Bacterial accumulation on silicate and composite materials.

It was shown in a previous study that more plaque accumulates on composite filling materials than on silicate cement and amalgam. The purpose of the present investigation was to compare the accumulation of Streptococcus mutans on silicate cement and on composite material by scanning electron microscopy. Whether the adhesion was dependent on the presence of sucrose was also tested. Round disks, 6 mm in diameter, were made from the two materials. The disks were submerged in media with and without sucrose and inoculated with S. mutans OMZ 176. The disks were removed after 1 or 30 minutes, rinsed in saline and prepared for SEM. Along the diameter of each disk pictures were taken at similar intervals. From a total of 48 pictures from each material 18 pictures were selected at random and the number of microorganisms counted. The results indicated that bacteria initially adhered to both silicate and composite in about the same number. The presence of sucrose did not influence the initial adsorption. After 30 minutes bacteria were scarcely found on silicate, whereas large clumps of bacteria were attached to the composite. Sucrose increased bacterial accumulation on composites but did not affect the adherence to silicate cement.