Crown & Bridge Fabrication Flashcards
7 cards from real CDT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Crown & Bridge Fabrication flashcards as text
In a three-unit fixed partial denture, the connector between the retainer and pontic should have a minimum cross-sectional area of approximately:
Answer: 4 mm²
A minimum connector cross-sectional area of 4 mm² is generally required for anterior bridges, with 9 mm² recommended for posterior units to resist fracture under occlusal load.
Which occlusal scheme is most commonly prescribed for implant-supported crowns to minimize off-axis loading?
Answer: Mutually protected occlusion (canine guidance)
Mutually protected occlusion (canine guidance) is preferred for implant crowns because it limits lateral forces to natural canines, reducing harmful off-axis loading on the implant.
The term 'hygienic pontic' refers to a pontic design that:
Answer: Spans the edentulous space without contacting the ridge tissue
A hygienic (also called sanitary) pontic is designed with a space between the pontic and the ridge so that oral hygiene can be maintained easily beneath it.
During porcelain firing, what phenomenon causes the porcelain to shrink as it reaches its fusion temperature?
Answer: Sintering and particle coalescence as glass flows
Shrinkage during porcelain firing occurs because sintering causes glass particles to coalesce and fuse, reducing the total volume and eliminating interparticle voids.
What is the function of opaque porcelain in a porcelain-fused-to-metal (PFM) restoration?
Answer: To mask the dark metal coping and bond to the alloy oxide layer
Opaque porcelain masks the dark metal coping and chemically bonds to the oxide layer on the alloy surface, establishing the ceramic-metal bond.
Which condition would most likely result in a 'rocking' or unstable crown on the die before cementation?
Answer: Internal nodule or positive irregularity inside the crown
An internal nodule (positive irregularity) inside the crown prevents uniform seating and causes the crown to rock on the die.
For a mandibular posterior three-unit bridge, which pontic design provides the best combination of esthetics and cleanability in a patient with a flat, keratinized ridge?
Answer: Modified ridge-lap pontic
The modified ridge-lap pontic offers good esthetics by contacting only the buccal aspect of the ridge while leaving the lingual surface convex for easy hygiene access.