Preparing teeth for a metal-ceramic crown

Author of the article:

Anastasia Vorontsova

Photo: Tooth ground for metal-ceramics

Preparation or grinding of teeth for metal ceramics is a rather unpleasant procedure that is required for dental prosthetics.

An exception to the rule is prosthetics on implants.

Grinding (preparation) is one of the important stages of preparing teeth for prosthetics.

It involves the removal of hard tooth tissue to level the surface.

Until recently, preparing teeth was quite lengthy and unpleasant.

Modern techniques and anesthetics have made the turning procedure absolutely painless and reduced the time it takes.

Description of the procedure

Tooth preparation is the removal of hard tissues that are damaged or interfere with the fixation of the crown.

Previously, turning under metal ceramics was long and painful. However, thanks to modern anesthesia drugs and the latest instruments, the duration and pain are significantly reduced.

During the procedure, the doctor strives to preserve healthy organs as much as possible. In this case, it is necessary to create natural forms, which is achieved through the formation of ledges.

For proper preparation, the following criteria must be met:

• the dental organ has retained its natural shape;
• the tooth stump is reduced and slightly tilted;
• the tooth is reduced in size by up to 2 mm;
• There are no unpleasant consequences near the dental organ.

Thanks to the preparation of teeth, the metal-ceramic crown receives the place it needs, so that it does not exceed the neighboring teeth in height and does not protrude outward or inward.

The crown should fit tightly under the gum, which is facilitated by a ledge under the gum.

To install a solid crown, up to 0.3 millimeters must be removed from the lateral surface without damaging adjacent teeth. To install a metal-ceramic prosthesis, the tooth is depulped and then 2 millimeters are removed from it. There should be a ledge on each side.

The doctor determines what size layer to remove based on the size of the tooth and the characteristics of its position in the dentition.

Types of ledges during turning

For reliable fixation of the crown, it is necessary to carry out turning with a shoulder.

The most common types of teeth grinding are:

Photo: Grinding teeth with a ledge

• A knife-shaped ledge, the width of which is 3–4 mm, is a commonly used type. It is used for all-metal crowns and is optimally suited for turning inclined teeth.
• The grooved rounded ledge allows you to preserve dental tissue in the maximum amount. Its width is 0.8 - 1.2 mm. This is a classic option for metal ceramics.
• The shoulder ledge is the most uneconomical type of turning, requiring depulpation. The width of the ledge is 2 mm. However, such a ledge allows the crowns to be fixed more firmly and has higher aesthetic values.

Peculiarities

Grinding teeth for metal ceramics has the following features:

1. The need to remove a significant layer of enamel and dentin (up to 2 millimeters).
2. The use of anesthesia so that the patient does not feel pain during grinding. The most common methods are infiltration and conduction anesthesia.
3. The main goal of specialists is to preserve as much bone tissue as possible and remove all damaged areas.
4. After removing the tissue, a truncated cone is obtained, the edges of which are then slightly rounded.
5. Grinding should be done intermittently after every 2-3 seconds.
6. The tool must be constantly cooled during grinding so as not to cause a burn to the pulp.
7. The contact surfaces must be ground with the device at low speeds.

Rules for grinding on a living tooth

• Dissection is carried out under anesthesia, slowly, intermittently, and with sufficient water.
• For turning it is necessary to use a new bur and a special tip.
• Application of a special coating that prevents infection from entering the nerve and further development of the inflammatory process.
• Immediately, immediately after the procedure, temporary crowns must be installed on the ground teeth, which are fixed with special cement containing an antiseptic.

Stages of the procedure

Let's take a step-by-step look at how teeth are ground for a metal-ceramic crown:

1. Creating grooves. The doctor makes peculiar incisions that will show how much hard tissue needs to be removed. These grooves subsequently contribute to uniform grinding. Creation of notches can be done with a bur or a shaped head in the form of a wheel. They are carried out from the vestibular side to a depth of 1.5 millimeters. The ledges on the palatal and vestibular sides are removed.
2. Removing tissue from the vestibular and oral sides. Maximum caution is important at this stage. Diamond burs directed parallel to the tooth remove the required layer. When working on the palatal side, the palatal tubercle is preserved.
3. Preparation from the occlusal surface. This stage consists of preparing one and a half to two millimeters, while not disturbing the anatomy of the chewing surface. The living crown of the anterior dental units is thus shortened by 25%.
4. Separation of the contact side. It is important to separate the medial surface from the distal one and then remove the tissue. A diamond bur with flame-shaped or needle heads is used. 0.5 millimeters are left above the gum. To prevent periodontal injury, a dental matrix and an interdental wedge are used.
5. Gum retraction. If it is necessary to immerse the bur deeply, you need to protect the gums. Therefore, it is moved away with the help of special threads, rubber rings and a spatula. This stage is important for taking an impression so that a high-quality model can be easily made.
6. Formation of the ledge. The width of the ledge can be 0.5-1.5 millimeters, depending on the anatomy of the dental organ. It is made with a face bur.
7. The final stage of processing. The dental stump should be in the form of a uniform cone. At this stage, irregularities are cut off, protruding edges are removed, and the stump is rounded.

Are there any complications?

In most cases, complications are temporary and completely reversible:

1. Damage to the gums due to improper processing. Collapse of the gum line may occur, leading to pain, inflammation, and gradual atrophy of the soft tissue. The problem requires surgical treatment. When an infection occurs, gingivitis can develop.
2. Tooth opening during grinding. The doctor will accumulate (restore) the destroyed fragment or remove the pulp and install a pin.
3. Inflammation of the pulp after the procedure. It is characterized by swelling and discomfort and is temporary.

Laser processing

Thanks to laser pulses, a thermal effect occurs on the fluids contained in the teeth. In this case, the structure of the material is microscopically destroyed. Unnecessary tissue is then cooled with an aqueous solution or air, and then removed without hindrance.

Laser preparation has the following advantages:

• no noise when the tool operates;
• safety of the procedure due to the absence of tips in the device that rotate at high speed;
• the frame for the future crown is obtained quickly and without pain;
• infection during the procedure is excluded, since the instrument does not touch the tissues.

Cost of services

If treatment is started on the day of treatment, consultation and treatment plan are free

Tunnel preparation

Tunnel turning is carried out using turbine units with diamond or metal tips. At the same time, it is important that the equipment is new, since a worn-out instrument can cause overheating of the tissues and their destruction.

Note: With this method, it is possible to save as much material as possible for future crown installation. The result of removal can be predicted in advance, and during the procedure it is easy to control the volume of the removed layer.

This type of preparation is used today more often than other methods.

Where to put high-quality crowns of any variety?

Regardless of whether you choose metal, metal-ceramics or ceramics as the material for prosthetics, you should only contact real professionals for crowns. After all, we are talking about a complex high-tech procedure that requires both the skill of all the specialists involved in it and the impeccable quality of materials. The service life and ease of use of a crown increase significantly if it is made using the most modern equipment, including computer modeling.

The Unident network is a clinic that combines all the components of successful prosthetics. Each of our dental centers is equipped with the latest technology, and we purchase materials and components only from reliable, world-famous manufacturers. And, of course, our main asset is our excellent specialists, who are capable of solving the most complex and non-standard problems. Add to all of the above also reasonable prices - and you will understand why Unident is so popular among patients.

Preparation with abrasives

An alternative to a drill with its rotating drills is also the supply under pressure of air mixtures containing an abrasive powdery substance. By acting on the enamel, this mixture gradually removes hard tooth tissue.

Features of preparation with abrasives are as follows:

• speed of the procedure;
• absence of tissue overheating and painful sensations;
• gentle effect on the dental shell;
• careful grinding, which allows you to obtain the necessary stump while preserving a significant amount of healthy tissue.

Techniques

There are a number of methods for grinding teeth.

Ultrasound

Advantages of ultrasonic turning:

• Minimum pressure on the tissue of the working tips.
• There is no overheating of enamel and dentin.
• Painless procedure.
• No chips or microcracks on the walls of the pin.
• There is no negative effect on tooth tissue.

Laser

Photo: Laser turning of a tooth
Pulsed lasers are used for preparation.

Their effect is that the water in the tooth tissues is strongly heated under the influence of the laser. This leads to disruption of the integrity of enamel and dentin.

With the help of a water-air mixture, their microscopic particles are destroyed and removed.

Advantages of laser turning:

• Silent operation of the equipment.
• Low heating of tooth tissues.
• The procedure is highly secure, since there are no rotating elements.
• High preparation speed.
• No chips or cracks on the pin.
• Absence of factors contributing to infection.

Tunnel preparation

Turbine units are used for grinding teeth, allowing you to regulate the speed of work, as well as metal or diamond tips.

The quality of such equipment has a direct impact on the result of turning, since instruments used for a long time cause overheating of the tooth tissue, which increases the risk of tooth destruction.

When tunnel grinding, it is necessary to leave as much tooth tissue as possible.

The advantage of the technique is a clear prediction of the result and the ability to control the thickness of the tissue layer being removed.

Disadvantages of the technique:

• The possibility of tissue overheating and severe pain with insufficient pain relief.
• Injury to soft tissues due to violation of the procedure technique.
• There is a high risk of cracks and microchips of hard tissue when using low-quality instruments.

Air abrasive method

An air mixture with abrasive powder is used, supplied under high pressure. When it gets on the tooth enamel, minor destruction and removal of tooth dust occurs.

Advantages:

• High speed and simplicity of the procedure.
• No pain or heating of tooth tissue.
• When preparing living teeth, the absence of vibration has a positive effect on the condition of the pulp.
• Maintaining maximum tooth volume.

Chemical turning method

It involves the use of a chemical substance that promotes the destruction of enamel and dentin.

The disadvantage is the duration of the procedure. Sometimes the duration of exposure reaches thirty minutes.

Advantages:

• No need for pain relief.
• There is no thermal damage to the tooth.
• There are no small cracks or chips on the enamel.
• The presence of psychological comfort due to the absence of sound from the drill.

Is dissection painful?

Removing hard tissue is a painful procedure. But with high-quality anesthesia, the patient does not feel pain at all. However, there are situations when, after the anesthesia wears off, the tooth or gums around it begin to hurt.

The main cause of pain in this case is the removal of a large amount of tissue from the vital dental organ. In this case, the tooth, the pulp of which is located under the remaining thin layer of hard tissue, hurts when touched, as well as when exposed to cold or sour food. In such a situation, it is better to consult a doctor so that he can install a temporary crown to protect the ground tooth or cement the thinned area.

Pain may also be a consequence of pushing back the gums with a special thread in order to see the working area when grinding. The floss puts pressure on the soft tissue between the tooth and gum, creating swelling and pain. This pain should go away within two days. If it occurs after a longer period of time, it is better to consult a doctor, as this may be a signal of nerve inflammation or the development of periodontitis.

Preparation for inlays: principles and rules

Inlays are partial dentures and are used to replace large defects in dental tissue.

Depending on the form, there are the following types of tabs:

• Inlay (inlay) - minimally invasive, since they do not affect the tubercles of the tooth;
• Onlay (onley) - serve to replace the internal slopes of the dental tubercles;
• Overlay - cover the entire volume of at least one tubercle;
• Pinlay (pinlay) - cover all dental cusps and have a special pin in their design - pin;
• stump inlays are a metal pin used in cases of severe destruction of tooth tissue and serving as a support for the crown.

Depending on the materials used, the inlays can be ceramic, metal or reinforced composite.

The main feature of preparing teeth for inlays is the need to create parallel side walls near the cavity for proper insertion of the finished structure, as well as to create sufficient depth for reliable fixation of the element.

Basic principles of turning for inlays:

1. The prepared cavity must have an optimal shape for the smooth insertion and removal of the prosthesis. In this case, it is necessary to strive for maximum parallelism of the vertical walls. We allow only a slight angle of their deviation.
2. The angle of transition of the cavity walls to the bottom should approach a straight line. The relationship of all walls should contribute to the uniform distribution of chewing pressure and maximum stability of the inlay.
3. When forming the day, it is necessary to take into account that a minimum layer of tissue should remain above the pulp to ensure its protection from external factors. In adults, this value is 0.6 mm, and in children and adolescents - 1.4 mm.
4. When forming complex cavities, additional fixation points should be formed to allow the inlay to be firmly fixed.
5. When forming a cavity for metal inlays, it is necessary to create a bevel at the level of the enamel with a width of at least 0.5 mm and at an angle of 45°, which will ensure more accurate marginal contact of the prosthesis and tooth tissue.
6. In the manufacture of metal-free structures, the presence of a bevel is contraindicated due to the fragility of materials with a small thickness.

Purpose of installing temporary crowns

After grinding down the tooth, a temporary crown made of plastic is placed on it, which will remain in the oral cavity for two or three weeks while the permanent prosthesis is made.

For some patients, the fact that a doctor makes and places a temporary crown is incomprehensible and even seems meaningless.

But this procedure is simply necessary. Since temporary crowns protect teeth from external influences, and also correctly distribute the load when chewing.

The advantages of using temporary crowns are as follows:

1. Teeth ground for a crown are not protected from the harmful effects of pathogenic bacteria, which can cause inflammation of the teeth under a permanent crown, and temporary products protect them from infection.
2. When biting, a ground tooth can be displaced by the opposite dental organ, which can lead to unwanted errors during prosthetics.
3. Temporary dentures give the oral cavity an aesthetic appearance, and with it the patient’s self-confidence. They operate in the same way as permanent ones, only they are made from budget material.

Is turning necessary?

Unfortunately, despite the latest technologies and advances in dentistry, it is not possible to skip the stage of tooth preparation.

• In order for the crown to be firmly fixed on the tooth, it must fit to it with maximum precision. The natural shape of teeth is not ideal; their side walls have a convex shape, which excludes the possibility of creating a crown of this shape.
• As a result of grinding down the enamel, the surface of the tooth becomes the correct shape, onto which a crown can be easily fixed.
• In addition, the design itself has a certain thickness, which must be taken into account so that you do not feel discomfort in the oral cavity when eating and talking.

Grinding of teeth for a crown in the gingival area

The edge of the artificial crown in relation to the marginal gum can be located above, at the level of, or extend into the dental gingival sulcus. In the first case, the periodontium is not damaged, but aesthetics suffer. It is possible to compensate for this drawback by introducing the edge of this structure into the groove, but not more than half its depth, which avoids trauma to the dental-gingival attachment.

Another feature of this site is the preparation of the ledge. This is a kind of step that allows you to make an aesthetic and fairly thick edge of an artificial crown. In addition, its edge, ending at a ledge, does not have a harmful effect on the gum, does not push back or injure it. Also, this preparation technique increases the mechanical strength of the installed structure. The ledge can be flat, trough-shaped or beveled at an angle of 135◦. The latter is the most common.

Cost of a metal-ceramic tooth, reviews

The cost of a metal-ceramic tooth is influenced by the pricing policy of the clinic and the manufacturer of the ceramic coating. Surely, having decided to replace lost teeth, metal ceramics, reviews, photos and attractive prices prove their advantages, and also allow you to replace your natural teeth. Metal-ceramics, the cost of which is determined mainly by the type of ceramic powder, will last a long time with proper prosthetics.

Therefore, when paying attention to the cost of a metal-ceramic tooth, you should also take care to study reviews and get advice from a doctor who provides dental prosthetics. Metal-ceramics, reviews from specialists and patients as a whole with photo support can give the right direction and finally replace the missing tooth. Metal ceramics and the cost of prosthetics services are related to the qualifications of the prosthetist and the reputation of the clinic. We always take into account individual characteristics and explain in detail whether it is worth installing metal ceramics in a particular case and what the cost of our services is.

Possible negative consequences

If the doctor prepares the tooth incorrectly, the patient may experience severe discomfort or other complications.

1. If the preparation procedure is carried out carelessly, the integrity of the tooth may be compromised. This in turn leads to irritation of the pulp and the formation of edema. This complication goes away without a trace over time.

   If the doctor prepares the tooth incorrectly, swelling of the gums may occur.

2. After the anesthesia wears off, pain in the tooth or gum may occur. What are the reasons for this phenomenon? First of all, this means that the preparation was carried out on a living tooth. Increased sensitivity may occur due to thinning of the tooth walls after grinding. The tooth begins to react sharply to various external factors. They can be taste, temperature factors, physical effects. To correct this phenomenon, an additional portion of cementing material is applied to the surface of the sensitive part of the tooth.
3. When manipulations are carried out deep in the gum, for example, when forming a ledge, it is necessary to expand the visible working area. For these purposes, a special thread is used. With its help, the edges of the gums are moved back. Sometimes this effect on soft tissue can cause pain and swelling of the gums. Usually these symptoms do not last long and disappear on their own after some time.

   Gum retraction

4. If more time has passed and these symptoms have not gone away, it may be a more serious complication and treatment is necessary.

Metal-ceramic dental bridge

A frequently encountered case in the practice of a prosthetist is a dental bridge made of metal ceramics. Probably, even to beginners in prosthetics, the word “bridge” hints at what this method of prosthetics represents. A metal-ceramic bridge is a metal structure with a ceramic coating that is attached to adjacent natural teeth, creating an imitation of a bridge. How long have bridges been around and in what cases should they be installed?

Dentures, now called bridges, already existed in Ancient Rome, when artificial teeth were attached to healthy teeth with threads made of precious metals. Currently, a dental bridge made of metal ceramics is very popular, since the cost of this material is quite affordable, and reviews and real photos show how convenient and high-quality such a bridge can be.

In order to install a metal-ceramic bridge, you need to treat the dental cavity, ensuring it is in a healthy condition, and grind the adjacent teeth. The good thing about bridges is that the doctor minimally prepares the teeth before attaching the crown. Since we are talking about turning, it is worth carrying out this procedure under local anesthesia.

After preparation, the prosthetist takes an impression of the jaw to further cast the bridge. While the clinic is making a metal-ceramic bridge, a temporary bridge is installed during this period, which protects the dental cavity from external negative factors.

How much does a tooth cost? Metal ceramics, price

Of course, what is important for us when setting prices is how much a metal-ceramic tooth costs, and what price we can offer the patient so that this does not become a stumbling block before placing a tooth. Metal ceramics, the price of which is significantly lower than the cost of other materials, receives grateful reviews because it combines a number of advantages.

Sometimes the necessary grinding is confusing, but any prosthetics involves preliminary processing in order to install artificial teeth. Metal-ceramics - the prices it offers in addition to photos and reviews confirming the high quality - it is not for nothing that it so proudly retains the title of leader in prosthetics. Until recently, when asked how much a tooth costs, metal-ceramics was practically the only answer with an affordable price.

Agree that walking without teeth when there are so many charming photos with beautiful teeth around is not an easy task. What if, after reading the reviews, you get the impression that the cost of the clinic’s services will be too high and is it worth installing artificial teeth at all? Metal-ceramics, the price of the material and the cost of the service are attractive due to their availability. Studying different options for how much a tooth costs, metal-ceramics will always offer the optimal price-quality ratio.