The zero degree anatomic teeth is used in:

Monoplane Occlusion Cuspless teeth (0o) on a flat plane with 1.5-2.0 mm overjet. No cusp to fossa relationship No anterior contacts in centric position Poor residual ridges Poor neuromuscular control (Bruxers, CP, etc.,) Previously successful with monoplane dentures or severely worn occlusion on the previous denture Arch discrepancies - Class II or III or Cross-bite Immediate Dentures - Except when opposing natural dentition Potential poor follow-up.