Seriously, consider switching to a water flosser. They're very thorough cleaners of both the bits between your teeth and the bacteria in the gum line. It has vastly improved my oral health and once a day is plenty. Initial price is higher as you would expect, but it's rare to replace any parts at all. The model I use is a basic Waterpik that I've had for about 8 years was $40 US when I got it. Think it now costs $60 (inflation sucks).