Which of the following is NOT a suprabulge form?

Which of the following is NOT a suprabulge form?

• A. I-bar
• B. Ring clasp
• C. Embrasure clasp
• D. Reverse action clasp

Answer: (A)

Suprabulge versus infrabulge clasps are distinguished by where the retentive part engages the tooth relative to the height of contour (survey line). Suprabulge clasps have their active retention above that line, often encircling or engaging the tooth coronal to the height of contour. Ring clasp, embrasure clasp, and reverse action clasp are designed to engage undercuts above this line, making them suprabulge forms. The I-bar, on the other hand, provides retention from undercuts that lie below the height of contour, so its retentive portion sits infrabulge. Therefore, the I-bar is not a suprabulge form.

Suprabulge versus infrabulge clasps are distinguished by where the retentive part engages the tooth relative to the height of contour (survey line). Suprabulge clasps have their active retention above that line, often encircling or engaging the tooth coronal to the height of contour. Ring clasp, embrasure clasp, and reverse action clasp are designed to engage undercuts above this line, making them suprabulge forms. The I-bar, on the other hand, provides retention from undercuts that lie below the height of contour, so its retentive portion sits infrabulge. Therefore, the I-bar is not a suprabulge form.