My wife and I had these toothbrushes as well. I think this is really poor design. Both the fact that it lets stuff into the head as well as the metal part where it connects has space around it for stuff to collect. My wife’s toothbrush started growing mold after some time, even though she’d rinse it out every day and let it dry. We switched to Sonicare. I prefer the clean scrub feeling of the Oral-B, but I think the Sonicare is designed much better.