The problem I think is that you have an uncomfortable relationship with your own sense of identity. I struggle with the same thing and believe many people that stutter do. That’s what I believe the reason is that many of us stutter on our name. I think when you use your own name, you unconsciously recognize your own existence. Which then forces you to recognize the way you feel in relationship to other people. Superior, inferior, lost, confused, etc. (some thought that makes you feel uncomfortable) This then shocks your system and causes a freeze response, thus stuttering. Then other words that start with the first letter of your name connect to your sense of identity like a chain leading into your unconscious, which you are uncomfortable with. This causes freeze responses (stuttering), and more repression of your emotions. I think you need to feel your emotions, know your identity, and feel and accept who you are. And for you it’s a double whammy, because your career choice also starts with a “D”, so you’re basically fighting against yourself and an extension of yourself at the same time. So you have to accept yourself as a dentist too, and feel yourself and accept yourself as being a dentist too. The d sound is just too emotionally charged for you. And then our dad is another emotionally charged word that starts with a d, so you gotta process that relationship if their is any issues there. This is a bit deep but I think it can be helpful.