Молодежный инновационный вестникМолодежный инновационный вестник2415-7805Федеральное государственное бюджетное образовательное учреждение высшего образования "Воронежский государственный медицинский университет имени Н.Н. Бурденко" Министерства здравоохранения Российской Федерации7346Conference ProceedingsSTUDY OF POLYMERIZATION SHRINKAGE OF COMPOSITE MATERIALSBayazovaOlga Alekseevna<p>student</p>ol.jus417@bk.ruhttps://orcid.org/0000-0003-3644-5725NurmetovNavruz Shuhratovich<p>student</p>nurmetoff.navruzz@gmail.ruhttps://orcid.org/0000-0002-7249-1246Voronezh State Medical University named after N.N. Burdenko30062022114154172202202223022022Copyright © 2022, Bayazova O.A., Nurmetov N.S.2022<p>ABSTRACT</p>
<p>Composites are dental materials used for the treatment and restoration of teeth. Today, the range of composite materials is very wide. Each of them has its own positive and negative properties. One of the most important quality indicators is polymerization shrinkage, which we would like to test and compare during the experiment.</p>
<p>Purpose. Compare and analyze composite shrinkage of dental materials.</p>
<p>Materials and methods. Theoretical, empirical and mathematical research methods were used to determine the composite shrinkage.</p>
<p>Results. Composites were chosen, which are most often used in the daily practice of a dentist therapist. An experiment was carried out, during which the relationship between the fullness of the composite and polymerization shrinkage was revealed.</p>
<p>Discussion. The main value of the work lies in the fact that we tried in the laboratory to place the composite in the conditions in which it is in the oral cavity. We were able to consider the polymerization shrinkage of various composite materials.</p>
<p>Conclusion. As a result of the study, we found that the Restavrin composite (Technodent) has the highest polymerization shrinkage, and the lowest SDR (Dentsply).</p>composite materialsfullness of the compositepolymerization shrinkageкомпозиционные материалынаполненность композитаполимеризационная усадка<p>The composite must have a certain set of positive qualities in order for the restoration to last as long as possible. These include sufficient strength, good polishability, acceptable aesthetic properties, high wear resistance, and, most importantly, low polymerization shrinkage [5]. Why was the last quality singled out separately? Composite shrinkage is the percentage reduction in the volume of the material relative to the original. The concept is very simple, but very important for the long-term sustainability of the restoration. The composite experiences stress during polymerization, i.e., tension occurs at the border between the tissues of the tooth and the filling. As a result, cracks in the enamel, chips, marginal and internal gaps may appear [2]. Why is it so? To understand this, it is necessary to consider the composition of composite materials. They consist of an organic base and an inorganic filler. The organic base is the BIS-GMA monomer, which is obtained by combining the diglycidyl ether of diphenylolpropane with methacrylic acid [4]. The inorganic filler can be represented by borosilicate glass, aluminosilicate glass, diamond dust, catalysts, dye, and initiator [3]. Knowing the composition, we can guess which component can cause polymerization shrinkage. We hypothesize that all this is due to the amount of filler, the reduction of which leads to a loss in volume as it cures.<br />Target. Analyze and compare composite shrinkage of restorative materials.<br />Materials and methods. For the experiment, we compared the same portions of the most popular composite materials in the practice of a dentist therapist: SDR (Dentsply), Estelite Asteria (Tokuyama Dental), Harmonize (Kerr Dental), Restvrin (Technodent), Megafill MH (Megadenta). All composites had A2 color, except for SDR (has one universal shade). For each of the five composites, 10 samples of containers from under the anesthetic carpule 5 mm high were made, which imitated cavities according to the 1st class according to Black. Next, sandblasting of these containers was carried out, adhesive preparation, after which the same portion of composite materials was added for no more than 45 seconds. After that, the polymerization of the material was carried out using a lamp. Those containers in which the material had polymerized shrinkage burst.<br />Results. Shrinkage is inherent in many materials in dentistry. In the context of filling materials, we are talking about linear or volumetric shrinkage. Linear shrinkage can be from 0.8 to 2%, and volumetric polymerization shrinkage of composites ranges from 2 to 4%. Polymerization stress creates a shrinkage stress between the composite and the tooth walls, which can reach about 13 MPa [1]. As a result, microcracks appear between the composite material and the tooth, which cause a violation of the marginal fit. In informational guidelines for the use of filling materials, some manufacturers indicate information about their shrinkage (Table 1). However, these data are very approximate, since it is not yet possible to build time dependences of technological and strength properties for light-cured composites due to the fact that the curing processes proceed for several tens of seconds, during the period of exposure to the material of the light flux, in addition, the color is very important. , opacity and transparency of the composite. In addition, it is necessary to take into account the volume content of the filler in the composite and what the organic matrix actually consists of. For example, it is known that low molecular weight components of the binder are able to give the highest possible degree of conversion of carboncarbon double bonds, and the presence of acidic functional groups in the composite can reduce the efficiency of catalysts and prolong the shrinkage process over time.<br />Table 1<br />Characteristics of the studied composites</p>
<p>Material name Shrinkage (%) Content (%)<br />Estelite Asteria<br />(Tokuyama Dental) 1.3 (linear) 82<br />Megafill MH (Megadenta) 1.7 (linear) 80<br />Restvrin (Technodent) 1.8 (linear) 80<br />SDR (Dentsply) 3.5 (volumetric) 68<br />Harmonize (Kerr Dental) 1.5 (linear) 82</p>
<p>As a result of our research, 2 containers were cracked after polymerization. After flashing "SDR", "Haermonize" and "EsteliteAsteria" no changes occurred. Restavrin and MegafillMH have shrunk. The container in which there was "Restaurin" cracked at 15 seconds of exposure, "MegafillMH" at 18 seconds.<br />Such results demonstrate the ability of composites with a large volume of filler to cope with the occurrence of shrinkage stress, while the SDR material, despite the low filling (68%), according to the manufacturer, has the ability to give volumetric shrinkage inside the portion, which was confirmed during our experiment.<br />Discussion. The main value of the work lies in the fact that we tried in the laboratory to place the composite in the conditions in which it is in the oral cavity. We managed to consider the polymerization</p>[Национальный стандарт Российской Федерации Композиты полимерные. Препреги и Премиксы. ГОСТ Р 57785-2017 (EN 1842:1997)][Nakano, E. L., de Souza, A., Boaro, L., Catalani, L. H., Braga, R. R., & Gonçalves, F. (2020). Polymerization Stress and Gap Formation of Self-adhesive, Bulk-fill and Flowable Composite Resins. Operative dentistry, 45(6), E308–E316. https://doi.org/10.2341/19-166-L][Erhardt, M., Goulart, M., Jacques, R. C., Rodrigues, J. A., & Pfeifer, C. S. (2020). Effect of different composite modulation protocols on the conversion and polymerization stress profile of bulk-filled resin restorations. Dental materials : official publication of the Academy of Dental Materials, 36(7), 829–837. https://doi.org/10.1016/j.dental.2020.03.019][Rizzante, F., Mondelli, R., Furuse, A. Y., Borges, A., Mendonça, G., & Ishikiriama, S. K. (2019). Shrinkage stress and elastic modulus assessment of bulk-fill composites. Journal of applied oral science : revista FOB, 27, e20180132. https://doi.org/10.1590/1678-7757-2018-0132]