I am going into debt. Robin, To answer your question about your porcelain crowns cracking, I need to give a little background information. There are two basic kinds of porcelain crowns , or caps as you call them, and then sub-categories. There are porcelain fused to metal crowns that practically never crack, and there are all-porcelain crowns which are strong enough for the front teeth but can crack sometimes when used on molars.
But now, even with all porcelain, there are zirconia ceramics that are extremely strong. And then there is a wide variety of patients, as far as the strength of their bites. Most practices will have a handful of those patients, and they can break a tooth clean off, but the porcelain fused to metal crown will stay intact. What I want to say with all of this is that, even with good dentists, there is often a learning curve of dealing with real patients where they do what they were taught in dental school but the patient still breaks things.
Our dentists will also work with you to treat the issue that caused the dental crown to become damaged, if needed. For example, we may recommend that patients who suffer from bruxism wear night guards to protect their new restorations from harm.
If you suspect you may have a damaged dental crown or simply want to better preserve your restoration, do not hesitate to contact our dental practice and schedule an appointment with one of our dentists. The hygenist was professional and did a great job with my cleaning. Thank you very much! What Is a Dental Crown? Causes of Damaged Dental Crowns There are numerous ways this type of restoration can become chipped, cracked, warped, or misaligned.
These include: Caries. If decay damages the enamel beneath the crown, the crown may become dislodged or begin to slip off of the tooth. An improper bite can put undue pressure on your crown, causing it to fracture, chip, or shift. The force of an accident or other oral trauma can chip, crack, or misalign your crown. Teeth grinding. Some patients suffer from a condition known as bruxism, in which they grind their teeth together due to stress, misalignment, or other oral problems.
This can wear down the chewing surface of or break a crown. Poor dental habits. It is said that you can drive a truck over one of these crowns without breaking it. Problem is the colors and translucence of Zirconia is not as good as the traditional porcelain crowns. They tend to look kind of fake if they are used for the front teeth. This is why Zirconia crowns are most often used for the back teeth.
The takeaway here is that there are many choices. Each offer their own advantages and disadvantages. The dentist must become an expert in the science of dental materials so that he or she can help advise the perfect choice of materials to be used in each specific case. The other takeaway is that it is very important for the patient to have these types of conversations with their dentists before their tooth is worked on.
The answer comes when I look into the crown and see the tooth structure that the crown was attached to is still cemented solidly in the crown. The tooth has broken off below the crown margin. This obviously cannot be simply cemented back onto the tooth. If a crown were made to fit a perfect cylinder it would have a natural retention when forced onto the cylinder which would be directly proportional to the height of the cylindrical walls.
For this reason the dentist tries to mill the tooth crown prep so that it is slightly less than a perfect cylinder, somewhat more like a slightly tapered cylinder or very slight cone shape to it. The more the cone shape the less the frictional retention. There are obviously going to be some differences in the technical skills of each dentist but if we disregard that, the other important consideration is this; the taller the parallel walls of the prepared tooth, the greater the frictional retention and vice versa.
The skilled and knowledgeable dentist will size up the tooth before he or she starts to drill and assess whether the prepped tooth cylinder will be tall enough have long enough parallel or nearly parallel walls to have sufficient frictional retention so that it will be able to withstand the anticipated forces of chewing on it. However, what really holds the crown in place is the cement that is used to cement glue the crown in place.
To date there are no cements glues that are strong enough to hold a flat crown onto a flat tooth prep. All crowns need some initial frictional retention first. No matter how good the initial fit and retention of a crown, over time the cement will eventually start to wash out from under the crown.
As soon as these small movements start they promote more cement to wash out. Before long the crown comes loose and falls out.
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