I heard someplace that he never had his overbite/bucktooth condition corrected because he thought it would affect the character of his vocalization.He thought it would end his career.
I heard the same thing being said as to why Barbra Streisand never had her proboscis slimmed down, gotten a nose job for movie roles due to her fear that it might have a detrimental affect on her voice.
When a singer makes it to the show, they never get those types of things corrected becasue it will change the sound of their voice....