Which of the following is true of an occlusal rest for a removable partial denture?
1. One-third facial lingual width of the tooth
2. 1.5 mm deep for base metal
3. 2.0 mm labiolingual width of the tooth
4. Floor inclines apically toward the center of the tooth
Rests are critical for the health of the soft tissues underlying the denture resin basis and the minor and major connectors. It should prevent tilting action and should direct forces through the long axis of the abutment tooth. In order to function as specified, an occlusal rest should have a rounded (semicircular) outline form, be one-third the facial lingual width of the tooth, one-half the width between cusps, and at least 1.5 mm deep for base metal. The rest floor inclines apically toward the center of the tooth and the angle formed with the vertical minor connector should be less than 90 degrees.
All of the above
1, 3, and 4
1, 2, and 4
3 and 4