Instrument used to plane buccoproximal and linguoproximal walls in class II cavity is:
With the enamel hatchet or the bin-angle chisel or both, the dentist can cleave away any remaining undermined proximal enamel, establishing the proper direction to the mesiolingual and mesiofacial walls.
Enamel hatchet
Bibeveled hatchet
Chisel
Single sided chisel