I am 68 and preventing teeth and bone loss is very important to me. We all change from our ways of thinking when younger. I even think differently than I did five years ago, let alone fifty.
We become in effect, different people as we age. That’s just how it is, and we don’t believe it fully until we are old. So, what I say is from experience, not from research or a book. When young, you think it always happens to the ‘other guy’, and never to us.
I have learned there is a bacteria that causes tooth decay. So, you kill it with iodine . This is how I stop cavities besides eliminating sugar and refined carbs. There is also another way in that if you remove sugar it will starve.
Why not introduce Xylitol as a sweetener to your diet? To me, it’s the only sweetener that comes close to tasting exactly like white refined sugar. You might want to read this article on ‘remineralizing‘ your teeth 
Preventing tooth decay goes a bit further in that you must keep the pH higher in your mouth. In other words, a more alkaline diet is better than acidic. See lower pH foods, Approximate pH of Foods and Food Products.
And, as far as our bones go, it is important to get enough vitamin D. And, how I do it is not consume dairy, but make sure I sit outside in the sun and get my skin reddened. This is what causes the body to manufacture it.
‘Many of us nowadays are deficient in vitamin D. But in my opinion, the sun is our best source’
Also, what I have done is revamp my diet as far as sodium intake goes. For example, all the high salt snacks like chips are out. So are salted nuts like pistachios. Too high sodium intake will cause calcium loss from the bones, and why not from our teeth, too?
I don’t use a fluoride (fluoride is poisonous) toothpaste anymore, I use Tom’s® without it. It is also sweetened with Xylitol. I also floss my teeth often and brush after each meal. And, I especially water floss my teeth with a water and iodine, salt and baking soda mixture. All I can say is that what I’ve written in this post is working for me.
I have heard of ‘oil-pulling’. That’s where you swish either sesame or coconut oil in your mouth and spit it out after 10-20 minutes. Haven’t tried this, but you might want to. Don’t know if it works or not though.
‘Chemical demineralization of teeth is caused by acidic attack through two primary means: dietary acid consumed through food or drink and microbial attack from bacteria present in the mouth ’.
Source- 1 “Povidone-Iodine.” Wikipedia, Wikimedia Foundation, 3 July 2020, en.wikipedia.org/wiki/Povidone-iodine.
2 Lisa Bryant, ND, and wikiHow. “How to Remineralize Your Teeth: Can Natural Remedies Help?” WikiHow, WikiHow, 11 June 2020, www.wikihow.com/Remineralize-Your-Teeth-Naturally.
3 Abou Neel, Ensanya Ali, et al. “Demineralization-Remineralization Dynamics in Teeth and Bone.” International Journal of Nanomedicine, Dove Medical Press, 19 Sept. 2016, www.ncbi.nlm.nih.gov/pmc/articles/PMC5034904/.
Note- before you change your diet consult your medical doctor, and check with your dentist about your teeth first.