FAQ
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Q: Does silane treatment improve the bond strength of a resin cement to a zirconia coping?
A: No, but the use of Rocatec/Cojet (3M ESPE) does. Silica particles are embedded into the surface of zirconia and then silanated. This treatment can increase the bond strength of a resin cement to a zirconia coping.
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Q: Is it ok to grind on a zirconia coping without water spray?
A: Water spray is necessary when grinding on a zirconia ceramic coping. The white light or hot spot you see between a diamond and a zirconia ceramic has been measured at 1500 ºC. If the temperature of zirconia ceramic rises above 1000 ºC, a phase change can occur that will induce cracking and surface defects, lowering the strength of the coping.
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Q: Is preparation design of a zirconia coping important since the zirconia ceramic is so strong?
A: Preparation design of the zirconia coping is very important. The thickness of unsupported porcelain should not exceed 2 mm. The zirconia coping should be as thick as needed to avoid unsupported porcelain.
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A: The fractures are most likely caused by insufficient support of the overlay porcelain in the marginal ridge area. Porcelain is much stronger in compression that in is in tension and shear. If the marginal ridge area isn’t built out with sufficient zirconia, it will leave the porcelain in that area unsupported and vulnerable to tensile and shear forces. If t…
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A: The overlay porcelain should not be thicker than 1.5 to 2 mm depending on the location and should be adequately supported by the zirconia coping.