 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Medical Forum / General / Dentistry / April 2007Chipping crown
Hello, I seem to have a problem with ceramic crowns done on a first upper molar. I have so far done 3 Empress 2 crowns on this tooth and they always get sheared off on the front side towards the pre-molar. It's not a problem with the strength of the core but the external porcelain that always seems to break. Even though the dentist adjusted the bite very carefully, taking care to lower the vulnerable portion, it still broke within a few weeks. I wear a night guard regularly while sleeping since I've been known to grind my teeth but have occasionally forgotten to wear it. I have spoken with a few dentists and they have so far advised to leave it alone since the core is intact. I was wondering if the different types of porcelain used for the external portion of the crown are of differing strength. Is the external porcelain for say a PFM crown stronger than say that used for Empress 2 or Inceram? A dental technician I spoke to says they're all the same - even though the actual material used is different for different types of crowns, their strength is the same. How true is this? I am aware a full metal crown would never chip but I cannot accept the esthetics. Would it make a difference if I went for a PFM crown? Thanks in advance for any advice. If you are clenching on this cusp, you will break it no matter what. You could put gold there, but then the damaging stress will be transferred to the "neck" of the tooth. You need to stop the harmful habit, then you can restore the tooth with any material.  Signature/ Amatus / > Hello, > [quoted text clipped - 21 lines] > > Thanks in advance for any advice. > If you are clenching on this cusp, you will break it no matter what. You > could put gold there, but then the damaging stress will be transferred to > the "neck" of the tooth. You need to stop the harmful habit, then you can > restore the tooth with any material. IME, less than half of my patients really give a damn about their clenching and expect me to put something in their mouths that will withstand the abuse (which many somehow want to deny exists<sigh>). Standard PFMs are more resistant to fracture than Empress and the like. IMO, a porcelain occlusal surface would be a mistake in this case. I would recommend a porcelain facing only (plus an NTI of course). D I always want the patient to understand that *they* are putting enough force on this tooth to break it. If they continue to place this much force on the tooth, something will eventually give again. When it fails next time, do they want it to be simple or complex. A crown with a metal coping (or a full gold crown), will transfer the stress that would normally chip a cusp tip, to the neck of the tooth. This causes ditching at the margins as abfraction forces begin. Then, a deeper abfraction lesion forms. Too often, followed by the tooth breaking off at the gum line. Doesn't happen to all teeth, but happens to enough teeth to deserve discussion. Signature/ Amatus / > >> If you are clenching on this cusp, you will break it no matter what. You [quoted text clipped - 11 lines] > > D In the real world of most dental practices, the patient is going to blame the dentist if a restoration fails. Period. End of story. I still tell patients that they are exerting unusual stress on their teeth and that they need to do something to control it. Some listen, some don't. For me, it is better to have an *eventual* tooth failure than a restoration failure soon after treatment. I extract hundreds of teeth a year. This year, I will have extracted ONE tooth where the restoration survived over the tooth itself. This was a full gold crown on an upper second molar that had a root canal, but no post. The roots fractured. The crown did not break off at the gumline. It was 8-10 years old. JME, D > I always want the patient to understand that *they* are putting enough force > on this tooth to break it. If they continue to place this much force on the [quoted text clipped - 5 lines] > often, followed by the tooth breaking off at the gum line. Doesn't happen > to all teeth, but happens to enough teeth to deserve discussion. > > If you are clenching on this cusp, you will break it no matter what. You > > could put gold there, but then the damaging stress will be transferred to [quoted text clipped - 10 lines] > > D Since metal wears down faster than porcelain, won't the porcelain eventually be exposed and chip off, thanks to be my clenching? > Since metal wears down faster than porcelain, won't the porcelain > eventually be exposed and chip off, thanks to be my clenching? Not likely if it is designed correctly. Porcelain occlusal surfaces do two things. They abrade the opposing teeth/restorations, and they can fracture under clenching. Unless you address the clenching with an NTI and are totally faithful in wearing it, porcelain posterior restorations would never enter my treatment plan. Full metal casting would be the best alternative (IMO). D >If you are clenching on this cusp, you will break it no matter what. You >could put gold there, but then the damaging stress will be transferred to >the "neck" of the tooth. You need to stop the harmful habit, then you can >restore the tooth with any material. Can we use macerated frog tissue for restoration ? <g> You have to mix that particular material with cephalopod dermal scrapings to get it firm enough to use. Signature/ Amatus / > >>If you are clenching on this cusp, you will break it no matter what. You [quoted text clipped - 3 lines] > > Can we use macerated frog tissue for restoration ? <g> Tend to prefer cetacean adipose tissue as a stroma. >You have to mix that particular material with cephalopod dermal scrapings to >get it firm enough to use. [quoted text clipped - 5 lines] >> >> Can we use macerated frog tissue for restoration ? <g> Harder to see the articulating paper marks on that particular choice. Signature/ Amatus / > > Tend to prefer cetacean adipose tissue as a stroma. [quoted text clipped - 12 lines] >>> >>> Can we use macerated frog tissue for restoration ? <g> >You have to mix that particular material with cephalopod dermal scrapings to >get it firm enough to use. Of course you mean from dibranchiata >Hello, > [quoted text clipped - 21 lines] > >Thanks in advance for any advice. Sounds like there may need to be more occlusal reduction. As far as PFM, IMO Captek is the best choice for esthetics. I routinely use these on any tooth but tend to use all porcelain on anterior teeth. A Captek is an excellent choice for a first molar. > >Hello, > [quoted text clipped - 23 lines] > > Sounds like there may need to be more occlusal reduction. As I was saying, the dentist carefully filed down the tooth and was absolutely certain there was no contact with the lower teeth. Perhaps the stress in that area is somehow so great that with food acting as the filler, it weakens and then breaks off. The current crown sheared off while chewing on an apple. > As far as PFM, IMO Captek is the best choice for esthetics. > I routinely use these on any tooth but tend to use all porcelain > on anterior teeth. A Captek is an excellent choice for a first molar.- Hide quoted text - > > - Show quoted text - Chewing food will only break a tooth if it already so weak that any pressure at all will shear off a piece. Does not matter how hard the food is. The mandible flexes a fair amount. If you clench hard enough, you can sometimes flex the mandible enough to bring a tooth into contact that would not touch during normal dental adjustments. This is especially true in latero-protrusive movements. Signature/ Amatus / >> >> >Hello, [quoted text clipped - 37 lines] >> >> - Show quoted text - |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.