Orale biofilm bliver patogene på grund af økologiske ændringer, som skyldes værtens kostvaner, mundhygiejne og immunrespons. Sådanne ændringer fører til dysbiose, hvor patogene bakterier dominerer og ødelægger det normale gensidige samspil mellem vært og mikrobiom. Cariogene biofilm fremmer vækst af syretolerante bakterier som mutansstreptokokker og laktobaciller. En forøget mængde supragingival biofilm nær tandkødsranden fører til gingivitis, men værtens immunrespons spiller en afgørende rolle i inflammationsforløbet. Den dysbiotiske tilstand kan progrediere til parodontitis, hvor parodontale pocher er hjemsted for komplekse mikrobielle miljøer. Antallet af anaerobe, proteolytiske bakterier stiger under indflydelse af inflammationen og tilførslen af næringssubstrater fra gingivalvæsken.

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.