CCE CCE Finishing & Surface Characterization 1 — Questions and Answers
Question 1: Which finishing method is preferred to achieve the highest surface smoothness on feldspathic porcelain before glazing?
- Coarse diamond bur adjustment followed by direct glazing
- Sequential polishing with decreasing grit silicone points and diamond pastes (Correct answer)
- Sandblasting with 50 µm alumina
- Acid etching with hydrofluoric acid
Correct answer: Sequential polishing with decreasing grit silicone points and diamond pastes
Sequential polishing with progressively finer abrasive instruments followed by diamond polishing paste achieves the smoothest surface prior to the glaze firing.
Question 2: Auto-glazing of dental porcelain refers to:
- Applying a separate glaze material and firing it
- Firing the porcelain to its fusion temperature so the surface material itself becomes smooth and glassy (Correct answer)
- Sandblasting to create a high-polish effect
- Applying a light-cure surface sealant
Correct answer: Firing the porcelain to its fusion temperature so the surface material itself becomes smooth and glassy
Auto-glazing (also called self-glazing or over-glazing) involves firing the ceramic to a temperature where the surface particles fuse together without adding a separate glaze material.
Question 3: What is the primary risk of over-polishing a ceramic restoration?
- Increased surface porosity
- Rounded and flattened surface anatomy reducing esthetic characterization (Correct answer)
- Weakening of the zirconia substructure
- Excessive glaze thickness
Correct answer: Rounded and flattened surface anatomy reducing esthetic characterization
Excessive polishing rounds cusp tips and flattens developmental grooves, erasing natural surface morphology and reducing the esthetic quality of the restoration.
Question 4: Surface texturing on anterior ceramic restorations serves primarily to:
- Increase the bond strength to the cement
- Mimic natural enamel lobes, perikymata, and developmental grooves for improved esthetics (Correct answer)
- Reduce the firing shrinkage of the ceramic
- Improve the accuracy of shade measurements
Correct answer: Mimic natural enamel lobes, perikymata, and developmental grooves for improved esthetics
Surface texture mimics the natural micro-anatomy of enamel (perikymata, lobes, developmental grooves), controlling light reflection and contributing to a lifelike appearance.
Question 5: Which instrument is most appropriate for adding fine surface texture to an unglazed feldspathic ceramic surface?
- Green stone
- Fine diamond bur or texturing stone used at low speed (Correct answer)
- Coarse sandpaper disc
- Ultrasonic scaler
Correct answer: Fine diamond bur or texturing stone used at low speed
Fine diamond burs or texturing stones used at low speed and light pressure allow precise, controlled addition of surface detail without fracturing the ceramic.
Question 6: After chairside adjustment of a glazed ceramic crown with a diamond bur, the ceramist should:
- Leave the adjusted area unfinished as it will self-polish in function
- Polish the adjusted area with rubber points and diamond paste, then re-glaze if possible (Correct answer)
- Apply composite resin over the adjusted area
- Sandblast the entire crown and refire
Correct answer: Polish the adjusted area with rubber points and diamond paste, then re-glaze if possible
Chairside adjustments must be re-polished or re-glazed because diamond bur grinding destroys the glaze, leaving a rough, plaque-retentive, and structurally weakened surface.
CCE CCE Finishing & Surface Characterization 1
Which finishing method is preferred to achieve the highest surface smoothness on feldspathic porcelain before glazing?