Effect of Different Surface Treatment Modalities on Surface Roughness and Shear Bond Strength of Orthodontic Molar Tubes to Lithium Disilicate Ceramics

Document Type : Original Article

Authors

1 Lecturer, Biomaterials Department, Faculty of Dentistry (girls), Al-Azhar University

2 Lecturer, Orthodontic Department, Faculty of Dentistry (girls), Al-Azhar University

3 Lecturer, Operative Dentistry Department Faculty of Dentistry (girls), Al -Azhar University

Abstract

Objectives; This study aimed to evaluate the effect of different surface treatment modalities on surface roughness(SR) and shear bond strength (SBS) of orthodontic molar tubes to lithium disilicate (IPS e-max CAD/CAM, Ivoclar Vivadent) ceramic and human enamel using different adhesives.
Materials and methods: A total of 150 e-max specimens were randomly divided into five groups (n=30) according to the method of surface treatment used. In group I (control group): no surface treatment, group II: sandblasting with 50 μm Al2O3 slurry particles, group III: etching with hydrofluoric acid 9.6%, group IV: etching with hydrofluoric acid 4.5% and group V: etching with phosphoric acid 37%. Further random distribution of e-max specimens into subgroups was performed according to the type of adhesive used (One coat 7, G-Premio Bond and Ortho solo). The surface roughness was investigated using digital profilometer and atomic force microscopy (AFM). Microstructural analysis was conducted using scanning electron microscope (SEM).The SBS was measured using universal testing machine. Results were statistically analyzed.
Results: Results showed that the sandblasting group had significantly highest surface roughness, while the lowest value was recorded in the Phosphoric acid 37% group. Furthermore, sandblasted group showed the highest SBS, while control group showed the lowest SBS. Strong positive correlation was found between the surface roughness of lithium disilicate and shear bond strength. Meanwhile, no significant differences were found between different adhesive agents use.
Conclusions: Shear bond strength was highly affected by the surface roughness which subsequently controlled by the surface treatment modalities and not by the adhesives types. Hydrofluoric acid 4.5% and phosphoric acid 37% are recommended techniques for reliable bond strength between metal tubes and lithium disilicate ceramic.

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