Excellent dental hygiene and regular professional dental care will most benefit those who have some crappy predisposition to problems (which can include, but not limited to, bacterial flora and saliva composition). If you are one of the fortunate persons who don't have any predisposition to problems, you can get away with a lot of neglect or poor habits for many many years.
My neighbor's smile is so perfect its sickening. He's hispanic (Mexican) and has been to the dentist about six times his entire life. For most of his life, he had sub-par dental hygiene and care. Probably has one crown and three fillings, all told. The rest of his teeth are perfect.
Meanwhile, I had above average dental hygiene and professional care most of my life, even braces. My teeth are dingy looking (due likely to dental fluorosis or antibiotic discoloration) and falling apart. I even had them professionally whitened using the bleach and UV light thing and it made them worse. It barely lightened my teeth by two shades but it actually made my smile look worse because it did not change some discolored areas of my teeth, making them contrast or stand-out more. I've had over half-dozen root canals, crowns, and nearly every tooth in my head has a filling.
To add insult to injury, I had silent nocturnal acid reflux for a few years that dissolved all the enamel from my teeth. The dentist told me I literally have no enamel left, so my teeth aren't going to last another 10 years unless I drop $15,000 ~ $20,000 to have them all capped/crowned (I'm on disability and have no dental insurance). I already spent $5,000 cash out of my savings a few years ago to have two root canals with crowns, revision of an older crown, and a half-dozen fillings (plus the bleaching, which was a complete waste of $500).
Fuck it. I'll just have them all pulled and get implants or something. No sense spending that kind of money trying to polish a turd.
