CDT Removable Prosthodontics 3 — Questions and Answers
Question 1: Which major connector design for a maxillary RPD covers the least palatal tissue and is indicated when all remaining teeth are anterior?
- Anteroposterior palatal strap
- Single palatal strap
- Palatal plate (full coverage)
- U-shaped (horseshoe) connector (Correct answer)
Correct answer: U-shaped (horseshoe) connector
The U-shaped (horseshoe) connector is used when all remaining teeth are anterior, though it is the least rigid and should be avoided when possible.
Question 2: In RPD design, a reciprocal clasp arm is placed to:
- Engage the primary undercut of the abutment tooth
- Provide indirect retention against vertical displacement
- Balance the force exerted by the retentive clasp arm (Correct answer)
- Connect the denture base to the major connector
Correct answer: Balance the force exerted by the retentive clasp arm
The reciprocal arm opposes the force of the retentive clasp as it flexes over the height of contour, preventing lateral movement of the abutment tooth.
Question 3: Denture teeth made of porcelain are preferred over acrylic teeth primarily because they:
- Bond chemically to the acrylic denture base
- Offer superior wear resistance and hardness (Correct answer)
- Are easier to adjust chairside
- Provide better shock absorption
Correct answer: Offer superior wear resistance and hardness
Porcelain teeth resist wear better than acrylic teeth, maintaining occlusal vertical dimension over time despite their brittleness and lack of chemical bonding.
Question 4: The labial flange thickness and extension of a maxillary complete denture is critical because it directly affects:
- The posterior palatal seal integrity
- Facial support and lip fullness (Correct answer)
- Retention via atmospheric pressure only
- The processing shrinkage of acrylic
Correct answer: Facial support and lip fullness
The labial flange provides critical support for the upper lip and perioral tissues, restoring lost facial contour after tooth and ridge loss.
Question 5: A RPI clasp system (Rest, Proximal plate, I-bar) is advantageous for distal extension RPDs because the I-bar:
- Provides the most rigid retention available
- Disengages from the undercut during functional loading (Correct answer)
- Is placed in the suprabulge area of the tooth
- Connects directly to the indirect retainer
Correct answer: Disengages from the undercut during functional loading
The I-bar is designed to disengage from the undercut when the distal extension base moves inferiorly under load, reducing torquing forces on the abutment.
Question 6: Neutral zone impression technique for complete dentures is used to position artificial teeth in the space where:
- Maximum bone support is available
- Muscular forces from the tongue and cheeks are balanced (Correct answer)
- The retromolar pad provides posterior support
- Occlusal pressure from the opposing arch is greatest
Correct answer: Muscular forces from the tongue and cheeks are balanced
The neutral zone is the area where forces from the tongue are balanced by forces from the lips and cheeks, providing the most stable position for denture teeth.
Question 7: When processing a complete denture using the compression molding (pack-and-press) technique, a trial closure is performed to:
- Test the final shade of the denture teeth
- Verify the wax is fully eliminated before packing resin
- Check for even distribution of acrylic and close flash lines (Correct answer)
- Determine the final vertical dimension of occlusion
Correct answer: Check for even distribution of acrylic and close flash lines
Trial closures confirm even resin distribution throughout the mold and allow excess material (flash) to be trimmed before the final press and processing.
CDT Removable Prosthodontics 3
Which major connector design for a maxillary RPD covers the least palatal tissue and is indicated when all remaining teeth are anterior?