Without exaggeration, zirconium crowns are a universal and technologically advanced orthopedic design. Strength and durability, like metal. And the aesthetics are like ceramic dentures. At the same time, dental crowns are comfortable and safe to wear, do not cause allergies, and do not harm the body.
In addition, a zirconium dioxide prosthesis can be installed on any dental unit - in the front row, on molars and premolars. The design is also suitable for fixing bridges of 2-3 teeth. Service life with proper use is from 10 to 15 years. Now more details.
Peculiarities
Modern prostheses are made from natural stone, zircon, which is white. Externally, the material resembles real teeth, and in terms of hardness and strength it is often compared to metal. Like everything natural, zirconium dioxide crowns are completely compatible with the human body, take root well and do not cause discomfort when worn constantly. Unlike metal ceramics, a zirconium prosthesis does not cause darkening of the gums, galvanism, and is suitable for people with high sensitivity to foreign materials.
The prosthesis is made using CAD/CAM computer technology - a painstaking and complex process that requires highly qualified doctors and dentists. This explains the high cost of the orthopedic design.
But if you look at the characteristics of zirconium crowns, it becomes clear that the investment is completely justified:
- The strength of the material is 2.5 times higher than that of ceramics (900-1000 MPa).
- The automated manufacturing process reduces the risk of errors, unlike manual production. The technology is so precise that often after installing crowns, additional grinding and turning of the prosthesis is not required.
- The aesthetic properties of a zircon prosthesis are slightly worse than porcelain crowns. They have lower capacity (less transparent). However, from the outside, it is difficult even for a specialist to distinguish zirconium crowns from real natural teeth.
What are the differences between zirconium crowns?
Crowns made of zirconium dioxide are metal-free structures - one of the types of ceramics. Zirconium is a silvery, grayish metal that is obtained from the naturally occurring mineral zircon.
In dentistry today, metal-free structures are widely used to restore teeth. And models made of zirconium or zirconium dioxide are especially popular. The material is obtained from a natural mineral by stabilization with yttrium and enrichment with aluminum. The resulting zirconium dioxide has very high strength, moderate transparency and a white color without shine. Technologies for manufacturing metal-free ceramics appeared relatively recently, but they immediately gained well-deserved popularity among dentists and patients.
Dental material is produced in the form of fairly soft and plastic blank blocks. The best zirconium crowns are obtained from transparent multilayer blanks of the new generation (Katana line of zirconium discs, Kuraray Noritake, Japan, etc.). The required structure is made from them and its final baking is carried out. After this, the model acquires its main properties: high strength and aesthetics. Externally, artificial teeth made of zirconium are almost no different from natural ones.
And yet, until recently, the high strength of zirconium dioxide did not allow the manual production of monolithic structures. This became possible only with the advent of the latest computer technologies CAD/CAM (computer-assisted design and manufacturing), which includes processing patient data using digital scanning, transferring it to a computer and building an accurate model, and finally manufacturing the desired one on a robotic machine. designs. For chewing units, pure zirconium monolithic structures are used, for the anterior ones, they are covered with porcelain ceramics on top.
Varieties
The issue of aesthetics helps to decide the type of design and manufacturing method. There are classic and monolithic types of crowns.
In the first case, a zirconium base is used as a frame. And ceramics are applied on top in several layers. Thus, the design perfectly combines the strength of zircon and the impeccable aesthetics of ceramics.
Monolithic crowns are made from a single block, without additional cladding. But the mineral in its “pure form” has a milky tint, and differs from natural teeth. Therefore, monolithic zirconium crowns are used to restore chewing teeth.
The second type of prosthesis is more reliable, because eliminates possible chips on metal-free ceramics. To improve aesthetics, manufacturers began to produce colored zircon blocks (for example, Prettau technology). These crowns can be used to restore teeth in the smile area.
There is a material similar in external properties to zirconium dioxide - aluminum oxide. But the design is less durable, so it is used less often and only for prosthetics of the front teeth.
What is zirconium dioxide?
This is a material obtained by chemical processing of zirconium orthosilicate ZrSiO4. It reproduces the natural color and transparency of natural teeth, for which it is highly valued and loved by orthopedic dentists. Combines the strength of metal and the aesthetics of ceramics.
In orthopedic dentistry, zirconium dioxide is used with the following composition: 95% ZrO2 + 5% Y2O3 (yttrium oxide) + 0.4% Al2O3 (aluminum oxide).
When making crowns, we use certified German and Italian zirconium dioxide.
Advantages of zirconium dioxide crowns
The popularity of zirconium crowns is due to many advantages.
The main thing is strength, which we have already talked about. Let us only add that the reliability of the prosthesis is confirmed by its use in complex bridge structures. The material is also used for prosthetics of the entire jaw, with complete or partial edentia. The second argument in favor of zircon is minimal grinding of the tooth when installing a prosthesis. The thickness of the crown is not at all large, so no more than 0.3-0.5 mm of enamel is removed from the supporting tooth. If the tooth is healthy and the pulp is not inflamed, then the dental nerve remains inside the tooth. This allows you to save your natural tooth for the maximum period, even if it is severely damaged.
Interestingly, throughout the entire period of use, zirconium dioxide crowns retain their external qualities. The surface of the prosthesis does not darken and is not subject to pigmentation. Zircon is also resistant to temperature changes, so the patient does not have a reaction to hot or cold food.
Making a prosthesis using digital technology ensures a tight fit of the internal cavity of the artificial tooth to the stump. This prevents the dental cement on which the prosthesis is attached from being washed out. As well as food getting and getting stuck inside the structure.
The main differences between monolithic zirconium crowns
Monolithic zirconium products are made from a block of zirconium dioxide by milling. The surface is sanded and fired to give additional strength. But the outer ceramic layer, like on classic ones, is not applied to monolithic crowns.
Since porcelain gives the tooth a natural appearance and imitates the color and transparency of natural enamel, monolithic structures look less aesthetically pleasing. The zirconium dioxide monolith has a milky tint and low transparency. For this reason, the zirconium prosthesis will stand out in the smile area. The exception is crowns made of zirconium dioxide with high levels of transparency.
The advantage of monolithic crowns is their high strength. In this indicator, the crown is not inferior to a metal one. Solid crowns can easily withstand chewing loads. Since they do not have a more fragile ceramic layer, there is less risk of damaging the denture. Such characteristics have determined the main area of application of solid crowns: prosthetics of premolars and molars, supporting crowns for fixation on implants.
The doctor chooses the type of crown at the preparation stage. Come for a preliminary consultation with an orthopedist at our clinic. After the examination, the doctor will tell you about the possibilities of prosthetics in your clinical case, and suggest which crowns you can use. This way, together with your doctor, you can make the right choice.
Cons of zirconium crowns
Prostheses made of zirconium are considered the most expensive among their analogues, in terms of the cost of material and manufacturing methods. In addition, the ceramic layer in the classic design of zirconium crowns is less durable. Chips may appear on the surface of the tooth, and the structure will have to be repaired or replaced.
The imperfection of aesthetics also falls into the “cons” column. Monolithic zirconium cannot convey the natural translucency of tooth enamel, so with a single tooth replacement it may look unnaturally white. However, if you restore the entire front row, there will be no problems with aesthetics.
Due to its strength, the material can wear away the enamel of neighboring teeth. The degree of abrasion is insignificant, but it is necessary to visit an orthopedic dentist periodically, once every six months, to prevent the destruction of healthy teeth.
Production process
As mentioned above, zirconium dental crowns are made using CAD/CAM computer technology. The first part of the abbreviation stands for computer modeling of prostheses. And CAM is the subsequent milling of crowns according to the developed three-dimensional model.
In other words, “manual” intervention in the process is minimized. This eliminates possible errors in the production of the structure associated with the human factor.
The prosthesis manufacturing process consists of several stages:
- To transfer data to the program, the dentist scans the oral cavity with a special scanner. This is done immediately after treating the supporting teeth.
- The program develops a virtual model of the jaw with a new prosthesis. At the same time, the doctor selects the shade for the crown according to the Vita scale.
- Based on the calculations, a three-dimensional model of the prosthesis is created, according to which a zirconium dioxide crown will be made using a milling cutter.
- The finished product is subjected to heat treatment. If the prosthesis is two-layer, then the zirconium dioxide base is “baked” first, and then a second time after lining with ceramics.
At the final stage, the dentist paints the crown in the desired shade and transfers the structure to the dentist. Production of the prosthesis takes 1-2 weeks, depending on the complexity of production.
If the teacher is not perfect...
Of course, it is not always possible to perfectly prepare a tooth for a zirconium crown. Sometimes the specified 4 mm and 20º cannot be obtained. What to do in such cases? Dr. Christensen says that many dentists use composite cement in these cases, either self-adhesive (bonding included) or conventional (bonding applied separately). Materials offered by Gordon as an example are RelyX Unicem 2 (3M ESPE), Maxcem Elite (Kerr Dental), Multilink Automix (Ivoclar Vivadent), Panavia (Kuraray Dental).
At the same time, the loss of zirconium crowns fixed with such cements is a more frequent phenomenon than the loss of crowns with RMGI cements. To achieve a more reliable result when using composite cements, Dr. Christensen suggests applying the bonding agent to the prepared tooth and to the inner surface of the crown.
. The advice is based on CR's practical experience, but not on the recommendations of cement manufacturers: Gordon regrets the fact that there is simply no consensus among them on this issue.
Installation of crowns
The procedure for fixing a zirconium dioxide crown to a tooth is standard. First, the doctor conducts an initial examination and diagnosis of the jaw to determine the condition of the oral cavity. If the patient requires preliminary treatment, the installation of the prosthesis is postponed until therapy is carried out.
If there are no pathologies, the dentist carries out professional teeth cleaning to remove soft and hard plaque. Then the doctor begins to grind the restored teeth. If the tooth is severely damaged, a pin, inlay or implant can be used as support.
If the root of the tooth is not damaged, then it is filled and the font is fixed on top. If the patient is allergic to metal, then a rod made of zirconium or titanium can be used. This method is not applicable in the presence of periodontal pathologies. And also in the presence of diseases of the nervous system.
The stump tab is also installed in the sealed root canal and ensures reliable fastening of the prosthesis. But the most common technique is fixing a zirconium crown to an implant. It is used when a tooth is missing. The titanium rod imitates a tooth root, preventing bone tissue atrophy. The material is biocompatible with the human body and fuses seamlessly with the jaw bone.
The process of attaching the crown to the supporting tooth or pin takes about 30 minutes. The structure is fixed with dental cement under the influence of light. Sometimes a so-called “temporary mixture” is used so that the patient can test the prosthesis as usual. If defects appear during wearing, the design is sent to the laboratory for revision. At the final stage, the zirconium crowns are placed on the support using dual-curing cement.
Indications and contraindications for the installation of zirconium crowns
Zirconium crowns have good performance properties. But they cannot be considered a panacea. In some cases, their installation is impractical. To restore a beautiful smile, you need to consider many factors. We employ experienced implantologists and orthopedists. You can ask them any question about the advantages and disadvantages of each of the possible prosthetic options and receive a detailed answer.
Zirconium crowns are optimally suited in the following cases:
- One chewing tooth is destroyed or lost. For patients with this problem, we recommend durable monolithic zirconium dioxide crowns. The strength of the structure is sufficient to restore chewing function. Aesthetics in the lateral zone can be neglected, since teeth are not visible here even in people with a wide and open smile.
- Prosthetics on implants. Can be used in any area of the dentition. A bridge with crowns made of monolithic zirconium dioxide is better suited for the masticatory zone, and with classic ones - for the frontal area.
There are a number of situations when using zirconium crowns is not advisable. Solid ones will not be able to provide the necessary aesthetics, and classic crowns increase the risk of chipping and reduce their service life. It is not recommended to use zirconium structures in the following cases:
- One tooth was lost in the frontal area;
- Replenishment of a dental defect in the smile area of less than four teeth.
For such patients, the doctor will recommend crowns made from other modern materials. For example, glass-ceramic crowns are highly durable and aesthetically pleasing. I make them from lithium disilicate. The advantage of this material is its light transmittance, which almost completely matches natural tooth enamel. Therefore, a monolithic glass-ceramic crown looks natural and at the same time the risk of damage is minimal.
Also, zirconium crowns should be chosen with caution if the patient has bruxism. Zirconium is a durable material, so if teeth are involuntarily clenched, it can lead to increased abrasion of the enamel. If a prosthesis has already been installed in place of the antagonist teeth, zirconium dioxide crowns can also be used for prosthetics. Despite this, only a doctor will give a clear answer to the question of whether a zirconium prosthesis can be used in your case after examination and diagnosis.
The patient needs to consider one more factor when choosing zirconium crowns. Prosthetics with such structures require extensive experience from the orthopedist and dentist. The material has practically no adhesion, so fixation occurs due to retention. The crown must perfectly fit the abutment tooth or abutment.
In the production of crowns, computer systems are used: the model is created based on images taken by an intraoral scanner, milling and grinding are done on a CNC machine. This allows you to reduce the risk of inaccuracy to almost zero. The dental laboratory of our clinic is equipped with modern equipment. Thanks to this, we can guarantee our patients high-quality prosthetics with crowns made of any material, including zirconium.
Adaptation
The procedure for fixing zirconium crowns does not have a recovery period. The only restriction is not to eat food for 2-3 hours after installation of the prosthesis.
Of course, at first you may experience unusual sensations from the presence of a foreign structure in your mouth. There may be slight disturbances in diction, increased salivation, and discomfort in the facial muscles. As a rule, these sensations disappear after a few days, after the patient gets used to the new teeth. If discomfort persists or worsens, you should immediately consult a dentist. You should not try to straighten the structure yourself - this can lead to its breakdown and health problems.
TOP-6 advantages of prosthetics with zirconium crowns
Prosthetic dentists highlight five main advantages of restoring a smile with zirconium dioxide crowns:
- Strength is no worse than that of metal ceramics.
This quality is achieved thanks to the stage of zirconium firing in a furnace. Thus, there is no risk that the crown will crack at the slightest pressure on it. The material zirconium dioxide is 30 times more durable than ceramics. On the other hand, if you bite into food carelessly (the same nuts, seeds, etc.), a zirconium crown is not immune to accidental splitting; - Minimal preparation.
Since a zirconium dioxide crown has thinner walls (the average thickness of the frame is 0.4 mm) than metal-ceramics (metal-ceramic crowns have walls up to 2 mm thick), teeth are prepared for it to a minimum; - No allergies or irritation.
Zirconium is considered one of the most “loyal” materials to the environment in the oral cavity, and therefore allergies to such crowns are extremely rare. In most cases, people immediately get used to the new prosthesis; there is no metallic taste in the mouth; - Combined with an implant.
Modern implantation systems imply the presence of zirconium dioxide abutments, which guarantees impeccable gum aesthetics; - Reduced load on the gum and root.
The zirconium frame weighs an order of magnitude lighter than the metal one, and therefore the gums and roots are protected from unnecessary overloads; - Flawless natural aesthetics.
For zirconium dioxide crowns, the shade is selected at the level of the frame. Thus, the frame does not become translucent, as in metal ceramics, and does not oxidize over time. Also, over time, a dark rim around the gums does not appear. The zirconium material of the prosthesis demonstrates resistance to dyes and does not change its tone depending on the lighting.
Lifetime
A zirconia prosthesis does not have a fixed service life. On average, this is 10-15 years. With careful care and wear, crowns can last much longer. This depends on the condition of the teeth, the quality of the installation of the prosthesis and regular oral hygiene.
What can cause damage or damage to the structure:
- Lack of tightness. The reason is usually careless handling of the prosthesis, as well as poor quality material.
- Recession (exposed gums). Occurs due to inflammation in soft tissues. Or due to improper hygiene.
- Destruction of hard tooth tissues (periodontal disease, bruxism, inflammation).
Dental trauma caused by eating hard foods or lack of calcium in the body can also damage the prosthesis.
If you need to make a crown on a damaged tooth, or restore an entire area with several missing teeth, you may face the problem of choosing a material for the prosthesis. Of course, only an orthopedic doctor can give the necessary recommendations, taking into account the depth of the lesion and the location of the tooth. But in order to better understand this issue, we will talk about the modern material used for the manufacture of orthopedic structures - zirconium dioxide.
If you want crowns to be no different from the rest of your teeth, then zirconium dioxide is what you need!
We keep up with the times and practically do not use metal and metal-ceramic crowns in our work. Most of our guests, when they come for a consultation with an orthopedic doctor, themselves ask for dental prosthetics with more durable and aesthetic designs.
What is zirconium dioxide?
Zirconium is a metal, but its dioxide is not. This compound contains transparent crystals that are not subject to change when exposed to water or temperature changes. Zirconium dioxide itself is soft - this allows you to create products of any size and any shape from it. But after the sintering (sintering) process, zirconium dioxide becomes strong and hard, not inferior to metal in these characteristics. This material is approximately 2-4 times stronger than ceramics used in prosthetics. It is thanks to this that structures made from it can withstand high loads and can last for decades.
A zirconium crown is a prosthesis that has a bright white color and is particularly durable. It is installed to replace the lost tissue of the crown part of the tooth or even the tooth or teeth itself (if prosthetics is carried out on an implant or using a bridge).
The melon type of structures is relatively young. In 1994, Matt Anderson introduced the Procera system to the dental community, a new technique for making zirconia crowns.
Zirconium crowns do not have a metal frame, so they can let light into the tooth, making them look more natural.
In addition, zirconium dioxide is not subject to corrosion and oxidation, and as a result, the gums above the crown do not darken over time (as happens with metal-ceramic dentures).
From all of the above, we conclude that zirconium crowns have clear advantages, namely
- The strength of the zirconium dioxide structure allows for the creation of extended bridges
- Thickness of tooth tissue preparation Possibility of keeping the tooth “alive”. Since the frame of zirconium dioxide crowns is quite thin (namely about 0.3-0.6 mm layer), it is not necessary to depulpate the tooth (remove the nerve), the pulp chamber is not damaged during the preparation process.
- Biocompatibility. Zirconium dioxide is a hypoallergenic material that combines ideally with tooth tissue, which avoids the occurrence of pathological processes. There is no need to injure the gum and “hide” the edge of the crown under it, since there is no dark metal edge on the crown. Also, the absence of metal eliminates pigmentation of the gums due to oxidation.
- No sensitivity to temperature changes.
- The prosthesis very accurately conveys all the anatomical features of the structure of the teeth.
- Durability. The warranty period for a zirconium microprosthesis is on average about 2-3 years. But for patients who maintain oral hygiene and regularly undergo professional cleaning by a hygienist, zirconium dioxide caps last 10-15 years. Moreover, they do not change shape and color throughout their entire service life.
- For more than 30 years, the use of zirconium dioxide in medicine has proven the biocompatibility of zirconium dioxide with any tissues of the body (as we said earlier). Including in the oral cavity!!!
- One of the most important qualities is also the absence of galvanosis effect.
- The highest aesthetic indicators also influence the choice! Color rendition and some transparency of the design allows you to make a prosthesis that is not noticeable in the oral cavity.
This type of prosthesis also has some disadvantages.
- The cost is primarily due to the complexity of manufacturing, as well as high quality and a fairly long service life, and the use of expensive computer equipment to create a prosthesis.
- Possibility of chips or cracks, but this is due to failure to follow recommendations for the use of prostheses or installation of a prosthesis in the presence of contraindications.
When is it not recommended to install zirconia crowns?
- for some malocclusion pathologies
- with hypertonicity of the masticatory muscles
- with bruxism
During the consultation, the doctor will determine whether there are contraindications for the use of orthopedic structures made of zirconium dioxide and will offer the best solution to the problem. Do I need special care for installed zirconium dioxide crowns?
There is no rule for cleaning teeth covered with zirconium crowns that differs from caring for your own teeth. You need to understand that home oral hygiene should be carried out 2 times a day (in the morning after tomorrow and in the evening before bed), both for natural teeth and for teeth covered with orthopedic structures. Of course, in addition to a toothbrush and toothpaste, you need to use dental floss and mouth rinse. An additional hygiene product is an irrigator. We recommend using this device for those who have orthopedic structures, including those made of zirconium dioxide.
Of course, professional oral hygiene 2 times a year is recommended. Home care is not enough to maintain proper hygiene. Hard-to-reach areas of the oral cavity, periodontal pockets, bridges - all this requires the work of a hygienist. Our dentists use special tools to perform professional hygiene with zirconium dioxide crowns.
Compliance with the recommendations of an orthopedic doctor for the care of crowns made of this material guarantees their long service life.
Our clinic has been specializing in orthopedic structures made of zirconium dioxide for many years. We offer patients single crowns, bridges, and crowns on implants made from this material. In many respects, zirconium dioxide, products from which do not deform over time, is superior to any dental alloys. Dentures made from this material are difficult to distinguish from the enamel of your own teeth in appearance, and are comparable in strength to this fabric. Being manufactured using high-precision equipment, these products are perfectly similar in shape to natural teeth and have a perfect fit to your own dental tissues.
Contraindications
The restrictions on installing zirconium crowns are the same as with standard prosthetics. Contraindications include bruxism, the presence of inflammatory processes in the oral cavity in the body as a whole, and chronic diseases in the acute stage. As well as malocclusion, blood clotting disorders, and the rehabilitation period after surgery.
Rules of care
Although zirconia crowns are not susceptible to decay, deposits on the surface of artificial teeth can lead to damage to adjacent teeth, bad breath, and poor digestion.
In addition to brushing your teeth, it is recommended to use dental floss and irrigators to remove food debris in the interdental space. A special oral solution also helps get rid of bacteria.
Do not overuse very hard foods, do not crack the shells of nuts and seeds with your teeth. This may damage the surface of the prosthesis. Especially, the surface of zirconium crowns with ceramic veneer.
If you smoke, try to quit this habit. Tobacco leaves a yellow coating on the teeth that cannot be removed even by professional cleaning. In this case, the prosthesis will have to be changed after 2-3 years.
Visit your dentist's office every six months. The doctor will conduct professional oral hygiene and promptly identify the development of pathologies.
For which teeth is a zirconium crown suitable?
This is a suitable solution for the manufacture of fixed dentures for any tooth. There are minor differences between dentures. A ceramic-coated crown is placed on the front teeth, which are visible when you smile. It makes the prosthesis invisible - its color matches the rest of the dental units, and in the light it acquires a pleasant shine. For chewing teeth, all-zirconium dentures are used - not so shiny and without a translucent effect, but more durable. The products do not chip and can withstand the highest loads.
A zirconium crown on a tooth repeats all the anatomical features of the native dental units. Therefore, the prosthesis is also called an anatomical crown.
Price of zirconium crowns
The cost of zirconium crowns is influenced by the material, the chosen production and installation method, as well as the doctor’s qualifications. If the dentist chooses the method of prosthetics, then the responsibility for choosing a specialist lies on the shoulders of the patient. After all, your future health depends on who you entrust with dental treatment. Redoing someone else's poor-quality work is not only difficult, but also very expensive.
On average, the price of a zirconium dioxide prosthesis ranges from 15 thousand rubles and more. To receive qualified dental care, pay attention to whether the clinic has its own dental laboratory. And what equipment does a specialist use when producing a zirconium prosthesis?
At EspaDent clinics you can undergo a free initial diagnosis and find out the final cost of the procedure before treatment begins.
Advantages of dental prosthetics at the EspaDent clinic
- Diagnostics . At your service is a premium computer tomograph Sirona Ortophos SL 3D (Germany), which allows you to accurately plan treatment. The result of prosthetics can be assessed on the computer screen even before the manipulations begin.
- Implantation . The operation to install implants is quick and painless. The EspaDent clinic uses low-traumatic methods and uses 3D surgical templates.
- Manufacturing . Zirconium crowns are made in our laboratory, so the process takes a minimum of time. The latest CAD/CAM equipment operating in automatic mode is responsible for accuracy.
- Installation . We install permanent dentures with zirconium crowns on implants only after they are completely stabilized in the bone.
The article was checked by: Aivazov Tigran Georgievich
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