lingual concavity studies with CBCT was performed. The data on the prevalence, depth and angle of concavities was analyzed. RESULTS: The analysis included 5 articles from 2011 to 2016 years. Totally 1713 mandibular concavities were evaluated in 1232 patients. The prevalence was 46.7-68%; mean depth was from 2.4 mm to 5.4 mm; and the mean angle varied from 143 to 156.6 degrees. CONCLUSION: Though morphologic data of lingual concavities showed similar pattern it is necessary to provide CBCT evaluation prior to dental implant placement to define available bone and its morphology. It is recommended to use guided surgery if U-type is evident.