With an electric toothbrush with extra brush attachments, you get a supply of brush attachments in addition to your toothbrush. That way, you don't have to think about this for a while. After 3 months, the brush attachment needs to be replaced. It's important to replace them in time, so you can keep brushing thoroughly. Get an Oral-B toothbrush with enough brush attachments for a year, for example. There are also Philips bundles with extra Philips Sonicare brush attachments.