Crowns and Caps, Inlays and Veneers
Several people have asked questions about what type of crown or cap is best and what is the difference between caps, crowns, inlays, and veneers and related issues. I'll try to give a non-technical review that can help in making appropriate decisions.
First, caps and crowns are the same things. Just different words. Inlays and veneers are basically "partial" caps. I'll explain more later.
Caps / Crowns
Caps are also called crowns and they are a very common type of restoration. To cap a tooth the tooth needs to be reshaped smaller all around to it can be covered by the cap so the end result is not larger than the tooth was, except for parts where the tooth needs to be made larger. For example a front tooth can be capped so that the cap is longer, or wider than the natural tooth was in order to make it look nicer.
Caps can be made using metal or not using metal. For the past 40 or 50 years, the most common type of cap was made with an inside covering, or coping, made of metal that fit the reshaped shape of the tooth. Porcelain was then baked onto the outer surface of the metal to create a tooth colored tooth. The metal used could be "base" metal - an inexpensive mix of non-precious metal that might contain nickel, cadmium, steel and other not very desirable metals. Many people had allergic reactions to these metals. If a dentist was willing to use a more expensive lab, he could request precious metals only. These caps would be made using some gold mixed with silver, paladium, platinum or any of a number of other metals that are not as likely to cause allergic type of reactions. It could contain just a little gold or it could be mostly gold. One type of cap contains a thin layer of pure gold. Generally the gold is alloyed with other metals to give it more strength. In some cases a cap can be made entirely of metal and of course it looks like metal - gold or silver in color - and is used where highest strength is most important and appearance is not.
Caps can also be made of metal-free materials that have been available for many years, but in recent years new non-metal materials have been developed that are much stronger - some rivaling the strength of metal! In recent years I have rarely made caps with any metal in them.
Porcelain fused over metal crowns
Caps made of metal with porcelain baked over the surface - porcelain fused to metal [PFM] - work well but have some shortcomings. Esthetically it is difficult to make this type of crown in a way that looks very natural. Because the metal is very dark in color and is totally opaque, the porcelain has to be quite opaque to cover it and not let the dark metal show through. Compared to natural teeth these caps usually look opaque and less "alive". There are some excellent lab technicians that can make these crowns look quite realistic by clever use of porcelain coloring and layering. The cost is higher for this kind of craftsmanship and labor.
Another problem with these PFM's that as the porcelain gets thin at the edge, the metal starts to show so that usually with these PFM's there is a dark blue or black discoloration at the gumline if the cap fits under the gumline. If the gum shrinks back a little bit, the dark edge can be seen as a black line and is not very attractive.
PFM's also suffer from a problem with the porcelain fracturing off - debonding - from the underlying metal. The process of fusing the porcelain to the metal is very critical and subject to manufacturing errors and to stresses from biting and grinding.
When a missing tooth needs to be replaced it can be replaced by a "fixed" [not removable] bridge or by a removable bridge [partial denture]. It can also now be often replaced by an implant. I discuss implants in another article on this website. Basically a fixed bridge is made by capping a tooth or two in front of and in back of the space where the tooth is missing. Caps are made for the teeth on either side of the space and a dummy cap [or caps] is made for the missing tooth or teeth. The caps and the dummy cap[s] are all attached to each other so that when the caps are cemented into place, they hold the dummy cap[s] in the space just passively sitting on the gum. If done artistically, it can look like the dummy cap[s] really are growing out of the gums.
Crowns can be made metal-free using porcelains. While porcelain crowns have been available for a great many years, they suffered from low strength and were easily broken. But they were VERY beautiful and lifelike!
Fortunately, in very recent years, high strength porcelains have become available so that beautiful AND strong AND metal free crowns can be made. My favorites are lithium disilicate [common brand name eMax], and zirconia [common brand name BruxZir]. Technically zirconium is a metal but it does not act like a metal or look like metal and is non reactive to the point that it is used to make medical implants and artificial joints. Zirconia crowns are VERY strong and almost impossible to break. They don't look quite as natural and pretty as lithium disilicate but for back teeth they look very good. In fact they are sometimes being used for front teeth and they look quite good. But for optimal esthetics along with very good strength the lithium disilicates are a great choice.
Inlays are sort of "partial caps". The parts of the tooth that need to be rebuilt because of breakage, wear, decay, or for cosmetic reasons, can be replaced and rebuilt with an inlay without grinding down the entire tooth all around as is done for a cap. It is therefore much more conservative in terms of tooth removal. Generally natural tooth is the best material for health of the gums and if the tooth is in good shape and good color, it is nicer than most artificial materials. And less grinding is less trauma to you and to your tooth. Inlays can be made of gold which is very good and strong but most people now prefer tooth colored porcelain or composite. The lithium disilicate mentioned above is a very good material for inlays. Composite is also very good but it is not as strong and wears more quickly; however it is very kind and gentle to the tooth and can be repaired in several ways more easily than porcelain in the event of new decay or a small chip or crack.
Veneers are really a sort of partial cap or inlay. If you think of an inlay getting larger and larger and covering more and more of a tooth's surface, it eventually becomes a cap. So it is with a veneer. Mostly, a veneer covers and rebuilds the front surface of a tooth, and usually on teeth in the front of the mouth - the teeth that are seen in a big smile. Sometimes the veneer is only on the front surface and sometimes it wraps over the biting edge and or part way or all the way inbetween the teeth.
Veneers are usually made of porcelain and at this time - March 2013 - lithium disilicate is a very common and good choice due to its strength and esthetic qualities.
Many people have heard of and sometimes ask for "Lumineers" because of the heavy promotional infomercials that have been done in magazines and TV ads. They advertize as "drill-free and needle-free", which of course sounds great. The reality is that they are just another brand name of veneer with no special qualities that I am aware of. While they promote doing Lumineers drill-free and needle-free, rarely is that possible without making the end result bulky and too opaque looking. This is a look we dentists mockingly refer to as looking like "Chicklets" for obvious reasons. Any brand of veneer can be done drill and needle free, like when the natural teeth are too small and what is needed is to make the teeth thicker and wider and longer. This works if you have too small teeth especially with spaces between them. Almost all the time, however, at least SOME drilling needs to be done to end up with a pretty, natural looking result. So don't get hung up on a "brand name".
I hope this article has helped answer most of your questions about caps, crowns, inlays and veneers!
Michael C. Goldman, DDS
General and Cosmetic Dentistry
3815 East-West Highway
Chevy Chase, Maryland 20815 Phone (301) 656-6171
More info about the following is available if you select "topics".
Holistic dentistry is an approach to dental treatment, primarily caring for patients' health and safety from both a conventional as well as "alternative healthcare" point of view. It is sometimes called "biological" dentistry or "biocompatible" dentistry. In it's fullest sense, I believe it acknowledges and deals with the mind, body and spirit of the patient, not just his or her "teeth". See Topics / Info.....
Cosmetic dentistry is about doing quality , esthetic dentistry in a way that looks natural to begin with, and furthermore, can even improve one's attractiveness through techniques such as bonding, bleaching, veneers, caps, implants and more. It can be like "instant orthodontics" in correcting crooked, twisted or misplaced teeth in many instances. Dark or mis-shapen teeth can be restored. Smiles that lack youthful vigor or beauty can be revitalized! See Topics / Info..
In holistic dentistry there is an effort to find biocompatible materials to use to reduce toxicity for everyone, especially the chemically sensitive. Amalgam use is avoided in holistic dentistry (" amalgam free" or "mercury free") due to concern about possible toxicity problems. Amalgam removal and replacement with natural-looking bonded materials is a common holistic dentistry treatment as well as a common cosmetic dentistry treatment. Detoxification, especially of residual mercury deposits in body tissues from amalgams is often done. Root canals are controversial in holistic dentsitry and are discussed under topics. And much more....
Bleaching, veneers, bonding, caps, bridges, and implants are cosmetic dentistry treatments that are also discussed in Cosmetic Dentistry, and more...