Crowns

Porcelain-to-Metal ⟩

This patient had a previous dentist place a crown on her left central incisor. She was obviously unhappy with the result. We remade her crown with porcelain fused to gold and obtained a beautiful result. Notice the gums are still slightly red since the photograph was taken the day the crown was inserted.

Here is another example of a PFMC to change the color and contours of a dark root canal treated tooth. All of her front teeth were natural, with no other crowns visible. Note the natural translucency of her teeth. We chose a PFMC since we needed to block out the underlying dark root. If I had used an all porcelain system, the darkness may have bled through, creating a poor result.

This patient had crowns on all of her posterior teeth, but her front teeth were all natural and unrestored with the exception of the bonding on this lateral incisor. This tooth was previously root canal treated and required both a post/core as well as a crown. The canine and premolar behind the crown demonstrate the opaqueness of unaesthetic crowns. We are planning on redoing these crowns in the future. Notice how the lateral incisor crown mimics the translucency and brilliance of her central incisor.

Porcelain Margins / Butt Crowns ⟩

This crown on the left central incisor demonstrates all of the bad aspects of ugly crowns. It is the wrong color, the wrong shape, and shows a dark black line at the crown margin. We removed this crown and fabricated a porcelain fused to metal crown with a porcelain butt margin as shown below.

In the photograph on the left you see the inside view of a crown. On the right photograph you see the front as it appears on a model which the lab uses to make the crown. Notice the dark metal on the inner aspect, which provides for an ideal fit of the crown to the underlying tooth. If the metal extended to the edge (margin), the black line present in the original crown would recur. Instead, we cut back the metal and applied shoulder porcelain to create a porcelain butt margin. Notice that this allows light to transmit through the neck of the tooth creating a much more esthetic result.

This is another example of a misshapen, bright crown with a dark margin at the gumline. It was replaced with a porcelain fused to metal crown with a porcelain butt margin. Notice the marked improvement in appearance.

And once again a crown which was too bright due to underpreparation of the tooth coupled with the wrong anatomy led this patient to replace her crown.

All Porcelain ⟩

In this case the patient's teeth were severely worn due to years of using a hard bristled tooth brush. He was tired of looking at the worn out teeth and he wanted a change. The two lateral incisors were not worn looking since they were porcelain fused to metal crowns placed by a previous dentist. I chose to place two porcelain laminates and two all porcelain crowns (In-Ceram), one one the right central incisor and one one the left canine. This case demonstrates how different techniques need to be matched in order to get a good esthetic result. It also demonstrates how the face and lips are truly needed in order to assess overall esthetic harmony. In the postoperative photograph it appears that the teeth slant and get smaller and this seems odd, but when you see that the lip is asymmetrical, but symmetrical with the teeth, the final look is esthetic harmony.

This patient had moderate periodontal disease which had been treated by her periodontist for years. It was under control and she was in an active three month recare schedule. She was unhappy with her smile and wished to have something done. Due to the severe overlapping positions of her teeth we chose to place In-Ceram Alumina crowns on two central incisors. The remaining teeth visible in her smile had porcelain laminates placed. She was very happy with the final result.

This patient also had a combination approach taken. She had two crowns, three porcelain laminates and a removable partial denture fabricated in order to enhance her smile.

Crowning or Capping a tooth is a longer lasting, although less conservative, treatment alternative that requires reducing the outer 1.5-2 millimeters of tooth in all dimensions in order to make space for a laboratory created tooth replacement. Although we would always prefer to save as much tooth structure as possible, it is not always feasible nor preferable for all situations. More severe corrections can be created by appropriate use of crowns. Despite their drawbacks, crowns can be beautifully sculpted works of art which can not be detected by even a trained eye.

There are many types of crowns on the market today, each with its pros and cons. Ask your dentist which is most appropriate for your situation. In this section you will see examples of porcelain fused to metal crowns, porcelain fused to metal crowns with porcelain margins and all ceramic crowns. Each has its place in cosmetic dentistry.

Porcelain fused to metal crowns (PFMCs) are the "gold standard" by which all crowns are measured as far as fit, strength and durability. They have been used for many years and have an excellent track record. The one problem with PFMCs has been their inability to esthetically emulate natural teeth. The main reason for this is the inherent nature of the materials. Teeth get their esthetics from their reflected as well as transmitted light through the multiple layers which comprise their structure. The blood supply in the center, the dentin layer, and the enamel matrix provide a dazzling array of optical effects which are impossible to replicate exactly with porcelain fused to metal crowns. The main reason for this is that the metal blocks out all light transmission through it's path and all light is then reflected only. There also needs to be an opaque layer of porcelain applied over the metal substructure in order to mask out the gray colored metals most commonly used. Frequently this opaque layer is visible in the final crown, unless enough tooth has been removed in order to create thick enough overlying porcelain to mask it too.

We have all seen bad PFM crowns. They stand out like a sore spot in a smile. They look too bright, frequently are misshapen, or have a dark line at the gumline. These crowns can easily be remade and with the knowledge and expertise available today, the new crowns can look as good as natural teeth. You will see some examples in the PFMC section.

Because of the need for esthetic crowns, many techniques have been developed to deal with certain situations. The second section, PFMCs with porcelain butt margins are a slight modification whereby the metal edge is removed from the metal substructure and it is replaced with a special kind of porcelain (shoulder porcelain), which extends down to the junction of the tooth and crown (the margin). In the past this technique was unavailable because porcelains shrank too much during the firing cycle, leaving the margins open. When a margin does not fit the underlying tooth intimately, the tooth is susceptible to caries and the crown will ultimately fail and need to be replaced. Shoulder porcelains were specially created, low shrinking ceramics which eliminate this problem when used properly. They give us the ability to create highly esthetic crowns, without dark margins, while providing the strength of porcelain fused to metal crowns.

All porcelain crowns have been around in many forms for years and years. They were commonly called Porcelain Jacket Crowns or PJCs. In Hollywood they were and are a common occurrence. When done well, they are hard to distinguish from natural teeth. Esthetically they have no equal. Unfortunately, they had a tendency to fracture due to crack propagation throughout the ceramic material as they were used. This problem had led us to develop newer ceramic systems which are either pressed into a mold in a molten state or Slip cast. The newest Pressed Ceramic systems are called Empress or Optimal. They have a high Leucite content, which prevents the microcracks from propagating. They are highly esthetic and have a good track record so far in front teeth They are not regularly recommended for back teeth since they do not seem to be able to withstand the biting forces applied in this area.. They gain much of their strength by being BONDED to the underlying tooth using composite resin bonding systems.

The slip cast systems were developed by a company called VITA, and are called In-Ceram. They have developed two systems called In-Ceram Alumina and In-Ceram Spinnell. The Alumina variant is a magnesium, aluminum infiltrated glass and creates a crown which is strong enough to be used in back (posterior) teeth. The Spinnell version is more translucent, but is also weaker. It is ideal for front teeth as well as Inlays, where the tooth provides the strength.

Depending upon the esthetic result required, the dentist and ceramist must determine which of the systems is right for your particular needs. Each one has pros and cons, just like each of the techniques described in this website. It is only by understanding the needs of the patient together with understanding the materials' strengths and limitations, that a great final result can be obtained.