Why is a porcelain-fused-to-metal crown chosen for a back tooth needing both strength and looks? The metal coping underneath bears the heavy chewing loads (metal is tough), while the ceramic veneer on top provides the tooth colour. An all-ceramic crown looks better but needs more tooth reduction for thickness and is more brittle under molar forces. The PFM is the taught compromise: metal for strength where it hides, ceramic for appearance where it shows.