How can you distinguish between a dental crown and a porcelain veneer?
A fundamental difference between porcelain veneers and dental crowns is the amount of a tooth's surface each respective type of dental restoration covers over. Dental crowns typically encase an entire tooth whereas porcelain veneers only cover over the front side of a tooth (the side that shows when the person smiles).
More details about distinguishing dental crowns.
As we have just mentioned, dental crowns typically cover over and entirely encase the tooth on which they are cemented. When preparing a tooth for a dental crown a dentist will grind down all sides of the tooth so to reduce its overall size, and also to transform the tooth into a tapered shape. The idea is that the dental crown that is made for this tooth will be cemented into place over this tapered nub, thus providing a new contour and cosmetic appearance for the tooth.
The amount of tooth reduction needed for a dental crown depends on a several factors. Of course the tooth will need to be trimmed at least as much as the thickness of the crown being made. This thickness is usually on the order of 2 millimeters or more (2 millimeters is just slightly greater than one sixteenth of an inch), however the specific amount of reduction is dictated by the materials that will be used to create the crown: porcelain (ceramic), metal, or a combination of both.
Another factor is related to the fact that there is some idealized surface shape that the dentist is trying to achieve for the tooth (related to both cosmetic and functional concerns). The dictates of both of these concerns come into play when the dentist determines how much they must reduce the tooth's size when preparing it for the dental crown.
How do porcelain veneers differ from dental crowns?
In comparison to a dental crown, the classic porcelain veneer is a wafer thin shell of ceramic that is bonded onto the front side of a tooth. Whereas a dental crown covers over and encases the entire tooth, a porcelain veneer just covers over the side of the tooth that shows when the person smiles. Dental crowns and porcelain veneers also differ by way of their relative thickness. The classic porcelain veneer will measure 1 millimeter in thickness or less, as opposed to a dental crown that typically measures 2 millimeters or more.
These characteristics together mean that significantly less tooth reduction is needed when a dentist prepares a tooth for a porcelain veneer as opposed to when a dental crown is made. This is a very positive thing. Less sound tooth structure is sacrificed. The preparation process is less traumatic for the tooth.
The grey area that lies between porcelain veneers and dental crowns.
There can be a fair amount of uncertainty when trying to determine if a particular dental restoration is a porcelain veneer or a dental crown. It can be that the dentist will feel that circumstances are such that a porcelain veneer needs to be much thicker and cover over a larger percentage of a tooth than is characteristic of the classic form of this technique. Taken to an extreme, a "porcelain veneer" might be very thick (2mm or more) and cover over even as much as 3/4th's of a tooth's surface. At this point the question might be, is this restoration really a porcelain veneer or should it now be considered a dental crown (or a "three quarters" dental crown)?
This type of variation, or at least the potential for it, is the reason why in our cosmetic dentistry treatment plan discussions we are typically vague in stating whether a porcelain veneer or else a dental crown would be needed to produce the type of result we have illustrated. We realize it is up to the dentist performing the dental treatment to make this determination, not us. Additionally, the precise term used to refer to a dental restoration is relatively less important than the clinical purposes it fills.
Comparing characteristics of dental crowns and porcelain veneers.
There are characteristics associated with both porcelain veneers and dental crowns that, in general, make one or the other more suitable for certain situations. Here are some of the factors a dentist takes into consideration when determining which type of dental restoration would be the more ideal choice.
Dental Crowns:
- Can be used to produce significant color and shape changes for a tooth.
- Are often used to rebuild teeth that are badly broken or decayed.
- Are very strong. Dental crowns are a good choice in those situations where the tooth is subject to significant chewing and biting forces (occlusal forces) or else tooth clenching and grinding (bruxism).
- Require a significant amount of tooth reduction when made.
- Once a crown has been made for a tooth the tooth will always require a dental crown.
Porcelain Veneers:
- Can be used to produce significant color and minor shape changes for a tooth.
- Are placed on teeth whose underlying tooth structure is generally healthy and intact.
- Are strong but brittle. Porcelain veneers typically do best in those situations where the occlusal forces they are subject to are somewhat passive.
- Typically require much less tooth reduction than dental crowns.
- For all practical purposes, once a porcelain veneer has been made for a tooth the tooth will always require a veneering of some type, although this could be another porcelain veneer, possibly another form of tooth veneering, or else the tooth could be further reduced and a dental crown placed.
