No black gumlines
All-ceramic (all-porcelain) crowns capture the translucency of natural teeth. Traditional porcelain fused to metal crowns have an opaque layer to block out the appearance of the dark metal underneath. This is why, over time, an unsightly dark line can develop at the gumline of porcelain fused to metal crowns, where the edge of the crown meets the tooth. All-ceramic crowns mimic the natural tooth.