Abstract
Introduction: When the orthodontic brackets are bonded to the etched enamel, the ideal orthodontic adhesive should have optimal bond strength and be able to withstand masticatory forces as well as orthodontic forces. At the same time, when the treatment is completed, the bracket should debond without causing any damage to the enamel. There have been many recent advances in composites in general and their applications in orthodontic use is questionable. Aim: The study compares the shear bond strength of Nanohybrid and Microhybrid flowable composites used for bonding orthodontic brackets to the enamel.Materials and Methods: One hundred freshly extracted premolar teeth were divided into four groups. Group I VertiseTm (Nanohybrid); Group II Endure Nano Flowable (Nanohybrid); Group III Te Econom Flow (Microhybrid); Group IV Esthet X flow (Microhybrid). Etching was done with 37% phosphoric acid in all groups and Transbond XT Primer is applied except for the Vertise group. Pre-adjusted edgewise premolar stainless-steel brackets were attached to the tooth. The shear bond strength and the adhesive remaining on the enamel surfaces was also evaluated using modified adhesive remnant index (ARI).Results: There was no statistically significant difference (P=0.233) between the two nanohybrid groups, i.e. Vertise and Endure flow, and also microhybrid subgroups showed no statistically significant difference (P=0.691) in their shear bond strengths. The medians for Modified ARI scores of Vertise flow, Endure flow, Te econom flow and Esthet X flow were 3, 1, 1, 3, respectively. Conclusion: It can be inferred that both nanohybrid and microhybrid flowable composites have clinically acceptable shear bond strengths.