A radiograph shows flattening and erosion of the mandibular condyle, and the patient has a progressive anterior open bite. Symptoms are worst on waking and improve through the day. Which systemic condition is MOST likely?

Correct answer: D. Rheumatoid arthritis

• A. Osteoarthritis is degenerative, typically unilateral, associated with crepitus, and characteristically WORSENS with use through the day — the reverse of this pattern. It also rarely produces a progressive anterior open bite.
• B. Ankylosing spondylitis primarily affects the axial skeleton and sacroiliac joints; TMJ involvement occurs but the described occlusal collapse pattern is characteristic of RA.
• C. Gout involving the TMJ is rare; it presents as acute monoarticular attacks from urate crystal deposition, not progressive bilateral condylar erosion with occlusal change.
• D. Correct. RHEUMATOID ARTHRITIS is an inflammatory synovial disease that erodes the condyle bilaterally. Progressive loss of condylar height rotates the mandible down and back, producing a progressive Class II relationship and ANTERIOR OPEN BITE. Morning stiffness that improves with activity through the day is the classic RA symptom pattern and distinguishes it from osteoarthritis.