Question on lateral movement of the mandible

Discussion in 'NBDE Exams & Licensure Exams' started by wireless_doc, Jul 25, 2006.

  1. wireless_doc

    wireless_doc Member
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    Question: The arrows indicate the direction of movement of the mandibular teeth over the maxillary teeth during this mandibular movement. Which movement is this?
    Answer: Right lateral movement of working side.

    Could someone please explain? I thought it would be the left lateral movement.

    Also on the back of the card, it states if arrows are relatively straight, pointing buccal, they indicate right working side. Is this always true? Does it matter if the question states movement of mandible relative to maxillary or maxillary relative to mandible?

    Thanks.
     

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  2. Typo

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    Here's how I understand it: The picture is of the maxillary right molars and premolars. Turn the card so that the teeth are facing the direction they would in your mouth, and then imagine the mandible moving in the direction of the arrows. That makes it a right working movement.

    If it's the working side, the mandible does what's called a Bennett shift, I think, which is moving immediately to the right. The non-working side does more sliding, so its arrows would be pointed toward the palate and anteriorly.
     
  3. wireless_doc

    wireless_doc Member
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    Thanks for replying. Why do you think those are the maxillary teeth? I thought those were mandibular. I'm not seeing the cusp of carabelli. That was what confused me. If those were the maxillary, then it makes sense.

    FYI:
    . Non-working side: goes downward, forward and medially
    . Working side: moves laterally (generally rotates about a vertical axis and translates laterally.) Arrows point posteriorly.
     
  4. Typo

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    I see what you're saying, I was thinking that too. Considering that the cusp of Carabelli isn't always present, though, I think that it's more likely those are the maxillary teeth. Here's why: There is no 5th (distal) cusp on the first molar, and the plus-shaped, symmetrical pattern you see on a mandibular second molar is definitely not there. Also, the maxillary molars have wimpy distolingual cusps, which seems to be the case in that picture. That's my reasoning.

    Thanks for the FYI - that's from the decks, right?
     
  5. Prosdoc

    Prosdoc New Member

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    Those are definitly right maxillary posterior teeth. Look at the large ML cusp on the first molar. That being the case, the arrows indicate the movement of the mandibular arch. Here that would mean than the mandibular teeth are moving towards the right side. Right side mand. teeth moving to the right = working side. If the arrows were pointing to the left, the answer would be left lateral movement, non-working side. If they were pointed forward, that would indicate a protrusive movement, and if the arrows were pointing backwards, that would mean retrusive movement. Hope that helps
     
  6. wireless_doc

    wireless_doc Member
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    Thanks. I haven't got to review the tooth part yet. But what you're saying makes sense. Yes, those FYIs are for the decks.
     
  7. DrAngie

    DrAngie Junior Member
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    If looking at a picture if the arrow is pointing straight mesial (arrow is mand teeth) or distal (max) it is always protrusive. Straight buccal (mand) or lingual (max) is working side movement and an arrow pointing at an angle mesiolingual (mand) or distobuccal (max) is a non-working side movement (the mandible is moving downward, forward, and mesially). Looking at the occlusal pattern these are max teeth but it is a piss-poor picture (look at the 1PM). Also, remember that the arrow is always indicating the cusps of teeth on the opposite arch. Using these pictures are great tools, but you need to be able to verbalize what is going on as well because there are NO pictures on the actual board. Also, there are errors on some of the dental decks so you might want to look some things up.
     
  8. AU INLAY

    AU INLAY Junior Member

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    Bad picture indeed (it looks mandibular), but the only way it makes sence is to assume the teeth are maxillary - afterall, the question states that.

    BTW, in a previous reply, someone said Bennett movement was a working side phenomenon. This is incorrect. Bennett movement (which is comprised of immediate and progressive side shifts and gives us the Bennett angle) always occurs on the orbiting condyle - the NON-WORKING SIDE. As viewed from the horizontal plane, this movement is medial, from the sagittal plane it is downard.
     
  9. AU INLAY

    AU INLAY Junior Member

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    I think you meant to say: downward, forward, and MEDIALLY, not mesially.
     
  10. King Tut

    King Tut senior member
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    Hi,
    does anyone have the decks?
    Thanks
    king Tut
     

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