How does a dentist's own visibly poor smile undermine their credibility with patients? Severely, in the same way that a 100-pound overweight, three-pack-a-day, fifth-of-Jack physician giving healthy-living advice undermines their own credibility. Patients evaluate the believability of professional recommendations partly through whether the professional appears to follow their own advice. A dentist selling cosmetic work, comprehensive smile design, restoration of broken-down dentition, or any aesthetic improvement creates an immediate credibility gap if their own teeth visibly compromise the message. The patient sees the doctor's smile and forms a working hypothesis about why the doctor has not invested in their own dental [...]