Aim: Aims of the study were to measure shear bond strength of different composite
types used in bonding fixed retainer. Subjects and methods: The sample of this study
consists of sixty extracted sound human premolar teeth that were divided into three
wire groups and three fiber-reinforced composite groups. In wire and fiber-reinforced
composite groups, one group is bonded with control conventional composite and
two groups bonded using different types of flowable composites. Each sample was
etched, bonded and then inserted into the universal testing machine. The resulted data
were collected and then analyzed to obtain the mean values of shear bond strength
of each sample. Results: In wire groups, the results demonstrated that the difference
between groups was statistically non-significant (p value>0.05) as indicated by one way
ANOVA. In FRC groups, the results demonstrated that the difference between groups
was statistically significant (p value>0.05) as indicated by one way ANOVA. There
was a statistically significant difference between conventional composite and Tetric-N
flowable composite when used, respectively. Conclusion: In all FRC groups the results
of shear bond strength were less than the results of wire groups. It was found that the
FRC weakens instead of strengthens the fiber/composite complex.