I just went back to the dentist two days ago, for a 6 month recheck and cleaning. I had gone years without seeing a dentist and I think I was having temperature sensitivity - that's what inspired me to go in the spring.
At my first visit, they were telling me about too deep pockets in my gums (I don't remember the numbers, but maybe 3 and 4 mm) and mostly exclaiming that my enamel was quite worn and did I maybe grind my teeth? They wanted to make sure I wasn't using a toothpaste with clay or other polishing substances that might be wearing away at my tooth enamel.
I'm not sure if I 'fessed up to brushing my teeth with hydrogen peroxide. I've been doing it for decades, eventually locating and buying food-grade H2O2 that I dilute 10:1 with distilled water. Over the years I'd moved from using just drops of it to swigging maybe half an ounce and swishing that around before brushing. It makes my teeth *so* smooth and slippery, and really blocks tartar formation.
After that visit, I did some more research on H2O2 and teeth and this time I found evidence that H2O2 damages tooth enamel. (I'd looked for information probably 20 years ago, but it was harder to find in those days.) I couldn't stop using it, my teeth feel gross in the morning if I don't, but I backed off to less than 1mL again, which honestly is plenty to make a nice foam and clean my teeth. I'm using a baking soda tooth powder, also sprinkled on the toothbrush bristles.
Well, at my return visit, I got no lecturing about my tooth enamel being dangerously thin and they didn't ask if I grind my teeth. The hygienist went all through my mouth measuring the depth of my gums, and it was lots of 2-1-2 instead of higher numbers. She did say I need to pay more attention to the back side of my upper incisors.
One thing they recommended at my first visit to use in lieu of flossing was these plastic scrubby toothpicks. (GUM soft-picks, they are white and green.) I hesitate to mention them as they're not very "permie," but I think they were an important part of the changes I made. In my defense, I think the package I bought will last me possibly the rest of my life as I'm not throwing them away after one use, I'm using more like one a week. I now have the original sample (in a little paper envelope) the dentist gave me in my purse, very convenient for when I feel like there's something stuck in my teeth and I'm out and about!
Anyway, hydrogen peroxide is like magic in terms of knocking back bacteria, but it is strong, and damaging to tooth enamel over time, so go easy on the quantities. (Oh, and I do NOT recommend using it on wounds, unless your fear of infection outweighs any concerns about scarring. Hydrogen peroxide kills everything, including healthy skin cells.)