I haven't posted much, but as an "experienced" dental patient I figure I'll throw in my two cents. Thanks to one incident in high school in which I broke my jaw and damaged my front teeth, I've gotten a lot experience at the dentist's office. That incident required oral surgery for my jaw, gluing my chipped front tooth back together, and eventually three root canals. Additionally, my dentists have said I'll likely need crowns at some point on the teeth with the root canals since they are "dead" and will likely start to decay or lose color.
All of my experiences with my various dentists and specialists have been phenomenal, however. And I think that is because all of them were focused on protecting and preserving my existing teeth instead of trying to do as much work on my mouth as they can. They had a philosophy that nothing can truly replace your real teeth and function as normally as your real teeth. They've taken a very cautious approach and I've always felt that they're working in my best interest.
It's too bad that there are dentists out there just looking to make a quick buck off of people...I wish there was more integrity in this world.
My word of advice would be to find a dentist you trust and one that wants to monitor for any potential issues rather than "fix" any little problem they might find.