Flowable Composite Cut Retainer Bonding Time 46% With No Added Failures

Edited by Orthotown staff

A flowable composite reduced chairside bonding time for mandibular fixed orthodontic retainers by 46% without increasing bond failures over six months, according to a randomized clinical trial published Aug. 24 in BMC Oral Health.

The trial allocated 56 patients to receive mandibular fixed retainers bonded with either GC Flowable or GC Gradia composite. Retainer failures were recorded at intervals of zero to one month, one to three months, and three to six months. Chairside bonding time was timed with a digital stopwatch.

No statistically significant difference in bond failure rates emerged between the two composites, either at the level of individual teeth or at the level of the retainer as a whole.

Investigators also collected bracket failure counts from each patient’s active treatment phase to test an exploratory question: whether some patients carry what the authors term a debond-prone phenotype that shows up in both bracket and retainer failures. The association did not reach significance, at a relative risk of 1.279 and P = .07. The authors wrote that larger studies are needed before any firm conclusion can be drawn.

Failure and bracket analyses were conducted per protocol on 52 patients, while the bonding time analysis followed intention to treat across all 56.

The authors concluded that the flowable composite delivered a clinically meaningful reduction in chairside time and is an acceptable alternative for bonding mandibular fixed retainers.

Arsalan Khorram, Aydin Sohrabi, and Mehdi Ravadgar conducted the trial, which was registered with the Iranian Registry of Clinical Trials in November 2023.

Follow-up ran six months, which covers the early retention period when bond failures cluster but says nothing about durability over the years a fixed retainer is expected to stay in place. The sample was also modest for detecting a difference in a relatively infrequent event.

Sources:
BMC Oral Health, “Flowable vs. conventional composite for mandibular fixed retainers: bond failure, chairside time, and association with bracket debonding — a 6-month randomized clinical trial,” published online Aug. 24, 2026: link.springer.com/10.1186/s12903-026-09667-8