MDS AIPGDEE preparations B-IDS | mesiobuccal cusp of the maxillary MCQ

The mesiobuccal cusp of the maxillary first molar occludes in:
a. The mesial marginal ridge of the mandibular second molar
b. The distal marginal ridge of the mandibular first molar
c. The central groove of the mandibular first molar
d. The buccal groove of the first mandibular molar


Ans. D. Buccal cusps of maxillary teeth are guiding cusps, not holding cusps. Therefore, they do not occlude on marginal ridges or central fossae. The general rule for maxillary buccal cusps is that they occlude in the facial embrasure between their mandibular counterpart and the tooth distal to their counterpart, EXCEPT for the mesiobuccal cusps of the molars, which occlude in the buccal grooves of their mandibular counterparts, and the distobuccal cusp of the first molar, which opposes the distobuccal groove of the mandibular first molar. In this question we are dealing with the exception of the mesiobuccal cusps of maxillary molars, which occlude with the buccal groove of their mandibular counterpart. In this case, the maxillary first molar mesiobuccal cusp contacts the mandibular first molar buccal groove.