Effect of sonic and mechanical toothbrushes on subgingival microbial flora: A comparative in vivo scanning electron microscopy study of 8 subjects

Objectives: The purpose of this initial study was to evaluate the effects o f both a sonic and a mechanical toothbrush versus the effects of no treatme nt on depth of subgingival penetration of epithelial and tooth-associated b acteria. Method and materials: Eight adult subjects exhibiting advanced chr onic periodontitis with at least 3 single-rooted teeth that were in separat e sextants with facial pockets greater than or equal to 4 mm and less than or equal to 8 mm and that required extraction constituted the experimental sample. Teeth were either subjected to 15 seconds of brushing with a mechan ical toothbrush or a sonic toothbrush or left untreated. The test tooth and the associated soft tissue wall of the periodontal pocket were removed as a single unit. Samples were processed and coded for blind examination by sc anning electron microscopy. Distributional and morphologic characteristics of dominant bacteria with specific emphasis on spirochetes were evaluated f or both epithelial- and tooth-associated plaque. Results: No differences we re found in morphotypes or distributional and aggregational characteristics of epithelial-associated microbes in the 1- to 3-mm subgingival zone betwe en the mechanical and sonic toothbrush-treated groups and the control group . Both toothbrush groups featured disruption of microbes that extended up t o 1 mm subgingivally. Root surfaces on the sonic-treated samples appeared p laque-free at low magnification; however, at 4,700x, a thin layer of mixed morphotypes and intact spirochetes was found supragingivally and slightly s ubgingivally, In comparison, mechanical brush samples featured incompletely removed plaque, both supragingivally and subgingivally, with intact spiroc hetes present on subgingival root surfaces. Conclusion: Results suggest sim ilar effects for both sonic and mechanical toothbrushes on epithelial- and tooth-associated bacterial plaque in periodontal pockets and adjacent root surfaces that extend up to 1 mm subgingivally. Further, the presence of int act subgingival spirochetes suggests limited exposure to acoustical or mech anical energy from the toothbrushes evaluated.