Do porcelain crowns adhere to dentin?

This question refers to central upper incisors (the 2 front upper teeth). The reason I ask is because part of my teeth (lingual side) is nothing but dentin, the labial side as well as the lateral edges still have a good amount of enamel. Also, how much room do I need behind these teeth and the lower ones to make sure there is sufficient room for a porcelain crown - when I bite down that is? Thank you.