BONDING ORTHODONTIC RESIN CEMENT TO ZIRCONIUM OXIDE UNDER ORTHODONTICS LOAD AND THERMOCYCLING EFFECT

What is it about?

Purpose: Evaluate the microshear bond strength (µSBS) of orthodontic resin cement to monolithic zirconium oxide ceramic (MZ) under orthodontic load (OL) and thermocycling (TC) effect. Materials and Methods: Glazed MZ blocks (Zenostar, Ivoclar Vivadent) were tested after air abrasion with 30-µm silica coated aluminum oxide (Al2O3) particles (CoJet, 3M ESPE). The specimens were randomly divided into 4 groups (n = 15): G1, OL with TC; G2, OL without TC; G3 no OL with TC; and G4, no OL, no TC (control). Orthodontic cement cylinders (Heliosit Orthodontic, Ivoclar Vivadent) were bonded to the primed samples (Monobond Plus, Ivoclar Vivadent) using the Ultradent SBS system and light cured (SmartLite Max, Dentsply Sirona, 1400 mW/cm2, 40 s). G1 and G2 were subjected to 70 ± 15 N load perpendicular to the cylinder axis, G1 and G3 were thermo-cycled (5000 cycles 5-55°C, 90 s/cycle). G2 and G4 were stored in distilled water at 37 ± 1°C. The specimens were subjected to µSBS test (crosshead speed 0.5 mm/min). Data were analyzed using two-way ANOVA, and one-way ANOVA and Tukey test (HSD). Results: Two-way ANOVA for µSBS values (MPa) showed significant (p = 0.0004) load effects, but not thermal effect (p = 0.2455) with significant load/thermocycling interactions (p < 0.0001). The ranking of the single groups by Tukey test (α = 0.05) showed that G1 exhibited the highest µSBS (8.4 ± 2.8 MPa), G4 (6.3 ± 1.1 MPa) and G2 (5.8 ± 1.1 MPa) as a group was second, and G2 and G3 (4.7 ± 1.1 MPa) as a group was the lowest. Conclusion: G1, which is the closest to clinical reality, yielded the best results. Keywords: orthodontics, dental materials, orthodontic resin cement, monolithic zirconium oxide ceramic, microshear bond strength test.

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