Firstly I'd say that although there are 180 dental practices, there is only one patient, I think a study would need a lot more than that. I cannot read the arti

Firstly I'd say that although there are 180 dental practices, there is only one patient, I think a study would need a lot more than that. I cannot read the article but at how many practices did this person have x-rays taken? I doubt it was many if any. How did they get out of that, by bringing their own x-rays with them and saying that they were a recent set from their last dentist who'd retired? If they didn't have x-rays taken and didn't bring any with them then the dentist would be diagnosing blind to a large extent. In any case diagnosing cavities is not a binary true/false affair and x-rays can mislead also. There is a lot of human judgement involved. Some cavities never need filling, others can increase massively in size over a short period. Two questions that a dentist will typically ask a new patient are, how long since your last attendence at dentist and are you a regular attender or do you just go when you have problems? If a new patient is a regular attender, a dentist will be happier to keep a cavity they are unsure of, under observation. Sometimes they may schedule shorter recall periods for review until such time as they are comfortable that the patient does not have active decay. Generally a cavity does not need to be filled unless it extends into dentine. Determing if this is the case is not always straightforward. Generally a filling does not need to be replaced unless it is leaky. Again this is not always easy to determine and like programmers, dentists tend to be more critical of other dentists' output than their own. Recent experience also colours judgement. If a dentist has had a run of cavities that turned out to be deeper than expected then they are more likely to diagnose a cavity when unsure and vice versa. Different sub-populations in the aggregate, depending on wealth, diet, dental hygiene and typical frequency of attendence have different dental decay characteristics which can colour a dentist's judgement. There are crooked and incompetent dentists just like there are in every job. Dentists in general get a bad rap. One reason I've heard is the fear of dental treatment breeds an instinctive, subconscious dislike and mistrust of dentists as persons. Certainly doctors, despite being equally good at extracting money from their patients don't suffer from the same degree of antipathy and suspicion.