The efficacy and safety of a new sonic toothbrush were studied in this single-blind study. The sonic toothbrush combines acoustic vibrations and dynamic fluid activity surrounding the bristles with direct mechanical scrubbing of tooth surfaces. Fifty-one subjects were randomly assigned to either the sonic or the manual toothbrush. Plaque scores were assessed before and after a 2-minute brushing at baseline and 1, 2, and 4 weeks. Gingivitis and sulcular bleeding scores were also taken at each evaluation. To assess long-term safety, 29 subjects returned after 6 months of product use. Repeated measures analysis of variance of the total mean plaque score indicated a significant difference between the devices over time (P < 0.01), with the sonic toothbrush demonstrating a greater level of plaque removal on all tooth surfaces. On average, the plaque reduction from the baseline score for the sonic toothbrush was 3 times greater than the manual brush. However, when broken down by dental region, the sonic toothbrush demonstrated an improved level of plaque removal ranging from 1.5 to 11.9 times better than the manual brush, with the greatest improvement in the interproximal and lingual areas. Both the gingivitis and sulcular bleeding scores exhibited a similar, significant reduction (P < 0.005) over time for both devices with an approximate 17% decrease in the gingivitis index and a 33% decrease in sulcular bleeding sites. Safety assessment after 6 months of use indicated no soft tissue abnormalities which could be attributed to the products.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

The physical effects of low-frequency acoustic energy on Actinomyces viscosus were studied with electron microscopy to explore both acoustically induced damage to fimbriae on the surface of these bacteria and acoustic removal of bacteria from saliva-treated hydroxyapatite disks. A bacterial suspension was exposed to acoustic energy from a laboratory acoustic generator (50 kPa, 200 Hz) and from a new electronic toothbrush, the Sonicare. The exposed bacteria were examined with electron microscopy after negative staining. A decrease in both the percentage of bacterial surface covered with fimbriae and the fimbria length was observed after acoustic exposure. To study the acoustic effects on adherent bacteria, A. viscosus bound to hydroxyapatite disks were exposed to acoustic energy and examined with scanning electron microscopy. Quantitative evaluation of the micrographs for the number of bacteria present after exposure revealed that acoustic energy removed both bacteria adherent to the hydroxyapatite surface and adherent to each other. The results support the concept that an electronic toothbrush employing low-frequency acoustic energy may help prevent and control periodontal diseases by altering bacterial adherence.