Inside the brush head is a small microchip.
When the brush head is fitted to the brush handle, the chip is detected and the warning light will flash 3 times. This acts as confirmation that the handle has detected the head and that the electronics inside the handle will now keep track of it.
As you use the brush head, the handle continues to track how often it has been used.
The handle knows that the brush head should be replaced every 3 months, so once the handle detects that the brush head has been used for this amount of time, the ‘BrushSync’ LED on the brush handle will light up an amber/orange colour to tell you it is time to change the brush head.
But, the brush is cleverer still.
If it detects you have brushed 3 times a day every day or brushed with more pressure, it will activate the BrushSync alert system sooner, as the bristles will have worn out sooner than the typical 3 month time period.
By the same token, it will delay alerting you to replace the brush head. If you used that head just once a day over 3 months, it would not tell you to replace it until it had been used for the equivalent to 4 minutes a day for 3 months.
This is a very neat touch and shows how technology can be used in a positive way to better the nations oral health whilst also being cost effective (by not replacing brush heads too soon).