TMJ Arthroscopy Compared to Arthrocentesis in Disc Displacement Without Reduction

The goal of this clinical trial is to compare the intervention arthroscopic lysis and lavage to the intervention arthrocentesis in treating disabling and painful temporomandibular joint disc displacement without reduction. The main questions it aims to answer are: * Which surgical method that best improves mouth opening capacity, TMJ pain, and TMJ disability? * If any pre- or peri-operative variable/-s could be identified as a predictor for surgical outcome? Researchers will compare arthroscopic lysis and lavage to arthrocentesis to see if arthroscopic lysis and lavage works better to treat temporomandibular joint disc displacement. Participants will: * Have one of the two interventions under general anesthesia, not knowing which intervention. * Visit an external clinic for regular checkups at 1, 3, 6, 12, and 24 months after surgery. * Answer three different quality of life surveys at the checkups.