The first thing a patient should know is when a dental crown should be used by a dentist. Dental crowns are used in situations where the teeth are weak, worn and possibly broken or fractured. These are all situations where a dentist would use a dental crown.
Crowns have been around for a very long time. Because of advances in technology, the process has been streamlined down to other types of restorations such as onlays and emax restorations. When a dentist decides to use a dental crown, it is for the specific reason of trying to re-strengthen a tooth that is very weak. The dentist is aiming for long term success with the tooth.
Emax is a specific type of porcelain called lithium disilicate and it is basically a block of porcelain. Because it is a block of porcelain as opposed to one that the ceramic artist or dental technician creates by hand, the block increases the strength factor of the material. Lithium disilicate is hard porcelain to begin with and that allows for its inherent strength to be kept with the restoration. With emax, there is no core material that needs to stay with this material because all the strength is built within the porcelain. EMax can be used as a core material whereby porcelain can be layered on the surface to increase the esthetic value of restoration for anterior eMax resto
Zirconia is an interesting type of crown that has been used for the past eight to ten years continues to be used today. Most people know the phrase “cubic zirconia.” It is like a diamond substitute used in jewelry. The material used by dentists is not in the cubic form. It is in a form known as a tetragonal form that still has the hardness of zirconia but can be manipulated and used as a core material for dentistry. Instead of having to use metal as a core material for the strength of the crown, dentists are able to have a white material such as the zirconia. This material gets away from the metal aspect of dentistry. Since zirconia is a very hard substance, it is able to withstand a lot of the pressures caused by chewing.
Pure zirconia can be used as a crown and many dentists use this under the brand name “BruxZir crowns”. BruxZir crowns are primarily for people who have a lot of strength in their bite. People who do a lot of bruxing (teeth grinding or clenching) are in need of some material that is extremely strong. Pure zirconia crowns are very popular for that type of situation because these patients could break up restorations (including emax restorations) with their grinding and clenching. They are in need of extreme strength with these restorations. In the past, all these patients could use was metal on the surface. However, patients do not want to see metal now and that is why pure zirconia crowns are very popular. Patients are able to have something white back there instead of something that is gold.
Zirconia and emax can be used on the front teeth. However, zirconia cannot be used as a veneer material. It can only be used as a crown material. The one thing about zirconia that is still being researched is its ability to bond to tooth structure. There are people who say zirconia can be bonded to teeth but there is not enough evidence. Emax can be used as a veneer form and can be a very beautiful restoration when done correctly.
Zirconia and emax can both be used on front teeth but zirconia has to be in a crown form. Zirconia needs to have a micromechanical retention fit on the tooth which should be in the form of a crown. From there, the dentist can cement on the zirconia restoration.
The choice of which one to use depends on the individual patient and the strength factors. If a tooth is reasonably strong and a patient does not have a super hard bite, emax restorations would probably be the best way to go for the best strength and beauty.