Evaluation of brittleness of restorative materials of light polymerization based on the analysis of signals obtained by acoustic emission method.

Abstract

Topicality. A large number of light polymerization materials used in dentistry for the restoration of both anterior and canine teeth due to their aesthetic and mechanical properties determine the relevance of their comparative studies. Any restorative dental material, similarly to natural teeth, must possess sufficient mechanical durability in order to function in the oral cavity over an extensive period of time. In view of this, investigation of mechanical properties of such materials is the clinical task of paramount importance. The objective of the research is to analyse strength characteristics and features of destructive processes of lighthardening composite materials under three-point pressure with the application of the acoustic emission method (AE). Materials and methods. Samples were made from composite filling materials Latelux, Tetric N-Ceram, Charisma Classic, Filtek Z250, which were afterwards pressed until their complete destruction on the CBP-5 machine. In the process of fracture initiation and development signals were recorded by a portable eight-channel SKOP-8M measuring system. Flexural strength and elastic modulus were determined, in addition to dynamics of material fracture being studied by the acoustic emission method. Results. It has been established that the nature of the destruction of Latelux, Tetric N-Ceram and Charisma Classic materials is elastic and plastic at the initial stage of pressure, with the transition to brittle during its further growth, whereas the destruction of the Filtek Z250 material is brittle. Conclusion. The signals accompanying the destruction of the Tetric N-Ceram composite appear to have the highest amplitude and energy, while those accompanying the destruction of Latelux demonstrate the lowest amplitude and energy. Tetric N-Ceram nanohybrid composite shows the highest resistance to destruction. Key words: composite materials, strength, elasticity, pressure, destruction, acoustic emission.