Controlled-release local delivery antimicrobials in periodontics: prospects for the future.

New knowledge about the microbial etiology of periodontal diseases emerged in the 1970s and 1980s and led to widespread interest in the use of antimicrobial agents to treat periodontitis. The controlled-release delivery of antimicrobials directly into the periodontal pocket has received great interest and appears to hold some promise in periodontal therapy. Some techniques for applying antimicrobials subgingivally, such as subgingival irrigation, involve local delivery but not controlled-release. Controlled-release local delivery systems, in which the antimicrobial is available at therapeutic levels for several days, have been evaluated in several forms and using different antimicrobials. Although most studies with such systems have focused on drug delivery kinetics and "proof of principle" evaluations, some controlled clinical trials have recently been reported. The most widely tested system, monolithic tetracycline-containing fibers, has shown significant clinical benefit when used alone as compared to no subgingival therapy. Similarly, controlled trials involving chlorhexidine strips used subgingivally every 3 months in place of routine supportive periodontal therapy have shown significant clinical benefit for up to 2 years. Although these data are now emerging, many questions concerning the optimal use and role of this therapy in clinical practice remain. This review attempts to summarize and interpret current data and to outline key remaining questions that must be addressed as this technology is transferred into clinical practice.