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
When evaluating the marginal fit of a cast metal crown clinically, what is the generally accepted maximum marginal gap?
Answer: 50–120 micrometers
A marginal gap of 50–120 micrometers is considered clinically acceptable; gaps beyond this range can increase cement solubility and risk of secondary caries.
The 'suck-back' porosity defect found in cast metal restorations is best prevented by:
Answer: Increasing the sprue diameter and ensuring directional solidification from casting to sprue
Suck-back porosity is prevented by designing the sprue system so the sprue remains liquid longer than the casting, creating a reservoir that feeds metal as the casting solidifies and contracts.
In an all-ceramic zirconia crown, which surface treatment most effectively increases the bond strength of a resin cement to the zirconia substructure?
Answer: Air-particle abrasion with aluminum oxide followed by a MDP-containing primer
Zirconia cannot be etched with HF; instead, air-particle abrasion roughens the surface and MDP (10-methacryloyloxydecyl dihydrogen phosphate) primer chemically bonds to the zirconia oxide layer.
Which articulator movement is adjusted using a protrusive interocclusal record in a semi-adjustable articulator?
Answer: Condylar inclination (sagittal condylar guidance angle)
A protrusive interocclusal record is used to program the condylar inclination (sagittal condylar path) of a semi-adjustable articulator.
When fabricating a long-span fixed partial denture, which design strategy is used to manage the difference in flexure between rigid abutments and the pontic span?
Answer: Incorporate a stress-breaker or non-rigid connector
A non-rigid (stress-breaker) connector allows slight independent movement between segments, reducing the transmission of torquing forces to abutment teeth with differing mobility.
The coefficient of thermal expansion (CTE) of dental porcelain must be slightly lower than the CTE of the alloy it bonds to in a PFM restoration primarily because:
Answer: A higher alloy CTE ensures the metal contracts more, placing the porcelain in slight compression
When the alloy (higher CTE) contracts more than the porcelain upon cooling, the porcelain is placed in slight compression, which ceramics tolerate well and which prevents crack propagation.
A technician receives a master cast with a fractured die. The best course of action before fabricating the crown is to:
Answer: Contact the dentist and request a new impression
A fractured die cannot reliably reproduce the preparation margins, and the only correct course is to request a new impression to ensure an accurate, well-fitting restoration.