Main problems 2: Whitish, spot, black spots.
Reasons
1. The improper operation of the incisal liquid, flows to the dentine part, causing part of the crown to become opaque and stained. Be cautious when brushing the incisal liquid and operate properly.
2. Applying more or less incisal liquid will affect the shade.
3. During the dyeing process, the mutual contamination of different dyeing solutions causes spots on the crown. Staining tools should be clean, leaving some time to sinter the crown after drying and baking it.
4. If the heating elements have used for a long time, the glass layer on the surface will fall off, which will contaminate the crowns, and cause it become whitish, opaque or dark. The sintering tray needs a cover to prevent contaminants from falling into the sintering tray.
When the sintering oven has used for one or two weeks, sinter the milled waste materials in the furnace, and clean the glass layer on the heating element.
5. The teeth are contaminated before sintering or the furnace is contaminated, those may cause black spots on crowns after sintering.
Before sintering, make sure the crown are clean, and clean the furnace.
6. The crown should be placed in a clean space to avoid contamination.
7. The top of the sintering furnace and the surrounding environment should be kept clean too. The sintering furnace has a fan during operation, and dust will fall into the oven to contaminate the crowns.
8. The sintering tray should not be placed randomly, keep the sintering tray and the zirconia beads clean. Don’t sinter different shades crown in one sintering tray at the same time , as they may cause pollution.
