Occlusion question help!

[sanscilantro]

Hi!

I came across this question in the ASDA I-N packet, and was confused about the answer.

Question: Which of the following anatomic structures of a maxillary first molar moves through the distofacial groove of a mandibular first molar?
a. Mesial marginal ridge
b. Distal marginal ridge
c. Mesiofacial cusp
d. Distofacial cusp
e. Oblique ridge
Ans: D. Distofacial cusp

Could someone please explain why D is the correct answer (preferably w/ a diagram or something if possible)? I'm having a lot of problems with occlusion questions >.<

(I am preparing for NDBE I).

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[cooliyak]

Hi!

I came across this question in the ASDA I-N packet, and was confused about the answer.

Question: Which of the following anatomic structures of a maxillary first molar moves through the distofacial groove of a mandibular first molar?
a. Mesial marginal ridge
b. Distal marginal ridge
c. Mesiofacial cusp
d. Distofacial cusp
e. Oblique ridge
Ans: D. Distofacial cusp

Could someone please explain why D is the correct answer (preferably w/ a diagram or something if possible)? I'm having a lot of problems with occlusion questions >.<

(I am preparing for NDBE I).

 

[averageasian]

When you make a laterotrusive movement, the MB cusp of the MX1 will move thru the buccal groove of MN1. The DB cusp of MX1 will move thru the DB groove of MN1.

Remember that the buccal of MN1 has THREE cusps, so there will be TWO facial grooves that occlude with the MX1.

Assume Class I unless otherwise stated!