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Published on: December 20, 2024
Shear bond strength and adhesive remnant index of orthodontic brackets bonded to 3D-printed crown materials: An in
Shohreh Ghassemi1, Amir Nejat2, Qingzhao Yu3
1Department of Orthodontics, LSU Health-New Orleans, School of Dentistry, 1100 Florida Avenue, New Orleans, LA 70119, United States.
Objective:
This study evaluated shear bond strength (SBS) and adhesive remnant index (ARI) of metal and ceramic orthodontic brackets bonded to three 3D-printed crown materials and one milled control.
Material And Methods:
In all, 128 samples were fabricated from VarseoSmile Crown TriniQ®, SprintRay Ceramic Crown, Flexcera™ Smile Ultra Plus, and Lava Ultimate™ (n=16 per group; 8 groups total). Metal (Mini Master®) and ceramic (Radiance Plus®) brackets were bonded using 50μm aluminium oxide air abrasion and Transbond™ XT. Samples underwent thermocycling for 1000 cycles (5°C to 55°C). SBS was analysed using two-way ANOVA with Tukey's HSD; ARI scores were analysed using Kruskal-Wallis test with Dunn's post hoc comparisons.
Results:
All groups exceeded the clinically acceptable SBS threshold to enamel of 6MPa. Restorative material significantly affected SBS (P<0.001), and a significant interaction between bracket type and material was observed (P<0.001). SprintRay Ceramic Crown produced the highest mean SBS for ceramic (28.18±4.15MPa) and metal brackets (22.68±4.96MPa), significantly exceeding all other materials (P<0.001). Bracket type had no significant overall effect on SBS (P=0.26); however, ceramic brackets showed significantly higher SBS than metal brackets on SprintRay and Lava Ultimate™, while metal brackets showed significantly higher SBS than ceramic brackets on VarseoSmile® and Flexcera™. Metal brackets produced predominantly higher ARI scores, while ceramic brackets showed more mixed failure patterns.
Conclusions:
Standard bonding with aluminium oxide air abrasion and Transbond™ XT produced SBS higher than that reported for enamel across all materials. Restorative material significantly influenced bond strength, and bracket performance varied by substrate, suggesting bracket selection may account for the specific restorative material. ARI findings indicate failure location differs between bracket types.
