Volumetric Assessment of Oral Microcosm Biofilms Grown on Resin Composites

Objective:  To assess the volume of biofilm attached on composite materials of multi-species oral microcosms derived from children with a history of Early Childhood Caries. 

Method:  Plaque and saliva samples were collected from multiple pediatric patients (n=8).  After saliva coating (filtered sterilized) with matched donors, plaque microcosms were incubated on material circular coupons of Z100 and LS (3M ESPE) and hydroxyapatite.  The disks were placed in a CDC based biofilm reactor system for 72 hours with sucrose pulsing occurring 4 times daily.  After removal from reactor, biofilms were stained and incubated for 2 hours with FilmTracer SYPRO Ruby Biofilm Matrix Stain and FilmTracer Calcein Green Cell Viability Stain.  A confocal laser scanning microscope (Olympus FluoView 1000) was used to analyze the stained biofilms and to construct 3D images of each sample.  Average volume of each biofilm sample was then measured with custom software created in MATLAB. 

Result:  The biofilm reactor system produced thick biofilms that made simple volume assessment difficult.  A custom algorithm was constructed to interpolate the total biofilm volume on each material: Hydroxyapatite (.352 ± .0589mm³), LS (.376 ± .138mm³), and Z100 (.358 ± .108mm³).  There was considerable variation in biofilm volume between patients, but there was no significant difference in volume between materials within patients (Repeated-MeasuresANOVA).

Conclusion:  Our results suggest that, under the parameters of our system, the source of donor plaque may be a more important determinant of biofilm growth than the nature of the material. Future studies will run time series to determine if detectible differences in volume between materials occur earlier during the 72-hour incubation period.

Supported by NIH grant DE021366 and a UMSOD Summer Research Fellowship.