LOCAL-DELIVERY OF ANTIMICROBIAL AGENTS TO THE ORAL CAVITY

Bacterial infections in the mouth are caused mainly by the normal endogenous flora and are rarely of exogenous origins. The bacteria may play a primary aetiological role in disease or be secondary contaminators of disease caused by other pathogenic mechanisms. Antibacterial agents used topically are logical in the management of some of these infections and could be used for prevention or therapy. In both situations a variety of delivery methods has been proposed and can conveniently be classified according to duration of delivery as: short, medium and long-term. Most interest in antibacterial agents has been in the control of plaque-related diseases, particularly chronic gingivitis. Effective compounds show persistence of action for many hours, notably chlorhexidine. Chemical plaque control agents are of limited therapeutic value and are more valuable in the preventive mode. Such agents also are of no value in the treatment of chronic periodontitis unless delivered directly into pockets by irrigation or sustained-delivery vehicles. In fact, even by irrigation, antibacterials appear to offer limited action above that of a washing-out effect. Sustained delivery vehicles are relatively numerous, but it is the antibacterial rather than the vehicle which appears important. Most data are available for chlorhexidine, metronidazole and tetracycline, with again chlorhexidine appearing of little value in a therapeutic mode. Despite encouraging results for metronidazole and tetracycline, more data are required demonstrating lasting adjunctive benefits of local antibacterials to conventional mechanical treatments. Despite the logic behind the use of topical antibacterials for oral infections, many prescribed uses are somewhat empirical and more controlled studies are required.