I have been wearing a night guard for about 8 years now. I cracked two teeth that needed root canals done because of it within a year of each other. The second time I went to the Endontist, he told me I can either keep coming back and paying him for the repair work or get myself a night guard. I didn't want to pay the high cost out of pocket since my dental insurance didn't cover the guards so I always bought the drugstore ones that you heat in water and then mold to your teeth. I would go through about 3 a year of those, but still less money. Last January, I started having major teeth pain that would radiate up into my jaw. I thought I had a tooth problem again and went to my new dentist. She checked me including x rays and could not find anything wrong with my teeth. She told me to contact my PCP to get a referral to a TMJ specialist. I was referred and they said yes, it is a grinding/clenching problem that is causing jaw pain. He told me the cheap ones from the drug store are not sufficient and since they were not molded correctly, my teeth were not lining up at night and I was putting too much pressure on my left side teeth when grinding and causing the jaw pain. They fitted me with a hard guard that sits on my bottom teeth (I always had one for the uppers before). The fitting took almost an hour to get it exactly correct so it would fix my problem. Even now, if I have a very stressful couple of days, I will start having some slight pain, nothing like before, but enough I know I am grinding a lot at night. They have given me muscle relaxers to take at night during those times to get me through until I am less stressed. They work, but I hate the side effects so use them very sparingly. The next step is a special type of guard that hooks to both my upper and lower teeth that will not allow my teeth to touch in my sleep. I really don't want to go that path, but not being able to eat anything but soft foods because my jaw/teeth hurt on one side is not a long term solution. The only good thing I can say is that because this is classified as a jaw issue for me and I see a TMJ specialist the guards are covered under my medical insurance instead of dental, so I pay nothing out of pocket for the guards or the muscle relaxers.
If your dentist is recommending it, I would absolutely get one. Even if you don't want to get the hard one from them at least get the drug store ones and see if those make a difference. They worked for me the first 7 years. Covid pushed me past my normal stress point and needed to upgrade. Last thing you want is thousands of dollars over the years in out of pocket dental work because of damage you are doing while grinding in your sleep.