The vertical dimensional change resulting from polishing or glazing porcelain

Studies have shown that polishing porcelain can produce a smooth surface similar to that resulting from a natural glaze. It has been reported that glazing porcelain causes changes in the occlusal vertical dimension. This study evaluated the changes in vertical dimension after natural glazing and polishing procedures. Twenty uniform-size tricuspid porcelain-fused-to-metal crowns were constructed on a mandibular typodont tooth. A inch steel ball was cradled between the three cusps, and the occlusal vertical dimension was measured from the top of the steel ball to the base of the castings. Contact areas were marked and lightly removed. Ten crowns received natural glazing and the remaining 10 were polished with a Shofu polishing kit. Measurements of occlusal vertical dimension were repeated. All of the crowns showed a loss of occlusal vertical dimension. The mean loss for polished crowns was significantly higher than that recorded for the glazed crowns.