Abstract: A toothbrush (10) includes a brush assembly (16) with at least three bristle arrangements (12), each having opposing inwardly-directed bristles (122, 124, 126) for simultaneously contacting facial and lingual surfaces (52, 54), and preferably also occlusal surfaces (56) of the teeth (50). Flexible linkages (14), interconnecting the bristle arrangements (12), maintain a relative spacing between the bristle arrangements (12) while allowing variation of an effective curvature of the brush assembly (16) such that the bristle arrangements (12) can ride along, and conform to a non-uniform curvature of, the arch of teeth. The toothbrush (IO) preferably also includes an actuation mechanism (22) for generating to-and-fro motion of the brush assembly (16) along the arch of teeth, most preferably combined with a more rapid small-amplitude oscillatory motion.