Which description correctly characterizes disc displacement with reduction (DDwR) and disc displacement without reduction (DDw/oR)?

Which description correctly characterizes disc displacement with reduction (DDwR) and disc displacement without reduction (DDw/oR)?

• A. DDwR: the disc is anterior to the condyle in a closed mouth but reduces to a normal position during opening, often with a click; DDw/oR: the disc remains displaced during opening, producing limited opening with no click.
• B. DDwR: the disc remains displaced during opening, with no click; DDw/oR: the disc reduces during opening with a click.
• C. DDwR: there is no joint sound; DDw/oR: there is always a joint sound.
• D. DDwR: causes restricted movement only; DDw/oR: unlimited movement.

Answer: (A)

Displacement with reduction means the disc moves forward in a closed mouth but returns to its normal position between the condyle and the articular eminence as the mouth opens, usually with a noticeable click as it reduces. Displacement without reduction means the disc remains displaced during opening, so the condyle cannot move through its normal path, leading to limited mouth opening and no click because the disc does not snap back. The description that matches this pattern states that in a closed mouth the disc is anterior to the condyle and that it reduces during opening with a click; in contrast, without reduction the disc stays displaced during opening, producing limited opening with no click. The other descriptions either swap these roles, claim an always-present sound, or imply movement that doesn’t align with how reduction and non-reduction affect opening.

Displacement with reduction means the disc moves forward in a closed mouth but returns to its normal position between the condyle and the articular eminence as the mouth opens, usually with a noticeable click as it reduces. Displacement without reduction means the disc remains displaced during opening, so the condyle cannot move through its normal path, leading to limited mouth opening and no click because the disc does not snap back.

The description that matches this pattern states that in a closed mouth the disc is anterior to the condyle and that it reduces during opening with a click; in contrast, without reduction the disc stays displaced during opening, producing limited opening with no click. The other descriptions either swap these roles, claim an always-present sound, or imply movement that doesn’t align with how reduction and non-reduction affect opening.