RESUMEN
Bacteria are the major etiologic factor of periodontitis, which exhibits inflammation and destruction of periodontal tissue. Aim of the periodontal treatment is elimination or reduction of periodontopathogens by means of mechanical instrumentation and oral hygiene instruction. Subgingival recolonization of periodontal pathogens was slowly occurred in a few months after mechanical treatment although well plaque control was performed. Local antimicrobial agents were introduced for periodontal therapy as an adjunctive treatment. It has low side effects to oral and non-oral sites and shows higher drug concentration in gingival crevicular fluid than those by systemic route. This review article included general principles to be considered of local drug use, type of drug, effect of oral environment on drug stability, relationship between concentration and contact duration, effect of biofilm on drug concentration, and local drug use in an initial therapy and after active phase of treatment. It will be information for dentist to use the local drug as an adjunctive treatment of periodontitis. Key Words: Periodontitis, antimicrobial agents, antibiotics, local drug use