The life span of a dental crown: zirconia or metal-ceramic?

Sometimes, when we go to the dentist’s office, we have the dilemma of choosing between zirconium or metal-ceramic crowns (usually the latter are less expensive). The current tendency, when we can afford it, is to choose zirconium crowns, thinking that because they are more expensive they will be better or more appropriate. However, this is not exactly the case. For a crown to last for many years, many factors must concur, the material it is made of being the least important.

The lifespan of a dental crown

The most important thing for a crown to have a long, trouble-free life is that the root is healthy and has been properly endodontically treated; the latter depends on the good hands of the professional.

Another important factor is that the carving of the tooth to be crowned is done correctly and that the impression (measurement sent to the dental technician) has been perfectly taken. These two things also depend on the skill of the dentist or stomatologist who performs it.

No less important is the work of the dental technician to whom the impression is sent. The workshop must be able to make a well-fitting crown, with perfect contact points between the adjacent teeth (if food does not get in between them), color, staining and occlusal height, so that it does not stick incorrectly on the opposing tooth.

This indicates that in order to achieve a good crown, several factors and different people are involved. If any of this fails (regardless of the material used), the crown will not last, or food will get between the teeth, or the gums will be irritated (bleeding, bad breath).

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Is a zirconium or a metal-ceramic crown more esthetic?

A zirconium crown does not necessarily have to be more esthetic than a metal-ceramic crown and vice versa. It all depends on the stomatologist or dentist who endodontic, carves and takes the measurements, as well as on the skillful hands and artistic skills of the dental technician who makes it.

Although nowadays there are machines that help in the fabrication of the prosthesis, the final process is totally handmade, depending therefore on the skill and artistic sensitivity of the person who executes it.

The following is an example of a patient to whom we changed a zirconium crown (which was supposed to be very esthetic), which had been placed and which was excessively large, did not fit well to the gum, the dental tape got caught, and caused bad breath. Despite being zirconia, it looked much less natural than the made-up metal-ceramic crown, much better fitting, smaller to match the size of her molars and, moreover, aesthetically barely distinguishable from the previous tooth. It can also be seen that the other tooth, which still has a zirconia crown behind it, is much less natural than the metal-ceramic one and of an inappropriately large size.

Zirconia crowns can also be made to look very natural looking, but being a sintered ceramic material the fit that can be achieved is not as good as that of a metal that is cast or produced by CAD-CAM technique.

A good dental technician can make a zirconium crown or a ceramic crown equally esthetic, so that when placed they would not be distinguishable from each other. If the adaptation to the gingiva and the size are correct, the metal-ceramic will never show the neck of the tooth, or a dark line. If with the passage of time there is decalcification (the gum rises), the necks are exposed, and neither one nor the other will preserve the esthetics.