A toothbrush comprising: a handle (110, 210) containing an electrically powered drive (112, 212) having a rotor (132, 276); abase (108, 208) connectable to said handle (110, 210); an elongate hollow shaft or shank (118, 218) connected to and continuous with said base (108, 208), said shaft or shank (118, 218) defining a longitudinal axis (142, 232) at a distal end; a brush head (120, 220) mounted to said shaft or shank (118, 218) at an end thereof opposite said base (108, 208), said brush head (120, 220) including a bristle holder (104, 204) movable relative to said shaft or shank (118, 218) and said base (108, 208); and a power transmission assembly (106, 206) operatively connectable to the drive (112, 212) and operatively connected to said bristle holder (104, 204), said power transmission assembly (106, 206) including a camming element (134, 268) configured to convert a rotary motion of said rotor (132, 276) into a motion of said bristle holder (104, 204), said camming element (134, 268) executing a motion that is eccentric relative to said axis (142, 232), said camming element (134, 268) being fixed relative to said rotor (132,276), wherein said power transmission assembly (106, 206) including said camming element (134, 268) causes bristle tips (114, 214) of said bristle holder (104, 204) to trace a generally oval path (116, 216) relative to said shaft or shank (118, 218) and said base (108, 208), characterized in that said oval path (116, 216) includes a first path segment (116a, 216a) towards a tooth surface, a second path segment (116b, 216b) along said tooth surface and away from a respective gum line, a third path segment (116c, 216c) away from said tooth surface, and a fourth path segment (116d, 216d) in a direction opposite said second path segment (116b, 216b) and spaced away from the tooth surface, further characterized in comprising a circuit for controlling the direction of movement of said bristle holders (104, 204), said circuit including: an orientation sensor in the form of a ball sensor or a gravity switch or accelerometer mounted in said handle (110, 210) or said base portion (108, 208) for detecting an orientation; a hard-wired logic circuit or microprocessor, each configured for determining toothbrush orientation in accordance with signals from said orientation sensor; and a motor drive circuit connected to said hard-wired logic circuit or microprocessor and said electrically powered drive (112, 212). a handle (110, 210) containing an electrically powered drive (112, 212) having a rotor (132, 276); abase (108, 208) connectable to said handle (110, 210); an elongate hollow shaft or shank (118, 218) connected to and continuous with said base (108, 208), said shaft or shank (118, 218) defining a longitudinal axis (142, 232) at a distal end; a brush head (120, 220) mounted to said shaft or shank (118, 218) at an end thereof opposite said base (108, 208), said brush head (120, 220) including a bristle holder (104, 204) movable relative to said shaft or shank (118, 218) and said base (108, 208); and a power transmission assembly (106, 206) operatively connectable to the drive (112, 212) and operatively connected to said bristle holder (104, 204), said power transmission assembly (106, 206) including a camming element (134, 268) configured to convert a rotary motion of said rotor (132, 276) into a motion of said bristle holder (104, 204), said camming element (134, 268) executing a motion that is eccentric relative to said axis (142, 232), said camming element (134, 268) being fixed relative to said rotor (132,276), wherein said power transmission assembly (106, 206) including said camming element (134, 268) causes bristle tips (114, 214) of said bristle holder (104, 204) to trace a generally oval path (116, 216) relative to said shaft or shank (118, 218) and said base (108, 208), characterized in that said oval path (116, 216) includes a first path segment (116a, 216a) towards a tooth surface, a second path segment (116b, 216b) along said tooth surface and away from a respective gum line, a third path segment (116c, 216c) away from said tooth surface, and a fourth path segment (116d, 216d) in a direction opposite said second path segment (116b, 216b) and spaced away from the tooth surface, further characterized in comprising a circuit for controlling the direction of movement of said bristle holders (104, 204), said circuit including: an orientation sensor in the form of a ball sensor or a gravity switch or accelerometer mounted in said handle (110, 210) or said base portion (108, 208) for detecting an orientation; a hard-wired logic circuit or microprocessor, each configured for determining toothbrush orientation in accordance with signals from said orientation sensor; and a motor drive circuit connected to said hard-wired logic circuit or microprocessor and said electrically powered drive (112, 212). an orientation sensor in the form of a ball sensor or a gravity switch or accelerometer mounted in said handle (110, 210) or said base portion (108, 208) for detecting an orientation; a hard-wired logic circuit or microprocessor, each configured for determining toothbrush orientation in accordance with signals from said orientation sensor; and a motor drive circuit connected to said hard-wired logic circuit or microprocessor and said electrically powered drive (112, 212).