Composition of the oral flora
The healthy periodontium is colonized predominantly with aerobic, Gram-positive “beneficial” bacteria. These form part of the normal local flora and help to maintain stable oral conditions. Anaerobic/facultatively anaerobic, Gram-negative periodontopathogenic bacteria are present even in individuals with a healthy periodontium, however, albeit in smaller numbers. These marker bacteria become a problem when their concentrations spiral upwards because of poor oral hygiene or declining immune competence.