[Reinforcement of photosensitive material for bases of orthodontic appliances]

The objective of the study was to improve the strength properties polymer by modifying its basis with various materials.

A polymer in the form of a pink-colored plasticine mass with veins was studied, a quartz mesh «Quartz splint mesh» manufactured by RTD (France) and two metal gold-plated wire mesh (0.1 mm and 0.15 mm in diameter) manufactured by Renfert (Germany). Modified test specimens, 65×40×3.5 mm in size were covered with a lavsan film and at a slight pressure the material was rolled out with a glass cylinder flush with the frame. Curing was carried out in Fhotopress photopolymer (Aveyron, RF) under the 460-470 nm wavelength light for 6 minutes on each side. The plates were sawn with a mill in the form of strips 64×10×3.3 mm and kept in distilled water at 37 °C for 50 h before testing. The test of the reinforced samples was carried out with a middle and lower location of quartz and metal grids pre-treated with adhesive and subjected to a 4-point bending test. Bending strength, bending modulus, and fracture deformation were determined using a Zwick/Roell Z010 testing machine with a constant crosshead speed under loading (5±1) mm/min. The statistical significance of the influence of reinforcing elements on the performance of the basic physical and mechanical properties of the base material was determined using Student's t-test.

The value of fracture toughness index K1 at the lower location of the quartz mesh was 3.72±0.43 MN/m1.5, which was 4.9 times significantly higher than K1 for the non-reinforced material (p=0.0001).

The ability to achieve maximum material strength with the lower reinforcement method increases the functional usefulness of removable orthodontic and orthopedic structures with a basis of «Nolatek» light-cured material.