The mesiobuccal cusp of the mandibular second molar occludes with which maxillary tooth surfaces?
a. The mesial marginal ridge of the second molar and distal marginal ridge of the first molar
b. The distal marginal ridge of the second molar and mesial marginal ridge of the third molar
c. The embrasure between the first and second molars
d. The central fossa of the maxillary second molar
a. The mesial marginal ridge of the second molar and distal marginal ridge of the first molar
b. The distal marginal ridge of the second molar and mesial marginal ridge of the third molar
c. The embrasure between the first and second molars
d. The central fossa of the maxillary second molar
Ans. A. The mesiobuccal cusp of a mandibular molar is a holding
(supporting) cusp. The general rule of occlusion of mandibular holding cusps is
as follows: the holding cusps of the mandibular teeth occlude on the mesial
marginal ridge of their maxillary counterpart, and the distal marginal ridge of
the maxillary tooth mesial to their counterpart, EXCEPT distobuccal cusps of
mandibular molars occlude with central fossae of their counterparts, the distal
cusp of the mandibular first molar occludes with the distal triangular fossa of
its counterpart, and the first premolar occludes only with the mesial marginal
ridge of its counterpart (but not the canine). In this case, the maxillary
counterpart is the maxillary second molar, and the tooth immediately mesial to
it is the maxillary first molar.
