if you're mid-30s you probably had an extra enamel coating applied to your teeth at some point that may be doing some pretty awesome work protecting your molars
why would someone in their mid 30s "probably had an extra enamel coating applied"? I've never heard of that. Of course, they give you “super fluoride” when you go in for cleanings, but that's not an extra coat of enamel. I'm pretty sure there is not such technique, when your adult teeth reach their full size that's pretty much all the enamel they'll ever have, dentists can't just apply another layer or we'd all be cavity free.
it's usually called a dental sealant and yes I did have that when my adult teeth came in. it's all chipped off by now but we'll see the next 10 years I guess.
my childhood dentist said at 18 that if I just regularly take care of my teeth I shouldn't have any issues the rest of my life.