Lecture 3 - Part 2: Design & Enamel Modification Class II RPD

What are the abutment teeth for our project?

#18, #22, #29

Where are undercuts needed in our design?

#18 = 0.01" DB (Akers)

#29 = 0.01: mid-buccal (I-bar)

How far away from the free gingival margin should the undercut on #18 buccal be?

more than 2mm

Where should the survey line on #29 buccal be?

middle 1/3 or slightly toward occlusal 1/3

How far away from the free gingival margin should the undercut on #29 buccal be?

more than 3 mm

What rest seats are used in our design?

#18 M: occlusal rest

#22 L: cingulum rest

#29 M: occlusal rest

What types of retentive clasps are used in our design?

#18: cast circumferential/Akers clasp engage DB 0.01"

#29: I-bar engage mid-buccal 0.01", extend up ~1mm & not beyond survey line (HOC)

Where is the reciprocal clasp in our design?

#18 L: area middle 1/3 toward occlusal 1/3 above survey line

What are the measurements for the I-bar?

3 mm from free gingival margin, vertical portion at least 5 mm from denture base

What are the measurements of the lingual bar?

at least 3 mm away from the free gingival margin in mandibular arch, 6-gauge half pear shape cross-section, at least 7-8 mm of vertical space must be present between the gingival margins of the teeth and the floor of the mouth, bar height is 4-5 mm

Where is the tissue stop on our design?

Distal extension

What are the steps of enamel modification?

1. prepare parallel guiding planes

2. Adjust height of contour (survey line) if necessary

3. Prepare rest seats

4. Prepare undercuts for retention

Where are the guide planes in our design?

#18M, #22D, #29D

What should the height of the guide planes be adjacent to tooth supported area?

2-4 mm

What should the height of the guide planes be adjacent to an extension base segment?

1.5-2 mm (reduced height results in decreased contact with minor connector and permits greater freedom of movement

Why does moving the HOC downwards allow proper placement of prosthesis component?

undercut is lower for increased retention

Where should the lingual reciprocal arm or plate be located?

middle 1/3

Where should be retentive arm be placed?

Occlusal 1/3

Where should the reciprocal arm be placed?

Middle 1/3