Strength of the adhesive connection "veneer - composite material - tooth"

The study was conducted to compare the adhesion strength of glass-ceramic indirect restorations to tooth tissues after their fixation using light- and combined-curing composite materials, fifth- and sixth-generation adhesive systems. Laboratory studies were performed on sections of extracted human teeth in accordance with GOST R 59423-2021 (ISO 29022:2013). The shear strength test of the adhesive bond of an E-max sample to tooth enamel was performed on an UltraTester Bond Strength Testing Machine in three series of experiments using composite materials: Variolink Esthetic LC, Multilink N, Premise Flowable. In terms of adhesion strength, the fixing materials were distributed as follows: Premise Flowable flowable composite with photopolymerization (Mm=99.611.3 MPa); Variolink Esthetic LC with photopolymerization (Mm=96.413.8 MPa); Multilink N without photopolymerization (Mm=79.811.3 MPa). Studies of the strength of the "veneer - composite material - tooth enamel" connection using composite materials showed no differences between them (p=0,40252). In clinical situations of tooth tissue preparation within the enamel, a high degree of strength of the connection of indirect restorations made of E-max material with a tooth is predicted when using a light-curing composite, dual-curing composite, and flowable light-curing composite. To achieve effective fixation of indirect restorations, the main conditions are maximum preservation of enamel during tooth preparation; compliance with the technique of using the material outlined in the instructions; and rules for photopolymerization of the composite.