It could be a dental or jaw issue, but it could simply be how you've learned to speak over the years. Just like people who speak with a lisp, it's simply how they've developed their speech and sometimes can be influenced by the way their mouth is formed. So it might be possible to try and learn to correct it with time by learning how it feels to speak in the way you want to speak, whilst looking in the mirror. If you feel you can't physically change how you speak, then maybe mentioning it to your dentist would be a good idea. They can offer advice or possible treatment options for things like this.
Ultimately though, learning to love every part of yourself is something to work on and takes time.