What is biofilm? An updated evidence base

What is biofilm? An updated evidence base

The first in a series of three, this article considers the basics of biofilm, taking the reader on an evidence-based journey.

‘The oral microbiome is diverse and exists as multi-species microbial communities on oral surfaces in structurally and functionally organised biofilms’, wrote Marsh and colleagues (2017).

Adding to the picture, they continued: ‘The microorganisms found within these oral biofilms live in close proximity with one another, which results in a wide range of potential interactions, which can be synergistic or antagonistic.

‘The composition of the microbiome is influenced by the oral environment, and changes in local conditions can affect the microbial interactions within these oral communities and determine, in part, whether the relationship between the oral microbiome and the host is symbiotic or potentially damaging (dysbiotic), thereby increasing the risk of diseases such as caries or periodontal diseases.’

Symbiosis and dysbiosis

Looking at the need for balance in the biofilm for health, Sanz and colleagues (2017) stated: ‘A health-associated biofilm is associated with an active balance between slow rates of acid production and compensatory alkali generation, resulting in an environment with a broadly neutral pH.

Such conditions help to stabilise the composition of health-associated species while restricting the growth of microorganisms associated with caries and periodontal diseases.

Microbes in a health-associated biofilm can produce substances including H2O2 [hydrogen peroxide] and also bacteriocins that may suppress the growth of microorganisms associated with disease.’

 Thus, evidence indicates that the oral cavity may shift from health to disease as a result of dysbiosis of the oral microbiome, resulting in the structure of microbial biofilms going through significant changes.

Exploring this issue further, Simon-Soro and colleagues (2017) have suggested that there are three ‘irrefutable’ principles in relation to biofilm and periodontal disease: 

  1. Community change – this represents the idea that microbial communities change in patients diagnosed with periodontal disease, when evaluated against the organisms normally found in healthy individuals
  2. Microbial complexes – supports the concept that different microorganisms group together, and have been consistently detected doing so in studies of microbial populations. These co-associations appear to work together for microbes’ mutual benefit
  3. Commensal involvement – involving such organisms being commensal and associated with health, so that, for instance: ‘The absolute requirement of the commensal microbiome in order for P. gingivalis to induce periodontal disease in the murine model underscores the functional importance of the microbial community associated with health to the progress of disease.’

Reducing pathogenicity

Although this will be explored in more detail in parts two and three of this series of articles, for now, in terms of practical steps that may be taken to help reduce the possibility of biofilm dysbiosis, Gurenlian (2007) suggests: ‘Although dental biofilm cannot be completely eliminated, its pathogenicity can be lessened through effective oral hygiene measures.

‘Daily toothbrushing, interdental cleaning, and the use of topical antimicrobial chemotherapeutics are patient-based strategies to reduce the bacterial biofilm and to help prevent periodontal diseases.’

For further information, visit listerineprofessional.co.uk.


Marsh PD et al. Dental biofilm: ecological interactions in health and disease. J Clin Periodontol 2017; 44 (Suppl. 18): S12-S22

Sanz M et al. Role of microbial biofilms in the maintenance of oral health and in the development of dental caries and periodontal diseases. Consensus report of group 1 of the Joint EFP/ORCA workshop on the boundaries between caries and periodontal disease. J Clin Periodontol 2017; 44 (Suppl. 18): S5-S11

Kilian M et al. The oral microbiome – an update for oral healthcare professionals. BDJ 2016; 221(10): 657-666

Simon-Soro MA et al. Role of microbial communities in the pathogenesis of periodontal diseases and caries. J Clin Periodontol 2017; 44 (Suppl.18): S23-S38; doi: 10.1111/jcpe.12671

Gurenlian JR. The role of dental plaque biofilm in oral health. Journal of Dental Hygiene 2007; 81(5): 116.

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