>>How can I tell the difference between crack and craze lines? How do
>>these crack lines form? Does loss of one tooth produce too much
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> this a sleeping occurance which the patient can not detect they are doing
> until a dentist points out the damage.
I have routinely seen these radiating out from amalgams of various
signs with absolutely no other signs of parafunction. Not saying that
just because I can't see it means it ain't there--but considering the
well-known setting expansion of amalgam, together with differences in
coefficients of thermal expansion between tooth structure and
restorative materials, I think it might be overdoing it to say that
"all" cracks should be considered the result of parafunction.
Steve

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Mark & Steven Bornfeld DDS
http://www.dentaltwins.com
Brooklyn, NY
718-258-5001
Amatus Cremona - 27 Feb 2007 16:49 GMT
Remember that all but the very newest composites expanded thermally,more
than amalgams did on oxidization. The resins just start to decay before the
fractures appear. The alloy keeps trying to reseal through oxidation.

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Amatus
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>>>How can I tell the difference between crack and craze lines? How do
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>
> Steve
Dartos - 27 Feb 2007 17:01 GMT
How can lots of mine still work after 20+ years?
D
The resins just start to decay before the
> fractures appear.
Amatus Cremona - 27 Feb 2007 17:46 GMT
Not saying they don't last, I am pointing out why the ones that fail often
do not show the same radiating fracture lines in the parafunctional patient.

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Amatus
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> How can lots of mine still work after 20+ years?
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> The resins just start to decay before the
>> fractures appear.
Newbie - 27 Feb 2007 18:05 GMT
>>>How can I tell the difference between crack and craze lines? How do
>>>these crack lines form? Does loss of one tooth produce too much
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>
>Steve
Also there is the occurrence of microfracturing cause by
the bur itself. 557's are notorious for causing these fractures
Quit using them shortly after starting to use magnification.
Could actually see the fractures (craze linew) as they were
being caused.
Mark & Steven Bornfeld - 27 Feb 2007 18:18 GMT
>>>>How can I tell the difference between crack and craze lines? How do
>>>>these crack lines form? Does loss of one tooth produce too much
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> Could actually see the fractures (craze linew) as they were
> being caused.
I've heard this and it seems to make sense. Perhaps I'm just not
looking closely enough.
Steve

Signature
Mark & Steven Bornfeld DDS
http://www.dentaltwins.com
Brooklyn, NY
718-258-5001
Newbie - 27 Feb 2007 19:24 GMT
>>>>>How can I tell the difference between crack and craze lines? How do
>>>>>these crack lines form? Does loss of one tooth produce too much
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>
>Steve
It seems to be caused by the sharp angle where the end cutting
portion of the bur meets the side cutting portion.
Seems to be straight fissure and straight fissure cross-cut as
the worst offenders. I don't use them any more, and tend
to 'section' an old restoration rather than grind it out.
Am using 331L and 331's as my workhorses.
Amatus Cremona - 27 Feb 2007 18:42 GMT
Personally, I have never used cross-cut fissure burs to cut teeth. (Except
for surgical burs.)
I like burs to shatter amalgam out of prep's, and diamonds to refine the
walls. Burs tend to vibrate a bit. You can use that vibration to help
"chatter" an old restoration and get out of the prep without having to grind
against the walls of the tooth. Just switch to a diamond after all the old
stuff is out.

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Amatus
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>
>>>>How can I tell the difference between crack and craze lines? How do
[quoted text clipped - 30 lines]
> Could actually see the fractures (craze linew) as they were
> being caused.