My dentist recommended that I purchase a Philips Sonicare toothbrush last year. You can see the difference this has made to my teeth and gums and my dentist was very impressed with the results at my last dental checkup. As you receive only one toothbrush head with the toothbrush I needed to order a replacement. Buying the 3-pack is a really good deal. You can set up an automatic reorder which is delivered to your door every 6 months if you wish without having to reorder. The price is obviously cheaper by doing this. The brush heads need replacing approximately every 3 months, but if you are like me and can't remember when you last changed it, the dark blue bristles at the top of the head turn white. I would definately recommend this product.