Veneers are porcelain or composite plates that replace the outer layer of teeth . They allow you to correct violations of the shape and color of the tooth , and also protect the teeth (for example, when playing wind instruments ). As a result, the restored tooth gains strength and does not differ from the rest. Veneers are made in accordance with the shape, color of the patient’s teeth and his wishes.
Veneer is a plate with a thickness of 0.2 mm or more, if it is composite, then it is an organic bisgma resin filled with ceramic or glass microparticles, and if it is ceramic, then, for example, lithium-disilicate glass ceramics glued to the vestibular, i.e. labial side of the tooth, aesthetic, restorative, masking, phonetic and alimentary functions.
For the manufacture of veneers, by and large, aggressive preparation of tooth enamel is not required, in some cases (microdentia or abrasion) it is possible to manufacture veneers without preparation of tooth tissues. Subject to observance of occlusal and gnatological principles in the clinic by the operator and observance of all technological regulations in the laboratory by a technical engineer, this restoration method has long-term forecasts and can be widely recommended for use.
- 1 Materials and technology
- 1.1 Ceramic Veneers
- 1.1.1 Veneers made of feldspar ceramics (porcelain)
- 1.1.2 IPS Emax Glass Veneers
- 1.1.3 Zirconia Veneers
- 1.2 Composite veneers
- 1.3 Lumineers
- 1.1 Ceramic Veneers
- 2 Indications and contraindications for use
- 2.1 Indications
- 2.2 Contraindications
- 3 Advantages and disadvantages
- 3.1 Advantages
- 3.2 Disadvantages
- 4 See also
- 5 notes
Materials and Technology
Veneers come in various forms - composite and ceramic. Composite veneers can be made by direct (in the dentist's chair in one visit) and indirect (with the participation of the dental laboratory ) methods.
Ceramic veneers are made from various types of ceramics. Most often feldspar ceramics (porcelain) and IPS Emax glass ceramics are used for this, less often ceramic veneers are made from blocks of zirconium dioxide. Ceramic veneers are made only in a laboratory way. First, the doctor prepares (grinds) the tooth, then receives an impression of the teeth, which is sent to the dental laboratory , where for two weeks the patient will make a permanent ceramic veneer. To prevent the patient from walking with his teeth turned, a temporary plastic veneer is fixed on the tooth while waiting. Below we will consider the main types of ceramic veneers.
Feldspar ceramic (porcelain) veneers
The first ceramic veneers began to be made of porcelain, because This type of ceramic allows you to perfectly simulate the optical properties of the tooth (shade and translucency of enamel). Porcelain veneers have very good aesthetics - no worse than in comparison with E.max glass ceramics. Porcelain veneers are made in three laboratory ways. Firstly, this is the method of layer-by-layer application of porcelain mass, when after applying each layer of porcelain sintering of porcelain is carried out at a high temperature in a special furnace. Secondly, the method of pressing porcelain under high pressure and temperature. The third method, which appeared relatively recently, is the milling of feldspar ceramic blocks (for example, Vita Mark 2 blocks) on devices of the CEREC type (CAD / CAM technology).
When using porcelain, the best of these three methods will be pressed ceramics, as veneers from it have significantly greater strength. Bending strength of veneers with a layer-by-layer method of applying porcelain is only 50-75 MPa . When using the pressing method or CAD / CAM - the bending strength will be about 150 MPa . The last indicator is quite enough if you have the right bite and there are no bad habits. However, the following type of ceramic has even greater strength.
IPS Emax Glass Ceramic Veneers
Glass ceramic IPS Emax (manufacturer Ivoclar Vivadent) - consists of lithium disilicate crystals, which have the same transparency coefficient as real tooth enamel. Therefore, veneers made of this material are as similar as possible to real teeth. There are 2 types of IPS Emax material. Firstly, it is the material Emax PRESS, which is intended for the manufacture of veneers by pressing. Veneers from this material are the most durable - they have a bending strength of about 400 MPa , which almost completely eliminates the risk of chips. It is from Emax PRESS that the so-called “thin veneers” are made, which have a thickness of only 0.3-0.4 mm (standard ceramic veneers have a thickness of 0.6-1.0 mm).
The second version of IPS Emax glass ceramics is E.max CAD material, which is produced in the form of special blocks for milling on a machine with program control like CEREC (CAD / CAM technology). The same manufacturing method is applied to the next type of ceramic veneers - zirconia veneers. By the way, the strength of E.max CAD veneers is also very high - about 360 MPa, but veneers no thinner than 0.6 mm can be made from this material.
Such veneers are made of zirconia blocks by milling them (CAD / CAM technology). The strength of such veneers is highly dependent on the type of blocks of zirconium dioxide. If blocks of the so-called raw soft zirconia are used, the veneers will have a flexural strength of about 900 MPa, but such veneers will have poor aesthetics due to the lack of transparency of the material and its milky white color . If blocks of zirconia with yttrium are used, veneers from such zirconia are translucent and have good aesthetics, but their bending strength will already be less (about 550 MPa).
In aesthetics, zirconia veneers are significantly inferior to porcelain veneers (feldspar ceramics), as well as IPS Emax. Clinical studies ( source ) showed that the closest aesthetics to IPS Emax glass ceramics are Katana® UTML (Japan), followed by Katana® STML (Japan), BruxZir® Anterior or Prettau® Anterior (Germany).
In order to install a composite veneer, the doctor grinds a thin layer of enamel, then, using adhesive systems, layered composite filling material. Such veneers are made in the oral cavity and serve from 3 to 5 years. More often, such veneers are used if they want to improve one or two teeth from the general row. They are also made by the laboratory method: after taking the impression, a model is obtained, then the veneer is modeled and then polymerized in special polymerization furnaces. In the clinic, the veneer is fixed on a fluid composite. The advantage of this method, in comparison with direct veneers, is a more complete polymerization of the composite and, as a result, its enhanced strength.
The manufacturing technology of ultra-thin ceramic veneers, patented by Cerinate (USA), was called Lumineers. This type of veneer is made exclusively in the laboratory of the company Cerinate, located in the state of California (USA). The advantage of this type of veneer over the classic are:
- non-invasiveness - no turning of hard tissues of teeth is required;
- enhanced aesthetics in the style of so-called. "Hollywood smile";
- the ability to remove and replace installed veneers without damaging tooth tissue.
It is not recommended to apply in cases of "spotty" or multi-colored enamel, since the lumineer is transparent.
Indications and contraindications for use
- cracks and gaps between teeth;
- curved tooth shape;
- wedge-shaped defect;
- tooth abrasion no more than the second degree;
- cracks and chips of tooth enamel;
- stains and darkening of tooth enamel.
- lack of molars;
- second and more degree of tooth abrasion;
- the presence of bad habits that can damage veneers (smoking);
- presence of fillings on most of the tooth;
- severe damage to the inner surface of the tooth;
- past use of the resorcinol-formalin treatment method.
- bruxism (gnashing of teeth during sleep)
Strengths and weaknesses
- Speed of production, in the case of composite veneers, one visit is enough.
- Durability, especially in the manufacture of ceramic veneers.
- Excellent cosmetic effect due to the lack of metal and other opaque materials.
- Modern ones let in light so that the teeth look natural.
- Low strength, especially composite veneers.
- Low masking ability with a significant change in tooth color.
- The high price of ceramic veneers.
- Enamel grinding is irreversible. If the veneer is completely removed, an additional tooth restoration will be required.
- Dental crowns