Evaluation of a "Flash-free" Adhesive Resin for Orthodontic Bracket Bonding

Use of a "Flash-free" Adhesive Resin for Orthodontic Bracket Bonding: a Clinical Study of Bonding Time, Bond Survival, and Adhesive Remnant Cleanup

The purpose of this study is to compare bonding time, bond survival, amount of adhesive remaining on the tooth surface after bracket debonding, and time required for adhesive remnant cleanup between a new "flash-free" and a conventional adhesive resin for orthodontic bracket bonding.

Patients presenting for comprehensive orthodontic treatment with fixed appliances at the University of Minnesota, who are willing to participate, will be included in the initial study. Selection criteria will include full permanent dentition through the first molars, teeth with sound, non-carious buccal enamel and no pretreatment with chemical agents such as hydrogen peroxide, and no previous orthodontic treatment with fixed appliances. The patients will have their maxillary incisors, canines, and premolars bonded with ceramic orthodontic brackets pre-coated with a "flash-free" adhesive resin (Clarity Advanced Brackets APC flash-free, 3M Unitek, Monrovia, CA, USA) on one side and a conventional adhesive resin (Clarity Advanced Brackets APC II, 3M Unitek) on the other side. The side allocation and order of bonding will be randomized for each patient.

The time taken to bond each tooth was timed to the nearest second using a digital stopwatch. Timing was started after enamel surface preparation and stopped before light curing. Outcome reported in seconds.

Bond failure (yes or no) was recorded at standardized appointments at intervals of 4 weeks. Outcome is reported as the cumulative number of failed bracket bonds across all participants at 1 year post-treatment.

In case of a bond failure, the adhesive remnant index (ARI) was scored. The ARI is a point-based system ranking: 0, no adhesive left on the tooth; 1, less than half of the adhesive left on the tooth; 2, more than half of the adhesive left on the tooth; and 3, all adhesive left on the tooth.

If adhesive remained after bracket de-bonding, then the time required to remove the remnant adhesive was measured using a digital stop-watch. Outcome is reported in seconds.

Inclusion Criteria: Full permanent dentition including incisors, canines, premolars, and first molars Teeth with sound, non-carious buccal enamel and no pretreatment with chemical agents such as hydrogen peroxide No previous orthodontic treatment with fixed appliances Exclusion Criteria: Mental/emotional/developmental disability Cleft lip and/or palate, craniofacial anomaly, or syndrome Obvious oral hygiene issues such as excessive plaque accumulation, gingivitis, and/or pre-existing white spot lesions Prosthodontic or restored substrate extending on the labial surface of maxillary teeth Known allergies to any acrylates contained in the study materials

Grunheid T, Larson BE. Comparative assessment of bonding time and 1-year bracket survival using flash-free and conventional adhesives for orthodontic bracket bonding: A split-mouth randomized controlled clinical trial. Am J Orthod Dentofacial Orthop. 2018 Nov;154(5):621-628. doi: 10.1016/j.ajodo.2018.05.012.

Grunheid T, Larson BE. A comparative assessment of bracket survival and adhesive removal time using flash-free or conventional adhesive for orthodontic bracket bonding: A split-mouth randomized controlled clinical trial. Angle Orthod. 2019 Mar;89(2):299-305. doi: 10.2319/030918-195.1. Epub 2018 Sep 19.