Actinomyces naeslundii in initial dental biofilm formation

Abstract

The combined use of confocal laser scanning microscopy (CLSM) and fluorescentin situhybridization (FISH) offers new opportunities for analysis of the spatial relationships and temporal changes of specific members of the microbiota of intact dental biofilms. The purpose of this study was to analyse the patterns of colonization and population dynamics ofActinomyces naeslundiicompared to streptococci and other bacteria during the initial 48 h of biofilm formation in the oral cavity. Biofilms developed on standardized glass slabs mounted in intra-oral appliances worn by ten individuals for 6, 12, 24 and 48 h. The biofilms were subsequently labelled with probes againstA. naeslundii(ACT476), streptococci (STR405) or all bacteria (EUB338), and were analysed by CLSM. Labelled bacteria were quantified by stereological tools. The results showed a notable increase in the number of streptococci andA. naeslundiiover time, with a tendency towards a slower growth rate forA. naeslundiicompared with streptococci.A. naeslundiiwas located mainly in the inner part of the multilayered biofilm, indicating that it is one of the species that attaches directly to the acquired pellicle. The participation ofA. naeslundiiin the initial stages of dental biofilm formation may have important ecological consequences.