My father in law was on a hospital board for many years. He said that it was common practice to charge high prices for...say aspirin. This was so that they could recoup losses from other procedures, say a MRI, that the insurance companies would not pay the actual cost of the service provided.
This is an unending cat and mouse game between insurers and medical and dental providers. Really this applies to EVERY insurance covered loss. Those making the insurance claim, try to find and stay at the ceiling of what an insurance company will pay, on a claim. Insurance companies make decisions on how much they will pay for claims. When you think about it, it is not worth an insurance company's time and effort to push back on the price of small items.
Some years ago, I was getting a crown on one of my molars. My dentist told me directly, he was going to price it aggressively, to determine what my insurance would cover. From his business perspective, not charging the maximum an insurance company would pay, is leaving money on the table.
The only real losers are... the person paying the premiums. As I posted earlier, insurance companies have an never ending option, to assure they are profitable.