Effect of Sonic/Acoustic Energy on Gingival Fibroblasts

Objective: The acoustic energy produced by sonic toothbrushes damages bacterial cells and removes adherent biofilm (Oral Microbiol. Immunol. 8:277, 1993). The objective of the present study was to determine if such energy exerts similar effects on mammalian cells. Methods: Fibroblasts derived from the healthy gingiva of an 11 y.o. male were seeded into 60 mm collagen-coated petri dishes at 100K cells per dish and permitted to proliferate in medium containing 10% fetal bovine serum for 72 hr. Exposure to acoustic energy was then accomplished by inserting the tips of the bristles of a sonic toothbrush into the medium with the tips 3.0 mm from the fibroblast monolayer, and then running the brush in triplicate cultures for 5, 15, 30, 60 or 120 sec. Control cultures were not exposed to the acoustic energy challenge. All cultures were then harvested by trypsinization and counted (Coulter Counter). Results: The control cultures proliferated from 100K to 260K cells in 72 hr. Acoustically challenged cultures yielded cell counts as follows: 5 sec, 300K; 15 sec, 240K; 30 sec, 270K; 60 sec, 260K; 120 sec, 260K. Statistical analysis revealed that exposure to acoustic energy did not cause any significant reduction in cell numbers compared to control cultures, regardless of the length of exposure (P = 0.53 - 0.66). Conclusion: Acoustic energy from a sonic toothbrush did not cause detachment of fibroblasts from a collagen-coated substrate. This in vitro study provides evidence that the use of a sonic toothbrush, while damaging to dental plaque bacteria, is safe for mammalian oral tissue cells.