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Why do some crowns turn black?
Started by toysareus
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Are we talking about crowns of teeth, or teeth that have been crowned?
Crowns (porcelin, pfm, gold etc) i have not heard turn black but i would have to guess corrosion/oxidation of the metals. Amalgams can turn black for that reason.
Isn't this poster the one touting toymed endlessly?
Crowns (porcelin, pfm, gold etc) i have not heard turn black but i would have to guess corrosion/oxidation of the metals. Amalgams can turn black for that reason.
Isn't this poster the one touting toymed endlessly?
OK people,a clinical talk....I love talking shop....any way here are my explainations for both situations:
1)Natural teeth:
-on losing vitality, mainly due to trauma, could be because of decay
-excessive use of mouthwash,specially hydrogen peroxide.Not really black but almost there
-stains,tartar etc
2)PFM crowns:
first thing.....they don't turn black,they start appearing black. this is becausing of thinning of the ceramic layer.This mainly happens when the tooth is under-reduced.Then the thickness of the ceramic has to be compromised upen,as that of the metal has to be sufficient to withstand strength.
sometimes they appear black at the gingical margin.MAinly happens if margin is not sub-gingivally placed in endo treated teeth.
Corrosion of the metal and amalgam is also a possible reason.
If amalgam is used for post-rc filling in place of resin/GIC and a crown not made,the tooth appears black due to leakage of mercury into the dentinal tubules.
does this solve your doubts?
1)Natural teeth:
-on losing vitality, mainly due to trauma, could be because of decay
-excessive use of mouthwash,specially hydrogen peroxide.Not really black but almost there
-stains,tartar etc
2)PFM crowns:
first thing.....they don't turn black,they start appearing black. this is becausing of thinning of the ceramic layer.This mainly happens when the tooth is under-reduced.Then the thickness of the ceramic has to be compromised upen,as that of the metal has to be sufficient to withstand strength.
sometimes they appear black at the gingical margin.MAinly happens if margin is not sub-gingivally placed in endo treated teeth.
Corrosion of the metal and amalgam is also a possible reason.
If amalgam is used for post-rc filling in place of resin/GIC and a crown not made,the tooth appears black due to leakage of mercury into the dentinal tubules.
does this solve your doubts?
GPG, nice post
If a patient has had root canal therapy it is likely that the natural crown may discolor. This may happen if the canals are not cleaned out thouroughly. Internal bleaching is a process that is used that may turn the natural crown back to a lighter shade.
If a patient has had root canal therapy it is likely that the natural crown may discolor. This may happen if the canals are not cleaned out thouroughly. Internal bleaching is a process that is used that may turn the natural crown back to a lighter shade.
thanks for the compliment.....
I agree with you when you say that it is the natural crown and not the prosthesis which becomes black after RC. How ever bleaching I feel is a temporary solution as we have to do it again every 6 months. Hence a Sub-gingival margin is a must. Also the recession of the gingival margin exposes the tooth structure which then gets decayed again giving it a black appearance.
A better solution,albeit temporary, would be to remove the decay and place a composite restoration over that area using an opaque shade or a opaquer beneath the compo.
gpg
I agree with you when you say that it is the natural crown and not the prosthesis which becomes black after RC. How ever bleaching I feel is a temporary solution as we have to do it again every 6 months. Hence a Sub-gingival margin is a must. Also the recession of the gingival margin exposes the tooth structure which then gets decayed again giving it a black appearance.
A better solution,albeit temporary, would be to remove the decay and place a composite restoration over that area using an opaque shade or a opaquer beneath the compo.
gpg
