contact in ideal centric n eccentric relation

[era]

i have doubt with this..............
Q:which of the following marginal ridges have little or no contact in ideal centric n eccentric maxillomandibular contact relationships?
a.distal of max 2nd pm
b.distal of mand.1st pm
c.distal of mand.2nd pm
d.mesial of max. canine
e.mesial of mand 1st pm

ANS:b,c,e

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[Ibanez]

i have doubt with this..............
Q:which of the following marginal ridges have little or no contact in ideal centric n eccentric maxillomandibular contact relationships?
a.distal of max 2nd pm
b.distal of mand.1st pm
c.distal of mand.2nd pm
d.mesial of max. canine
e.mesial of mand 1st pm

ANS:b,c,e

1. Well only the option "E" sounds true to me according to the question (centric + eccentric); MMR of mand 1st premolar.
The MMR of mand 1st is opposed by lingual surface max canine, but does not contact (Ant. Occlusion/ Mutually protected)

2. a The DMR of mand premolars of does come in contact with max counterpart in CENTRIC (but how intimately they are in contact... I don't know. Maybe a "little") but during eccentric I think they are not in contact (Mutually protected Occlusion)

2.b The DMR of mand 1st premolar is more occlusal cf. MMR... So contributes more to centric cf. MMR (to stablize the post. occlusion at 1st premolars).

3. Also, MMR of Max Canine will have NO contact in CENTRIC but will definitely come in intimate contact during lateral eccentric (/Canine Guidance)

Since MMR of mand 1st premolar stands 100% good, the only available options left are Option 4, 5 but I'm not quite sure.

This is such a BS question... I seriously question the intention of question maker. If it is research based, I say there are some 34296157313448159890189447890490834890463 research(-es) done/in-process, well if its such an important and valid point (which it seems; Restorative dentistry) it should be quoted in every dental anatomy/restorative dentistry book (but sadly I haven't yet heard of such a thing as DMRs of mand. premolars playing a little role in occlusion.

My question to them is if DMRs of mand. premolars do not take part in centric and eccentric, why are they even there. The ridges give strength to the tooth structure by supporting the enamel rods (provides resistance to fracture). If they do not participate in mastication (centric + eccentric) why does mand premolars have DMRs. why aren't they flat distally... are they vestigeal?


Mayank.

PS Help!