Reduction in adherence of Actinomyces viscosus after exposure to low-frequency acoustic energy

The ability of low-frequency (200 Hz) acoustic energy to reduce the adherence of Actinomyces viscosus T14V to saliva-treated hydroxyapatite (SHA) disks was studied. An acoustic pressure range between 0 and 65 kPa and exposure durations between 0 and 8 min were used to study the levels necessary to significantly alter adherence. The effects of acoustic exposure on both bacteria in liquid and bacteria already adhering to SHA disks were studied. A modified enzyme-linked immunosorbent assay was used to assess bacterial adherence. For bacterial suspensions exposed prior to addition to SHA disks, it was found that reductions in adherence were greater for lower bacterial concentrations. Exposure of bacteria already adhering to SHA disks resulted in a decrease in adherence that was independent of the bacterial concentration and linearly related to the logarithm of the exposure duration. In addition to affecting adherence, acoustic energy also dispersed bacterial aggregates. Our results support the concept that low-frequency sonic energy applied orally may be of therapeutic value in reducing adherence and colonization of teeth by plaque bacteria.