Hvordan ser den dentale biofilm ud ved caries, gingivitis og parodontitis? Hvornår bliver biofilmen patogen?

English summary What does dental biofilm look like in caries, gingivitis, and periodontitis? When does the biofilm become pathogenic? Nor Tannlegeforen Tid. 2025; 135: 18-21. The present review summarizes the contemporary knowledge on the healthy oral microbiome and on oral biofilms in caries, gingivitis, and periodontitis. In addition, the influence of the human host on the development of oral disease is highlighted. Oral health is maintained through a symbiotic relationship between the oral microbiome and the human host. Perturbations in the oral ecosystem, however, such as the frequent intake of dietary sugars or insufficient oral hygiene, may change the ecological conditions, induce local compositional changes of the oral microbiota and lead to diseases like dental caries, gingivitis, and periodontitis. Recent findings suggest that an individual’s disposition to the development of gingivitis and/or periodontitis is not a sole consequence of the mere amount of biofilm, nor of the abundance of specific putative pathogens. Rather, different clinically observed trajectories to gingivitis and periodontitis are influenced by the inflammatory response of the host to dental biofilm and associated virulence factors. Dental caries is caused by a gradual shift of the oral microbiota towards acid-producing and acid-tolerance species. Importantly, the extracellular polymeric matrix of dental biofilms contributes to the preservation of low pH and is thus an essential determinant of virulence in cariogenic biofilms.