A Comparison of Shear Bond Strength of Orthodontic Brackets Bonded with Four Flowable Composites Bonded under Contamination: An Ex-Vivo Study

Objective: To evaluate the shear bond strength of the brackets bonded with adhesive and flowable composites under contamination by human blood and human saliva& to evaluate enamel damage post debonding using ARI index. Material and Methods: 100 human premolars extracted for orthodontic reasons were used & shear bond strengths of 4 flowable composites and one conventional composite were evaluated under 2 bonding conditions: (1) contamination with saliva (2) contamination with blood. Contamination was done after the application of primer in all the groups and before bonding the brackets, decontamination was done by using the air water spray for 5 seconds and air drying the surface. Shear bond strengths were measured with universal testing machine after placing the bonded specimen in deionized water and incubator at 37˚C for 72 hours to permit adequate water absorption and equilibration. After debonding, each specimen was examined under a stereoscopic zoom microscope (10X) to identify the location of the bond failure. The residual composite remaining on the premolar was assessed by using the remnant index (ARI), where each specimen was scored according to the amount of material remaining on the enamel surface. Results: conventional composite showed the highest bond strength in both blood and salivary contaminations. Among the flowable composites, each behaved differently. Blood contamination showed reduced bond strengths in all the groups. Decontamination with air water spray and air drying the surface before bonding the brackets seems to be satisfactory. Conclusion: with use of a primer, flowable composites can be used to bond the orthodontic brackets under contamination and decontamination with air water spray for 5 seconds and air drying the surface before bonding seems to be satisfactory if contamination occurs after the application of the primer.