What is pressed ceramic dental crown?

August 05, 2021

  

Earlier, stainless steel crowns were the choice of crowns for most dental cases where the tooth needed a protective cover. These crowns were also available for the front teeth. Patients were uncomfortable with this, as it directly affected their aesthetics and smile value. The advances in dental sciences, particularly with respect to ceramics and resins helped in procuring crowns with longer life and with a great aesthetic value.

A pressed ceramic dental crown is particularly made for anterior (front) teeth. These crowns are made by taking ingots of ceramic, heat pressing them, and finally firing it with enamel porcelain. The final product which is in the shape of a tooth is translucent enough to match the surrounding tissues. These crowns have very good margins, which favors their retention around the tooth surface.

The level of opacity is a laboratory procedure. The dental surgeon matches the shade of the tooth (stump shade) and sends the information to the laboratory technicians. In the lab, a die of appropriate colour is made, from which the ingot is later heat pressed. There are two types pressed ceramic crowns: full-contoured and layered. Full-contoured crowns are more translucent and have better aesthetics compared to layered crowns. Layered crowns are more opaque and require some skilful modification in order to match the tooth colour.

Before placing a pressed ceramic crown, the dentist prepares the tooth by slicing it in the required dimensions for the crown to seat on the tooth. This preparation is such that the tooth structure must be preserved as much as possible, and most of the disking is done on the lingual (tongue-facing) side of the tooth. It is important to note that if a higher amount of dentin (the second layer of the tooth, below the enamel) is removed, then the pressed ceramic crown might not justify the aesthetics. The reason for this is that pressed ceramic crown, owing to its translucency, simply enhances the color of the dentin of the tooth. Moreover, it reflects the light from the adjacent tooth structures, which gives it a more natural appearance. In cases where the tooth structure is significantly missing, a more opaque pressed ceramic crown must be preferred.

Another factor to consider is the size of the crown. Once again, this depends on the amount of tooth structure available after the tooth is prepared to receive the crown. But challenges arise when there is spacing between adjacent teeth or when the adjacent tooth are teeth also require a crown. In such cases, it is the clinician's judgement for each particular case in how much width and length of the crown is to be opted for. Moreover, relationship of the tooth of concern to the opposite arch is also considered as an improper bite can lead to disorders of the temporomandibular joint and muscle spasms.

Heat-pressed ceramics have been in the clinical scenario for over three decades. Initially, when stainless steel crowns were less accepted by patients for front teeth, a porcelain-fused-metal crown was developed. Even though this crown satisfied the aesthetic component, the presence of a metal covering in its core failed to give it a natural appearance. Make no mistake, PFM crowns are one of the best crowns that are used even today. However, they lacked the property of refracting natural light, which made heat-pressed ceramics superior in terms of aesthetics.

The core of heat-pressed ceramics are made of microstructures of lithium disilicate, alumina, zirconia, glass fillers or leucite. These crystals are responsible for giving these crowns a range of hue and translucency to select from. One of the disadvantages of using these crowns is that it may abrade the opposing natural tooth. However, if the tooth is polished after being seated, the chances of abrasion can reduce to a great extent. This is the reason why patients with bruxism (teeth grinders) are warned beforehand when they are thinking to opt for ceramic crowns.

Heat-pressed ceramics provide one of the best crowns for front teeth. Mimicking the natural teeth, these crowns are relatively expensive, but certainly worth every penny. They are even bettered when the raw material is processed with modern technology of Computer Aided Design and Computer Aided Manufacturing (CAD-CAM). The heat-pressed ceramic crowns are a great clinical alternative for restoring the lost functionality and facial value of the natural teeth.

Comments