Oh one more thing to relay. I avoided buying a new head for my toothbrush for like nearly a year and a half and i had a hard to fix cavity way back on a molar. And I noticed it took longer to clean that time. And I was like, “Shit, maybe I should stop cheaping out and get a new head.” My frequency hadn’t changed nor my habits, but the brush was looking used.
When I did, it certainly felt different and my hygienist said they do wear out. And the next visit was one of my fastest ever as far as cleaning goes. So now I try to do every 6 mo or so.