easy but difficult question

[enobeno]

what is the strongest part of dentin ?

some of you may think that it is so easy to answer this question

but please think about it ..... and then answer

 

[Yah-E]

roughly 70% calcium hydroxyapatite (calcified), 18% collagen fibers, and 12% water. Based on this info, I would say that calcium hydroxyapatite would be the strongest and hardest part of dentin!

 

[enobeno]

i don't know if it really a difficult question or not
but anyway
Yah-E .... sure the hydroxyaptite is the strongest part ... because it is the only calsified structure in the dentin

but it is not exactly the answer

i will make it easier

is it a) mantle dentin
b) pretubular dentin
c) intertubular dentin
d) primary dentin
e) secondary dentin
f) tertitiary dentin
g) circumbalbale dentin

think about them ..... and try

 

[Yah-E]

I would have to say it's either the PERITUBULAR dentin because its high mineral contents OR it's the MANTLE dentin because it's right next to the DEJ and it is the first layer of dentin formed.

By the way, it's CIRCUMPULPAL dentin and not "circumbalbale" dentin.

 

[ItsGavinC]

Of course, I don't know as much as Yah-E in this catergory, but I'm also going to go with mantle dentin. The limited knowledge I have makes this seem like a correct decision, because the mantle dentin is deposited peripherally in the dental papilla beneath the enamel organ. Like Yah-E said, this happens at the onset of dentin formation. Seems like a wise choice.

By the way, what is the purpose of this question? It seems as though you have an answer in mind and are baiting us towards it.

 

[Yah-E]

Gavin,

I think this person is studying for the NBDE Part I board or something....this is definitely a board caliber question, especially the multiple choice answer format that (s)he had posted!

 

[enobeno]

Yah-E .........
as you said it is the pretubular dentin ......

but as we know that the hardness of dentin increase from the area near to the pulpal-predintin junction to the area near the DEJ ....
so it is the pretubular dentin which is present in the mantle dentin . ( that what i think )

but they say that the mantle dentin is the strongest part of dentin because it has more pretubular dentin than the inner portions of dentin ........


so what do you think .....what is the right answer ?