Classification of dental cements by composition.

General characteristics of the material

Dental cement

It contains powder and liquid, when mixed, a paste-like mass is formed.
Dental glass is used to mix dental cement .

An accompanying attribute is dental glass for mixing cement, available without a hole, with 1, 2, 3 holes

During the hardening process, the mass begins to harden and becomes like stone. Hardening occurs as a result of the components entering into a chemical reaction.

The main indicators that high-quality dental cement

, the following:

• mixing time;
• work time;
• curing time.

Mixing time refers to the period of time recommended for preparing the solution. Typically this figure is 90 seconds , and it is not recommended to exceed it.

The time during which the doctor must have time to apply the mixture to the tooth and model the filling is called working time. Each manufacturer of dental cement has its own characteristics, but the average varies from 4 to 10 minutes .

The period allotted for hardening of the cement mass also varies among manufacturers. Sometimes it can take a week for the ingredients to react and cause hardening. An important role in the setting of the material is played by the temperature and mixing proportions of dental cement.

with liquid.

How to choose composite cement?

E. M. Ioffe

Candidate of Medical Sciences, Doctor of Dentistry (DDS, PhD)

Direct restorations account for approximately 96% of our market. Most dentists, in one way or another, associate their activities with direct dental restoration - the most common intervention. At the same time, indirect restorations offer much greater possibilities and better esthetics for our patients.

Porcelain and glass-ceramic crowns and bridges are constantly being improved. These are not only metal-ceramic structures, but products created on a zirconium base, on the basis of aluminum oxide, lithium disilicate, composite, etc. Some of them are manufactured by layer-by-layer application of material to the base, others are a solid structure obtained on a computer-controlled machine (CAD/CAM).

The strengthening of fixed structures is of particular importance: we strive for the durability of our restorations, especially when it comes to active rehabilitation of the oral cavity. As the strength of ceramics increases, its strengthening plays a special role due to certain difficulties in preparing the substrate and bonding it to the tooth. Crowns, veneers, inlays, etc. require our special attention when they need to be permanently strengthened.

As with other restorative materials, we expect certain properties from our cements:

Compatibility with all materials.

Ligament strength.

The initial strength of the ligament is of particular importance. It should be noted that glass ionomer-based cements are not recommended for use on ceramic restorations: glass ionomer tends to absorb moisture and expand, leading to cracks and fractures of the restoration.

Compressive and bending strength.

Nature of curing (LC/SC phases).

This is especially important for self-etching cements. For many manufacturers, the first phase - light curing - proceeds normally, but the second phase - self-curing inside the crown - is not implemented, the conversion does not reach optimal values, and the strengthening, of course, is incomplete. One dentist said that once, after light polymerization and subsequent waiting, the bridge prosthesis separated when trying to remove excess cement at the edges. Although this can happen later - what we call de-cementing.

Easy
to use.
No need for an activator. As with all composite materials, particularly adhesives, an additional activator is required for self-curing or combination with dual or self-curing materials. Some manufacturers use a trick and introduce the catalyst directly into the cement. But we need the opportunity to use the cement we want, when we want, and not what the manufacturer “slips” to us.

Versatility

- the ability to polymerize and achieve maximum strength with various adhesives, and not just those that are selectively offered by the manufacturer.

The thickness
of the layer is of particular importance for the precise fit of the indirect restoration.
Since many indirect restorations, particularly crowns, today have a significant precision in fit, I recommend that you apply the cement not inside the restoration, as we are used to doing, but on the preparation. Then install the restoration, clean the edges, apply Vaseline around the edges and cover everything with foil. This will prevent the margins of the restoration from being washed away by cement early on when exposure to saliva is greatest.

Durability.

Bonding strength tends to decrease.
Therefore, it is necessary to use a material with the highest degree of conversion. Such material, for example, is DuoLink Universal.
Studies have shown that the conversion rate of this cement is the highest, especially if it is used with
AllBond Universal
. It is interesting that in this case, even if, due to forgetfulness, the material is not light-polymerized initially (in the case of an opaque base: metal or zirconium), it is completely polymerized inside.

• DuoLink Universal, BISCO (USA)

  Storage stability.

  We want to maximize the full potential of the material within its shelf life. In order to better understand the features of using various cements in certain situations, we need to imagine when and what we choose for various restorations and why:

  For example:

  Plain porcelain

  - the weakest material for isolated restorations - veneers and crowns.
  It has good aesthetics. The best cement for strengthening such restorations is Choice2
  . It does not contain amines, which affect the change in shade of the cladding over time.

  Choice2, BISCO (USA)

  Read also:  6 stages of professional teeth cleaning with before and after photos

  Zirconium

  - the most durable material, but it does not transmit light, which is necessary for light polymerization of cladding.
  To strengthen zirconium-based restorations, it is necessary to use the Z-Prime Plus
  , which creates a chemical bond between the substrate and the cement. The best cement is DuoLink Universal in two shades: universal and milky white. It's important to note one often overlooked fact: AllBond Universal is a universal adhesive as we know it, but it is also a primer, similar to Z-Prime. It can also be applied to the inner surface of a substrate other than eMax, but, unlike Z-Prime, it must be light-cured.

  Z-Prime Plus, BISCO

  Lithium disilicate (eMax)

  - glass ceramics, a common modern material with strength and transparency, which is important for cladding.
  eCement
  contains both light-curing and dual-curing cement in the kit, in case the veneer is thicker than 1 mm. The cement is available in A1, translucent and bright milky colors to cover all necessary clinical situations. eMax restorations require the use of 4% porcelain etchant (hydrofluoric acid) and silane. Both eCEMENT and DuoLink Universal make it very easy to clean the edges of excess cement after consolidation of the restoration.

  eCement, BISCO (USA)

Like many of you, I often use BisCem

. A convenient and fast way to strengthen restorations and posts. Unlike products from other manufacturers, it does not require an adhesive, exceeds the strength of similar cements and, like all Bisco developments, is of course compatible with all substrates and restoration materials.

BisCem, BISCO (USA)

If you need to achieve maximum strength, such as when strengthening a restoration on a short implant abutment or a short core, you can use the BISFIL-2B

. This material does not belong to the group of cements, but its consistency and fluidity distinguishes it from others. Its film thickness is less than C&B self-curing cement and the strength is very high as it is essentially a very strong hybrid self-curing composite.

BISFIL - 2, BISCO (USA)

Production of filling material

When developing a high-quality mixture for use in dentistry, manufacturers strive to ensure that its composition closely resembles the natural, inherent component of the tooth. For this purpose, additives are used that divide dental cement.

into several types:

• phosphate;
• polycarboxylate;
• polymeric;
• silicophosphate;
• glass ionomer.

Each subtype of cement is used in certain cases of oral treatment. The phosphate type is used for filling teeth with increased chewing load; polycarboxylate solution is characterized by rapid hardening. Polymer cement does not leave gaps between the gums; the silicophosphate type is good for its increased plasticity properties, and the glass ionomer solution is hypoallergenic and color resistant.

From the family of dental cements: Silicin Plus, Cemilight, Cemion, Uniface-2...

When contacting your dentist, ask him what materials are used to treat your tooth.
You can also choose the type of cement yourself, having previously studied its features and consulted with your dentist about the advisability of using it. Moscow metro station Zvezdnaya, Danube Avenue, 23

What other problems are associated with dental cement?

In addition to the loss of cementum, which can be the result of periodontitis and at the same time cause tooth sensitivity, there are several other dental problems directly related to the condition of this tissue.

Cementoblastoma

This long word refers to a rare benign tumor on the root of a tooth. It occurs when specific cells, cementoblasts, grow in the area of ​​the root apex. Typically, cementoblastoma affects one tooth root, but sometimes it can develop on several roots and spread to the surrounding bone. The growth of cementoblastoma is sometimes accompanied by dull pain, but often the disease is asymptomatic. Being a benign tumor, cementoblastoma, however, is constantly increasing in size; Over time, it can begin to interfere with the normal functioning of the teeth and affect the patient's appearance.

Adolescents and young adults under 30 years of age are at higher risk of developing cementoblastomas. Treatment of cementoblastoma involves surgical removal of the tumor and the affected tooth, which most often turns out to be a premolar or molar of the lower jaw. Sometimes several teeth have to be removed. Although tooth extraction is by no means the optimal solution, the risk of tumor regrowth makes it necessary. Although cementoblastoma is a rare condition, it is best to make sure that pain or strange thickening in the area of ​​the tooth roots is not associated with it. To do this, you should contact your dentist.

Exposure of the cemento-enamel junction (CEJ)

The cemento-enamel junction is a special zone around the perimeter of the tooth where the enamel covering the crown meets the cement protecting the root. In most cases, the cement partially extends onto the enamel, covering it, but in some people there is a thin strip of unprotected dentin between the hard enamel and the less mineralized cement.

sensitivity to cold and hot foods may occur The exposure of the CEJ is associated with recession, that is, drooping of the gums.

To confirm that the sensitivity is caused by gum recession, the dentist will need to measure how much the gums have receded. To do this, use a special tool, a periodontal probe, which the dentist inserts between the gum and tooth. This examination will determine whether the periodontal ligament is in good condition or whether there is a risk of infection, inflammation and further gum recession.

Hypercementosis

Hypercementosis is the process of formation of an excessively thick cement layer on the roots of teeth. Local thickening of the cement leads to a change in the size and shape of the root, which in some cases even begins to interfere with neighboring teeth.

Although the exact causes of hypercementosis are unknown, dentists typically diagnose it in patients with certain medical conditions, such as arthritis, rheumatoid arthritis, acromegaly, and Paget's disease. Researchers have also associated hypercementosis with vitamin A deficiency. Hypercementosis also occurs in patients with periodontal disease or dental trauma caused by occlusal disorders. For the most part, hypercementosis occurs in adults, and the risk of developing it increases with age.

That's how many new words you learned today! Of course, this amount of information is difficult to digest at once, but understanding the important role of cement will help you take a more responsible approach to protecting your teeth. Start with proper oral care to avoid lost or damaged cementum. By regularly brushing your teeth and using dental floss, an interdental brush or irrigator, and an antiseptic mouthwash, you can maintain the health of your teeth and all their tissues.

Possibilities of dental cement

Glue for crowns makes it possible to tightly attach the crown to the root socket and prevent it from falling out of the gums. You can buy such material in specialized stores or at a pharmacy. Each dentist prefers to use a mass familiar to him, from a certain manufacturer. It must be said that if you buy inexpensive material, you can’t hope for a positive result.

Crown adhesive allows you to:

• firmly attach the crown to the tooth socket and thereby hold it during chewing movements;
• prevent the process of tooth decay from the inside;
• create a durable protective coating that will prevent bacteria from entering the tooth.

In what cases is it advisable to install on cement?

• Complete, partial edentia;
• single restoration;
• angulation of implants, during which high aesthetic and functional indicators become impossible;
• several designs with non-parallel mesio-distal or vestibulo-lingual angulation;
• the patient's desire to choose this method himself.

Cement fixation is possible:

• with a height of the upper part of the abutment of 5 mm or more;
• when the height of the attached gum around the structure is at least 3-5 mm;
• if the bone wall volume around the implant neck is at least 2-2.5 mm;
• with a crown-to-body height ratio of at least 1:1.5;
• antagonist teeth are in the correct position.

Polycarboxylate dental cement for dentures and crowns

The main component is specially processed zinc oxide, without residual products, which reacts quickly with polyacrylic acid.

And the liquid part contains water and polyacrylic acid.

Polocarboxylates are characterized by:

• Lowest adhesiveness and strength.
• Excellent biocompatibility.
• Almost zero chance of developing allergies or irritation.
• Creating a thin layer of composition.
• Additional prevention of caries.

REMEMBER : Polycarboxylate cement for fixing crowns is ideal for fixing single crowns with increased tooth sensitivity. For all other clinical situations, there are better options.

Types of dental cements for fixation of fixed dentures and crowns - classification

Today, the dental clinic market offers a lot of different compositions that are used to permanently secure permanent crowns and dentures in the patient’s oral cavity.

There are four main types of cement identified through experiments conducted by scientists and specialists over the past ten years. Their classification depends on the type of binding component present in the matrix and the specific indications for use.

But, nevertheless, cement for fixing crowns, etc. is divided into several main groups, presented:

• Zinc phosphates.
• Polycarboxylates.
• Glass ionomers.
• Composites.
• Polymers modified with glass ionomers.

Requirements for cements

1. Resistance to the environment present in the oral cavity.
2. Strong adhesion to tooth tissues using mechanical adhesion and adhesion.
3. High strength not only in compression, but also in tension and shear.
4. Sufficient time for work and hardening.
5. Biological compatibility with hard dental tissues.
6. Low toxicity to dental pulp.
7. Good radiopacity.

Glass ionomer cement for fixation of crowns and fixed dentures

The liquid part of glass ionomer cement is represented by polyacrylic acid, and the powder part is not similar to those described in this material.

Aluminosilicate glass contains a high fluorine content.

Application

1. Ideal for cases where the risk of developing caries due to the release of fluoride is increased.
2. It has proven itself excellent among patients with moderate tooth sensitivity.
3. Time is not a very useful factor when fixing long bridges.

Properties

• Excellent prevention of caries.
• Very thin film.
• Low risk of developing allergies and pulp damage.
• With not very high strength, high adhesion.

PLEASE NOTE : This material cures slowly and is very dependent on moisture.

Features of cement fixation

Before cementing, it is necessary to take an x-ray and carefully remove any remaining temporary dental adhesive. Cementing makes it possible to circumvent a number of limitations of the screw type of fastening:

• low occlusal stability;
• difficulty in manufacturing restorations with passive fitting.

There are also other features:

• soft tissues are mainly supported by the abutment;
• the crown is seated in such a way that its edge is at the same level or slightly apical to the gingival margin.

How does crown cementation occur?

Fixation is the final stage of prosthetics. Basic actions:

1. The prepared abutment is sandblasted to create a rough surface.
2. Fitting in progress. Before placing the crown on permanent cement, you need to make sure that it is positioned correctly.
3. The inner surface of the prosthesis is coated with dental glue and then placed on the abutment.
4. After installing the structure, it is irradiated with a special lamp to speed up the hardening process.
5. Carefully remove excess cement if it protrudes from under the crown.

An hour after the procedure, the prosthesis can be loaded. Maximum pressure is allowed every other day.