*2.2. Mechanical Properties of the Mouthguard Components*

A multilayered mouthguard construction was studied. The mouthguard was from EVA (Drufosoft, Dreve, Germany) with an embedded layer of A-silicone (UfiGelP, Voco, Germany). UfiGelP is a base paste and a catalyst paste, which can be mixed in certain ratios (in this case 1:1). Once cured, UfiGelP is a highly elastic polymer material. The proportion of base and catalyst pastes in the manufacture of the splice tray was selected empirically. Before solidification, the material is soft enough and easily adjusts to the required shape. That allows you to form a layer of A-silicone in the mouthguard. The properties of these materials were obtained from experimental studies performed by the research team from Perm National Research Polytechnic University, Perm State Medical University and Perm State National Research University [16,20]. The Young's modulus *E* and Poisson's coefficient *v* are *E* = 17.3 MPa, *v* = 0.46 (EVA) and *E* = 0.3 MPa, *v* = 0.49 (Asilicone). It was shown that EVA exhibits elastoplastic properties. The experimental plots are presented in Reference [20]. To describe the EVA mechanical properties, the deformation theory of elastoplasticity was chosen. A-silicone was shown to be an elastic material.
