Plaque removal characteristics of electric toothbrushes using an in vitro plaque model

The purpose of the study was to investigate and quantify the efficacy of plaque removal by commercially available electric toothbrushes using an in vitro system based on artificial plaque grown on glass slides.

Artificial plaque based on Streptococcus sanguis and Streptococcus mutans was cultured in a series of phosphate buffer solution, sucrose solution and brain heart infusion on sterile glass slides, for a period of 5 weeks. 7 different electric toothbrushes of current designs were operated in contact with the glass slides under loads of 1 or 2N for 10 s after which image analysis of the brushed slides was undertaken to calculate the absolute and relative areas of removal.

The electric toothbrushes showed a larger area of plaque removal as loading force increased from 1 to 2N. The area of biofilm removed also depended on the head design and ranged from 258 mm(2) (1N, Interplak) and 314 mm(2) (2N, Interplak), to 30 mm(2) (1N, Braun 3D), and 148 mm(2) (2N, Blend-a-Dent). The area of biofilm removal was significantly different among all electric toothbrushes at p<0.01 (ANOVA). All electric toothbrushes removed more biofilm than the actual contacting tufted area of the head.

The artificial plaque model system under different loading conditions showed differences in the absolute area of removal per electric toothbrush and also differences in the relative removal per unit contact bristle area. These differences on operating variables should be considered when evaluating new electric toothbrushes.