All are true about lingual ledges except:
Lingual ledges are small horizontal grooves placed on the lingual aspect while preparing a tooth for resin bonded retainers. These increase the retention and resistance forms, increase casting rigidity and aid in orienting the casting while cementation of the prosthesis.
Part of tooth preparation for a resin bonded retainer
Increases the retention and resistance form
Decreases the casting rigidity
Aids in orientation of the casting during cementation