A patient reports painless clicking at the right temporomandibular joint (TMJ) with no pain and full opening. X-rays show no bony changes. The most likely diagnosis is:

Correct answer: A. Internal derangement / disc displacement with reduction

• A. Correct. Painless pre-auricular clicking with full range of motion and no pain is the classic presentation of disc displacement with reduction (internal derangement). The click occurs when the disc reduces (snaps back) during opening and closing.
• B. Osteoarthritis causes crepitus (grinding), pain, and bony changes — not typically just clicking.
• C. Rheumatoid arthritis of the TMJ causes pain, stiffness, and bony changes — not painless clicking alone.
• D. Gout causes uric acid crystal deposition with acute severe pain and swelling — not painless clicking.