Comparison of Bond Failure Rates of Mandibular Canine-to-Canine Fixed Retainers Bonded with GC Flowable and GC Gradia in Orthodontic Patients: A Randomized Clinical Trial and Its Correlation with Bracket Bond Failure

Abstract

Background and Objective: Maintaining the stability of orthodontic treatment outcomes is a major challenge in this field. Fixed retainers are used to preserve treatment results without requiring patient compliance. Flowable composites have become a popular choice for bonding fixed retainers due to their ease of use and lower technique sensitivity. This study evaluated the six-month bond failure rate of mandibular fixed retainers bonded with two types of composites, GC Flowable and GC Gradia, and assessed the association between retainer bond failure and bracket failure during active orthodontic treatment. Materials and Methods: In this randomized clinical trial, 56 patients (336 teeth) were randomly assigned to two equal groups. Stainless Steel Multi-Stranded Retainers were bonded using either GC Ortho Connect Flow or GC Gradia Direct Anterior composite. All bonding procedures were performed in a standardized manner by a single orthodontist. Bond failure was assessed at follow-up visits at 1, 3, and 6 months. Results: No statistically significant difference in retainer bond failure rates was found between the two composites across different time intervals. However, in patients who had more than one bracket failure during orthodontic treatment, retainers bonded with GC Gradia showed a higher failure rate, whereas no significant association was observed with GC Flowable. Additionally, the working time for GC Flowable was, on average, 2.6 minutes shorter than for GC Gradia. Conclusion: Due to its lower technique sensitivity, shorter working time, and lack of association with bracket failure, GC Flowable composite appears to be a suitable choice for bonding fixed mandibular retainers, especially in patients with a high bracket failure rate.