How do I know when to replace my brush head on the Next-Generation DiamondClean 8000 - 9900?

When you attach a genuine Sonicare smart brush head to your Sonicare toothbrush for the first time, the display will indicate the number of remaining brushing sessions, which is 180, until a brush head replacement is recommended. The "Replace Brush Head -1" message appears when the number of brush head sessions remaining drops below 0. This message reminds the user to change the brush head.

Note: Replace Sonicare brush heads every 3 months to achieve optimal results. Use only Philips Sonicare replacement brush heads.