The concept of dental plaque has evolved to become oral biofilm: groups of bacteria in matrices that bind to surfaces. This is a key factor.
Bacterial diversity and interactions
Some 700 bacterial species can colonise the oral cavity, of which 400 can be found in subgingival biofilms
Association between biofilm and infection
Diseases that have proven to be directly associated with biofilm-related infections include caries, gingivitis and periodontitis.
Periodontal disease and systemic diseases
There is evidence that show the relationship between the periodontal disease and certain systemic conditions.