It’s really not fair to take an example of one unethical dentist and sell the story as “the truth about dentistry”.
However, the article does have this:
Studies that explicitly focus on overtreatment in dentistry are rare, but a recent field experiment provides some clues about its pervasiveness. A team of researchers at ETH Zurich, a Swiss university, asked a volunteer patient with three tiny, shallow cavities to visit 180 randomly selected dentists in Zurich. The Swiss Dental Guidelines state that such minor cavities do not require fillings; rather, the dentist should monitor the decay and encourage the patient to brush regularly, which can reverse the damage. Despite this, 50 of the 180 dentists suggested unnecessary treatment. Their recommendations were incongruous: Collectively, the overzealous dentists singled out 13 different teeth for drilling; each advised one to six fillings. Similarly, in an investigation for Reader’s Digest, the writer William Ecenbarger visited 50 dentists in 28 states in the U.S. and received prescriptions ranging from a single crown to a full-mouth reconstruction, with the price tag starting at about $500 and going up to nearly $30,000.
If you’ll permit me to grossly oversimplify, I feel like dentists are to medicine what software developers are to engineering.
Both professions tend to play faster and looser with rules and standards, and tend to be closer to trade careers than most of their superset.
I've always felt it was a little bit science and a little bit art. I don't think there's an exact set of steps to every tooth and it's problem. There's just too many variables, so they have to figure it out as they go.
Two dentists in the same clinic might not do it the same way. Problem wise, two identical repairs might wear differently, causing one to last a lifetime, but another to fall out in a couple of years. A mouth gets a lot of use.
I am, however, lucky enough that my dentist will see two paths, and offer the less expensive option with a "wait and see" disclaimer. I've had no problems with those repairs, where I'm positive some others would have immediately escalated from the filling to a root canal, filling, crown, etc path.