NBDE Part I questions...need ur help!!

[oasiswhy]

Hi, guys!
There are several questions for NBDE Part I. Really need your help...

1. Which of the following occurs when the distofacial cusp of a permanent mandibular right first molar moves through the facial groove from the central fossa of the maxillary right first molar?
A. direct lateral excursion to the right
B. lateral-protrusive excursion to the right

PS: What is the difference between A and B?


2. Under normal conditions, the presence of mamelons in a 14-year-old patient is indicative of
A. fluorosis
B. malnutrition
C. malformation
D. malocclusion
E. enamel composition


3. In a maxillary canine, which is greater, the mesiodistal measurement or the faciolingual measurement?


4. In which of the following molars is the mesial fossa most distinctly separated from the remainder of the occlusal table by a transverse ridge?
A. maxillary first
B. mandibular first
C. maxillary second
D. mandibular second


Is there anyone can help? Thx!!!

---

Members don't see this ad.

 

[oasiswhy]

Anyone can help.....?

 

[Basler30]

1.
Direct lateral excursion to the right.

The distofacial cusp of the right mandibular first molar occludes in the central fossa of the right maxillary first molar and moves through the facial groove of the maxillary first molar in a right lateral excursion.

 

[mentlegen]

Number 2 is malocclusion, most likely due to an anterior open bite. Otherwise, the mammelons would have worn down to the incisal ridge as they normally do.

 

[oasiswhy]

1.
Direct lateral excursion to the right.

The distofacial cusp of the right mandibular first molar occludes in the central fossa of the right maxillary first molar and moves through the facial groove of the maxillary first molar in a right lateral excursion.

Thank you for your explanation! That is correct! But what about lateral-protrusive excursion to the right? What is the differences between these two movements?

 

[oasiswhy]

Number 2 is malocclusion, most likely due to an anterior open bite. Otherwise, the mammelons would have worn down to the incisal ridge as they normally do.

Got it! Thank you very much!!

 

[kingbee888]

Hi, guys!
There are several questions for NBDE Part I. Really need your help...

1. Which of the following occurs when the distofacial cusp of a permanent mandibular right first molar moves through the facial groove from the central fossa of the maxillary right first molar?
A. direct lateral excursion to the right
B. lateral-protrusive excursion to the right

A. The distofacial cusp of the mandibular right molar rests near the central pit of the maxillary right first molar. In order to move to the central fossa, it would have to make a direct right lateral excursive movement.

PS: What is the difference between A and B?

Lateral-protrusive excursion is not a specific movement I'm familiar with. I assume its a combination of protrusive and laterotrusive movement. For ex, moving the distofacial cusp of the mandibular right molar to the mesiobuccal cusp of the right maxillary molar

2. Under normal conditions, the presence of mamelons in a 14-year-old patient is indicative of
A. fluorosis
B. malnutrition
C. malformation
D. malocclusion
E. enamel composition

D. More specifically open bite. Mamelons disappear over time through normal occlusal wear. If the teeth never meet, as with the case with anterior open bite, the mamelons will never wear.

3. In a maxillary canine, which is greater, the mesiodistal measurement or the faciolingual measurement?

This is a bit tricky. From the incisal view the shape of the crown is an asymmetrical diamond that is this thicker faciolingually on the mesial half but thinner faciolingually on the distal half. Otherwise it looks about the same.

4. In which of the following molars is the mesial fossa most distinctly separated from the remainder of the occlusal table by a transverse ridge?
A. maxillary first
B. mandibular first
C. maxillary second
D. mandibular second

D. The occlusal table of the mandibular second molar is rectangular with the 4 cusps forming the corners. This creates prominent transverse ridges that almost separate the mesial, central, and distal fossa (fossas? fossae?)

Is there anyone can help? Thx!!!

My answers in bold

 

[oasiswhy]

My answers in bold

Thank you very much!!!