Evaluation of Shear Bond Strength of Orthodontic Brackets Bonded with Nano-Filled Composites

Objectives: The purpose of this study was to evaluate the shear bond strength (SBS) of orthodontic brackets bonded with two types of nano-composites in com- parison to a conventional orthodontic composite. Materials and Methods: Sixty extracted human first premolars were randomly divided into 3 groups each containing 20 teeth. In group I, a conventional ortho- dontic composite (Transbond XT) was used to bond the brackets, while two nano- composites (Filtek TM Supreme XT and AELITE Aesthetic Enamel) were used in groups II and III respectively. The teeth were stored in distilled water at 37°C for 24 hours, thermocycled in distilled water and debonded with a universal testing machine at a crosshead speed of 1 mm/min. The adhesive remnant index (ARI) was also evaluated using a stereomicroscope. Results: AELITE Aesthetic Enamel nano-composite revealed a SBS value of 8.44±2.09 MPa, which was higher than Transbond XT (6.91± 2.13) and Filtek TM Corresponding author: M.S. Ahmad Akhoundi, Dental Research Center, Dentistry Research Institute, Department of Orthodontics, Tehran Uni- versity of Medical Sciences, Tehran, Iran ahmadakh@tums.ac.ir. Received: 15 March 2013 Accepted: 21 June 2013 Supreme XT (6.04± 2.01). Statistical analysis revealed a significant difference be- tween groups II and III (P < 0.05). No significant difference was found between groups I and III, and between groups I and II (P > 0.05). Evaluation of ARI showed that Transbond XT left fewer adhesive remains on teeth after debonding. Conclusion: Results of this study indicate that the aforementioned nano- composites can be successfully used for bonding orthodontic brackets