The installation of a crown is necessary for a complete tooth prosthetics. Modern crowns are able to eliminate almost all possible defects, as they are fixed 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.
Patients who see their dentist regularly can learn about the need for a crown directly from the dentist long before the need arises. In other cases (with prolonged neglect of dental disease or injury), the dentist needs some time for an examination (visual examination, x-rays and other tests) to conclude that dental prosthetics are necessary.
The main reasons for installing crowns include:
Spread of a carious lesion to more than 50% of dental tissues in the presence of a healthy, strong root for installing a pin;
Sharp damage to the aesthetic appearance (for example, discoloration) of one or more teeth;
Rapidly progressive tooth decay due to non-carious disease;
Complete loss of a tooth due to gum and periodontal disease;
Pathological erasure of the enamel of one or more teeth;
Removal of teeth adjacent to the damaged one for the installation of a ceramic-metal bridge.
Preparation for prosthetics
For most people, any dental procedure is associated with characteristically unbearable toothache and the inconvenience of the dental office. But do not be afraid of installing prostheses, because the most unpleasant of the stages of this operation - turning the tooth - is much easier to bear than the 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, as well as caries treatment. If the tooth on which the crown is placed is too damaged, it is restored before prosthetics.
To begin with, teeth, the treatment of which is recognized as meaningless, are removed. After two weeks, prosthetics continue with a complete 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, unable to hold the prosthesis, is also subject to removal.
All decisions regarding the methods of protection and prosthetics of the 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, in order to correctly distinguish them, there is a special classification according to several criteria.
By appointment are:
Restorative crowns, necessary for the maximum possible anatomical, functional and aesthetic restoration of a lost tooth.
Abutment crowns, which are the basis for the bridge prosthesis.
According to the material of the crown can be:
metal;
metal composite;
Metal-ceramic;
Ceramic;
porcelain;
Zirconium.
According to the design of the crown, they distinguish:
Complete - completely replaces the lost tooth.
Equator - are a metal strip that is tightened around the tooth to preserve its natural tissues in case of incomplete damage.
Stump - crowns recessed into the gum.
Semi-crowns - Replace all parts of the tooth, except for the inner (tongue-facing) side. Subsequently, they can serve 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 installation of the prosthesis.
Pin - used for installation on a titanium pin, replacing a too weak or affected root with severe tooth decay.
Jacket, fenestrated and others.
What are the best crowns for chewing teeth? 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 used for decades. The most common option is teeth "under gold".
The main advantages of such crowns are durability, reliability and strength. The elements are practically not subjected to the oxidation process, and their abrasion index is maximally correlated with natural enamel, so antagonist teeth are not damaged during chewing. There is only one drawback of such a design - an unaesthetic appearance, therefore, as a rule, it is installed in an area inaccessible to prying eyes.
All-metal crowns are cast and stamped. Stamped ones belong to an outdated type of construction, they are made on the basis of steel sleeves, which are coated in the color of gold. They look unattractive, unstable in comparison with cast structures. The advantages of these crowns are an affordable price and minimal damage to the tooth during the grinding required for their installation.
Solid crowns are made on the basis of a tooth, cast from metal, with 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 insufficiently tight fit to the tooth surface, due to which pathogenic bacteria can multiply under the crown, causing 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 with pure metal, is the natural appearance of the tooth.
In a metal-composite crown, the metal part is necessarily cast, so it holds firmly on the tooth root and does not allow bacteria to enter it.
Unfortunately, facing plastic wears out relatively quickly, which is manifested in its color change 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 only be installed by people who are not prone to allergic reactions, since plastic can release specific harmful substances into saliva.
Due to the disadvantages and advantages of the material, metal-composite crowns are used only as a temporary prosthesis. Most often, this is necessary to restore the tooth during the manufacture or engraftment of the pin and other prosthetic structures.
Metal-ceramic crowns
A 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. Various inert alloys and pure metals are used in dentistry: nickel, gold, palladium, platinum, etc.
The metal framework allows for a stronger hold of the crown, which is virtually 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 crowns are their strength, availability, reliability and good aesthetic match to the natural tooth. Unfortunately, to install a ceramic-metal prosthesis, it is necessary to depulp (remove the nerve) of the tooth and grind down natural hard tissues up to 2 mm long.
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, i.e. 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, zirconia or, in rare cases, aluminum oxide are used to create this type of prosthesis.
Porcelain crowns
Among the artificial materials available to humans, porcelain 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 the artificiality of an abstract observer. Thus, an ideal aesthetics is achieved, which any other known and convenient material for processing is unable to give.
Of course, a porcelain crown is an ideal prosthesis in its own way, but in some cases its installation is not relevant, for example, in the manufacture of a metal-ceramic bridge.
Zirconia constructions
The most perfect prosthesis is considered to be a ceramic crown based on zirconium. This type of crowns takes the best from ceramic-metal (strength, reliability) and ceramic (perfect aesthetics), although formally it is a subspecies of ceramic dentures.
Zirconia, unlike metals, is the best material for the frame, as it has light-transmitting properties and makes it possible to ensure greater fit accuracy.
Thanks to this, it is possible to produce excellent single and bridge ceramic prostheses, the only significant drawback of which is their high cost.
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Now that we have dealt with the types of crowns and the characteristics 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 pin is the most common method of fixing the crown, as it is not very expensive, it corresponds to a real tooth in strength and is quite easy to install. The pin itself is a metal, plastic or gutta-percha rod placed in the root hole 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 support an artificial abutment. For a tooth with a single canal, the possibility of placing a pin 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 to installing a pin.
In any case, the pin is also forbidden to be placed in such cases:
With serious diseases of the blood or nerves;
With injuries and periodontal diseases;
Fixed obstruction of the canals of the tooth, which prevents their high-quality filling;
If a cystic formation is found at the top of the root, in which the pin is supposed to be placed.
The technical characteristics of the prosthesis will largely depend on the material from which the pin is made: strength, elasticity, safety for tissues, etc. If a long-term high load on the tooth is expected, an elastic carbon fiber pin is used if there is a negative reaction of the tissues to any materials, recommend a titanium or zirconium rod. The installation of the pin is the second most unpleasant operation during prosthetics, after which the attachment and fixing of the crown occurs without pain and discomfort.
Fixing a crown with an inlay
The stump tab is a cast tooth stump with a root part. To install this design, the tooth root is sealed in the same way as for the pin, and a hole is prepared in it, into which the root part of the tab will be laid. If possible, the root part can be branched according to the number of tooth canals and assembled to facilitate the insertion of an inlay on non-parallel canals. The crown is placed on the stump in the same way as on a natural turned tooth.
For metal and metal-ceramic crowns, inlays made of a cobalt-chromium alloy are used, and for ceramic ones, a zirconium inlay is needed, since the dark metal shines through the ceramic and gives the crown a bluish tint.
The prosthesis on the stump tab is considered to be more durable than on the pin design.
Crowns supported by implants
Fixed dentures are much more reliable than removable structures, they also do not stand out among the dentition and can last much longer. However, in order to install a crown, a strong fixation on the patient's teeth is required, often with a long preparation necessary to form a support for the future prosthesis.
Unfortunately, a strong tooth root is not always preserved, on which a crown could hold. In this case, a complete prosthetic tooth is required, which begins with the installation of an implant - a titanium, plastic or fiberglass screw that looks like a small bolt screwed into the place of the lost root.
The implantation of a denture takes longer and is more difficult to install a crown on the remains of a tooth or its root, but as a result, the patient actually receives a new tooth that is not subject to caries and other diseases and is not capable of getting sick in principle. For the front 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 identical in appearance to the real one.
Tooth grinding before crown placement
To maintain the natural shape of the tooth after the crown is placed and to ensure its tight fit, it is necessary to grind the tooth. This is a painful and unpleasant procedure, during which 1-2 mm of hard tissue is ground off 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 constructions.
The procedure is performed under local anesthesia, so 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 are trying to keep them alive.
The procedure for removing the 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 down 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, based on the casts of the tooth provided by the dentist, plaster models are cast, which are then used to cast metal crowns.
During the manufacture of a permanent crown made of metal or ceramic, a temporary plastic construction can be installed for the patient, which will protect the turned tooth from damage and restore its chewing function. They are fixed with temporary cement and can be easily removed when it is necessary to install a permanent crown, allowing you to maintain the aesthetic appearance of the teeth.
Fitting and installation - the final stages of prosthetics
The installation of the crown takes place in three stages. The first of them is a fitting, it is necessary to determine the quality of the fabricated structure, how tightly it fits to the tooth. Only after that, ceramic layering is performed on the metal frame and fixed 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 bite problems. An important indicator of the quality of the installation of the crown is its closure with the antagonist teeth, otherwise the natural teeth will be severely damaged.
Only after a couple of weeks, in the absence of bite problems 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 cut the structure.
The crown may need to be removed in the following cases:
After the expiration of the service life;
In the presence of damage, deformation of chips or cracks of the crown;
If the tooth under the crown begins to hurt due to the inflammatory process, the crown must be removed in order to treat it; the cause of tooth pain may be a cyst, the remains of dental instruments, inflammation of the top of the canal;
When the procedure for installing the crown is not carried out correctly, as a result of which it does not fit snugly against the tooth.
The most common situation in which it is necessary to remove the crown is the doctor's mistakes at the stage of preparing the tooth and filling the canals. Perforation of the canal walls, fragments of instruments, unfilled canals 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 to constantly monitor the quality of the dentist's work during the treatment process using x-rays. Otherwise, the risk of complications increases, and the dentist's mistakes will have to be corrected in another clinic at his own expense.
Answers to frequently asked questions
The doctor suggests putting crowns on the teeth. Is it bad for a tooth to grind? For high-quality installation of the crown, it is necessary to grind the teeth so that the crown fits snugly against its surface. Turning itself is very traumatic, as it breaks the protective layer of tooth enamel and makes the tooth more vulnerable to bacteria and mechanical damage, but it cannot be dispensed with.
How much does a metal-ceramic crown cost? Prices for metal-ceramic crowns depend on the type of metal and its quantity used in the manufacture. The cost of crowns varies between 3-40 thousand rubles.
What does a ceramic tooth crown look like? Is it worth putting such a crown 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 ones. Therefore, for installation on chewing teeth that are subjected 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 a special adhesive or dental cement.
Do teeth deteriorate under a crown? Crowns protect the tooth from damage by reducing the mechanical load that falls on it in the process of chewing food, and also protect it from microbial attack. 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 a crown installed is no different - 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 quality treatment of the tooth, then there will be no complications in the future.
Prices for dental crowns
Prices for crowns depend on many factors, including the availability of a clinic's own laboratory and its pricing policy, the qualification level of staff, the amount and type of material from which crowns are made. At the same time, the material of construction is almost of paramount importance in determining the price of the crown.
So, metal solid crowns are among the most affordable - from 3 thousand rubles apiece. Metal-ceramic crowns will cost more - at least 5 thousand rubles. Porcelain ceramic crowns cost about 11 thousand, and zirconium dioxide ceramic structures cost at least 20 thousand.
Author of the article: Muravitsky Boris Viktorovich, dentist, specially for the site site
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