This common condition is part of a generalized musculoskeletal pain disorder, typically associated with anxiety and stress. All stress muscles must be examined and treated if necessary. TMJ is often treated by dentists with night splints - these help, but there is rarely necessity for major dental procedures such as changing the bite, lengthening the teeth or caps. TMJ is not fundamentally a dental condition).
Treatment is to the jaw and neck, especially the upper trapezius, splenius capitis, and cervicis, scalenes, and paraspinal muscles. But before treating the jaw, measure mouth opneing by number of fingers that can be inserted between incisors.