Which of the following conditions is characterized by a jaw that "locks" during opening?

The condition characterized by a jaw that "locks" during opening is typically associated with an anteriorly displaced disc without reduction. In this scenario, the articular disc, which normally allows for smooth motion of the jaw, becomes displaced in a way that prevents it from returning to its proper position during mouth opening. As a result, patients experience a "locking" sensation or inability to fully open their mouth until the condition is resolved, often accompanied by jaw pain or dysfunction.

In contrast, disc displacement with reduction allows for the disc to return to its normal position during some aspects of the jaw movement, often leading to intermittent locking but not a constant inability to open the mouth fully. Other conditions, such as maxillary sinus disease, typically present with different symptoms related to sinus issues rather than direct jaw movement problems, and amelogenesis imperfecta primarily affects the quality of enamel and does not influence the mechanics of jaw opening.