The vast majority of dental issues are caused by poor dietary choices. Couple those with a lack of proper cleaning by you, and not having regular dentist visits, and poor oral health isn't a surprise. I have had several teeth pulled because I was just too lazy to properly care for my teeth for many years. Now I am finally doing what I should have done all along - to include going to the dentist BEFORE there is pain or an issue.
My mother became ill during her pregnancy with my younger brother and I. We both have "tetracycline teeth" as a result. She did not have the illness issue while pregnant with my older brother and sister, and their teeth reflect it - their teeth are white as can be.
Not all dentists are crooks. Mine is a fine young man and he treats me like an intelligent human. He explains everything thoroughly and helps me make decisions based on cost, my age, expected quality of life impact, etc.
As someone who is in the last stage of my life, not taking proper care of my teeth when I was younger remains a big regret. Armed with that experience, my wife and I were relentless on our son with regards to his dental hygiene and care. He is now 35, has beautiful straight teeth and has had exactly zero fillings. His braces cost us $4,000 back in the day and they were well worth it. Straight teeth, properly gapped, are much easier to floss and clean...
It amazes me how I was able to justify in my brain that spending <$500 per year on my oral health was just not affordable, yet I have $20K in solar crap at a house where electricity costs $0.09 / KWH. Like many things in life, it comes down to choices and priorities. My son prioritizes his oral health. He has checkups and cleanings every 6 months. Even without insurance, it is less than $400 per year - a pittance to pay when you consider the return on the $$ invested.
FWIW - the Philips Sonic-Care toothbrush has been a life-changer for my wife and I. Because it cleans so well, and it has a timer that helps you to brush long enough to be effective, our oral health has been dramatically improved. I bought a two pack, with two chargers and travel cases, for $99 at Costco. We change the brush heads every 6 months. As a result of religiously using it, my dentist visits have gone from emergency, pain-filled events to just cleanings and checkups.