Crown on a tooth: what are they, how are they placed, does it hurt?
Installation of a crown is necessary for a complete dental prosthetics. Modern crowns are capable of eliminating almost all possible defects, since they are non-removable structures of a natural shape, identical to a healthy tooth or even better in terms of chewing properties. With the help of the latest advances in dentistry, crowns can eliminate even serious deficiencies in the dentition.
Content:
- Indications for installing crowns
- Preparation for dental prosthetics
- Types of dental crowns
- Crown fixation methods
- Grinding a tooth before installing a crown
- Laboratory stage of preparation for prosthetics
- Fitting and installation - final stages
- When should a crown be removed?
- Answers to frequently asked questions
- Prices for dental crowns
Indications for installing crowns
Patients who regularly visit their dentist can find out about the need to install a crown directly from him long before the onset of an urgent need. In other cases (with prolonged neglect of dental disease or injury), the dentist needs some time for examination (visual examination, X-rays and other tests) in order to conclude about the need for dental prosthetics.
The main reasons for installing crowns include:
- The spread of carious lesions to more than 50% of dental tissues in the presence of a healthy, strong root to establish the post;
- Sharp deterioration of the aesthetic appearance (for example, discoloration) of one or more teeth;
- Rapidly progressive tooth decay due to non-carious disease;
- Complete tooth loss due to gum and periodontal disease;
- Pathological abrasion of the enamel of one or more teeth;
- Extraction of teeth adjacent to the damaged one for the installation of a metal-ceramic bridge.
Preparation for dental prosthetics
For most people, any dental procedure is associated with a characteristically unbearable toothache and the inconvenience of the dental office. But do not be afraid of installing prostheses, because the most unpleasant stage of this operation - tooth grinding - is much easier to tolerate than standard cleaning of caries with a drill. Moreover, all operations are performed under local anesthesia with the most effective drugs.
Other steps in preparing teeth for prosthetics include cleaning plaque and removing tartar, and treating caries. If the tooth on which the crown is installed is too damaged, it is restored before prosthetics.
To begin with, the teeth, the treatment of which is considered pointless, are removed. After two weeks, prosthetics continues with a full antiseptic treatment of the oral cavity, filling of canals and carious cavities with constant monitoring using X-rays. If a pin is installed, the root of the tooth, which is unable to hold the prosthesis, must also be removed.
Sometimes the crown is placed on living teeth, i.e. the part of the tooth damaged by caries is cut off and a prosthesis is placed on it. A lighter version of the procedure is possible for young people on teeth affected by a single focus of caries. (read also: what is caries?)
All decisions regarding methods of protection and prosthetics of teeth are made by the patient himself after consulting a dentist.
Types of dental crowns
To date, many varieties of crowns have been developed, therefore, to correctly distinguish them, there is a special classification based on several criteria.
By appointment there are:
- Reconstructive crowns, necessary for the greatest possible anatomical, functional and aesthetic restoration of a lost tooth.
- Abutment crowns, which are the basis for a bridge.
By material, the crown can be:
- Metallic;
- Metal composite;
- Sintered metal;
- Ceramic;
- Porcelain;
- Zirconium.
By design, crowns are distinguished:
- Full - completely replaces the lost tooth.
- Equatorial - are a metal strip that is tightened around the tooth to preserve its natural tissues with incomplete damage.
- Stump - crowns deepened into the gums.
- Half-crowns - Replaces all parts of the tooth, except for the inner (facing the tongue) side. Subsequently, they can act as a support for a bridge or cantilever prosthesis.
- Telescopic - special crowns, the height of which relative to the gums can be adjusted after the prosthesis is installed.
- Pin - used for installation on a titanium pin, replacing a too weak or affected root with severe tooth decay.
- Jacket, fenestrated and others.
Metal crowns
What kind of chewing crowns are the best to put on? Many experts offer metal structures, because they have a lot of advantages, and their cost is relatively low. This option can be made of various metals.
Metal crowns are a classic example of prosthetics and have been in use for several decades. The most common option is “gold” teeth.
The main advantages of such crowns are durability, reliability and strength. The elements practically do not undergo the oxidation process, and their abrasion index is maximally correlated with natural enamel, therefore, antagonist teeth are not damaged when chewed. There is only one drawback of such a design - an unaesthetic look, therefore, as a rule, it is installed in an area inaccessible to prying eyes.
All-metal crowns are cast and stamped. Stamped ones are an outdated type of structures, made on the basis of steel sleeves, on which they are sputtered in the color of gold. They look unattractive, unstable in comparison with cast structures. The advantages of these crowns are affordable price and minimal damage to the tooth during the turning required for their installation.
One-piece crowns are made on the basis of a tooth, cast from metal, at their low cost, they do not wear out the teeth and serve for a long time, although they are not aesthetic.
The significant disadvantages of these crowns include their unattractiveness - a tooth with a metal crown differs significantly in appearance from natural teeth, as well as low wear resistance due to thin walls. But, perhaps, their most important negative property is an insufficient tight fit to the surface of the tooth, because of which pathogenic bacteria can multiply under the crown, provoking tooth decay.
Metal composite crowns
Composite crowns are made from a metal base and a plastic frame. This is one of the fairly affordable materials, the advantage of which, compared to pure metal, is the natural appearance of the tooth.
In a metal-composite crown, the metal part is necessarily cast, so it firmly adheres to the tooth root and does not allow bacteria to enter it.
Unfortunately, facing plastic wears out relatively quickly, which is manifested in its discoloration to gray, swelling due to frequent contact with liquids and weakening of its strength until it falls out of the metal base.
Also, metal-composite crowns can be installed only for people who are not prone to allergic reactions, since plastic can release specific harmful substances into saliva.
Due to the advantages and disadvantages of the material, metal-composite crowns are used only as a temporary prosthesis. Most often, it is necessary to restore the tooth during the manufacture or engraftment of the post and other prosthetic structures.
Metal-ceramic crowns
The metal-ceramic crown consists of a metal base 0.2-0.5 mm thick and a ceramic veneer. The metal for the manufacture of the frame is chosen by the patient based on the cost of the material and its properties - wear resistance, hardness, inertness in relation to the body and other qualities. In dentistry, various inert alloys and pure metals are used: nickel, gold, palladium, platinum, etc.
The metal framework allows for a stronger grip of the crown, which is practically indistinguishable from a real tooth, and reduces the cost of the prosthesis compared to an all-ceramic or porcelain base.
The advantages of this type of crown are their strength, accessibility, reliability and good aesthetic compliance with the natural tooth. Unfortunately, for the installation of a metal-ceramic prosthesis, it is necessary to depulp (remove a nerve) of the tooth and grind down natural hard tissues for a long time to 2 mm.
Ceramic crowns
As the name suggests, a ceramic crown is made entirely of ceramic without a framework. The absence of a metal part makes the prosthesis indistinguishable from a natural tooth, due to which it does not stand out from the dentition at all, that is, it has excellent aesthetic properties. At the same time, in terms of strength and reliability, a ceramic crown is not much inferior to a metal-ceramic crown, but it costs much more.
Porcelain, zirconium dioxide or, in rare cases, aluminum oxide are used to create this type of prosthesis.
Porcelain crowns
Porcelain among the artificial materials available to humans has the closest physical and optical properties to natural teeth. A correctly made porcelain prosthesis has a shade and translucency that matches the rest of the teeth, and does not raise doubts about artificiality in the distracted observer. This achieves the ideal aesthetics that any other known and convenient material for processing is unable to provide.
Of course, a porcelain crown is in its own way an ideal prosthesis, but in some cases its installation is not relevant, for example, in the manufacture of a metal-ceramic bridge.
Zirconia structures
The most perfect prosthesis is considered to be a zirconium-based ceramic crown. This type of crowns takes the best from metal-ceramic (strength, reliability) and ceramic (perfect aesthetics), although formally it is a subspecies of ceramic dentures.
Zirconium dioxide, in contrast to metals, is the best material for the frame, as it has light transmitting properties and makes it possible to ensure greater accuracy of fit.
As a result, excellent single and ceramic bridges can be produced, the only significant disadvantage of which is their high cost.
Crown fixation methods
Now that we have figured out the types of crowns and the features of the materials from which they are made, it is necessary to understand how the prosthesis will be fixed in the jaw, whether this affects the adjacent teeth and how durable the resulting artificial analogue is.
Modern dentistry allows you to install a crown in one of three ways.
Pin fixation
The post is the most common method of fixing the crown, as it is not very expensive, corresponds in strength to a real tooth and is quite easy to install. The pin itself is a metal, plastic or gutta-percha rod placed in the root socket of the tooth and fixed in it with the help of special hardening solutions.
An intracanal post requires a healthy tooth root that is large enough to accommodate an artificial support. For a tooth with a single canal, the post placement is limited in the case of small root sizes, and for a tooth with several canals, even if they are healthy, twisted and too thin passages will become an obstacle for the installation of the post.
In any case, it is also forbidden to put the pin in such cases:
- For serious blood or nerve problems;
- With injuries and periodontal diseases;
- Fixed obstruction of the tooth canals, which prevents their high-quality filling;
- If a cystic formation is found at the apex of the root in which the post is supposed to be placed.
The technical characteristics of the prosthesis will largely depend on the material from which the post is made: strength, elasticity, safety for tissues, etc. If a prolonged high load on the tooth is expected, an elastic carbon fiber post is used, if there is a negative tissue reaction to any materials, a titanium or zirconium rod is recommended. The installation of the post is the second most unpleasant operation during the prosthetics, after which the attachment and fixation of the crown occurs without pain and discomfort.
Fixation of the crown with an inlay
The stump tab is a cast tooth stump with a root part. To install this structure, the tooth root is filled in the same way as for a post, and a hole is prepared in it, into which the root part of the inlay will be laid. If possible, the root part can be branched according to the number of tooth canals and prefabricated to facilitate insertion of the inlay on non-parallel canals. The crown is placed on the stump in the same way as on a natural ground tooth.
For metal and metal-ceramic crowns, inlays made of cobalt-chrome alloy are used, and for ceramic crowns, a zirconium inlay is needed, since the dark metal shines through the ceramics and gives the crown a bluish tint.
The prosthesis on the stump tab is considered to be a more durable structure than on the post.
Implant-supported crowns
Fixed prostheses are much more reliable than removable constructions, they also do not stand out among the dentition and can last much longer. However, in order to install a crown, a firm fixation is required on the patient's teeth, often with long-term preparation necessary to form the support of the future prosthesis.
Unfortunately, a strong dental root is not always preserved, on which the crown could hold. In this case, a complete dental prosthetics is required, which begins with the installation of an implant - a titanium, plastic or fiberglass screw, similar to a small bolt screwing into the place of the lost root.
Denture implantation takes longer and is more difficult than installing a crown on the remains of a tooth or its root, but as a result, the patient receives, in fact, a new tooth that is not prone to caries and other diseases and is not capable of pain in principle. For the anterior teeth, it is possible to install a ceramic abutment, thanks to which the implant becomes completely invisible, which means that the artificial tooth will be outwardly identical to the real one.
Grinding a tooth before installing a crown
In order to maintain the natural shape of the tooth after the installation of the crown and ensure its tight fit, it is necessary to turn the tooth. This is a painful and unpleasant procedure, during which 1-2 mm of hard tissue is grinded from the surface of the tooth. The amount of turning depends on the thickness of the crown and varies depending on the material used in its manufacture - for example, ceramic crowns require minimal turning, unlike metal-ceramic structures.
The procedure is performed under local anesthesia so that the patient does not feel pain. In some cases, it is recommended to remove the pulp so as not to burn it during turning. When processing chewing teeth, the risk of burns is not so great, so they try to keep them alive.
The procedure for removing a nerve or depulpation takes place with the processing of the canals and their filling, otherwise inflammatory processes are possible. If the depulpation and filling of the canals were performed poorly, it may be necessary to cut the installed structure for treatment, which threatens with unnecessary expenses and can be traumatic for the tooth.
Laboratory stage of preparation for prosthetics
In the dental laboratory, on the basis of the dental impressions provided by the dentist, plaster models are cast, which are later used to cast metal crowns.
During the manufacture of a permanent crown made of metal or ceramic, a temporary plastic construction can be installed on the patient, which will protect the ground tooth from damage and restore its chewing function. They are fixed with temporary cement and can be easily removed when a permanent crown needs to be installed, allowing the aesthetic appearance of the teeth to be maintained.
Fitting and installation - the final stages of prosthetics
The installation of the crown takes place in three stages. The first of them is fitting, it is necessary to determine the quality of the manufactured structure, how tightly it adheres to the tooth. Only after that ceramic layering is performed on the metal frame and its fixation on the stump with temporary cement.
The crown is kept on temporary cement for several weeks, during which it is observed whether it interferes with the chewing process, whether it creates problems with the bite. An important indicator of the quality of the installation of the crown is its closing with the antagonist teeth, otherwise the natural teeth will be severely damaged.
Only after a couple of weeks, in the absence of problems with the occlusion and complaints from the patient, the crown is finally fixed using dental cement.
When should a crown be removed?
The process of removing the crown is complex and time-consuming, it is carried out only by a specialist with an arsenal of necessary tools - dental discs, which are used to saw the structure.
It may be necessary to remove the crown in the following cases:
- After the expiration of the service life;
- In the presence of damage, deformation of chips or cracks in the crown;
- If the tooth under the crown begins to ache due to the inflammatory process, the crown must be removed in order to treat it; the cause of tooth pain can be a cyst, the remains of dental instruments, inflammation of the canal apex;
- If the procedure for installing the crown is incorrectly carried out, as a result of which it does not fit tightly to the tooth.
The most common situation in which it is necessary to remove the crown is the doctor's mistakes at the stage of tooth preparation and canal filling. Perforation of the canal walls, fragments of instruments, canals that are not filled at the apex lead to inflammation and soreness of the tooth, which makes it impossible to wear a crown until treatment is carried out.
To prevent this, it is necessary in the course of treatment to constantly monitor the quality of the dentist's work using X-rays. Otherwise, the risk of complications increases, and the dentist will have to correct the mistakes in another clinic at his own expense.
Answers to frequently asked questions
- The doctor suggests placing crowns on the teeth. Is it bad for a tooth to grind? For a high-quality installation of the crown, turning the teeth is necessary so that the crown fits snugly against its surface. Grinding itself is very traumatic, as it disrupts the protective layer of tooth enamel and makes the tooth more vulnerable to bacteria and mechanical damage, but you cannot do without it.
- How much does a metal-ceramic crown cost? Prices for metal-ceramic crowns depend on the type of metal and its amount used in the manufacture. The cost for crowns varies between 3-40 thousand rubles.
- What does a ceramic crown look like on a tooth, should it be placed on chewing teeth? Ceramic crowns look very aesthetically pleasing and are absolutely indistinguishable from natural teeth, but they are noticeably inferior in strength and wear resistance to metal-ceramic. Therefore, for installation on chewing teeth, which are exposed to heavy loads, it is preferable to use metal-ceramic crowns.
- How are dental crowns glued to the tooth? To ensure a snug fit of the crown to the tooth, the dentist uses special glue or dental cement.
- Do teeth deteriorate under the crown? Crowns protect the tooth from damage, reducing the mechanical stress that falls on it during the process of chewing food, and also protect it from microbial effects. Therefore, with the correct installation of the crown, the tooth will not deteriorate.
- How to clean dental crowns? The hygiene of natural teeth and teeth with an installed crown does not differ - they are also cleaned with a toothbrush and paste, and the interdental spaces are treated with floss.
- Can there be any complications after installing a crown on the teeth? If, before installing the crown, the dentist performed a high-quality treatment of the tooth, then there are no further complications.
Prices for dental crowns
Prices for crowns depend on many factors, including the presence of its own laboratory in the clinic and its pricing policy, the qualification level of the staff, the amount and type of material from which the crowns are made. At the same time, the material of construction is almost of paramount importance in determining the price of a crown.
So, metal solid crowns are among the most affordable - from 3 thousand rubles per piece. Metal-ceramic crowns will cost more - at least 5 thousand rubles. Ceramic porcelain crowns cost about 11 thousand, and ceramic structures made of zirconium dioxide - at least 20 thousand.
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The author of the article: Muravitsky Boris Viktorovich, dentist, especially for the website ayzdorov.ru
