EVALUATION OF STRENGTH PARAMETERS OF POLYMER COMPOSITES USED FOR DENTAL RESTORATION BY THE METHOD OF ACOUSTIC EMISSION

The aim of the study is to create a technique and perform mechanical tests to determine the strength parameters of dental composites from the standpoint of linear fracture mechanics, and using the phenomenon of acoustic emission to determine the origin and development of destruction of light-curing dental composites under quasi-static local compression load. The following hybrid dental composites of domestic and foreign manufacturers were selected for comparison: Latelux (Latus, Ukraine), TETRIC N-CERAM (Ivoclar Vivadent, Liechtenstein), CHARISMA CLASSIC (Kulzer, Germany). 10 disc samples of 13 mm diameter and 5 mm thick of each material were made by using a specially designed mould for study purposes. Packaging and moulding of the material into the mould was performed in laboratory conditions at an air temperature of 18 – 21°C. Before testing, the samples were kept for 24 hours at a temperature of 37°C in saline solution. The samples were loaded on the SVR-5 machine using a ball indenter. During the experiments, acoustic emission data were simultaneously recorded using the SKOP-8 measuring system. In the post-processing stage, the dependencies of the load change during the experiment, the distribution of the amplitudes of the registered AE signals and their sum over time were recorded. The fracture load, indenter displacement, and the features of composite fracture were determined from the obtained dependencies based on the analysis of AE generation under the load. Analysis of the parameters of the AE signals showed that during the destruction of the Tetric N-Ceram composite the signals had the largest amplitude and energy, and of Latelux had the smallest ones.