Diseases caused by oral bacteria

The chapter describes the characteristic and diverse collection of microorganisms that generally live in harmony with, and provide benefit to, the host by contributing to the normal development of the physiology and host defences of the oral cavity. The chapter then explains how this harmony can break down on occasions owing to changes in the local environment, which increases the competitiveness of previously minor components of the microbiota, thereby increasing the risk of dental caries and periodontal diseases. The chapter concludes by describing how many oral microbes are also opportunistic pathogens and can cause acute and chronic infection either within the mouth or at distant sites in the body.