Buschang article review

[Chad Carter (Course Director)]

On Case #1 – you are correct. The max molar extruded less than expected.

On Case #2 you bring up an excellent point. How to estimate effects when they are giving us no measurements, just teeth outlines, and asking for us to guess? I found that guessing at the percentage of crown eruption (using the superimpostion and the tracing of the clinical crown height) and multiplying this by the average height of a molar gave me the “number” I was looking for. In Case #2 that would come out to about 3.5mm or more of eruption. At 0.9mm/yr average for a mandibular molar over the course of 2 years 8 months, we would expect about 2.5mm of eruption. So we got about 1mm more than expected.

Case-2-Buschang-Growth-Estimate.png 199 KB Image File - Click to view

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[Joti Kaler]

The equation is helpful! I always find myself squinting and guessing. So 7.5mm for eruption of molar. Do you have any similiar equation for the mesialization and the incisor?

[Chad Carter (Course Director)]

That’s interesting, So I think the incisal edge could be helpful here. The incisal edge of the max/man incisor templates appear about 2mm thick so then I’d ball park the AP movement thinking about how far that movement appears to be a multiple of that traced thickness.

[Antonia Alfonso-Pagan]

First of all, I’m happy to have subscribed to this course. You are all doing a superb job!

Could you please go over the skeletal changes expected with different cervical stages? For instance, during circumpubertal vs C5 (where only 5-10% of pubertal growth is expected). Could you use a sample case superimposition to go over these items in those instances? I appreciate it!

[Chad Carter (Course Director)]

Antonia, thank you for your kind words! We are so glad you’re here. I firmly believe this course is setup to help guid your studying, eliminate the overwhelming and secure success for your exam!

I’m going to post the Scammon growth curves related to Maxillary / Mandibular growth from Proffitt Chapter 4. On this I have marked where I think of CS relating to the Velocity of Height Growth.

Does this help a bit?

I don’t have a superimposition handy but I’ll dig through some cases at the office.

[Adedolapo Ayediran]

Could you please shed some more light on how you do this mathematically. Could you use the maxillary molar as an example?

If am understanding the example for the mandibular molar correctly; the 3.25mm is the actual eruption; versus what we expected 2.5mm from the predictions. So if I can mathematically deduce that then no need for eyeballing?

[Chad Carter (Course Director)]

Adedolapo,

You are correct. If you have all the numbers presented and do the math then there is no guess work. However, in the sample cases presented by the ABO there are no “measurements” given so that is when we are doing a little bit of “eyeballing” ourselves on the measurements.

[Adedolapo Ayediran]

Got it!, thanks

[Dr. Golden]

For Case #2:

The article stated that the maxilla displaced inferiorly and rotated anteriorly more than expected.

I see how the maxilla displaced inferiorly. But, can you explain how the maxilla rotated anteriorly more than expected.

As per the article, the maxilla should have 0.7mm/ year anterior movement. To me that looks like the maxilla moved less than expected.

Thanks!

[Chad Carter (Course Director)]

Interesting question, when looking at it again it seems that the PNS point stayed the same and ANS and A point moved so that would be a Clockwise rotation (anterior down rotating) of the maxilla in addition to the growth.

Keep ’em coming!

[Leah Stetzel]

I think for Case #2, I agree that the rotational aspect is treatment related AKA not expected from normal growth. But I also think ANS was held in the AP position (treatment effect) AKA I wouldve also expected ANS to move anteriorly more than it did, as Alice mentioned.

I am finding myself confused on the growth pattern of the maxilla as well. Please see screenshots below where it appears the article contradicts itself? In the figure, it shows ANS moving inferiorly 0.6mm whereas PNS only moves inferiorly 0.3mm. If the anterior moves inferiorly more than the posterior, this to me is clockwise (or backward) rotation. The article itself states “the posterior maxilla is displaced inferiorly more than the anterior maxilla (i.e., it rotates forward slightly).” I think it is clear from the picture that the posterior maxilla is displaced inferiorly LESS THAN the anterior maxilla.

Please let me know your thoughts on this.

Also, just to be extra clear on language, can you verify that posterior rotation = clockwise = backward rotation

anterior rotation = counterclockwise = forward rotation?

Thanks

[Chad Carter (Course Director)]

Leah, I’ve been mulling over how to reply on this.

First, I would say – good for reading for detail.

Second, the terms “rotation” “clockwise” and “counterclockwise” get super confusing. In addition, they vary if you have the patient facing left or right (some European cephs taken with patient facing left instead of facing right as we present in the course)

I’m going to think on it some more and get back with you. I don’t want to add further confusion but BOTTOM LINE landmark movements are key. That’s what we are given measurements for as a board reference.

[Leah Stetzel]

Thanks, Chad. I have been mulling over it myself and have kind of decided to just move on and focus on the fact that PNS moves inferiorly 0.3mm while ANS moves inferiorly 0.6mm.