Metal crowns are made from base metal alloys like cobalt chromium and they do not cause any reaction with surrounding tissues. They have excellent strength but metallic color of these crowns limits their usefulness to the back teeth only. For pediatric cases prefabricated stainless steel crowns from 3M ESPE are used.
Porcelain fused to metal or PFM crowns are made by giving a ceramic coating over a metal base cap. Ceramic coating enhances the cosmetic acceptance of these crowns. But due to metal base these are opaque and not an appropriate choice for front teeth. These crowns have a propensity to develop a black line at margin due to metal and chipping of outer ceramic layer.
Full Zirconia crowns are made from Zirconium dioxide mineral and are stronger than ceramic and some metal crowns. They are split resistant, stiffer and stronger. Therefore, they are an excellent option for back tooth cap and bridge. Cosmetic appeal of these strong crowns can be increased by layering them with porcelain / ceramic thus making them suitable for front teeth as well.
Full Ceramic crowns these crowns are made only from ceramic. These crowns have the exceptional quality of resembling natural tooth; reason being ceramic is translucent and light can pass through it making it appear life- like. Because of their cosmetic appeal they are a good choice for front teeth cap.