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Introduction The aim of this in vitro study was to determine whether there is a significant difference in the excess adhesive flash between the metallic APC™ Flash-Free adhesive system, the APC™ pre-coated adhesive system, and a conventional uncoated system. Materials and methods One-hundred-and-eighty-six freshly extracted human premolars were randomly and blindly divided into three groups according to the type of brackets: group A (control group, n=60) used the conventional uncoated metallic bracket (Victory, 3M Unitek®) with a Transbond XT™ Light Cure Adhesive Paste; group B (n=60) used the APC™ II metallic maxillary precoated premolar brackets; and group C (n=66) used the metallic APC™ Flash-Free adhesive system without flash clean-up. Images were taken at 40 magnifications using a dental microscope (Leica M320 for dental, Wetzlar, Germany) then analyzed using ImageJ software, with the area of excess adhesive flash measured. Results The mean percentage was significantly different between the three groups (p<0.001; ANOVA). It was significantly smaller for brackets in the APC Flash-Free group (p<0.001), and the difference was not significant between conventional brackets and APC (p=0.224). DiscussionThe new technique seems to reduce the amount of excessive adhesive around orthodontic brackets.