Can brackets be bonded with a composite resin after expiration date?

Introduction: The aim of the study was to compare shear bond strengths of brackets bonded with a composite resin before and after expiration dates. Methods: Forty-five freshly extracted premolar teeth were randomly divided into 3 groups of 15. Ormco Mini 2000 (Ormco Corp, Glendora, Calif) bicuspid metal brackets were used in the study. Group I: the brackets were bonded with Blugloo (Ormco Corp, Glendora, Calif) adhesive paste before the expiration date. Groups II and III: the brackets were bonded with same light cure composite resin 1 and 2 years after the expiration date. All of the groups were cured with a LED light. After bonding, the shear bond strengths of the brackets were tested with a universal testing machine. One-way ANOVA with post-hoc Tukey tests were used to compare shear bond strengths of the groups. The chi-square test was used to determine significant differences in the adhesive remnant index (ARI) scores between the groups. Significance for all statistical tests was predetermined at p<0.05. Results: No statistically significant difference was found in shear bond strengths and ARI scores between three groups (p<0.05). There was a greater frequency of ARI scores of 2 and 3 and 4 in all groups. Conclusions: Expiration dates do not have a significant effect on the shear bond strength of the composite material. Further studies are needed to investigate in other ways such as cytotoxicity of the composite resins after expiration date.