Anterior disc displacement with intermittent locking is:: (A) Type 1, (B) Type 2, (C) Type 3, (D) Type 4
Answer is B. Disk displacement is divided into stages based on sign and symptoms combined with results of aging studies. A simple classification system divides ADD in to

anterior disc displacement with reduction (clicking joint)
anterior disc displacement with intermittent locking
anterior disc displacement without reduction (closed lock)