Stages of preparation of a mandibular molar for a full cast crown. General principles of preparation for artificial crowns Preparation of teeth for a cast crown

Many people strive for a perfect smile. To achieve it, dentures help. Often preference is given to ceramic-metal. However, prior to placing a crown, it is necessary to prepare the teeth in order to improve retention and thus prolong the life of the crown.

One of the stages of preparing teeth for prosthetics is preparation (or turning) - grinding of hard tissues in order to level their surface, remove damaged areas. Previously, this procedure was painful and long, but modern methods and tools can significantly save time and do without pain.

In what cases is the preparation of teeth indicated?

Preparation is a mandatory stage before prosthetics, it cannot be avoided. The preparation of a tooth for a metal-ceramic crown has several indications, for example, the destruction of hard tissues by a carious process.

The procedure is indicated if the teeth have already been treated in the form of fillings, but the fillings have such defects:

• violation of contact with dental tissues;
• overhanging edges;
• unsatisfactory appearance.

Tooth fractures, accompanied by a violation of the shape and loss of function, increased sensitivity and pain, are also indications for grinding. Along with this, congenital defects in the shape of the teeth are isolated, but in such cases, the doctor must assess the situation in order to find out whether intervention is really necessary.

The main methods of grinding for a metal-ceramic crown

Preparation for a metal-ceramic crown can be carried out in various ways. Ultrasound, laser, special installations, acids - this is not a complete list of possible influencing factors. All of them are united by the result - teeth turned under a metal-ceramic crown. For the right choice of procedure, it is advisable to consult a specialist who will assess the condition of the oral cavity and recommend the best method.

When preparing a tooth for metal-ceramic, it is imperative to observe several conditions. Chewing elements ground for cermet should not contain pulp (the inner part containing blood vessels and nerves). It is also necessary to equip them with a ledge and remove 2 mm of tissue from the sides in order to fit the crown tightly.

Ultrasonic turning

Ultrasound has long been used by dentists to remove tartar, plaque and polish fillings. It has only recently been used for dissection. At first, the tools consisted of a tip and ceramic sharp tips. They were detrimental to dental tissue, as they significantly injured it.

Today, ultrasonic handpieces have several interchangeable tips, so they can be used repeatedly. They are used for minimally invasive treatment of caries, turning, temporary fillings.

This method has several advantages:

• a slight release of heat during the procedure, so the enamel and other tissues of the tooth do not overheat;
• no pain;
• the tool exerts minimal pressure on the tooth surface;
• after the procedure, there are no chips and microcracks, there is a complete alignment;
• no impact on the soft tissues of the oral cavity due to the special frequency of ultrasound.

Laser preparation

Together with ultrasound, the laser occupies a leading position among other methods of grinding teeth. The most commonly used and studied, to date, is the erbium laser.

The method is based on the use of an erbium crystal, which cuts tissue in a special way. It is called laser hydrokinetics and is characterized by the removal of tissues containing calcium by absorbing laser energy into water molecules. Evaporation of hard dental tissues occurs as a result of water evaporation with an increase in volume and destruction of hydroxyapatite crystals. Only the upper layers evaporate, since the laser pulses are short and do not have time to heat the inside of the tooth. Evaporation should not be taken literally, the fabric is simply crushed into small particles and then removed by air flow. The laser does not melt the surface, eliminating overheating.

Laser treatment has the following advantages:

• the infection does not spread to other teeth, as small particles of tissue are removed by air;
• painless - the procedure does not require the use of anesthesia;
• cost-effectiveness - the use of antibacterial agents, drills, etc. is not required;
• the speed of the procedure;
• no need for correction, it is possible to align the tooth in one procedure;
• The laser does not damage or heat the teeth.

tunnel turning

This type of preparation is a conservative approach to the treatment of caries. It involves the grinding of dental tissues with the help of turbine dental units, currently it is possible to control the speed of exposure. A wide range of quality diamond or metal tips are also available. The result depends on the equipment - if it is of poor quality, it will cause overheating of tissues and destroy them.

When applying this method, they tend to grind a minimum of fabric, the main advantage is the ability to adjust the thickness of the area to be removed. The dentist is able to predict the result.

However, the procedure has enough disadvantages:

• strong heating of the enamel;
• a highly qualified doctor is required, since if the technique is violated, the gums are easily injured;
• poor quality equipment in most cases gives poor results in the form of microcracks and chips;
• soreness of the procedure.

Air-abrasive method of preparation

Turning in this way is characterized by the action of an air stream containing a mixture of powders. Often used baking soda, silicon oxide and aluminum oxide. The powder is fed under high pressure through a narrow nozzle. So he is able to cut dental tissue and fillings.

The method has the following advantages:

However, due to the specifics of the procedure, it is advisable for patients to observe the following precautions:

• it is recommended to remove contact lenses before starting the manipulation;
• After the procedure, it is advisable to refrain from smoking for several hours.

There are also a number of contraindications. Patients with allergies to powder components, HIV, lung diseases, hepatitis and pregnant women should refrain from this procedure.

Chemical turning

This method consists in softening the tissues with chemicals and then removing them. Diluted lactic acid is often used - a swab is moistened in it, which is applied to the right place for 15-20 minutes. Then the acidic environment is neutralized with a solution of baking soda, and softened tissues are removed with special devices. Alignment in this way is common in the preparation of children's milk teeth for metal-ceramic.

The main drawback is the long execution time, which can reach 30 minutes. The procedure has the following advantages:

• comfortable temperature of the influencing substance;
• it is absolutely not painful, without anesthesia;
• there are no microcracks and other damage to the enamel;
• comfort for the patient, since a drill is not used, which inspires fear in many.

Stages of tooth preparation

Clinical stages of tooth preparation:

1. Creation of grooves. A groove is a notch that determines the amount of tissue to be removed.
2. Removal of tissue from the sides of the tooth.
3. Grinding of the chewing surface of the tooth. The crown becomes shorter by 1⁄4 part.
4. Retracting the gums to take an impression.
5. Formation of ledges. Ledge - a small amount of hard tissue on which the prosthesis will rest.
6. Finishing processing. Protruding edges are eliminated, uneven bumps are cut off, etc.

Varieties of ledges

The ledges are necessary for the installation of the prosthesis, their absence is contrary to the standards. Without them, the crown will not adhere tightly to the tooth, which can lead to serious consequences.

There are the following types of ledges:

• knife-shaped - used for solid crowns, its width varies from 0.3 to 0.5 mm;
• rounded (grooved) - often used for metal-ceramic prostheses, its width is 0.8-1.3 mm;
• shoulder - reaches a width of 2 mm, the most aesthetic and has higher strength characteristics.

Possible Complications

Dental preparation can be dangerous. Especially when referring to an inexperienced specialist or installing solid and metal prostheses. Poor quality of work can destroy the gingival margin, causing the patient's gums to become inflamed. Many dentists recommend injecting anti-inflammatory agents or using a laser.

Sometimes there is gingivitis, which is also characterized by inflammation of the gums. It is caused by trauma during the preparation process. In this case, particles of food may fall under the prosthesis, causing periodontitis.

At the beginning of the inflammatory process or prolonged pain in the tooth, you should immediately contact the clinic. It is possible that the prosthesis will have to be removed and reinstalled.

Why does pain occur?

The procedure is often performed under anesthesia, so it is considered painless. However, sometimes discomfort occurs after the pain medication wears off, which can be caused by the following reasons:

• removal of too thick a layer of tissue from the tooth, where the pulp was preserved;
• inflammation of the tissues of the tooth and gums;
• squeezing soft tissues with a special thread (pain disappears within 1-2 days).

The duration of the procedure depends on the chosen method. For more detailed information about the stages of tooth preparation, it is recommended to watch the video.

Algorithm for performing practical skills in orthopedic dentistry

“Preparation of teeth for a one-piece cast combined crown”

I. Material support:

• 
  dental unit;
• 
  dental handpieces (mechanical straight, turbine);
• 
  a set of dental instruments (mirror, probe, tweezers, spatula)
• 
  single-sided separating discs with diamond coating (push, push)
• 
  abrasive shaped heads and burs are cylindrical, cone-shaped with a diamond coating);
• 
  torus and diamond heads, burs for forming a ledge;
• 
  retraction rings and threads;
• 
  carbon paper, wax plate;
• 
  rubber gloves, mask, goggles.

P. Basic level of knowledge required to perform the skills:

• 
  know the anatomy of teeth and dentition;
• 
  know the safety zones within which it is possible to prepare hard tissues of the tooth with confidence;
• 
  know the classification of artificial crowns;
• 
  know the comparative characteristics of artificial crowns;
• 
  know the requirements for artificial crowns;
• 
  know the clinical and laboratory stages of manufacturing artificial crowns;
• 
  know the principles and stages of teeth preparation for artificial crowns;
• 
  know abrasive and cutting instruments for odontopreparation;
• 
  know the indications for the use of high-speed handpieces in the preparation of teeth;
• 
  know the effect of tooth preparation on the structure and function of the tooth;
• 
  know the possible complications of preparation and ways to prevent them;
• 
  know provisional crowns, indications for their use;
• 
  know the technique of subgingival preparation;
• 
  know the methods of gum retraction;
• 
  know the location of the edge of the crowns, depending on the type of artificial crown;
• 
  know the factors that affect the quality of fixation of crowns.

Sh. Indications for dental procedures:

Defects in the hard tissues of the teeth that cannot be restored by therapeutic methods of treatment;

• 
  with anomalies in the shape of the tooth - a change in the color of the tooth;
• 
  when prosthetics with bridges (supporting teeth are covered with fixing crowns);
• 
  for fixing various medical devices that are used for the duration of treatment;
• 
  fixation of the maxillofacial apparatus;
• 
  for fixing a removable prosthesis with clasps, if the supporting tooth has an unsatisfactory shape;
• 
  with pathological abrasion;
• 
  if necessary, significant grinding of the crown of the tooth, which has advanced or bent towards the defect of the dentition.

Contraindications for dental procedures:

• 
  the presence of severe systemic diseases in a patient (cardiovascular system, blood diseases, etc.);
• 
  local diseases;
• 
  psycho-emotional state.

^

IV. Algorithm for performing practical skills

State Budgetary Educational Institution of Higher Professional Education Bashkir State Medical University of the Ministry of Health of the Russian Federation Medical College Topic: “Technology for manufacturing a solid crown” Contents

Relevance of the topic

Indications and contraindications for the manufacture of cast crowns

Advantages and disadvantages of cast crowns

Clinical and laboratory stages of manufacturing cast crowns

List of used literature Relevance of the topic:

The widespread introduction of modern casting methods into the practice of dental laboratories has made it possible to produce accurate thin-walled solid crowns.

Solid crowns are used to restore the anatomical shape of damaged teeth, as supporting elements in bridges and the like.

A one-piece crown is used to prevent subsequent destruction of tooth tissues, to restore the lost anatomical shape and function of natural teeth, as a supporting element in bridge prostheses, to locate the fixing elements of removable dentures, in orthodontic and maxillofacial appliances.

Instructions for making:

significant damage to the crown of the tooth;

anomalies in the shape and position of the teeth;

· the location of the supporting and fixing arms of the clasps;

support for bridge prostheses;

in the treatment of pathological tooth wear;

in the pathology of occlusion;

with bruxism, parafunctions of masticatory muscles;

in some forms of pathological bite;

with small tooth crowns.

Contraindications:

Teeth with low clinical crowns;

Teeth with high clinical crowns;

Pathological tooth mobility;

Periodontal diseases, in the form of neck exposure, gingivitis, pathological gum and bone pockets.

With deformations of the dentition, accompanied by inclinations of the supporting teeth or their displacement.

Advantages of cast crowns:

· Easier manufacturing technology.

· High precision of designs.

Perfect marginal fit and tightness.

· High durability.

· Possibility of production from any alloy.

Disadvantages of cast crowns: · The need to remove a sufficiently large layer of hard tooth tissues.

The need for high-precision casting.

· Non-cosmetic.

High construction cost.

Clinical and laboratory stages of manufacturing solid crowns 1st clinical stage: Examination of the oral cavity, anamnesis, preparation of the abutment tooth, taking full anatomical impressions with silicone masses, a full anatomical impression with alginate masses from the opposite dentition.

Fixation of the central ratio of the jaws.

One of the features of cast crowns is that they only reach the gum.

Teeth for such crowns are prepared in two ways - without a ledge in the neck area and with a ledge.

After preparation of a shouldered tooth, its surface is smoothed with carborundum heads and given a slightly conical shape.

The preparation of teeth for a solid crown requires the removal of a significant amount of hard tooth tissues.

In this regard, the method of anesthesia during preparation must be selected individually.

The formation of a ledge for a cast crown is not necessary.

The tooth is prepared taking into account all the requirements of a gentle preparation, to prepare abruptly, without pressing on the tooth, with well-centered water- or air-cooled diamond or carbide burs.

The tooth tissues are ground, taking into account the selected design and the aesthetic requirements of the patient for a crown thickness of 1.0 mm. The side walls are formed parallel to the vertical axis of the tooth with a bevel of approximately 6-9°.

After the preparation of the tooth, the surface of the stump should be isolated from the irritants of the oral cavity.

1st laboratory stage: Making a combined demountable plaster model.

Making a plaster auxiliary model.

Plastering models in the articulator (occluder).

Modeling the wax composition of a one-piece cast crown.

Replacing wax with metal in a foundry laboratory.

Processing of a one-piece cast crown The resulting impressions are used for the manufacture of combined models with abutment teeth from high-strength grades of gypsum.

Pins are placed in the impressions of the prepared teeth and fixed in the impression.

To remove excess air from strong gypsum, it is recommended to use special installations (“vibrating table”) when stirring it.

The second layer of ordinary gypsum is poured after the installation of retention devices, which provide a mechanical connection between the first and second layers.

In the manufacture of crowns for several adjacent teeth, as well as in the manufacture of bridges, it is necessary to ensure that the pins in the model body are equally spaced.

For this, special devices have been developed - pin clamps.

The two-layer impression is fixed on the lower table with technical optosil.

Shanks, fixed on special needles parallel to each other, are installed in the impressions of the prepared teeth.

Before filling the impression with high-strength gypsum, the upper retainer with knitting needles and shanks is moved to the side by 900, then the imprints of the teeth and parts of the alveolar process are filled with hard varieties of gypsum (supergypsum, marble gypsum) and the table with the knitting needles is returned to its original position, that is, exactly above the imprints of the teeth being prepared .

After the plaster has hardened, the needles are removed.

An impression with teeth cast from durable plaster and shanks fixed in it is finally filled with ordinary medical plaster.

After the gypsum has hardened, the impression is removed, and the model is sawn with a jigsaw between the abutment teeth through the entire thickness of the high-strength gypsum.

The model of each supporting tooth is removed, the lateral surfaces of the root part are processed to the ledge or neck, strictly adhering to its perimeter and the profile of the transverse intersection.

And again they are installed in their place, checking the quality of workmanship and the accuracy of the installation on the model.

To compensate for the shrinkage of the alloy, the model stump of the prepared tooth is varnished twice. Cast crowns are made by two methods - by crimping a softened clasp wax plate and immersing it in a wax melter.

1st method:

A model for casting crowns is made from a refractory molding mass, and the tooth is modeled smaller by the thickness of the future crown, that is, by 0.30-0.35 mm, it is removed from the model and compressed with a softened plate of clasp modeling wax.

The crown modeled on the model is plastered into a refractory mass and cast in gold or steel.

2nd method:

At present, there is a modern highly efficient method for modeling wax compositions of cast crowns and other cast structures.

For the practical use of this method, it is necessary to have a set of materials and a device called a wax melter, as well as a set of special immersion modeling waxes.

Modeling is carried out as follows.

The immersion wax is melted in a wax melter to a temperature according to the manufacturer's instructions.

The dental technician, holding in his hand a plaster tooth removed from the combined model and previously isolated with varnish, immerses it in melted wax (hence the name "immersion waxes") for a certain time, which is 1-2 s.

A plaster tooth is immersed in wax up to the neck.

After checking how the wax has layered, if necessary, repeat the procedure again.

Also, if necessary, the dental technician carries out additional modeling of parts of the wax composition.

After completing the modeling process and checking the occlusal relationships, the wax composition is transferred to the foundry laboratory.

The use of this method makes it possible to obtain thin-walled solid crowns.

It is widely used in the practice of dental laboratories both abroad and in Russia.

Having received a one-piece cast crown cast by one of the above methods, the dental technician checks the quality of the casting, whether there are any defects in it and begins its processing.

Slotted discs removes the places where the sprues were.

It must be said that all manipulations on the processing of the walls of the crown should be carried out under control with a micrometer.

They try on a crown on a plaster supporting tooth, checking the correspondence of the walls of the crown to the neck on the plaster tooth.

Having finished this stage, check the occlusal relationship with the antagonist teeth, if necessary, carry out a correction.

After that, the cast crown is transferred to the clinic for fitting and correction.

2nd clinical stage:

Fitting a solid crown, checking occlusal relationships.

2nd laboratory stage:

Finishing, grinding and polishing of a cast crown.

If necessary, the dental technician grinds the places indicated by the orthopedic dentist with carbide burs or volcanic discs, if the doctor himself did not perform this manipulation.

Carries out the final processing, grinding and polishing of a solid crown, processes it from the remnants of the polishing mass, rinses under running water using detergents.

The finished cast crown is sent to the clinic for fixation.

3rd clinical stage:

Fitting and fixation of a solid crown with phosphate cement.

1. Abolmasov N.G., Abolmasov N.N., Bychkov V.A., Al-Hakim A.

Orthopedic dentistry.

— Smolensk.

Zhulev E.N.

Non-removable prostheses: theory, clinic and laboratory equipment. - N.Novgorod.

Konovalov A.P., Kuryakina N.V., Mitin N.E.

Phantom Course in Orthopedic Dentistry / Ed.

Trezubova.

— M.: Medical book;

Nizhny Novgorod: Publishing house of NGMA, 1999.

Trezubov V.N., Steingart M.Z., Mishnev L.M.

Orthopedic dentistry.

- St. Petersburg.

Shcherbakov A.A., Gavrilov E.A., Trezubov

ppt-online.org

General view

A one-piece cast crown is a metal product designed to replace one or more elements of the dentition.

At the same time, thanks to this technique, it is possible to manufacture both a single crown and a bridge prosthesis, the elements of which do not have to be soldered together. The manufacturing method increases the strength of the structure and the duration of its operation.

Kinds

In dental practice, several types of solid crowns are used, the choice of each of which depends on the wishes of the patient and the condition of his oral cavity.

Without spraying

Non-coated crowns are carefully polished products formed from an alloy of metals. Often, chromium or cobalt alloy is used for their manufacture.

Such designs are not distinguished by high aesthetic indicators, therefore, they are most often used when it is necessary to replace distant molars.

Coated

To improve the appearance of a one-piece cast crown, special spraying can be used. It is applied to the product by the vacuum-plasma method and gives the metal a resemblance to gold, silver or platinum.

Such crowns are highly durable, however, due to their strong difference from natural teeth, they are practically not used to replace anterior units.

In addition, spraying increases the risk of developing an allergic reaction, and also negatively affects the oral mucosa.

with cladding

Crowns with lining are used to restore the elements of the row included in the smile zone.

A ceramic-metal or plastic overlay is fixed on the front surface of the product, thanks to which the artificial tooth practically does not differ from the real one.

The disadvantages of such designs include their large thickness, due to which it is necessary to heavily prepare the tooth, and the susceptibility of the veneer to chipping.

One-piece bridge prosthesis

As a rule, crowns with veneer are used in the smile zone, and for the restoration of chewing teeth - solid cast products with or without coating. The main advantage of a cast bridge is its strength.

materials

For the manufacture of high-strength metal alloys are used. The most commonly used compounds are chromium and cobalt or nickel. In addition to these metals, titanium can be used, products from which have the following advantages:

• do not cause an allergic reaction;
• do not change color during operation;
• do not cause changes in the acid-base balance of saliva.

Products can be coated with precious metals. Often in this case, titanium nitride is used, due to which the structure acquires a golden color. At the same time, strength and wear resistance increase, as does the price.

In the video, see the material used for the manufacture of cast crowns.

Indications

• high degree of tooth decay - over 70%;
• the need to strengthen chewing teeth;
• pathological abrasion of enamel;
• malocclusion, abnormal shape or arrangement of teeth;
• small height of teeth;
• as a support for a bridge prosthesis;
• bruxism;
• uncontrolled contraction of the chewing muscles.

Manufacturing and installation

The manufacturing and installation process consists of several successive stages. Their precise execution guarantees the receipt of a quality product and its proper fixation in the oral cavity, thereby increasing the service life.

Clinical stage

At the first appointment, the dentist examines the patient's oral cavity to identify existing pathologies and diseases.

Based on these data, a decision is made to carry out the sanitation of the elements of the dentition - filling the canals, treating caries, treating pulpitis, strengthening the molar if necessary. At the same time, a decision is made on the type of crown that will be installed in the future.

In addition, at the clinical stage, after the preliminary preparation of the tooth, which will be restored with the help of prosthetics, its cast is made.

For the most accurate display of the shape and structural features of the row element, a silicone mass is used, with the help of which a working cast is made. An auxiliary impression is made from alginate material.

Tooth preparation involves the removal of 1.5-2 mm of hard tissue from its surface. The procedure is performed using an anesthetic drug.

In dental practice, several methods of preparation can be used:

• using a laser;
• using an ultrasonic device;
• air-abrasive way;
• using a turbine plant.

Manufacturing

Based on the obtained casts of the jaw row, two models are produced:

• a working combined model is made of silicone material;
• an auxiliary plaster model of the opposite dentition is made from the alginate composition.

After receiving the models of both jaws, they are plastered into the articulator, then the composition of the cast wax crown is modeled.

Most often it happens like this:

• the tooth that needs restoration is removed from the collapsible plaster model and isolated with varnish;
• in a special apparatus - a wax melter, immersion wax is melted to the required temperature;
• the prepared plaster tooth is immersed to the neck in molten wax for 1-2 seconds;
• after checking the degree of wax layering, the procedure can be repeated one more time;
• in some cases, additional modeling of some parts of the wax composition may be required.

At the end of the process, wax modeling and verification of occlusal relationships, the resulting model is transferred to the foundry laboratory, where the wax is replaced by an alloy of metals.

After that, the crown is returned to the dental technician, who checks the quality of its manufacture and carries out processing. At the request of the patient, a ceramic composition can be layer-by-layer applied to the metal base.

The cast crown is tried on a plaster tooth, its relationship with the antagonist teeth is determined.

If necessary, an adjustment is made, after which the product is transferred to the dentist for fitting and further installation.

Installation

After receiving a finished solid crown from the dental laboratory, the dentist tries it on the turned tooth, checks the fit strength, height in comparison with the dentition, and the ratio with the antagonist teeth.

In some cases, dentists resort to temporary fixation of the crown in the patient's jaw row. This allows you to determine the reaction of the tooth and mucous to a metal product, the presence of an allergic reaction or discomfort during chewing.

In the absence of any negative sensations, the specialist proceeds to permanent fixation of the product. The crown is cleaned of residual temporary cement, after which it is fixed on the tooth with permanent dental cement.

Upon completion of the procedure, the patient should not experience any discomfort or disturbance of chewing functions.

Advantages and disadvantages

Cast crowns are used in dental practice more and more often, which is explained by their advantages over other prosthetic structures.

Compared to stamped

Most often, solid crowns are compared with stamped products, which were popular several decades ago.

Compared to metal-ceramic

When choosing a prosthetic option, patients are interested in what to give preference to - solid or metal-ceramic crowns. Both options have both advantages and disadvantages.

Prices

The cost of cast crowns depends on their type. So, for a product without spraying, you will have to pay 3,500-4,000 rubles. A design for one tooth with a coating of titanium nitride will cost 4,500-5,000 rubles.

The average cost of a crown with a plastic lining will be 4,000 rubles, a ceramic one - 7,000 rubles. A cast product made of a gold-containing alloy costs from 9 to 10 thousand rubles.

Care

After installation, it is necessary to carefully care for the condition of the oral cavity - brush your teeth at least twice a day using a brush and paste, as well as additional devices such as floss, brush, rinse.

Particular attention should be paid to the condition of the gums, since their inflammation can cause the crown to loosen.

Another rule is regular visits to the dentist for timely detection of problems and treatment of emerging diseases.

Reviews

Reviews on the Internet indicate that solid crowns have many advantages without causing discomfort during use.

dr-zubov.ru

What is it, used alloys

A one-piece cast metal crown is made of a specific alloy according to individual sizes.

Such crowns are used more often for prosthetics of molars. Under certain conditions, it is possible to use them in the so-called "smile line", that is, on the front teeth. If desired, cast crowns can be placed on the teeth with or without coating, as well as with veneering.

Cast crowns are used in the restoration of a damaged tooth and as a support for bridges.

The following alloys are used for cast products:

• chromium together with nickel;
• chromium together with cobalt;
• titanium alloys;
• alloys with gold or platinum.

In addition, if the crown will be installed on the front teeth, a plastic or ceramic overlay is used as an addition.

Cast crown options

Indications and contraindications for installation

Dentists suggest using cast products if:

• the native crown of the tooth is severely damaged;
• teeth are located abnormally and have an irregular shape;
• need support for the installation of dental bridges;
• tooth enamel is pathologically erased;
• there is occlusion of one form or another, bruxism, parafunction of masticatory muscles;
• malocclusion;
• the crown of the tooth is abnormally small.

Contraindications:

• teeth with live pulp in children and adolescents;
• severe periodontitis.

Advantages and disadvantages of casting

The main advantages of solid cast crowns:

• long service life;
• tightness (it excludes food, saliva, paste under the crown);
• high strength.

Flaws:

• the need to remove most of the tooth tissue;
• in case of violation of the technological process of casting the crown, subsequent gum injury is possible;
• unaesthetic appearance (with a wide smile and laughter, metal prostheses will be visible).

Advantages over stamped products

Stamped crowns are an outdated method of prosthetics that is gradually fading away. Many dental clinics still provide such a service, but it is no longer in such demand.

To create a stamping, an impression is taken from the patient's jaw, and then a crown is formed on the plaster model. The finished crown is tried on, defects are eliminated, if any, and placed on permanent cement.

The price of such crowns is significantly cheaper than that of solid cast ones, but they cannot boast of durability and quality.

Disadvantages of stampings:

Why is a cast crown better:

• more advanced alloys with special additives are used, which makes the tooth surface smooth;
• long service life, such crowns can last about 10 years;
• reliable fit of the crown to the tooth;
• minimal preparation for a cast crown is required.

Advantages over cermets

Metal-ceramic is a popular dental solution. From an aesthetic point of view, it is better to put them on the front teeth. If we talk about chewing, then preference remains for solid ones.

Advantages of cast crowns over metal-ceramic ones:

• a one-piece cast crown has a smaller thickness compared to a metal-ceramic one, therefore, it is not necessary to grind the tooth so intensively, more dental tissue is preserved, which means that the tooth will last longer;
• Porcelain-fused-to-metal crowns are prone to chipping and often require restoration, while solid-cast crowns do not have this problem.

Manufacturing process

The manufacture of a cast crown involves the following steps:

The work of a master who makes such crowns is akin to the work of a jeweler.

Installation steps

Installation is not a matter of one day and it takes place in several stages:

• at the first stage, it is necessary to treat existing diseases of the teeth and oral cavity and remove plaque and deposits;
• then the tooth is turned;
• the cast crown is tried on and, if necessary, sent for revision;
• usually the crown is placed on temporary cement so that a person can understand whether it is comfortable for him, whether the bite is broken;
• the last stage is the installation of a crown on permanent cement, while it sinks into the gum by about 0.2 mm.

While the production of solid crowns is in progress, temporary crowns are placed on the prepared teeth.

Features of oral care

Caring for the oral cavity after the installation of the crown does not require any special efforts. It is only necessary to thoroughly brush your teeth, rinse them after eating and visit the dentist on time. However, you should be careful about the condition of the gums and avoid their inflammation.

With gingivitis and periodontitis, the crown can be unfixed.

With proper installation and the use of good materials, the service life of a cast crown reaches 15-20 years.

Opinions vary...

Reviews of people who have made their choice in favor of cast crowns for the correction of the dentition.

Issue price

The average price of a nickel-chromium solid crown without coating is about 2000 rubles. Its cost with gold coating (titanium nitride) is from 3000 rubles.

The price of crowns made of precious metals is much higher and depends on the type of material.

dentazone.ru

What is a one-piece crown?

If you want to save money, and you are not allergic to metal, your doctor will recommend ordering a crown made of an alloy of chromium and cobalt. It is called one-piece cast for the simple reason that it is made by casting in a mold. It's simple, fast, and fairly cheap. Thus, it is possible to make both a single construction and a bridge for several teeth. This saves time in manufacturing, because. artificial teeth will not need to be connected by soldering.

If you have previously had a crown made of any material and it needs to be replaced, you can easily replace it with a cast one. To do this, it is enough to contact a specialist in prosthetics. He will remove the old crown, make sure that the tooth stump is in good condition, and make an impression. According to the finished model, a new product will be made in the dental laboratory, completely repeating the shape of the patient's tooth. This refers not only to the general contour, but also to the features of the chewing surfaces. After all, if the bite is broken, complications are possible up to inflammation of the temporomandibular joint. Headaches and other unpleasant symptoms appear.

If, however, a crown is created with the same contours and relief, then the patient will not have a long period of addiction, the bite will remain, and the chewing function will be fully restored.

The main indications are:

• Strong tooth decay - 70% or more, in which it makes no sense to put a filling. The damage is so severe that the photopolymer pin will simply fall out;
• It is necessary to strengthen the chewing tooth;
• The patient was found to have pathological abrasion of tooth enamel;
• As a result of an injury, the tooth broke, a crack formed in it;
• bite pathology;
• Bruxism.

Are there any contraindications? In general, there are not many of them.

• The main one is an allergy to metals and alloys. It does not occur very often, but this option should be considered. If you have a similar problem, doctors will suggest other materials.
• If you have highly sensitive teeth, this option is also not suitable. Metal conducts heat well. The turned tooth will be constantly exposed to thermal stress. This will eventually lead to inflammation of the pulp.
• If the teeth, standing on the opposite jaw, and being antagonists to the prosthesis, are subject to increased abrasion. In contact with the metal surface of the crown, the negative effect is enhanced.

Types of cast crowns

Any metal crown can be offered with or without surface treatment. The simplest and most budget option - without spraying. In this case, a blank is cast, shaped like a patient's tooth. Its surface is polished to a shine.

Such a solution is relevant for 6-8 teeth, which are least visible during a conversation. For prosthetics of a tooth in the smile zone, a one-piece crown with a coating imitating gold is often used.

The next popular type of metal tabs is lined products. They are used in cases where it is necessary to restore the front teeth. It differs in that it has a layer of plastic or a ceramic coating on the front side. That is, when you smile, it is almost not noticeable that one of your teeth is artificial.

This option also has its drawbacks:

• The lining layer can be easily damaged. And the appearance of a metal base peeking out from under the shell does not look very aesthetically pleasing, to put it mildly;
• Price. A one-piece cast crown of this type is not much lower than a classic metal-ceramic crown. So there is not much savings here. It is better to add money and order a better option.

Application in the manufacture of bridges

If you put a "bridge" on several teeth, it is not necessary to spend a lot of money on installing expensive cermets. It should be installed on 5 and / or 6 teeth. For 7-ki and 8-ki, a regular one-piece cast crown is suitable. This method of prosthetics is recommended by many dentists. It's reliable, simple, and inexpensive. After all, prosthetics on zirconium dioxide is 2-3 times more expensive than a similar procedure using a cobalt-chromium alloy.

This type of bridge, in which two types of crowns are used, is called a combined bridge.

Here is the alignment, as with furniture. If you put an expensive and beautiful closet in the hall, then something simple and cheap, but practical, is suitable for a garage, workshop, pantry, barn. So it is with the smile zone / chewing teeth.

Advantages of cast crowns over metal ceramics

Many people will be surprised to see such a paragraph in our article. After all, they all know very well that cermet is one of the best materials for dental prosthetics. However, there are some nuances that you do not know about, or do not attach much importance to them.

If we are talking about premolars and molars, then metal cast products have their advantages:

• The design is much simpler. Instead of making a frame and a layer of ceramic for coating, one piece of a given shape is made;

• High reliability. If the lining of the cermet can theoretically be damaged and form a chip, then this does not threaten the all-metal counterpart;
• Metal is much cheaper. For low-income citizens, students, pensioners, etc. a solid crown is the way out;
• The material can withstand heavy loads;
• It is not required to remove a large amount of dental tissue when turning the stump for a crown. This is due to the fact that the thickness of the cast crown is less than the similar parameters of the metal-ceramic one.

Advantages of cast products in comparison with stamping

About thirty years ago, dentists did not bother with such questions. They used stamped from special sleeves. They were mechanically processed, and then, if required, covered with a sputtering layer. In the manufacture of bridges, metal blanks were interconnected by soldering. In large cities, this technology has not been used for a long time, but in the provinces it remains relevant.

What are the disadvantages of a stamped product?

• Loose fit. This leads to the fact that the tooth under the crown begins to rot. Over time, the patient goes to the doctor with complaints of pain. In most cases, the tooth cannot be restored;
• The workpiece is quite thin. Loads and chemical effects of the moist environment in the mouth gradually lead to destruction. As soon as the hole in the crown becomes through, access for infection from the outside appears. Secondary caries begins, then pulpitis;
• If "bridge" prostheses are made using this technique, the connections by which the crowns are connected to each other often break. Soldering is far from the best connection method;
• The crown itself and the alloy used for soldering have different compositions. As a result, galvanic currents occur, a negative effect on the mucous membrane, up to leukoplakia (a harbinger of oncology).

Now let's move on to the advantages of cast products:

1. Resistance to mechanical wear;
2. One-piece cast crown is durable and resistant to moisture;
3. Short production time;
4. Lack of welded joints;
5. Protection from irritation and other negative effects on the mucous membrane;
6. The service life is much higher (from 10 years);
7. High manufacturing precision and fit. This prevents the penetration of saliva and food with bacteria under the crown.

If a clasp system is installed, then it will be much more reliable on metal cast crowns.

The technology has been studied for a long time, there are statistics that make it possible to verify the effectiveness of this method of restoring damaged teeth.

One-piece cast crown - installation on the stump of the tooth, stump tab, implant

What is the basis for this type of dentures? There are several options. If this is a tooth that has not yet been depulped, it is ground, and then a crown prepared in shape is put on.

The option with stump tabs is also very popular. This is a simple design, consisting of a pin and a crown part, on which an imitation of a tooth is put on. Preparation requires the removal of part of the dental tissues, the creation of a recess in the canal by 1/3 of the depth. A tab is installed in it, made according to a model cast from special plastic.

The tab is securely fixed inside with a special cement. It allows you to restore teeth destroyed by 70%, and almost under the base. It can be made from cermets, alloys, gold and other materials.

The third method is relevant in cases where the tooth has already been removed, or will be removed for medical reasons. Doctors make a puncture of the mucosa, then drill a recess in the bone, and install a metal pin into it. An adapter called an abutment is put on it. After that, a crown is made in the dental laboratory, which is installed on this base.

There is an undeniable advantage of prosthetics on an implant - there is no need to grind adjacent teeth. Using implanted artificial roots, you can restore any number of lost teeth.

The cost of cast crowns

The average price in different clinics varies significantly. Amounts from 500 to 4000 hryvnia are indicated. It depends on many details:

• On what basis is the crown placed (tooth, inlay, implant);
• Alloy type (titanium, cobalt-chromium, gold, silver alloys);
• The complexity of manufacturing;
• Methodology.

We will analyze the last point in a little more detail. Any one-piece crown is not just a "stub". It should completely imitate the tooth, without disturbing the bite. In order to achieve high accuracy, experts use two methods:

• Casts of both jaws. So a specialist in a dental laboratory can customize the product;
• Creation of a computer model of bite. This option gives higher accuracy.

The price that you see in the price lists of clinics often does not include some items. As a result, you are dumbfounded by the amount for which you were not ready. The cost usually already includes installation and correction. But there are clinics in which these are separate services.

Separately paid:

• Sanitation (dental treatment) before prosthetics;
• Diagnostic procedures (computed tomography, orthopantomography);
• Preparation with pulp removal, endodontic procedures.

Be sure to specify what exactly is included in the amount indicated in the price list, and how much other services cost. There are clinics offering turnkey work. That is, the price includes all services, including the necessary pictures. Often this is the easiest option. You immediately know how much money you have to pay to get a tooth.

Solid crown - reviews

The problems described in the reviews are typical for any prosthetics. Most often, people have to deal with the destruction of the tooth under the crown. There are several reasons:

• The doctor treated the tooth poorly, and secondary caries arose there;
• Due to poor fit, a gap formed between the stump and the crown. Bacteria took advantage of it;
• The fixation device turned out to be of poor quality, and the crown fell out.

These problems only indicate that patients turned to specialists with low qualifications. Read other people's reviews to find out who to trust with your teeth and money.

All the best to you, dear readers. We are waiting for your comments. Don't forget to subscribe to the site's newsletter. We will talk about current topics.

expertdent.net

materials

The production of solid crowns is based on the use of high-strength alloys. To give greater strength to chromium, cobalt or nickel is added. Titanium also justifies its use as an excellent material for prosthetics. This metal does not change its original color under the influence of an aggressive environment in the oral cavity. It does not have a harmful effect on the human body and is not rejected by tissues.

At the request of the patient, a sputtering of precious metals can be applied to the alloy blank. More often from gold, because this metal provides a tighter fit due to its high ductility. Such prostheses wear out more slowly, but are more expensive than pure metal cast crowns.

Varieties

At the moment, there are several types of cast crowns for teeth:

• without spraying - consist of the original metal alloy, which is carefully polished.
• one-piece cast crown with spraying - a layer of another metal is applied to the source material, for example, gold or silver.
• with lining. The outer side is covered with special plastic or ceramic pads. Despite their attractive appearance, the crown veneer may chip over time. The high cost of materials used for lining significantly increases the cost of this type of prosthetics.
• bridges - suitable for prosthetics of the bridge of the anterior and lateral teeth at the same time. A crown with veneer is placed along the front line in the smile zone. The remaining cast teeth will be metal.

Manufacturing steps

To obtain a quality product at the output, it is necessary to adhere to its phased production. It consists of clinical and laboratory stages.

Stage 1

Includes a preliminary examination of the patient's oral cavity in order to identify problem areas with subsequent sanitation. After the treatment, the dentist must take a cast of the tooth for which the prosthesis will be made.

For the best display of anatomical features in modern dentistry, silicone impression masses are used. They do not cause allergic reactions, do not stick to the surface of the tooth and do not wet it. A temporary construction is installed for the patient to get used to the future solid crown as soon as possible. In addition, it performs an aesthetic function.

In the laboratory, a detachable model of the future gypsum prosthesis is being created. Based on this model, a blank is made of wax, which is later replaced with metal.

Stage 2

The clinical stage includes preparing the elements of the patient's oral cavity for wearing an all-metal prosthesis. For the purpose of the most accurate and tight fit of the crown, the dental tissue is additionally polished. A small hole is made in the prosthesis. The element is filled with wax and applied to the tooth. Excess wax is forced out and exits through the drilled hole. Once again, all inaccuracies are evaluated, and the finished design is sent to the laboratory.

Having assessed the coincidence of the finished product and the plaster model, the laboratory assistant can start polishing the cast tooth.

Accuracy of fit to adjacent teeth is also important. Even a small error in work can lead to unpleasant consequences. The patient will experience discomfort and pain while wearing the prosthesis.

Stage 3

The finished product is installed in the oral cavity. The coverage of a living tooth should be maximum, the design must fit completely and without difficulty between the antagonist teeth. In this case, the crown should not go deep into the gum area. If any discrepancies or inaccuracies occur, the product must be returned to the laboratory. Excess material is sanded off.

A perfectly fitting prosthesis is fixed with a special cement mortar. After the procedures, the patient should feel as comfortable as possible with the new prosthesis. Restriction of the functions of the jaw apparatus is unacceptable.

It takes a lot of time to make a cast crown on the teeth - up to one and a half months. Maximum concentration of attention is required when performing laboratory steps. Any inconsistency of the finished product with the dimensions of the plaster model at the “fitting” stage is fraught with re-sending to the laboratory for revision.

Advantages over stamped

The use of stamped crowns, although a thing of the past, is still used. Low accuracy when creating a crown from a stamp led to its loose fit to the jaw element. As a result, the patient's dental tissue rotted. Bridge prostheses from stamps were interconnected by soldering, which greatly shortened the period of wearing such a prosthesis. The heterogeneity of metals caused inflammatory processes inside the oral cavity.

A one-piece cast crown has a number of advantages compared to a stamped crown:

• a long period of wearing a prosthesis - 10 years or more. When preparing it, the anatomical features of the patient's jaw are taken into account. The tight fit of the crown to the tooth surface makes it impossible for food to get under the prosthesis.
• design requires maximum precision.
• when creating bridge structures, one-piece casting is used. As a result, a crown that does not have adhesions lasts longer.

Advantages of cast crowns

From an aesthetic point of view, the use of cast retainers to replace anterior teeth is not practical. Metal-ceramic crowns are excellent for this purpose. However, when it comes to restoring the chewing functions of the jaw, metal prostheses are indispensable.

Advantages of cast crowns for teeth:

• this type of prosthesis involves the grinding of dental tissue to a lesser extent than metal-ceramic.
• ease of manufacture. The preparation of a one-piece cast structure includes two main stages: the creation of an accurate anatomical model and the subsequent casting.
• Compared to metal ceramics, cast metal crowns are affordable.

Cons of solid structures

With all the variety of advantages, cast crowns have some disadvantages:

• limitation in the use of these structures for prosthetics of the anterior tooth line in the smile zone.
• the hard surface of the prosthesis can, over time, provoke the erasure of opposing teeth.
• long production time.
• restriction in the choice of the color of the cast tooth (gold, silver).
• a metallic taste in the mouth.

Dental prosthetics in the absence of teeth of the upper jaw

Tver State Medical Academy

Department of Orthopedic Dentistry with courses in Implantology and Aesthetic Dentistry

Head of the Department - Honored Worker of Science of Russia,

Doctor of Medical Sciences Professor A.S. Shcherbakov

Cast all-metal and combined crowns (metal-plastic, metal-ceramic). Conditions and indications for prosthetics. Principles and methods of tooth preparation. Double (corrected) impression with retraction of the gingival margin.

(guidelines for students)

Compiled by Candidate of Medical Sciences, Associate Professor I.V. Petrikas

Lesson topic:“Cast all-metal and combined crowns (metal-plastic, metal-ceramic). Conditions and indications for prosthetics. Principles and methods of tooth preparation. Double (corrected) impression with retraction of the gingival margin.

Purpose of the lesson: to study the conditions and indications for prosthetics with cast all-metal and combined crowns; learn how to take double impressions with silicone impression masses, master the technique of retraction of the gingival margin.

Key words and designations:

HF - upper jaw,

LF - lower jaw,

Rg - x-ray,

Mate - cast, combined crown,

STK - light-hardening composite material,

Initial knowledge.

Combined crowns- these are metal crowns with a plastic lining from the vestibular surface, or a plastic, composite or ceramic coating on all sides.

1. varieties of combined crowns are presented in table 1.

Table 1

Types of combined crowns

2. Silicone impression materials.

2.1. Two types of silicone impression materials (C-silicones and A-silicones),

2.2. Viscosity grades of silicone impression materials,

2.3. Positive properties and negative qualities of silicone impression materials.

3. Methods of retraction of the gingival margin.

3.1. Mechanical method of gingival margin retraction (indications and materials),

3.2. Mechano-chemical methods of retraction of the gingival margin,

3.3. Chemical methods of retraction of the gingival margin.

TASKS FOR CONTROL OF THE INITIAL LEVEL OF KNOWLEDGE.

1. SILICONE AND THIOKOLO IMPRESSION MATERIALS APPLIED

GO FOR

duplicating models,

obtaining double (corrected) impressions,

obtaining functional impressions from edentulous jaws,

obtaining functional impressions with partial loss of teeth,

volumetric modeling of the polished surface of a complete denture.

obtaining an impression during relining of the prosthesis,

taking an impression with a copper ring.

2. THE BASIS OF SILICONE IMPRESSION MATERIALS IS

sodium salt of alginic acid,

eugenol, talc, zinc oxide,

beeswax, paraffin, rosin,

silicon-organic polymers.

SILICONE AND THIOKOLO IMPRESSION MATERIALS OF LOW VISCOSITY ARE USED AS

the first, main layer in double prints,

the second, corrective layer in double prints.

SILICONE IMPRESSION MATERIALS ARE

1) Sielast (Ukraine), 5) Stomaflex (Czech Republic),

2) Vigalen (Russia), 6) Exaflex (Japan),

3) Elastic (Czech Republic), 7) Stomalgin (Ukraine),

4) President (Switzerland), 8) 1+2+3+5+7,

POLYSULFIDE (THIOKOL) AND SILICONE IMPRESSION MATERIALS ARE ARTIFICIAL _____________________ OF COLD VULCANIZATION.

To retract the gingival margin in a 20 year old patient, you will use:

retraction threads,

retractors and mechanical rings,

retraction gel

For gum retraction in a 60 year old patient with moderate periodontitis and cardiovascular disease, you will use:

1) threads impregnated with retraction fluids,

2) retractors and mechanical rings,

3) retraction gels and pastes with adrenaline-containing substances

A feature of the preparation of teeth in the manufacture of cast all-metal and combined crowns (metal-ceramic, metal-plastic) is that more significant grinding of hard tooth tissues is performed than in the manufacture of stamped crowns, i.e. at least 1 mm from all sides. This is due to the fact that the cast crown is thicker than the stamped one (for example, the minimum thickness of the metal-ceramic crown frame in the neck area is 0.2 - 0.3 mm along the vestibular or cutting surface - 0.5-0.8 mm) When preparing teeth for cast crowns the volume of preparation varies: in the neck region - 0.3 - 0.5 mm in the region of the coronal part of the tooth itself - 0.5 - 1.2 mm, along the occlusal surface - 1.0 - 2.5 mm, depending on the material, from which the future artificial crown will be made. The stump of the tooth is given a slightly conical shape, but not more than 5 - 7 °.

Four forms of preparation are considered classical, the functional effectiveness of which is confirmed by clinical experience and special studies. These include preparation forms: tangential, with a semicircular ledge with a rectangular circular ledge and with a ledge-bevel at an angle of 135 . To obtain them, standards have been developed 180 sets that provide appropriate forms of preparation and subsequent optimal distribution of impression and modeling materials, cements, etc.

In practice, in our country, preparation without ledge (tangential) is mainly used, since it is easier to perform, it is more familiar to most clinicians and, moreover, requires fewer tools, i.e., it is more economical, or the formation of the so-called ledge symbol is carried out with insufficient volume. hard tissues of the prepared tooth, for example, the lower incisors.

When preparing teeth for various types of cast crowns, it is possible to create a ledge in the cervical region. There are many different types of ledges, but in everyday practice the most common are the 135° beveled ledge and the semi-lunar ledge.

To form a ledge-bevel at an angle of 135°, torpedo-shaped drills are additionally needed, and for a semi-lunar ledge, cylindrical cone-shaped drills with a rounded end are required. The ledge can be located supragingivally (above the gum level), at the level of the gingival margin and subgingivally (under the gum).

The preparation must be programmed, i.e. the removal of a given amount of hard tissues must be carried out in accordance with the safety zones (according to A.G. Abolmasov) under X-ray control.

Grinding should be carried out with diamond-coated tools (it is possible to use modern carbide burs). In the process of preparation, it is necessary to carefully observe the precautionary measures, avoiding overheating of the tooth tissues. For this purpose, an intermittent preparation technique is used, air-water cooling is mandatory, especially when working on turbine installations. The preparation of the tooth is started from the proximal surfaces using a separation disc or a thin pointed diamond bur (see lesson 4).

If preparation with a ledge is planned, then during separation, the contact surfaces are ground from the cutting edge to the tops of the interdental papillae with the formation of a preliminary ledge 0.3-1.0 mm wide at a right angle to the longitudinal axis of the tooth. At the same time, the approximal surfaces are tapered towards the cutting edge with the angle of convergence of the walls relative to the longitudinal axis of the tooth (for solid metal crowns - 5-7°; for solid-cast crowns with lining - 6-8°). The lower the crown height, the smaller the angle of convergence, since sufficient surface area of ​​the prepared tooth core must be provided for better retention.

After that, the tooth is shortened along the chewing surface or cutting edge to achieve dissociation with antagonist teeth by about 0.7 - 1.0 mm with a solid crown or with a combined one (metal-ceramic, metal-plastic), when the lining is not applied to the occlusal surface. In the manufacture of a combined (metal-ceramic, metal-plastic) crown - by 1.5 - 2.5 mm (on average, by 1/5 of the crown height). The main reference point is the presence of space (1.5 - 2.5 mm) between the occlusal surfaces of the prepared tooth and the antagonist teeth. At the same time, in the upper frontal teeth and first premolars, a slope is created at an angle of 20 -15 of the ground cutting or chewing surface towards the palatal surface, and for the lower teeth of the frontal group I, the same slope is applied towards the vestibular surface (with orthognathic bite)

The next stage of preparation is the final grinding of the hard tissues of the tooth in the cervical area and the final formation of the ledge. Particular attention is paid to the creation of a ledge. The location and shape of the ledge depend on the type of crowns, on the condition of the periodontal tissues and the age of the patient.

Recently, in the literature there is a requirement to comply with the supragingival preparation margin, which is considered optimal in terms of safety, i.e., the absence of complications. In addition, the supragingival position of the preparation margin simplifies the taking of impressions and allows better control of the marginal fit of the crown margin. At the same time, other authors note the need to locate the preparation border and the edge of the crown in the area of ​​attachment of the gingival epithelium to the tooth, i.e., subgingivally, for reasons of caries prevention.

Experience shows sufficient safety in performing the preparation margin moderately subgingivally, taking into account the geometric parameters of the gingival fissure, both with a tangential shape and when creating a ledge-bevel at an angle of 115°. However, it should be noted that tangential subgingival preparation obliges the doctor to further apply an oral and vestibular garland or reduce the edge of the metal-ceramic crown to nothing. In this case, the preparation border can reach the middle of the gingival fissure, i.e., the edge of the artificial crown should not touch its bottom (epithelial attachment). This form of preparation makes it possible to achieve sufficiently stable results of orthopedic treatment with the help of solid-cast metal-ceramic and metal-plastic structures and the absence of the development of carious lesions of hard dental tissues.

In the manufacture of any single solid crowns on the oral surface of the crown, a groove is prepared from the occlusal surface to the gingival margin, 0.5 mm deep. This allows you to create an additional retention point and simplifies the fitting of the cast framework.

The ledge, as a rule, is created uniform in width. Its uneven width is allowed in the absence of conditions in the form of narrowing of the side surfaces.

After the formation of the ledge, all surfaces of the stump of the prepared tooth must be smoothed.

Plaster or silicone blocks are used to fix the correct ratio of the dentition in the position of central occlusion.

If it is necessary to determine the central ratio of the jaws, wax bases with occlusal rollers are made.

When working with teeth with vital pulp, electroodontodiagnostics must be carried out: before the preparation, not earlier than three days after the preparation, and before fixing the fixed structure with permanent cement. This is necessary to exclude traumatic (thermal) damage to the pulp. With signs of pulp damage, the issue of depulpation is resolved.

Teeth prepared for crowns are protected by temporary crowns (kappa), which can be made both in the clinic and in the prosthetic laboratory. When temporary mouth guards are made, they are fitted, if necessary, they are relocated and fixed with temporary cement.

To prevent the development of inflammatory processes in the tissues of the marginal periodontium, anti-inflammatory regenerative therapy is prescribed, including rinsing the mouth with oak bark tincture, as well as chamomile and sage infusions. If necessary, applications with an oily solution of vitamin A or other means that stimulate epithelialization.