Oral B Sonic Complete Toothbrush Heads

I have a toothbrush Oral-B Sonic Complete. I replace the brush head every 3 months. How often should I buy a new electric toothrbush?

The toothbrush can last for years. Keep changing the head every 3 months! :)

As long as the engine holds up, it will probably last long. The directions indicate that the brush head must be changed at least every three months