The phrase "how can a dentist tell if you have given head" refers to the idea that certain dental procedures and observations can potentially indicate whether someone has engaged in oral sex. However, it's important to note that there is no scientific evidence to support this claim, and any such assertions should be approached with caution.
Claims that dentists can determine whether someone has performed oral sex are often based on anecdotal evidence or speculation. There is no reliable method for a dentist to make such a determination based solely on a dental examination.