The potential role of controlled-release delivery systems for chemotherapeutic agents in periodontics

Following advances in periodontal disease etiology and pathogenesis, treatment strategies have evolved to eliminate specific pathogens or suppress the destructive host response. Research indicates that chemotherapeutic agents such as antimicrobials and antimetabolites can alter disease progression; consequently, three delivery systems have been investigated: systemic, topical, and controlled release. Using polymers to control drug administration, controlled-release delivery systems theoretically produce concentration profiles that are more constant and longer lasting than those of other systems. Furthermore, patient compliance can be maximized, and systemic complications avoided. During the past two decades, numerous investigations have been conducted to evaluate the potential role of controlled delivery in periodontal treatment. These investigations fall into two distinct categories: those documenting release kinetics, and those documenting clinical effects. Accordingly, pharmacologic agents can be released from drug polymers at therapeutic levels within the periodontal pocket. Many researchers have demonstrated that controlled delivery of antimicrobial agents such as tetracycline, metronidazole, and chlorhexidine can be effective in reducing the signs of periodontitis. In addition, controlled release of antimicrobial agents can alter the periodontal flora with a decrease in total bacterial mass and pathogenic species. Although the majority of these studies are proof-of-principle trials, many agents have been evaluated with undefined hypotheses, ill-suited outcome variables, unrepresentative patient populations, poor controls, and less-than-ideal therapy applications. The true test of controlled delivery will be the demonstration of its slowing disease progression. While future research will concentrate on developing more ideal polymers and introducing new agents, controlled delivery offers clinicians a potential adjunct or alternative to traditional treatment modalities.