Porcelain dental crowns are often used when a large portion of the tooth structure has been lost. The loss can be due to breakage, tooth decay, or a large filling has failed.
We prefer to use ceramic versions over those made with metal. All-ceramic versions are generally more aesthetic. The black line at the gum line of crowns containing metal won’t develop. Ceramic restorations can be made thinner requiring less tooth reduction. They will not stain or change color. Ceramics are more bio-compatible than metal which may reduce gum recession.
Types of porcelain crowns | How are they made?
E Max – layered
E Max crowns are the newest cosmetic porcelain. Like conventional porcelain on metal crowns, they are made with two layers. There is a strong and durable supporting layer called the coping. A lifelike top layer is applied on top of the coping by an ceramic artist to match the restoration to the natural teeth.
This is the preferred ceramic system for anterior teeth. E Max is both bio-compatible and has the long term wear pattern like that of enamel. It can be used for minimally prepared veneers or crowns as thin as 0.2mm. It makes beautiful restorations that are 2.5 to 3 times stronger than the other glass-ceramic systems used today.
E Max – Monolithic
E Max Monolithic is a one layer system using only the coping layer. The E Max coping has true-to-nature shade behavior and is beautiful on its own. It does not use the top layer and thus is more resistant to chipping. It is the custom top layer of porcelain that is the weak link in all porcelain crown systems. E Max monolithic is a good choice to create crowns suitable for nighttime bruxers or tooth grinders.
Zirconium crowns are considered to be the ultimate in strength. This ceramic is used to make one or two layer restorations. The coping is extremely strong but is opaque and ugly. Two layer versions can be made to be attractive but are no stronger than E Max layered. The base coping custom is milled and has a hand stacked feldspathic top layer. This top layer is used to make the restoration attractive and lifelike. The thicker the top layer the less you see of the coping underneath. More drilling allows the veneer to mask the opaque bright white coping.
These restorations can be beautiful when crafted by a master ceramist. This porcelain option is used commonly for bridges and implant abutments. Zirconium itself has a limited capability of being bonded and should not be used for veneers. There are many brands of this product and some have higher clinical success rates.
Should Zirconia crowns be used for front teeth?
Zirconium crown technology is still developing. The optics of the base coping material are improving quickly. Newer options are coming to market with more translucency and esthetic attractiveness. The newer versions soon to come to market will allow less drilling.
Do Zirconium crowns break?
Yes, everything can break including zirconium and natural teeth. A zirconium base coping is extremely strong. In fact much stronger than a natural tooth. The coping must be covered with weaker veneering porcelain to be pretty. This
veneering porcelain will chip. Zirconium is attractive to some dentists due to a false impression of superior strength.
The Strength of Monolithic Zirconium Restorations
Due to heavy marketing directly to dentists promising superior strength, many practitioners are choosing a base coping only option. These monolithic restorations can be very abusive to the opposing teeth. They also are not very aesthetic. The zirconium coping has the translucency and vitality of a toilet bowl. In other words, they are white and opaque. No matter what you hear or read, all dental restorations have a finite life span and eventually need replacement. They may not break but they still can leak and eventually decay. They can be very difficult to remove without hurting the underlying tooth. 100% Zirconium inlays and onlays are not recommended.
Empress crowns can be made with the appearance of natural teeth. Due to lack of strength, Empress is losing popularity. This ceramic has two layers, a base coping made of medium-strength pressed ceramic, and a weaker superficial glass layer. The top glass layer is hand stacked and fired on top of the pressed base coping. Blessed with only modest strength, Empress should never be used in grinders.
Many cosmetic dentists feel that this is the most attractive porcelain. This custom stacked one layer ceramic is difficult to work with. It requires the technician to have very high skills. Only high end dentists will use this ceramic system. Feldspathic choices cost more. These restorations are very technique sensitive to place and are much more costly to produce in the laboratory. These restorations have low to medium strength.
Cerec and Sirona | Trading Quality for Speed
Cerec and Sirona milling technology is growing in market share. The brand names Cerec and Sirona are “in the dental office” CAD milling machines. Onlays or caps are milled
from monolithic ceramic blocks. Monolithic means one layer and also one color. No natural tooth is one color. This type of restoration can be created in one visit. They are strong but they can only be customized by using surface stains. Surface staining is not life like. Surface stains wear off over time.
The popularity of these low priced milling machines is growing in average dental offices. There are three benefits that motivate dentists to use this inferior system. Cutting out the lab technician fees creates a financial incentive. The technology appears to be impressive to the patient. Trading quality for speed, it only takes one appointment to do a cap.
Are Porcelain Dental Crowns strong?
The strength is significantly stronger when a one layer porcelain system is used. Monolithic zirconium and E Max are the two strongest ceramic choices today. They are also the most popular. Zirconium is the strongest crown on the market at this time. When bonded properly to the tooth, both zirconium and E Max rival the strength of porcelain fused to metal crowns.
What does an All Porcelain Crown Cost?
The insurance industry tries to make dentistry a commodity. If a crown were a widget, then surely low price is best.
Crown costs vary with the time, expertise, and materials used. All three cost variables are determined by the quality level of the dental office and ceramist. Typically, a high end dentist will take more time, have better technique, and use better materials. They will work with a more expensive ceramist.
It is the ceramist who actually makes the crown and charges the dentist directly for his/her service. Lab fees for a single cap will vary widely from $25-$2500 for a single restoration. Obviously, so does the craftsmanship. The lab fee for a single all porcelain cap could be anywhere from $900 to $3500. Do not assume that the dentist charging $3000 is making any more money per crown than the dentist charging $2000.
Quality levels vary tremendously
A better version will look more natural. It will have a better bite, be stronger, last longer, fit better, and will not fray or snap your floss. The gum tissue will be healthier. The tooth underneath will be less likely to decay or leak.
The old adage “you get what you pay for” very often applies. Most dentists are trained to do one tooth at a time. General dentists are not trained to do complex cases. The level of difficulty goes up when multiple teeth need caps at the same time. Do your homework and get several opinions. Find a dentist that has the training and the experience. That dentist should do these procedures all of the time. They should have before and after photos of cosmetic dentistry to prove it.