Which statement correctly describes RPI and RPA configurations in terms of their location and components?

Which statement correctly describes RPI and RPA configurations in terms of their location and components?

• A. RPI is infrabulge with mesial rest, distal proximal plate, I-bar; RPA is suprabulge with mesial rest, distal proximal plate, Akers clasp
• B. RPI is suprabulge with mesial rest, distal proximal plate, Akers clasp; RPA is infrabulge with mesial rest, distal proximal plate, I-bar
• C. Both are infrabulge and include an I-bar
• D. Both are suprabulge and include an Akers clasp

Answer: (A)

In this topic, the position of the retentive component relative to the tooth’s height of contour (infrabulge vs suprabulge) is what differentiates RPI from RPA, along with the specific clasp used. The RPI design uses a retentive I-bar located below the height of contour (infrabulge) on the tooth, paired with a mesial rest and a distal proximal plate. This combination helps control tooth movement with a sub-occlusal retentive element and a guide plate that helps seal the embrasure. The RPA design, on the other hand, uses a suprabulge retentive component—an Akers clasp—placed above the height of contour, along with the same mesial rest and distal proximal plate. The Akers clasp provides retention from above the contour rather than below it. Thus, the statement that describes RPI as infrabulge with a mesial rest, distal proximal plate, and I-bar, and RPA as suprabulge with a mesial rest, distal proximal plate, and Akers clasp is correct.

In this topic, the position of the retentive component relative to the tooth’s height of contour (infrabulge vs suprabulge) is what differentiates RPI from RPA, along with the specific clasp used. The RPI design uses a retentive I-bar located below the height of contour (infrabulge) on the tooth, paired with a mesial rest and a distal proximal plate. This combination helps control tooth movement with a sub-occlusal retentive element and a guide plate that helps seal the embrasure.

The RPA design, on the other hand, uses a suprabulge retentive component—an Akers clasp—placed above the height of contour, along with the same mesial rest and distal proximal plate. The Akers clasp provides retention from above the contour rather than below it.

Thus, the statement that describes RPI as infrabulge with a mesial rest, distal proximal plate, and I-bar, and RPA as suprabulge with a mesial rest, distal proximal plate, and Akers clasp is correct.