Evaluation of shear bond strength of orthodontic ceramic and metal brackets with zirconia: effects of adhesive systems and storage conditions

Abstract

Objective: The current study assessed the shear bond strength of two orthodontic bracket materials to zirconia using two bonding approaches and two storage settings.

Methods: Two bonding strategies were selected to bond metal and ceramic brackets to zirconia samples. Before being tested for Shear Bond Strength [SBS], samples were either subjected to 5,000 thermocycles or kept in water for 24 h. Samples were divided into 8 Groups [n = 10] represented as Group 1: Ceramic Brackets + HEMA-Free Bonding System + Water Storage, Group 2: Ceramic Brackets + HEMA-Containing Bonding System + Water Storage, Group 3: Metal Brackets + HEMA-Free Bonding System + Water Storage, Group 4: Metal Brackets + HEMA-Containing Bonding System + Water Storage, Group 5: Ceramic Brackets + HEMA-Free Bonding System + Thermocycling, Group 6: Ceramic Brackets + HEMA-Containing Bonding System + Thermocycling, Group 7: Metal Brackets + HEMA-Free Bonding System + Thermocycling, Group 8: Metal Brackets + HEMA-Containing Bonding System + Thermocycling. Several independent groups were compared using the Kruskal-Wallis test, and two independent groups were assessed using the Mann-Whitney U test. A P-value < 0.05 was deemed significant.

Results: Shear bond strength was significantly greater in ceramic than in metal [5.9 ± 2.6 vs. 4.9 ± 2.3, p = .026] and in 2-Hydroxyethyl methacrylate HEMA-containing systems compared to HEMA-free systems [6.1 ± 2.3 vs. 4.8 ± 2.4, p = .034]. Water storage settings also yielded higher bond strength than thermocycling conditions [6.9 ± 1.8 vs. 3.9 ± 2.2, p < .001].

Conclusion: The findings indicate that shear bond strength was significantly influenced by bracket material and adhesive system to zirconia. Additionally, storage settings play a crucial part in shear bond strength.

Clinical relevance: Developing effective bonding techniques for orthodontic brackets and zirconia ceramic materials remains a major clinical obstacle.