Which crown is the best type for patients?

 At the moment there are a number of types of crowns that dentists can choose. These include : Full cast gold, porcelain fused to gold, porcelain fused to precious metal, porcelain fused to non precious, feldspathic porcelain, empress porcelain, lithium disilicate, and zirconium crowns. In addition, some of these (lithium disilicate and zirconium) can be veneered with porcelain. Milled composite resin crowns are still another option.

The truth of the matter is that currently there is no one best crown. Each has some inherent advantages and disadvantages and all can provide extremely satisfactory restoration when properly executed by a competent clinician who is familiar with how to execute them. When I speak with my students at NYU dental school, I often am asked this question and I usually point out that what type of crown a dentist chooses is less important than how well he or she executes the procedures involves with ensuring that the crown is done correctly.  In dentistry all types of these crowns can be great, as long as they are used in the right situation by a dentist who knows how to successfully execute the procedures involves with preparing and impressioning  the tooth and then fitting and luting the crown after it comes back from the lab. Often it's not what type of crown we choose, but how well we  do it, that really matters the most.

 Of course I have my personal favorite crowns that often make for my patients ( Full cast gold, Porcelain fused to metal, Full thickness Zirconium, full thickness lithium disilicate and feldpathic porcelain crowns) but I tend to preferentially employ these in different clinical situations.

My favorite crown for second and third molars is full cast gold. It has a simple "feather edge preparation" (that tends to conserve tooth structure), is virtually unbreakable and is kind to the opposing teeth ( when placed opposing a natural tooth gold wears more than the opposing tooth structure. They aren't terribly esthetic (unless you are a rapper) and do eventually tend to wear out after ten to thirty years ( the occlusal surface slowly wears out when it is opposed by porcelain crowns or natural teeth).

For all other teeth Porcelain fused to metal crowns have been used reliably in all situations and still are a popular choice for single crowns and bridges. I tell patients these are a little like a creuset pot since they have porcelain bake over a metal substructure. They are really the swiss army knife of crowns since they may not be the best in all situations but they have the versatility that will allow them to be used in almost any clinical situation. In addition they can be designed to have metal placed where opposing teeth contact them ( for example on the linguals of maxillary teeth) and porcelain placed where esthetics are more important ( anywhere the crown is normally observed by someone other than the dentist).  

Porcelain fused to metal crowns are usually made using the lost wax technique to fabricate the metal portion and then a ceramicist shapes and bakes the porcelain on top of it. It is my opinion that they are more forgiving of little eccentricities in a tooth preparation. If a dentist includes a bevel retention can be increased even for many non ideal preparations.  They do present some compromises. While I have successfully creasted esthetic smiles that include pfms in esthetic zones, often these crowns are less tansluscent than restorations that do not have a metal substructure. When light is shined on these they can look more opaque than natural adjacent teeth. Accordingly in the front of patients mouths, I usually will choose a metal free crown except when lack of sound supergingival tooth structure requires me to include a bevel in my preparation or when I am fabricating a fixed bridge. 

Zirconium and lithium disilicate crowns  are increasingly popular. They contain no metal and and are relatively easy to fit and usually less expensive than porcelain fused to metal crowns. The zirconium and some of the lithium disilicate crowns can involve digital scanning and computer milling for their fabrication. ( the digital scanning can be used directly in the mouth or can be done by scanning a hard model in the lab).

Increasingly I have been using monolithic milled zirconium crowns in the posterior region. They have certain advantages over porcelain fused to metal crowns. I tend to prepare them with 45 degree chamfers ( these are similar to the bevels I use with my pfm crowns) and when the margins are thinned and polished using a special medium grit polisher, they are extremely kind to the gingiva. When I probe with a periodontal probe there is usually no bleeding around these crowns. I wish I could say the same for subgingivally placed pfm margins.

Also, partially because I carefully prep and impression the teeth involved, fitting seems easier and the lab bill is less as well. They work well, as long as the bite is carefully adjusted in both normal biting and in all excursions. Since Zirconium is harder than porcelain and teeth, some say that these types of crowns can cause some breakage of either the opposing or prepped teeth. I haven't personally experienced this with my patients Zirconium crowns. In addition the zirconium can be utilized with various amount of opacity ( translucent,  medium translucent, and opaque) and the medium and opaque versions can be used even if there are some dark parts of the preparation that might show through a more transluscent restoration ( feldpathic porcelain or lithium disilicate).  Normal dental cements can be used to lute these restorations. There is still some disagreement among clinicians on whether these crowns should be bonded in with composite luting cements.  

Because they are digitally fabricated , technicians usually dial in enough relief to make fitting simpler, but sometimes zirconium restorations are far from ideal for short preparations due to their lack of retension in these situations.

Sometimes lithium disilicate restorations are better for shorter preparations because they can be bonded in with composite cements. This is especially true for anterior restorations where often times preparations are short and have less surface area than posterior preparations. They are also better if a clinician over tapers a preparation (this decreases the retentiveness of a preparation). Ideal taper is 3-5 degrees, but some clinicians tend to routinely taper their preparations from 10-20 percent. In that situation, lithium disilicate is often the best choice . In addition lithium restorations tend to be strong and relatively resistant to breakage while being one of the most esthetic materials. If sufficient reduction is provided these restorations can be made even more esthetic by veneering them with feldspathic  porcelain . The feldspathic porcelain can be "characterize" to better match the various colors of the adjacent teeth.

Lastly are restorations made of just feldspathic porcelain. These can be the most esthetic of all the restorations and are commonly utilized to fabricate translucent veneers or crowns on anterior teeth. They require the least tooth preparation and  are especially good for patients whose anterior bites have a favoratble occlusion and are willing to wear night guards after their fabrication. While these crowns and veneers are the best look option, often they are also the most breakable and patients need to be cautioned about applying undue forces on their anterior teeth when biting in thing that crunch when they chew them ( bones, stale bagels, etc). I had an  old fashioned cemented porcelain jacket that lasted a long time until I broke them while trying to get meat off a steak bone.

As I pointed out all of these types of crowns are good when properly handled and in terms of ensuring their long term success, the most important factor is that the dentist employing them is well versed in the particulars of the crown he is making.  Most times dentists have one or two types of crowns that they routinely use and they are  comfortable using them. It's probably best to go a crown that your dentist is familiar with and  recommends. Information read on the internet  can be helpful ( this article included) but if one wants the best restoration that a dentist is capable of making, its often best to follow their suggestion , but  if you are not sure , feel free to seek a second opinion elsewhere.

from Ask Dr. Spindel - http://lspindelnycdds.blogspot.com/2021/02/which-crown-is-best-type-for-patients.html - http://lspindelnycdds.blogspot.com/