Porcelain fused to metal (PFM) is a tooth-colored bridge with high strength. Unlike an all-ceramic bridge, the metal core of the PFM makes it stronger. Tooth-colored porcelain of the highest quality is baked on the outside of the metal core. But because there is metal under the porcelain, it blocks natural tooth translucency and is not as pretty (aesthetically) as an all-ceramic bridge.
However, ceramic bridges do not enjoy the longevity of PFMs. There are many different marginal configurations (the area where the bridge meets the tooth) of a PFM. How well the margin of the bridge fits, affects the health of the gums and ultimately the longevity of the bridge. We choose to do a porcelain butt margin, which is the most aesthetic option (also the most challenging for the dentist and the laboratory technicians to perform well). A porcelain butt joint, when done well, is aesthetic, healthy for the gums, and durable.