Dental crowns : types, what are they for and when to use?

What is a dental crown?

Dental crown is the name given to the portion of the tooth that is visible in the mouth, the other half being the root, which is located under the gum and allows the tooth to anchor to the bone.

Dental crown is also the name given to the common “pivot”. In this sense, a crown consists of a prosthetic piece that will restore the remaining structure of a tooth, covering its surface totally or partially. At the bottom, it constitutes a cover that will cover the dental surface in all or almost all its extension, returning the tooth to its correct function.

What are dental crowns for?

The dental crown is a form of fixed rehabilitation that aims to restore the lost dental structure, recovering the correct function. Thus, the aim of these pieces is to reinforce the dental remnant, to restore the appearance, shape, position and occlusion.

Reasons for using dental crowns

The main reasons that determine the need to put a crown are related to the amount of missing or missing tooth structure and aesthetics. More specifically:

How is dental crown treatment performed?

For the rehabilitation of a tooth with a dental crown, two consultations are always necessary, since it involves placing an indirect restoration, that is, a piece made in the laboratory.

In a first consultation, the tooth is prepared in order to receive the crown, after which an impression or mold is made. The latter will serve as a basis for making a piece that will be perfectly adapted to that particular dental preparation in that person.

In the second consultation, cementation is performed, that is, the final placement of the crown.

During the waiting period, the tooth is provisionalized with a temporary material - temporary crown.

Types of Dental Crowns: Temporary

As the name implies, temporary crowns are distinguished from permanent crowns by their temporary nature.

The purpose of using these crowns is to protect the prepared tooth and to condition the surrounding tissues, as well as to maintain function and aesthetics, while waiting for the final crown to be made in the laboratory.

There are several types of materials and techniques that can be used, depending on the case and the doctor's preference. Here are some examples:

Acrylic Resin Crowns | Composite Resin Crowns

In general, any temporary crown, whether produced in the laboratory or in the office, is made from one of these materials. Despite having different characteristics, both acrylic resins and composite resins have been improving their clinical and mechanical behavior, as well as their aesthetic appearance. The preference of one material over the other is usually related to the preference of the dentist, in its handling and polishing.

Polycarbonate Crowns | Acetate Crowns

They are prefabricated or standardized crowns that can be kept in stock and used by the dentist in urgent situations or as needed. They consist of universal matrices with the various shapes of teeth that can be adapted and used by anyone. In cases of trauma in which we have a fractured anterior tooth, these provisional crowns appear as a good option to return the lost structure quickly, in a single consultation and without the need to use laboratories.

Metal Crowns or Steel Crowns

Currently seen as an unsightly option, these crowns continue to be indicated in certain situations. One of them is in the case of bruxism patients, whose unconscious teeth gnashing movement can often fracture or cement crowns in acrylic or composite resin, who are not prepared to deal with this type of forces, especially if the period of provisionalization is prolonged. . Another case in which these pieces can be used focuses on their placement on children, where the steel crown will maintain and protect a certain time until the end of growth, where a definitive crown can then be made.

Types of Dental Crowns: Definitive

The final crown will then be the part that will permanently restore the tooth structure. However, it is important to note that, although lasting, these rehabilitations may not be lifelong, needing to be replaced. Just like a natural tooth, the permanent crown can “be for life” as long as we have certain oral hygiene care and periodically maintain and check it with our dentist or hygienist.

Here are the various types of permanent crowns:

Metal Crowns | Gold Crowns

Dental crowns composed of alloys based on semi-precious metals and gold have been considered for many years as the gold standard of dentistry, due to its biocompatibility and resistance. However, with the growing demand for aesthetic solutions, the use of this type of pieces with a contrasting color to the rest of the dentition was practically alienated from the current clinical practice in dental medicine.

 

Metal-Ceramic Crowns

The addition of a ceramic coating on the metallic crowns solved the great problem of aesthetics, without compromising the compatibility and resistance mentioned above. Metallo Ceramic crowns were, for this reason, the first choice in dental rehabilitation for many years, and have also been studied extensively. With a high rate of long-term success, however, these crowns require more preparation in order to have space for the new ceramic layer added on the metallic infrastructure.

Ceramic Crowns

With the technological advances that we have observed over the last few years, dental ceramics have developed in an extraordinary way, something motivated by the increase in the price of precious metals and by the aesthetic demand that has limited metal-based restorations.

There is currently a wide variety of ceramic materials that allow its use in the most varied situations, from areas where greater aesthetics are required or on the other hand in the rehabilitation of teeth where greater resistance is required.

The zirconia crowns have gained popularity for their hardness, strength and compatibility with the oral tissues. Allied to the fact that it can be less thick without compromising its properties, this material has been replacing the “old” metalloceramic crowns in the rehabilitation of posterior teeth.

The feldspar ceramic crowns, on the other hand, have properties of color and translucency that are very favorable to mimic natural teeth, so they are considered very aesthetic and indicated for use mainly in the anterior region.

The last novelty has been the lithium disilicate ceramic that appears as an intermediate of the previous two, since it has some of the mechanical resistance of zirconia but with better aesthetic properties.

Which material to choose for your dental crown?

The answer to this question is only possible after an evaluation of the candidate tooth (s) to receive a crown. Its location in the mouth, the position, the existing space and many other variables of the dental condition can limit the choice of a certain material. In addition, the patient's muscular strength, chewing and possible habits, such as grinding teeth, that may exist are also factors that weigh a lot when choosing.

With the standards of aesthetic demands of today's society and the development of biomaterials, there is an increasing trend, both for patients and dentists, for the choice of ceramic materials in the making of dental crowns, without compromising the success of the treatment.

Given the variability of ceramic materials that exist today and their increasingly better properties, it can be said that in almost all cases it is possible to place a ceramic crown. However, there is always the exception to the rule and sometimes there is a need to opt for a less aesthetic solution, but one that will be more functional and lasting.

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