Background and Aims: Orthodontic bracket failure during treatment is a common problem. With the introduction of low shrinkage composites the question is that whether: this sufficient has coefficient bond strength for bonding bracket during orthodontic treatment. The aim of this study was to compare the shear bond strength (SBS) of silorane-based and metacrylate-based composites to metal brackets.

  Materials and Methods: 30 human premolar teeth were collected and divided into 2 groups. In group 1, 15 orthodontic brackets were bonded using silorane-based composite, in group 2, 15 orthodontic brackets were bonded using metacrylate-based composite. The shear bond strength of each specimen was determined in an Instron machine. Amount of residual adhesive remaining on each tooth was evaluated using a stereomicroscope. Data were analyzed using T-test to compare the shear bond strength between groups and LSD method to compare the Adhesive Remnant Index (ARI) scores.

  Results: There was significant difference in the SBS between the test groups (P<0.001). The mean bond strength of bonding brackets to silorane-based composite was (42.42 ± 7.03) MPa, and the mean bond strength of bonding brackets metacrylate-based composite was (21.08±2.97 ) MPa. No significant difference in the ART was found between groups (P=0.66).

  Conclusion: Silorane-based composite provided higher bond strength to orthodontic metal brackets.