Porcelain fused to metal crowns (PFM crowns) are metal crowns with a layer of porcelain fused on the metal. This makes them almost as durable as pure metal crowns but a lot more esthetic. The porcelain layer can give good aesthetics but can wear off over time due to have lower strength exposing the black oxidized metal underneath. PFM crowns used to be the most popular crowns in dentistry for a long time. They are made from special metal alloys based on Titanium or Cobalt that are bio compatible and last a long time. The workflow for PFM is largely manual or analog starting with a waxup(digital or manual) followed by a metal casting and a porcelain layering on top for anatomy and aesthetics. PFM crowns are great for large splinted bridges with a lot of pontics.