Antifungal and antiviral chemotherapy.

Fungal and viral infections are difficult to treat, since fungal infections commonly rebound after suppression by the antifungal agent and current antiviral drugs are only virustatic, allowing the virus to reassert its pathogenicity if not eliminated by the host defenses. In addition, fungal infections commonly are associated with significant biofilms, retarding drug penetration, and the fluid nature of the oral cavity does not promote drug-fungus contact for long periods of time. Both mycotic and viral pathogens are developing sophisticated methods to elude the toxic effects of drugs intended to eliminate their existence. The drug therapy of oral fungal and viral infections is therefore limited but occasionally successful (more with fungal than viral infections) and is often relegated to palliative care. The specter of drug resistance and its promotion by prolonged, repetitive and frivolous use must always be foremost in the clinician's mind.