The strength of restorations of hard tooth tissues with changes in atmospheric pressure, in vitro studies

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 seal–tooth border.