There is no evidence to suggest that dentists can tell if someone has performed oral sex. This is a common myth that has been perpetuated for many years, but there is no scientific basis for it. Dentists are trained to look for signs of oral health problems, such as cavities, gum disease, and oral cancer. They are not trained to look for signs of sexual activity.
There are a number of reasons why this myth is not true. First, the mouth is a very complex organ, and there are many different factors that can affect its appearance. These factors include genetics, diet, and oral hygiene habits. Second, there is no specific sign or symptom that is unique to oral sex. Third, dentists are not trained to look for signs of sexual activity, and they are not likely to notice anything unusual if someone has performed oral sex.