For me just kinda depends how quickly the brush "wears out" so to say. Usually, I can use the brush through a tube of toothpaste and once I buy a new tube, I go ahead and buy a new brush as well. With the last toothbrush I just threw away, the bristles started getting really hard and stiff, even after wetting it so I knew it was time. It was just about the end of the toothpaste anyways so it happened to work out. |