My family has been in Dentistry for four generations.....I am a dental hygienist and my father and both of my brothers are dentists. That being said, I do believe that most people don't truly understand dentistry and can think they are being ripped off when they are not.
We have what we call the hyundai plan, the cadillac plan and the rolls royce plan. We are well aware that not everyone can afford expensive dental work. Teeth are not like vital organs.....there is USUALLY more than one way to restore a tooth, whether that be with restorations (fillings), crowns, veneers, bonding, etc. The best way to permenantly restore a tooth that has been badly decayed IF it doesn't require a root canal is with a crown. However, the tooth CAN be restored with restorations but a tooth with a four surface restoration is more likely to break down later on in life whereas the crown is not likely to break down. So if one dentist says you need a crown and one says he can fix it with filling....they can both be right, but the crown will last you longer.
Also, I have seen some DISers complain that their dentist was a scumbag because he charged them two times for filling the same tooth. Well, a tooth has 5 surfaces (mesial, buccal, distal, lingual and occlusal) and it is possible for that tooth to have MORE than one cavity. If a tooth is decayed on the mesial and distal then the dentist will have to drill and prep and fill two separate surfaces........hence the charge twice. Insurance companies know this and pay accordingly.
Someone said that yearly visits to the dentist are self-serving for the dentist...oh please! Most people do NOT floss regularly and calculus builds up around the teeth next to the salivary glands. This build up of calculus can not be removed by the patient at home and will gradually migrate beneath the gum and help cause peridontal disease. Regular cleanings keep the gums healthy and the teeth calculus free.
Finally, we have to charge all patients the same price. Galahad is right that it is against the law to do otherwise....atleast in my state it is.