CDC Clinical Procedures & Protocols 3 — Questions and Answers
Question 1: During ceramic layering, what is the consequence of applying an excessively thick layer of dentin porcelain in a single build-up?
- Improved color saturation
- Increased risk of cracking and delamination during firing (Correct answer)
- Faster completion of the restoration
- Better bond to the framework
Correct answer: Increased risk of cracking and delamination during firing
Thick single-layer applications create differential shrinkage stresses during firing that can cause cracking, delamination, or warping of the ceramic.
Question 2: A patient presents with a ceramic veneer that has debonded six months post-placement. What clinical factor should the ceramist investigate in the remake protocol?
- The shade selection used originally
- Surface preparation protocol and bonding system compatibility (Correct answer)
- The patient's oral hygiene habits only
- The firing temperature log
Correct answer: Surface preparation protocol and bonding system compatibility
Early debonding typically indicates inadequate enamel etching, incompatible bonding systems, or insufficient ceramic surface conditioning (HF etching/silanation).
Question 3: What is the significance of the 'critical angle' in porcelain contouring during occlusal adjustment?
- It determines the firing temperature needed
- It defines the point at which grinding breaks through the glaze into the body ceramic (Correct answer)
- It establishes the shade selection zone
- It indicates maximum veneer thickness
Correct answer: It defines the point at which grinding breaks through the glaze into the body ceramic
Once grinding penetrates the glaze layer into body ceramic, repolishing or refiring is required because rough ceramic surfaces abrade opposing dentition.
Question 4: In an implant-supported ceramic crown case, how does the absence of a periodontal ligament affect the ceramist's occlusal design?
- No modification needed as implants function identically to teeth
- Lighter occlusal contacts are recommended due to lack of proprioceptive feedback and shock absorption (Correct answer)
- Heavier contacts are needed to stimulate osseointegration
- Occlusion is irrelevant for implant restorations
Correct answer: Lighter occlusal contacts are recommended due to lack of proprioceptive feedback and shock absorption
Implants lack the PDL's proprioceptive feedback and viscoelastic shock absorption, requiring lighter occlusal loading to prevent ceramic fracture and implant overload.
Question 5: Which protocol should be followed when a ceramic restoration requires post-delivery adjustments that penetrate through the glazed surface?
- Apply topical fluoride to smooth the area
- Polish with diamond-impregnated rubber points in sequence ending with fine grit, then consider refiring (Correct answer)
- Leave the surface as-is since it will smooth naturally
- Apply bonding resin to seal the roughened surface
Correct answer: Polish with diamond-impregnated rubber points in sequence ending with fine grit, then consider refiring
After grinding through glaze, progressive diamond polishing can restore surface smoothness, with refiring as the optimal option for large adjustment areas.
Question 6: When fabricating ceramic restorations for a patient with a deep vertical overlap (overbite), which incisal edge design consideration is most critical?
- Maximum ceramic thickness regardless of available space
- Incisal clearance verification in excursive movements to prevent fracture (Correct answer)
- Using only monolithic ceramic to avoid layering
- Eliminating all anterior guidance
Correct answer: Incisal clearance verification in excursive movements to prevent fracture
Deep overbite cases require careful verification of adequate ceramic thickness and clearance during protrusive movements to prevent fracture under functional loading.
Question 7: A ceramist notices persistent porosity in fired ceramic despite following standard condensation protocols. What is the most likely cause?
- Using too little porcelain powder
- Inadequate vibration during condensation trapping air bubbles (Correct answer)
- Firing at too high a temperature
- Using the wrong shade of ceramic
Correct answer: Inadequate vibration during condensation trapping air bubbles
Insufficient vibration during slurry condensation fails to expel entrapped air, leading to porosity that weakens the ceramic and creates aesthetic defects after firing.
CDC Clinical Procedures & Protocols 3
During ceramic layering, what is the consequence of applying an excessively thick layer of dentin porcelain in a single build-up?