What is The reverse three quarter crown with complete coverage of the facial surface is used for: and explain in detail?
The reverse three-quarter crown, with complete coverage of the facial surface, is used only occasionally and is usually reserved for one or two situations:

It is ideal for restoration of mandibular molars that are severely inclined lingually, and
It can also be used on molars that have suﬀered destruction of the facial surface, but not of the  lingual.