dental anatomy

[buffer]

Hi everyone, studying dental anatomy and I have some doubts. I request you to look over these questions and share your answers Please.
1. How many cusp tips seen on a mandibular first molar when viewed form buccal surface?
Answer given is 5 (in NBDE Q/A book)
But in Kaplan review on page 804 it says from buccal surface 3 cusps are visible.
Should we choose 5 or 3 for this question?
2. Is mesial marginal ridge and mesial cusp ridge the same?
In Kaplan review page 796 says Mesial cusp ridge is longer than distal cusp ridge for maxillary first premolar.In NBDE Q/A PAGE 212 it says mesial marginal ridge is shorter buccolingually than the more convex distal marginal ridge for maxillary first premolar.I was not sure whether mesial cusp ridge and mesial marginal ridge are same.
3.in wheelers(mine is a very old edition-sixth) in chapter 3 it says eruption of deciduous teeth which is completed between 3 and 4 years of age.As for as my comprehension I understood that they are completed within 2 to 2and a half years.Is this correct?
My question is when will the deciduous teeth complete its eruption sequence?
thanks

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[pbkal]

Hi everyone, studying dental anatomy and I have some doubts. I request you to look over these questions and share your answers Please.
1. How many cusp tips seen on a mandibular first molar when viewed form buccal surface?
Answer given is 5 (in NBDE Q/A book)
But in Kaplan review on page 804 it says from buccal surface 3 cusps are visible.
Should we choose 5 or 3 for this question?
i would go with 5.since lingual cusps r higher than buccal so,will be visible from buccal view.
2. Is mesial marginal ridge and mesial cusp ridge the same?
In Kaplan review page 796 says Mesial cusp ridge is longer than distal cusp ridge for maxillary first premolar.In NBDE Q/A PAGE 212 it says mesial marginal ridge is shorter buccolingually than the more convex distal marginal ridge for maxillary first premolar.I was not sure whether mesial cusp ridge and mesial marginal ridge are same.
they r not same.if u take max 1st pm,with regard to buccal cusp-the mesial cusp ridge is longer than distal cusp ridge.
mesial marginal rige is the one forming the mesial boundary on the occlusal surface.
i dont know if i could clear ur doubt..........
3.in wheelers(mine is a very old edition-sixth) in chapter 3 it says eruption of deciduous teeth which is completed between 3 and 4 years of age.As for as my comprehension I understood that they are completed within 2 to 2and a half years.Is this correct?
My question is when will the deciduous teeth complete its eruption sequence?
thanks
deciduous second molars-complete eruption by 20-30 months of age......so,between 2.5 to 3yrs of age is answer.

hope this helps..

 

[buffer]

Thank you so much pbkal.Thank you for the explanation regarding mesial cusp ridge and mesial marginal ridge.

 

[Be positive]

DA questions from decks

Q.during a working side movement of the mandible,the oblique ridge of max 1st M passes through which sulcus of permanent mandibular 1st M?

-MB sulcus
-DB ''
-ML ''
-DL ''

I need explanation,pls some one come forward.

thanks in advance

 

[buffer]

I could not find proper explanation for this,but read in wheelers that

"during sliding contact position from the most facial contact points to centric occlusion,the teeth intercuspate and slide over each other in a directional line approxiamtely parallel to the oblique ridge of upper first molar.the obl.ridge relates to the combined sulci of the distobuccal and developmental grooves of the occlusal surface of the mand 1st molar."
Answer can be distobuccal,but not sure

can some one given an answer and explanation please.

 

[rose82]

DA questions from decks

Q.during a working side movement of the mandible,the oblique ridge of max 1st M passes through which sulcus of permanent mandibular 1st M?

-MB sulcus
-DB ''
-ML ''
-DL ''

I need explanation,pls some one come forward.

thanks in advance

If you see the rules of occlusion,DL cusp of 1st molar opposes distal Marginal ridge ( DMR) of the counter tooth and mesial marginal ridge of next tooth.now see oblique ridge...it is just mesial to this ridge.thus oblique ridge will oppose something just next to the DMR,which is groove btw the distal cusp and DB cusp.so in working movements,it will pass btw DB sulcus.

this is what i think...whats the ans??

here is my q...
released q

during working movement,facial cusp ridge of max 1st PM opposes what?
facial embrasure btw canine and 1st PM
distal cusp ridge of 1st PM and mesial cusp ridge of 2nd PM

2nd option is the ans...but my doubt is that facial cusps of max oppose the facial embrasures...what if an option of facial embrasure btw 1st and 2nd pm is given???

 

[Be positive]

If you see the rules of occlusion,DL cusp of 1st molar opposes distal Marginal ridge ( DMR) of the counter tooth and mesial marginal ridge of next tooth.now see oblique ridge...it is just mesial to this ridge.thus oblique ridge will oppose something just next to the DMR,which is groove btw the distal cusp and DB cusp.so in working movements,it will pass btw DB sulcus.

this is what i think...whats the ans??

here is my q...
released q

during working movement,facial cusp ridge of max 1st PM opposes what?
facial embrasure btw canine and 1st PM
distal cusp ridge of 1st PM and mesial cusp ridge of 2nd PM

2nd option is the ans...but my doubt is that facial cusps of max oppose the facial embrasures...what if an option of facial embrasure btw 1st and 2nd pm is given???

Thank u rose82.I got it.DB sulcus is the answer.
In ur Q they asked during working movement,so 2nd option is right.
If it z in intercuspal position then only it opposes the facial embrassure btw 1st n 2nd PM.correct me if wrong

 

[rose82]

dec 1977 paper doubt
In lateral excursion,mesial cusp ridge of mand 1st premolar contacts the

1.DL surface of max canine
2.DL slope of buccal cusp of maxillary 1st premolar
3. ML slope of buccal cusp of Max 1st PM
4.none of the above

pls explain what is the rule regarding cusp ridges..not able to solve such q's.

 

[Be positive]

dec 1977 paper doubt
In lateral excursion,mesial cusp ridge of mand 1st premolar contacts the

1.DL surface of max canine
2.DL slope of buccal cusp of maxillary 1st premolar
3. ML slope of buccal cusp of Max 1st PM
4.none of the above

pls explain what is the rule regarding cusp ridges..not able to solve such q's.

so many times it has discussued in this bt as far as know no one agree with the key.we r all thinking,the answer is 1.
God will help us.

goodluck

 

[goodluck29]

if there is no canine how does it affect in group function? any help

 

[rose82]

if there is no canine how does it affect in group function? any help

canine is imp in cuspid protected occlusion.which means in lateral excursion,suppose left,right side should get disoccluded totally.plus left side also,the occlusion should be heavy on canine.If not,atleast group function.But here,the force should be distributed by all posteriors..else grinding results.So im not sure what you are looking for from exam point of view.I think i just blabbered something