Conservation of mass for a chemical that is transported (fig. 1) yields the advection-reaction-dispersion (ARD) equation:
A full-arch Polyvinyl siloxane impression of the teeth prepared for the 5-unit PFM bridge shown in the photographs below. The salmon-colored impression material used near the crown preparations is of a lower viscosity than the blue, allowing for the capture of greater detail.
Why do dental crowns need to be replaced? There can be a variety of reasons why a crown might need to be slated for replacement. We've listed some of them below, along with the type of restoration (porcelain/ceramic, porcelain-fused-to-metal/PFM, metal/gold) most frequently affected or involved. Damage - Cracked or broken crowns (ceramic, PFM).