Lecture 6 - Class II RPD Design & Enamel Modifications

what is the width (F-L) of an occlusal rest?

1/3 the F-L width or 1/2 the width of the cusp tips of the tooth chosen

what is the length (M-D) of an occlusal rest on a premolar?

1/3 the M-D length of the tooth

what is the length (M-D) of an occlusal rest on a molar?

1/4 the M-D length of the tooth

what is the depth of an occlusal rest?

1.5 mm

is an occlusal rest inclined towards the center or edge of the tooth?

center

how is the angle between an occlusal rest and a minor connector described?

less than 90 degrees

how is a lingual rest described?

slightly rounded and broad inverted V at the junction of the gingival and middle 1/3

what is the M-D length of a lingual rest?

2.5 to 3 mm

what is the F-L width of a lingual rest?

2 mm

what is the I-A depth of a lingual rest?

1.5 mm

where is the superior border of the body of an I-bar located?

at least 3 mm from the free gingival margin

how much tissue undercut relief is considered excessive with an I-bar?

2 mm or more

how far from the denture base should the vertical portion of an I-bar be?

5 mm

how far from the free gingival margin should a lingual bar be?

3 mm

what are the dimensions of a guide plane?

2-3 mm I-A height, 2-4 mm B-L width

how tall should a guiding plane adjacent to a tooth supported area be?

2-4 mm

how tall should a guiding plane adjacent to an extension base segment be?

1.5-2 mm

what does the reduced height of the guide plane next to an extension base segment allow for?

decreased contact with the minor connector, allowing greater freedom of movement for the RPD and reducing damaging forces

where should a lingual reciprocal arm/plate be located?

middle 1/3 of the tooth

should occlusal rests have sharp or rounded exit corners?

rounded