A preliminary study on isolation and enumeration of mycoplasmas in dental plaques: the effect of sonication on viability of oral mycoplasmas.

The effect of sonication on the viability of Mycoplasma salivarium and Mycoplasma orale was examined as a preliminary investigation on the quantitative studies on mycoplasmas in the dental plaques. Mycoplasma cell aggregations suspended in PBS or liquid medium were sonicated and the samples were removed at 5-second intervals for 20 seconds to check the viable counts. Inactivation of the mycoplasmas was almost directly proportional to the sonication time. M. orale was more sensitive to sonication than M. salivarium. Mycoplasmas were damaged more readily in PBS than in the liquid medium. Dental plaques suspended in PBS were also sonicated exactly as mentioned above. The number of mycoplasmas in the dental plaques (1 mg) ranged from 1.09 x 10(2) to 1.75 x 10(5) cfu. The desirable sonication time to prepare the homogeneous suspensions of dental plaques was concluded to be 5 seconds.