Mouth preparation for removable partial dentures

Ring Rest Seat Design for Severely Tilted Molar Abutment Tooth: An Alternative Option

“…Ring rest seat design (Fig ) maintains the conventional RPD principles in terms of stress transition of the occlusal loads, despite the severe inclination of the abutment tooth …”

“…For tooth #16, after preparing a long guide plane, orient the handpiece to be parallel to the guide planes and perpendicular to the path of insertion using the same orientation to prepare the rest seat. Starting mesially as a conventional mesial occlusal rest seat preparation, the ring clasp should be prepared to wrap around the palatal cusp and should not encroach in the already located occlusal contact area. Extend the rest seat preparation distally following the central groove with a round end carbide bur (#1557 FG; Brasseler, Savannah, GA). As the distopalatal groove is approached, join and extend the preparation palatally to exit through the palatal aspect of the tooth. Prepare a palatal horizontal chamfer (more conservative) or shoulder finish line wrapping around the palatal cusp and joining the initial mesial occlusal rest seat preparation creating a ring shape (Figs and ). Maintain the preparation on enamel as much as clinically possible. Keep a conventional rest seat depth of 1 to 1.5 mm, while the orientation of the handpiece follows path of placement (Figs and ).…”

“…Maintain the preparation on enamel as much as clinically possible. Keep a conventional rest seat depth of 1 to 1.5 mm, while the orientation of the handpiece follows path of placement (Figs and ).…”

“…The proposed rest seat design offers several advantages for the existing situation: Conservative approach in contrast to additional and significantly higher reduction for a full‐coverage tooth preparation or extraction. Ring rest seat design (Fig ) maintains the conventional RPD principles in terms of stress transition of the occlusal loads, despite the severe inclination of the abutment tooth Maintenance of already existing and functional, occlusal contacting surfaces. Tooth preparation lends itself well to prevent overcontouring of the clasp. …”

“…Rests are the primary RPD components incorporated and designed to provide adequate support and favorable transmission of forces to the abutment teeth . Several studies have looked at commonly used clasp assembly designs, clasp component function, number of clasps, and retention . However, in the case of unfavorably inclined teeth or due to esthetic considerations, it is impossible to achieve appropriate loading without modification/s to a conventional rest designs .…”