The aim of the study was to evaluate the efficacy of plaque removal of three different toothbrushes on mentally disabled children in two different age groups. A manual triple-headed brush (SuperBrush; Dento Co. AS [junior, regular]) compared with a new manual toothbrush (CrossAction; Oral-B [35 compact, 40 regular]) and an electric toothbrush with an oscillating rotating head (Braun Plaque Control 3D [Braun 3D]; Oral-B [D15525]). Fifteen children aged 6-12 (Group A) and 15 children aged 13-18 (Group B) with mild mental disabilities participated in the single-blind clinical study. To obtain a plaque-free condition at baseline, professional tooth-cleaning was performed on each participant. After instructions on how to use the toothbrushes, each group started the experiment. After 1 week of application, the Quikley Hein (QH) plaque index and the approximal plaque index (API) were used to assess the oral hygiene status of each participant. This was followed by a week of recess before each group switched to the next type of toothbrush. The study lasted for 5 weeks. Compared to the two other brushes, the Braun 3D was more effective in removing plaque (means of QHI: 1.54 (Braun 3D), 1.77 (SuperBrush), and 2.15 (CrossAction) in total; means of API 1.37 (Braun 3D), 1.52 (SuperBrush), 1.94 (CrossAction). The study indicated that the electric toothbrush is the most effective for removing dental plaque in mentally disabled children, whereas the SuperBrush is a good alternative.