1
Q
class I
A
buccal groove of mandibular first molar aligns with mesiobuccal cusp for the maxillary first molar
2
Q
class II
A
buccal groove of the mandibular first molar is POSTERIOR to the mesio-buccal cusp of the maxillary first molar
3
Q
class III
A
buccal groove of the mandibular first molar is ANTERIOR to (mesially positioned) the mesio-buccal cusp of the maxillary first molar
