This is something that I suspected for a long time. The Atlantic’s Farris Jabr is taking a look at how often do we need to see a dentist:
Among other problems, dentistry’s struggle to embrace scientific inquiry has left dentists with considerable latitude to advise unnecessary procedures—whether intentionally or not. The standard euphemism for this proclivity is overtreatment. Favored procedures, many of which are elaborate and steeply priced, include root canals, the application of crowns and veneers, teeth whitening and filing, deep cleaning, gum grafts, fillings for “microcavities”—incipient lesions that do not require immediate treatment—and superfluous restorations and replacements, such as swapping old metal fillings for modern resin ones. Whereas medicine has made progress in reckoning with at least some of its own tendencies toward excessive and misguided treatment, dentistry is lagging behind.