If you have sensitive teeth both nHAP and novamin toothpastes help a lot there. I've tried both. nHAP is easier to get in the USA, there are several brands, for some reason some go nuts over the imported ones from Japan.

If you're going to use nHAP, get Apaguard from Japan. Their nHAP is rod shaped, not jagged. They were the first to make rod shaped nHAP and have been doing it for decades. It's not a great idea to introduce cheap/jagged nHAP into your mouth. Sharp nanoparticles tend to cause cancer.