An interdental treatment device, such as a toothbrush, includes a handle configured to accommodate an electric power source, a head carrying an interdental treatment tool, and a neck between the handle and the head. The head or neck includes a mechanical motorized vibratory device, including a drive which causes the head to vibrate. Electrical connections are operably connected to the mechanical vibratory device and the electric power source to power the mechanical vibratory device via the electrical connections. In various embodiments, a switch may be operably connected to at least one of the electrical connections to interrupt power from the power source to the mechanical motorized vibratory device. In various embodiments, a vibration-damping structure dampens vibration transmission from the head to the handle.