Arestin treatment is an FDA-approved, locally applied antibiotic designed to fight gum disease. Its active ingredient is minocycline, a type of antibiotic that has been proven effective against the bacteria responsible for periodontal infections. What makes Arestin unique is its delivery system. The antibiotic comes in the form of tiny bead-like particles called microspheres. These microspheres are so small that they can be placed directly into the infected gum pockets that form around teeth affected by periodontal disease.