<p>Extracellular DNA (eDNA) is a major matrix component of many
bacterial biofilms. While the presence of eDNA and its role in biofilm
stability have been demonstrated for several laboratory biofilms of oral
bacteria, there is no data available on the presence and function of
eDNA in in vivo grown dental biofilms. This study aimed to determine
whether eDNA was part of the matrix in biofilms grown in situ in the
absence of sucrose and whether treatment with DNase dispersed biofilms
grown for 2.5, 5, 7.5, 16.5, or 24 h. Three hundred biofilms from 10
study participants were collected and treated with either DNase or
heat-inactivated DNase for 1 h. The bacterial biovolume was determined
with digital image analysis. Staining with TOTO®-1 allowed visualization
of eDNA both on bacterial cell surfaces and, with a cloud-like
appearance, in the intercellular space. DNase treatment strongly reduced
the amount of biofilm in very early stages of growth (up to 7.5 h), but
the treatment effect decreased with increasing biofilm age. This study
proves the involvement of eDNA in dental biofilm formation and its
importance for biofilm stability in the earliest stages. Further
research is required to uncover the interplay of eDNA and other matrix
components and to explore the therapeutic potential of DNase treatment
for biofilm control.</p