A porcelain crown is a basic prosthetic device that is intended to serve as a replacement for the natural tooth crown, thus improving the desired appearance and function.
In what cases would we choose a porcelain crown as a prosthetic solution:
1. Teeth whose natural crowns have been extensively ruined due to caries, or teeth after root canal treatment, will be restored using a porcelain crown. The function of the crown in this case is to restore functioning and appearance, but it also has a role of protecting the tooth remaining after the damage caused by caries.
2. Weakened teeth due to extensive previous restorations.
3. Repair of grinded teeth to restore functioning and appearance.
4. As part of a rehabilitation plan for repairing the improper position of teeth, such as twisted or over-erupted teeth.
5. In cases of a missing tooth, adjacent teeth may be used as abutments for a bridge (multiple connected teeth) to replace the missing tooth (a suspended unit or pontic).
6. Replacement of missing teeth on implants.
1. Cast crown – a crown wholly made of metal without porcelain. Used for restoring functioning only, mostly in rear areas in cases in which there is not enough room for a porcelain crown.
2. Porcelain fused to metal crown – the crown has two parts: a metal cap and a porcelain coating that is fused to it. The metal cap is fitted to the shape of the prepared (ground) tooth. The metal dome may be made using various metal alloys (base, semi-noble and noble). Over the metal dome, a special oven is used to fuse porcelain so that the tooth appears esthetic on the outside. There are cases in which the metal margins of the crown become exposed over time due to irritation of the gums, resulting in a “grayish” halo.
3. Full porcelain crown – crowns of this type contain no metal at all.
There are various types of crowns from the family and we will review the two main families:
Zirconia crown – Zirconia is an oxide of the metal Zirconium, and oxidation gives the substance ceramic and esthetic properties. On the one hand, zirconia is as hard and strong as metal and on the other hand it is esthetic with the tooth’s color. Preparing the crown requires preparing a very thin (as thin as possible) Zirconia cap, with porcelain fused above it. Zirconia crowns excel in high esthetics and an excellent fit to the gums. In recent years, technology has allowed for creation of a crown that is wholly made of zirconia, a monolithic crown (used as an esthetic replacement to the cast crowns mentioned earlier – the esthetic advantages of zirconia without compromising on strength), or a crown that is mostly made of zirconia and only its front is coated with porcelain (making the most of the zirconia’s strength advantages).
An example of use of a zirconia crown
In this case, the central incisor has had a root canal treatment and a crown must be fitted to it.
In addition, the patient asked to have the gaps between her teeth (diastemas) closed and the position and color corrected. Therefore, we chose a zirconia crown in this case
for a central incisor with three porcelain coatings to obtain a perfect smile appearance.
In this case, a single crown on a central incisor had been made years ago, the crown has a metallic base that started to be exposed over the years.
The crown was replaced with a non-metallic esthetic zirconia crown.
e.max crown – e.max is a porcelain that has been significantly strengthened in its fabrication process, resulting in a material that on the one hand is very esthetic and on the other hand strong. The entire crown made be made of e.max (monolithic) or alternatively an e.max cap can be made and coated with ordinary porcelain.
An example of using an e.max type crown
Done by Dr. Meir Angi. Technician: Ilan Brosh
|Before: upper right central incisor after root canal treatment with a temporary crown and the adjoining tooth with a poorly done laminate veneer.||After: right tooth has been restored using an e.max crown and the adjoining tooth using an e.max porcelain laminate veneer.|
Examples of cases of prosthetic rehabilitation combining restoration with a zirconia crown and EMAX porcelain coating