In vitro evaluation of self-etch bonding in orthodontics using cyclic fatigue

Abstract

Objective: To evaluate the bond strength of a self-etch bonding system using static loading and cyclic fatigue with shear testing. This is a two-part evaluation; the first part will evaluate shear testing, the second part tensile testing. Materials and Methods: Bovine teeth (n 5 82) were randomly distributed to either a self-etch (Transbond Plus) or total-etch (37% phosphoric-acid + Transbond XT) group. The static shear (SSBS) and cyclic shear (CSBS) bond strengths were measured 24 hours after the bonding of mesh-based brackets. The adhesive remnant index (ARI) and failure sites were evaluated. Results: The mean SSBS was 34.25 6 9.21 and 24.64 6 9.42 MPa for the total-and self-etch groups, respectively. CSBS was 24.07 6 0.65 MPa and 18.92 6 1.08 MPa for the total-and selfetch groups, respectively. Cyclic loading produced lower bond strengths compared to static testing for both adhesives; the difference was only statistically significant for the total-etch system. Comparison of the two materials showed a statistically significant difference between the two techniques. The total-etch had higher bond strengths than the self-etch bonding system. The samples showed a predominance of ARI scored of 2 and 1, and their bonding failure sites were cohesive within the composite. Conclusion: Cyclic loading, simulating occlusal forces, reduces the bond strength of both bonding systems. Even though the self-etch bonding system had lower shear bond strength than the totaletch system, both were still clinically acceptable. (Angle Orthod. 2011;81:783-787.)

In vitro bond strengths post thermal and fatigue load cycling of sapphire brackets bonded with self-etch primer and evaluation of enamel damage

“…The use of a high initial cyclic loading (60% of the static SBS) and high cycle number (5000 cycles) resulted in 5 bracket failures (out of 40 bonded teeth) in this study. A similar fatigue protocol utilized in previous in vitro studies resulted in a significant drop in SBS of metallic brackets following the use of EaR protocol (21) and SEP protocol (28). Therefore, the successive exposure to both thermo-cycling and fatigue stands for the significant drop in SBS of both control and SEP subgroups in this study.…”

Effect of organic solvents and ultrasound on the removal of orthodontic brackets

“…In this study, the dissolution of the organic matrix of the composite and the adhesive emphasizes the methacrylate's solubility in organic solvents. Studies have reported a correlation between enamel preservation and higher amounts of residual adhesive , even for the self‐etching system . In this study, these solvents showed similar effectiveness on the Adhesive Remnant Index, regardless of the adhesive system used.…”

Resistance of bonded premolars to four artificial ageing models post enamel conditioning with a novel calcium-phosphate paste

“…In the present study, fatigue testing of the enamel-adhesi-ve-bracket complex affected the bond strength outcomes of all subgroups adversely in comparison with the results of 24 h WS experiment. This finding can be attributed to the use of a relatively high initial cyclic loading (60% of the SSBS) and cycle number (5000 cycles), being the highest values ever used in bracketed teeth fatigue studies (9,27), in which a significant drop in SBS was reported after fatigue testing. The control subgroups showed less CSBS reductions in comparison to the CaP subgroups, as indicated by maintaining higher percentages of SSBS (Control= 69.5-76.7% versus CaP= 63.3-76.3%).…”

“…Although these cyclic stresses could be of a lower magnitude than the static bond strength of a bonded bracket, repetitive subcritical forces occurring throughout the treatment period can cause adhesive micro-fractures and eventual breakdown of the bracket through a condition referred to as fatigue (8). Compared to static SBS, the cyclic SBS provides more realistic information about a material's long-term performance in the clinical situation (27).…”

“…The use of percentages reflects the fatigue ratio, i.e. ratio of the mean CSBS to the mean SSBS, which provides helpful information as a predictor of the survival behavior of materials and facilitates comparison with previous reported studies (9,27). The CaP subgroups yielded fatigue ratios between 0.63-0.76, which are in line with the findings of fatigue studies on clinically successful dental adhesive materials reporting fatigue ratios of 0.52-0.70 following etching with conventional 37% PA (8,28,29) indicating the potential effectiveness of using CaP pastes clinically.…”