Investigation of adhesive shear strength of universal adhesives for fixing ceramic braces

Abstract

Relevance. At the present stage, the choice of high-quality adhesive material is an important task of dentistry. The choice of the ideal adhesive material remains an urgent task to this day.The aim of the study was to study in laboratory conditions the adhesive shear strength for fixing ceramic braces of a universal adhesive system containing 3D-SR monomer (Universal Bond II (Tokuyama Dental)) and adhesive cement ESTECEM II PLUS (Tokuyama Dental) before and after thermal cycling, with and without the use of varnish.Materials and methods. For the preparation of samples, removed teeth without carious lesions and large fillings were used. Samples of 60 teeth were divided into 2 groups (n=30) with and without varnish. In each group, the adhesive shear strength was studied before and after thermal cycling (n=15). The following materials were used: two-component self-curing dental adhesive system Universal Bond II (Tokuyama Dental), varnish SHIELD FORCE PLUS (Tokuyama Dental), adhesive fixing cement double curing ESTECEM II PLUS (Tokuyama Dental). Tests of the adhesive shear strength of the prepared samples were carried out on a universal testing machine «SYNTHEZ 5» at a traverse speed of 5 mm/min according to the methodology of GOST R 56924-2016 (р. 7.15).Results. The adhesive strength index of the control group (before thermal cycling) was 4.33±1.28 MPa, in the main subgroup (after thermal cycling) 3.48±0.81 MPa. The presence of varnish on the enamel surface did not affect the adhesive strength of the bonding of the bracket system and tooth tissue and amounted to 4.50±0.25 MPa and 3.14±0.82 MPa, respectively (p= 0.0005).Conclusions. The presence of varnish on the enamel surface did not affect the adhesive strength of the connection of the bracket systems with tooth tissues in the control (before thermal cycling) and the main (after thermal cycling) subgroups (p≤ 0.05). The adhesive strength index in the control subgroups (before thermal cycling) and the main ones (after thermal cycling) of both groups differed slightly. Thermal cycling reduces the adhesive strength of braces with tooth tissues when using universal adhesive Universal Bond II (Tokuyama Dental) (p≤ 0.05).