Q: Does jaw deviation cause speech problems or vice versa?
A: Frequently it is the speech that is causing the jaw to have to move in an unnatural manner in order to produce the sounds correctly in connected speech. That is why it is important to rule out structural reasons such as a narrow palate, for example. The palate might not allow for the tongue to fit within it, forcing a shifting of the mandible/jaw in an attempt to sound more intelligible, thus, compromising speech precision. So, to answer your questions, “Does jaw deviation cause speech problems or vice versa,” either one can contribute to the other.