home Analyzes Application of laser technologies in dentistry. Laser for dentistry: types, applications, indications and contraindications

Application of laser technologies in dentistry. Laser for dentistry: types, applications, indications and contraindications

Laser technologies have long left the pages of science fiction novels and the walls of research laboratories, having gained strong positions in various fields of human activity, including medicine. Dentistry, as one of the most advanced branches of medical science, has included the laser in its arsenal, arming doctors with a powerful tool to combat various pathologies. Application of lasers in dentistry opens up new possibilities, allowing the dentist to offer the patient wide range minimally invasive and virtually painless procedures that meet the highest standards clinical standards providing dental care.

Introduction

The word laser is an acronym for “Light Amplification by Stimulated Emission of Radiation.” The foundations of the theory of lasers were laid by Einstein in 1917, but only 50 years later these principles were sufficiently understood and the technology could be implemented practically. The first laser was designed in 1960 by Maiman and had nothing to do with medicine. Ruby was used as the working fluid, generating a red beam of intense light. This was followed in 1961 by another crystal laser using neodymium yttrium aluminum garnet (Nd:YAG). And only four years later, surgeons who worked with a scalpel began to use it in their activities. In 1964. Bell Laboratories physicists have produced a laser with carbon dioxide(CO 2) as a working medium. In the same year, another gas laser was invented, which later turned out to be valuable for dentistry - the argon laser. In the same year, Goldman proposed the use of lasers in the field of dentistry, in particular for the treatment of caries. For safe work pulsed lasers were later used in the oral cavity. With the accumulation of practical knowledge, the anesthetic effect of this device was discovered. In 1968, the CO 2 laser was first used for soft tissue surgery.

Along with the increase in the number of laser wavelengths, indications for use in general and maxillofacial surgery have also developed. The mid-1980s saw a resurgence of interest in the use of lasers in dentistry to treat hard tissues such as enamel. In 1997, the US Food and Drug Administration finally approved the now well-known and popular erbium laser (Er:YAG) for use on hard tissue.

Benefits of laser treatment

Despite the fact that lasers have been used in dentistry since the 60s of the last century, a certain prejudice among doctors has not yet been completely overcome. You can often hear from them: “Why do I need a laser? I can do it with boron faster, better and without the slightest problem. Extra headache! Of course, any work in the oral cavity can be performed on a modern dental unit. However, the use of laser technology can be characterized as higher quality and more comfortable, expanding the range of possibilities, allowing the introduction of fundamentally new procedures. Let's look at each point in more detail.

Quality of treatment: using a laser, you can clearly organize the treatment process, predicting the results and timing - this is due to technical characteristics and the operating principle of the laser. The interaction of the laser beam and the target tissue produces a clearly defined result. In this case, pulses equal in energy, depending on the duration, can produce different actions onto the target tissue. As a result, by changing the time from one pulse to another, it is possible to obtain the most various effects: pure ablation, ablation and coagulation or only coagulation without destruction of soft tissues. Thus, by correctly selecting the duration parameters, the magnitude and repetition rate of pulses, you can select individual mode work for each type of tissue and type of pathology. This allows almost 100% of the laser pulse energy to be used to perform useful work, eliminating burns of surrounding tissues. Laser radiation kills pathological microflora, and the absence of direct contact of the instrument with the tissue during surgery eliminates the possibility of infection of the operated organs (HIV infection, hepatitis B, etc.). When using a laser, tissues are processed only in the infected area, i.e. their surface is more physiological. As a result of treatment, we obtain a larger contact area, improved marginal fit and significantly increased adhesion of the filling material, i.e. better quality filling.

Comfort of treatment: The first and, perhaps, most important thing for the patient is that the effect of light energy is so short-lived that the effect on the nerve endings is minimal. During treatment the patient experiences less pain, and in some cases you can refuse pain relief altogether. In this way, the treatment can be performed without vibration and pain. The second and important advantage is that the sound pressure created during laser operation is 20 times less than that of high-speed turbines. Therefore, the patient does not hear any frightening sounds, which is psychologically very important, especially for children - the laser “removes” dental office the sound of a working drill. It is also necessary to note more short stage recovery is easier compared to traditional interventions. Fourthly, it is also important that the laser saves time! The time spent on treating one patient is reduced by up to 40%.

Expanding capabilities: the laser provides more opportunities for the treatment of caries, carrying out preventive “laser programs” in children’s and adult dentistry. Huge opportunities are emerging in the surgery of bone and soft tissue, where treatment is carried out using a surgical handpiece (laser scalpel), in implantology, prosthetics, in the treatment of mucous membranes, removal of soft tissue formations, etc. A method for detecting caries using a laser has also been developed - in this case, the laser measures the fluorescence of bacterial waste products in carious lesions located under the surface of the tooth. Studies have shown excellent diagnostic sensitivity this method compared to the traditional one.

Diode laser in dentistry

Despite the diversity lasers used in dentistry, The most popular today for a number of reasons is the diode laser. The history of the use of diode lasers in dentistry is already quite long. Dentists in Europe, who have long adopted them, can no longer imagine their work without these devices. They are distinguished by a wide range of indications and a relatively low price. Diode lasers are very compact and easy to use in clinical settings. The safety level of diode laser devices is very high, so hygienists can use them in periodontics without the risk of damaging the tooth structure. Diode laser devices are reliable due to the use of electronic and optical components with a small number of moving elements. Laser radiation with a wavelength of 980 nm has a pronounced anti-inflammatory effect, bacteriostatic and bactericidal effect, and stimulates regeneration processes. Traditional areas of application for diode lasers are surgery, periodontics, endodontics, and the most popular are surgical procedures. Diode lasers make it possible to perform a number of procedures that were previously performed by doctors with reluctance - due to heavy bleeding, the need for sutures and other consequences of surgical interventions. This happens because diode lasers emit coherent monochromatic light with a wavelength from 800 to 980 nm. This radiation is absorbed in a dark environment in the same way as in hemoglobin - meaning that these lasers are effective at cutting tissues that have many blood vessels. Another advantage of using a laser on soft tissue is that there is a very small area of necrosis after tissue contouring, so the tissue edges remain exactly where the doctor placed them. This is a very significant aspect from an aesthetic point of view. Using a laser, you can contour your smile, prepare your teeth, and take impressions during one visit. When using a scalpel or electrosurgical units, several weeks must pass between tissue contouring and preparation to allow the incision to heal and the tissue to shrink before the final impression is taken.

Predicting the position of the incision edge is one of the main reasons why diode lasers are used in aesthetic dentistry for soft tissue recontouring. It is very popular to use a semiconductor laser to perform frenectomy (frenuloplasty), which is usually underdiagnosed because many doctors do not like to perform this treatment according to standard techniques. With a conventional frenectomy, stitches must be placed after cutting the frenulum, which can be uncomfortable in this area. In the case of laser frenectomy, there is no bleeding, no stitches are needed, and healing is more comfortable. The absence of the need for sutures makes this procedure one of the fastest and easiest in a dentist's practice. By the way, according to surveys conducted in Germany, dentists who offer patients diagnostics and treatment using lasers are more visited and successful...

Types of lasers used in medicine and dentistry

The use of lasers in dentistry is based on the principle of selective impact on various fabrics. Laser light is absorbed by a specific structural element that is part of the biological tissue. The absorbing substance is called a chromophore. They can be various pigments (melanin), blood, water, etc. Each type of laser is designed for a specific chromophore, its energy is calibrated based on the absorbing properties of the chromophore, as well as taking into account the field of application. In medicine, lasers are used to irradiate tissues with preventive or therapeutic effect, sterilization, for coagulation and cutting of soft tissues (surgical lasers), as well as for high-speed preparation of hard dental tissues. There are devices that combine several types of lasers (for example, to affect soft and hard tissues), as well as isolated devices for performing specific highly specialized tasks (lasers for teeth whitening). The following types of lasers are used in medicine (including dentistry):

Argon laser(wavelength 488 nm and 514 nm): Radiation is well absorbed by pigment in tissues such as melanin and hemoglobin. The wavelength of 488 nm is the same as in curing lamps. At the same time, the speed and degree of polymerization of light-cured materials with a laser is much higher. When using an argon laser in surgery, excellent hemostasis is achieved.

Nd:AG laser(neodymium, wavelength 1064 nm): radiation is well absorbed in pigmented tissue and less well absorbed in water. In the past it was most common in dentistry. Can operate in pulse and continuous modes. Radiation is delivered via a flexible light guide.

He-Ne laser(helium-neon, wavelength 610-630 nm): its radiation penetrates well into tissues and has a photostimulating effect, as a result of which it is used in physiotherapy. These lasers are the only ones that are commercially available and can be used by patients themselves.

CO 2 laser(carbon dioxide, wavelength 10600 nm) has good absorption in water and average absorption in hydroxyapatite. Its use on hard tissue is potentially dangerous due to possible overheating of enamel and bone. This laser has good surgical properties, but there is a problem with delivering radiation to tissues. Currently, CO 2 systems are gradually giving way to other lasers in surgery.

Er:YAG laser(erbium, wavelength 2940 and 2780 nm): its radiation is well absorbed by water and hydroxyapatite. The most promising laser in dentistry can be used to work on hard dental tissues. Radiation is delivered via a flexible light guide.

Diode laser(semiconductor, wavelength 7921030 nm): radiation is well absorbed in pigmented tissue, has a good hemostatic effect, has anti-inflammatory and repair-stimulating effects. The radiation is delivered through a flexible quartz-polymer light guide, which simplifies the surgeon’s work in hard-to-reach areas. The laser device has compact dimensions and is easy to use and maintain. On this moment this is the most affordable laser machine in terms of price/functionality ratio.

Diode laser KaVo GENTLEray 980

There are many manufacturers offering laser equipment on the dental market. The KaVo Dental Russland company presents, along with the well-known universal laser KaVo KEY Laser 3, called the “clinic on wheels,” the diode laser KaVo GENTLEray 980. This model is presented in two modifications - Classic and Premium. The KaVo GENTLEray 980 uses a wavelength of 980 nm, and the laser can operate in both continuous and pulsed modes. Its rated power is 6-7 W (at peak up to 13 W). As an option, it is possible to use the “micropulsed light” mode at a maximum frequency of 20,000 Hz. The areas of application of this laser are numerous and, perhaps, traditional for diode systems:

Surgery: frenectomy, implant release, gingivectomy, removal granulation tissue, flap surgery. Mucosal infections: canker sores, herpes, etc.

Endodontics: pulpotomy, canal sterilization.

Prosthetics: expansion of the dentogingival sulcus without retraction threads.

Periodontology: decontamination of pockets, removal of marginal epithelium, removal of infected tissue, gum formation. Let's look at a clinical example of using KaVo GENTLEray 980 in practice - in surgery.

Clinical case

In this example, a 43-year-old patient had a fibrolipoma on the lower lip, which was successfully treated surgically using a diode laser. He contacted the Department surgical dentistry with complaints of pain and swelling of the mucous membrane lower lip in the buccal area for 8 months. Despite the fact that the risk of traditional lipoma in the head and neck area is quite high, the appearance of fibrolipoma in the area oral cavity, and especially on the lip - rare case. To determine the causes of the neoplasms, it was necessary to conduct a histological examination. As a result clinical trials it was found that the neoplasm was well separated from the surrounding tissues and covered with an intact mucous membrane (Fig. 1 - fibrolipoma before treatment). In order to make a diagnosis, this formation was surgically removed under local anesthesia using a diode laser with a 300 nm light guide and a power of 2.5 Watts. Stitching the edges was not necessary, since no bleeding was noticed either during the surgical procedure or after it (Fig. 2 - fibrolipoma 10 days after the intervention). Histological studies The tissue taken for analysis showed the presence of mature non-vacuolated fat cells surrounded by dense collagen fibers (Fig. 3 - histology). Morphological and structural changes in tissue due to thermal effects no diode laser was observed. The postoperative course of treatment was calm, with a visible reduction in the surgical scar after 10 days and without signs of relapse over the next 10 months.

Bottom line: in the described case, the surgical operation to remove fibrolipoma of the lower lip took place without hemorrhages, with minimal tissue damage, which allows for subsequent conservative treatment. The patient's recovery is also rapid. The ability to avoid noticeable sutures after excision is also undoubtedly positive factor from an aesthetic point of view. Conclusion: surgery benign neoplasms of the oral mucosa using a diode laser is an alternative to traditional surgery. The effectiveness of this method was confirmed by the results of the removal of lip fibrolipoma.

Introduction

Lasers and laser systems in dentistry: description, classification and characteristics

Effect of lasers on tissue

Interaction of laser with hard tooth tissue

The mechanism and features of laser preparation of hard dental tissues

Bibliography

Introduction.

In the 1960s, the first lasers for medical purposes were introduced. Since then, science and technology have made huge leaps in development, allowing the use of lasers for a huge number of procedures and techniques. In the 90s, lasers made a breakthrough in dentistry; they began to be used to work with soft and hard tissues. Currently, in dentistry, lasers are used for the prevention of dental diseases, in periodontics, therapeutic dentistry, endodontics, surgery and implantology. The use of lasers is an appropriate method for daily assistance to dentists in many types of work. For some procedures, such as frenulotomy, lasers have proven so clinically effective that they have become the gold standard among physicians. They allow you to work in a dry field, which provides excellent visibility and reduces operating time. With lasers, the likelihood of scarring is very low and virtually no stitches are required. They also ensure absolute sterility of the working field, which in most cases is an absolute necessity, for example when sterilizing a root canal.

Lasers and laser systems in dentistry: description, classification and characteristics

Laser devices produce different wavelengths that interact with specific molecular components in animal tissues. Each of these waves affects certain tissue components - melanin, hemosiderin, hemoglobin, water and other molecules. In medicine, lasers are used to irradiate tissues with a simple therapeutic effect, for sterilization, for coagulation and resection (operational lasers), as well as for high-speed tooth preparation. Laser light is absorbed by a specific structural element that is part of the biological tissue. The absorbing substance is called a chromophore. They can be various pigments (melanin), blood, water, etc. Each type of laser is designed for a specific chromophore, its energy is calibrated based on the absorbing properties of the chromophore, as well as taking into account the field of application.

Laser interactions with calcium-containing tissues have been studied using various wavelengths. Depending on such laser parameters as pulse duration, discharge wavelength, penetration depth, the following types of lasers are distinguished: pulsed dye, He-Ne, ruby, alexandrite, diode, neodymium (Nd: YAG), goldmium (No: YAG), erbium (Er: YAG), carbon dioxide (CO2).

In medicine, lasers are used to irradiate tissues with a preventive or therapeutic effect, sterilization, for coagulation and cutting of soft tissues (operational lasers), as well as for high-speed preparation of hard dental tissues. Lasers produce surface changes in enamel such as crater formation, melting and recrystallization.

In dentistry, the CO2 laser is most often used to treat soft tissues and the erbium laser is used to prepare hard tissues. There are devices that combine several types of lasers (for example, for treating soft and hard tissues), as well as isolated devices for performing specific highly specialized tasks (lasers for teeth whitening).

There are several laser operating modes: pulsed, continuous and combined. Their power (energy) is selected in accordance with the operating mode.

Table 1. Types of lasers, penetration depths and chromophores

Laser	Wavelength, nm	Penetration depth, µm (mm)*	Absorbing chromophore	Fabric types	Lasers used in dentistry
Nd:YAG frequency doubling			Melanin, Blood
Pulse dye			Melanin, Blood
He-Ne (helium-neon)			Melanin, Blood	Soft, therapy
Ruby			Melanin, Blood
Alexandrite			Melanin, Blood
			Melanin, Blood	Soft, whitening
Neodymium (Nd:YAG)			Melanin, Blood
Goldmium (Ho:YAG)
Erbium (Er:YAG)				Hard (soft) Hard (soft)
Carbon dioxide (CO2)				Hard (soft) Soft

* light penetration depth h in micrometers (millimeters), at which 90% of the power of laser light incident on biological tissue is absorbed.

In dentistry, the CO2 laser is most often used to treat soft tissues, and the erbium laser is used to prepare hard tissues.

Operating mode of lasers and their energy.

Erbium:

Impulse, energy/impulse ~300…1000 mJ/imp.

CO2 laser:

Pulse (up to 50 mJ/mm2)

Continuous (1-10W)

Combined

A typical laser device consists of a base unit, a light guide and a laser tip, which the doctor uses directly in the patient’s oral cavity. For ease of use, various types of handpieces are available: straight, angled, for power calibration, etc. All of them are equipped with a water-air cooling system for constant temperature control and removal of prepared hard tissue.

When working with laser equipment, special eye protection must be used. The doctor and patient must wear special glasses during preparation. It should be noted that the danger of vision loss from laser radiation is several orders of magnitude less than from a standard dental photopolymerizer. Laser ray does not dissipate and has a very small illumination area (0.5mm² versus 0.8cm² for a standard light guide).

The laser operates in a mode that sends out an average of about ten beams every second. The laser beam, hitting hard tissue, evaporates a thin layer of about 0.003 mm. The dissection occurs quite quickly, but the doctor can control the process by immediately interrupting it with one movement. After laser preparation, an ideal cavity is obtained: the edges of the walls are rounded, whereas when preparing with a turbine, the walls are perpendicular to the tooth surface, and after that additional finishing has to be carried out.

In addition, the cavity after laser preparation remains sterile, as after long-term antiseptic treatment, since laser light kills pathogenic flora.

Laser dissection is a non-contact procedure; the components of the laser system do not directly contact the tissues - dissection occurs remotely. In addition to the undoubted practical advantages, the use of a laser helps to significantly reduce the cost of treatment. By working with a laser, you can completely eliminate burs, antiseptic solutions, and acid for etching enamel from everyday expenses. The time spent by the doctor on treatment is reduced by more than 40%.

Since ancient times, light has been used by humans as a healing and healing factor. The use of solar radiation, as well as the first artificial ultraviolet emitters for the treatment of certain diseases, showed the possibility of targeted use of light in practical medicine.

The era of fundamentally new light therapy is associated with the invention (N.G. Basov, A.M. Prokhorov (USSR), C. Townes (USA), 1955) and the creation (T. Meiman, 1960) of a laser - new, not having analogues in nature, a type of radiation. The word LASER is an abbreviation from English light amplification by stimulated emission of radiation, which translates as “light amplification as a result of stimulated emission.” The uniqueness of its physical nature and associated biological effects is due to the strict monochromaticity and coherence of electromagnetic waves in the light flux.

The beginning of the medical use of lasers is considered to be 1961, when A. Javan created a helium-neon emitter. Low intensity emitters of this type have found their application in physiotherapy. In 1964, the carbon dioxide laser was developed, which marked the beginning of the surgical use of lasers. In the same year, Goldman et al. suggested the possibility of using a ruby emitter for excision of carious tooth tissue, which aroused great interest among researchers. In 1967, Gordon tried to carry out this manipulation in the clinic, but despite good results obtained in vitro, failed to avoid damage to the dental pulp. The same problem arose when trying to use a CO 2 laser for these purposes. Later, for the preparation of hard dental tissues, the principle of pulsed action was proposed, special structures for the temporary distribution of pulses were developed, and emitters based on other crystals were created.

In recent years, there has been a steady trend towards an increase in the use of lasers and the development of new laser technologies in all areas of medicine. The introduction of lasers in healthcare has a great socio-economic effect. It is important to emphasize: the laser as a tool therapeutic effects today it is attractive not only for the doctor, but also for the patient. Medical use lasers are based on the following mechanisms of interaction of light with biological tissues: 1) non-perturbing action, which is used to create various diagnostic devices; 2) photodestructive action of light, which is mainly used in laser surgery; 3) the photochemical action of light, which underlies the use of laser radiation as a therapeutic agent.

Today, lasers are successfully used in almost all areas of dentistry: the prevention and treatment of caries, endodontics, aesthetic dentistry, periodontology, treatment of diseases of the skin and mucous membranes, maxillofacial and plastic surgery, cosmetology, implantology, orthodontics, orthopedic dentistry, manufacturing technologies and repair of prostheses and devices.

Laser operating principle

The principle diagram of the operation of any laser emitter can be presented as follows (Fig. 1).

Rice. 1. Scheme of operation of the laser emitter

The structure of each of them includes a cylindrical rod with a working substance, at the ends of which there are mirrors, one of which has low permeability. In the immediate vicinity of the cylinder with the working substance there is a flash lamp, which can be parallel to the rod or serpentinely surround it. It is known that in heated bodies, for example in an incandescent lamp, spontaneous radiation occurs, in which each atom of the substance emits in its own way, and thus there are fluxes of light waves randomly directed relative to each other. A laser emitter uses so-called stimulated emission, which differs from spontaneous emission and occurs when an excited atom is attacked by a light quantum. The photon emitted in this case is absolutely identical in all electromagnetic characteristics to the primary one that attacked the excited atom. As a result, two photons appear with the same wavelength, frequency, amplitude, direction of propagation and polarization. It is easy to imagine that in the active medium there is a process of an avalanche-like increase in the number of photons, copying the primary “seed” photon in all parameters and forming a unidirectional light flux. The working substance acts as such an active medium in the laser emitter, and the excitation of its atoms (laser pumping) occurs due to the energy of the flash lamp. Streams of photons, the direction of propagation of which is perpendicular to the plane of the mirrors, reflected from their surface, repeatedly pass through the working substance back and forth, causing more and more new avalanche-like chain reactions. Since one of the mirrors is partially transparent, some of the resulting photons exit in the form of a visible laser beam.

Thus, distinctive feature Laser radiation is monochromatic, coherent and highly polarized electromagnetic waves in the light flux. Monochromaticity is characterized by the presence in the spectrum of a photon source of predominantly one wavelength; coherence is the synchronization in time and space of monochromatic light waves. High polarization is a natural change in the direction and magnitude of the radiation vector in a plane perpendicular to the light beam. That is, photons in a laser light flux have not only constant wavelengths, frequencies and amplitudes, but also the same direction of propagation and polarization. While ordinary light consists of randomly scattering heterogeneous particles. To put it into perspective, the difference between the light emitted by a laser and an ordinary incandescent lamp is the same as the difference between the sound of a tuning fork and the noise of the street.

The following parameters are used to characterize laser radiation:

· wavelength (γ), measured in nm, microns;

· radiation power (P), measured in W and mW;

· power density of the light flux (W), determined by the formula: W = radiation power (mW) / light spot area (cm 2);

· radiation energy (E), calculated by the formula: power (W) x time (s); measured in joules (J);

· energy density, calculated by the formula: radiation energy (J) / light spot area (cm 2); measured in J/cm2.

Exists a large number of classifications of laser emitters. Let us present the most significant ones in practical terms.

Classification of lasers by technical characteristics

I. By type of working substance

1.Gas. For example, argon, krypton, helium-neon, CO 2 laser; group of excimer lasers.

2.Dye lasers (liquid). The working substance is an organic solvent (methanol, ethanol or ethylene glycol) in which chemical dyes such as coumarin, rhodamine, etc. are dissolved. The configuration of the dye molecules determines the working wavelength.

3.Metal vapor lasers: helium-cadmium, helium-mercury, helium-selenium lasers, copper and gold vapor lasers.

4.Solid state. In this type of emitters, crystals and glass act as the working substance. Typical crystals used are yttrium aluminum garnet (YAG), yttrium lithium fluoride (YLF), sapphire (aluminum oxide), and silicate glass. Solid material is usually activated by adding small amounts of chromium, neodymium, erbium or titanium ions. Examples of the most common options are Nd:YAG, titanium sapphire, chromium sapphire (also known as ruby), chromium doped strontium lithium aluminum fluoride (Cr:LiSAl), Er:YLF and Nd:glass (neodymium glass).

5.Lasers based on semiconductor diodes. Currently, in terms of their totality of qualities, they are one of the most promising for use in medical practice.

II. According to the laser pumping method, those. along the path of transferring the atoms of the working substance to an excited state

· Optical. The activating factor is electromagnetic radiation, which differs in quantum mechanical parameters from that generated by the device (another laser, incandescent lamp, etc.)

· Electric. The atoms of the working substance are excited by the energy of an electric discharge.

· Chemical. To pump this type of laser, the energy of chemical reactions is used.

III. By power of generated radiation

· Low intensity. They generate luminous flux power of the order of milliwatts. Used for physiotherapy.

· High intensity. They generate radiation with a power of the order of watts. They are used quite widely in dentistry and can be used for the preparation of enamel and dentin, teeth whitening, surgical treatment of soft tissues, bone, and for lithotripsy.

Some researchers identify a separate group of medium-intensity lasers. These emitters occupy an intermediate position between low- and high-intensity and are used in cosmetology.

Classification of lasers by area of practical application

· Therapeutic. They are usually represented by low-intensity emitters used for physiotherapy, reflexology, laser photostimulation, photodynamic therapy. This group includes diagnostic lasers.

· Surgical. High-intensity emitters, the action of which is based on the ability of laser light to dissect, coagulate and ablate (evaporate) biological tissue.

· Auxiliary (technological). In dentistry they are used at the stages of manufacturing and repair of orthopedic structures and orthodontic devices.

Classification of high-intensity lasers used in dentistry

Type I: Argon laser used for tooth preparation and whitening.

Type II: Argon laser used in soft tissue surgery.

Type III: Nd:YAG, CO2, diode lasers used in soft tissue surgery.

Type IV: Er: YAG laser, designed for the preparation of hard dental tissues.

Type V: Er, Cr: YSGG lasers, designed for tooth preparation and whitening, endodontic interventions, as well as for soft tissue surgery. By chemical structure The working substance is yttrium-scandium-gallium garnet, modified with erbium and chromium atoms. The operating wavelength of this type of emitter is 2780 nm (Fig. 2). Among surgical devices, due to their versatility and high manufacturability, various modifications of the YSGG laser are the most popular, although expensive.

Figure 2. Laser dental unit Waterlase MD (Biolase). Works on the basis of Er,Cr: YSGG - emitter, wavelength 2780 nm, maximum average power is 8 W. It is used for the preparation of hard dental tissues, endodontic interventions, operations on soft and bone tissues of the maxillofacial area. The tip for laser preparation of hard dental tissues is equipped with a shadowless illumination system, including the radiation of ultra-bright light-emitting diodes (LED), as well as a supply system for a cooling water-air mixture. The control panel has convenient touch navigation and works on the basis operating system Windows CE.

Depending on the temporal distribution of the light flux power, the following types of laser radiation are distinguished:

· continuous

· pulse

· modulated.

Graphically, the dependence of power on time for each of the types of radiation indicated above is presented in Fig. 3.

Rice. 3. Types of laser radiation

A separate type of pulsed radiation is Q-switch radiation. Its peculiarity lies in the fact that each pulse lasts nanoseconds, while biological tissue perceives pulses lasting more than a millisecond. As a result, the thermal effect of light is limited only to the site of irradiation and does not extend to the surrounding tissue.

The spectral range of lasers used in medicine includes almost all existing areas: from near ultraviolet (γ = 308 nm, excimer laser) to far infrared (γ = 10600 nm, CO 2 laser-based scanner).

Application of lasers in dentistry

In dentistry, laser radiation has firmly occupied a fairly large niche. At the department orthopedic dentistry BSMU is conducting work to study the possibilities of using laser radiation, which covers both the physiotherapeutic and surgical aspects of the action of the laser on the organs and tissues of the maxillofacial area, and issues of the technological use of lasers at the stages of manufacturing and repair of prostheses and devices.

Low intensity laser radiation

Implementation mechanism therapeutic effect low-intensity laser radiation on different levels The organization of biological systems can be represented as follows:

At the atomic-molecular level: absorption of light by a tissue photoacceptor → external photoelectric effect → internal photoelectric effect and its manifestations:

· occurrence of photoconductivity;

· emergence of photoelectromotive force;

· photodielectric effect;

· electrolytic dissociation of ions (breaking of weak bonds);

· occurrence of electronic excitation;

· migration of electronic excitation energy;

· primary photophysical effect;

· appearance of primary photoproducts.

At the cellular level:

· change in the energy activity of cell membranes;

· activation of the nuclear apparatus of cells, the DNA-RNA-protein system;

· activation of redox, biosynthetic processes and basic enzymatic systems;

· increased formation of macroergs (ATP);

· increased mitotic activity of cells, activation of reproduction processes.

At the cellular level, the unique ability of laser light is realized to restore the genetic and membrane apparatus of the cell, reduce the intensity of lipid peroxidation, providing antioxidant and protective effects.

At the organ level:

· decreased receptor sensitivity;

· reducing the duration of inflammation phases;

· reducing the intensity of swelling and tissue tension;

Increased tissue absorption of oxygen;

· increased blood flow speed;

· increase in the number of new vascular collaterals;

· activation of transport of substances through the vascular wall.

At the level of the whole organism (clinical effects):

· anti-inflammatory, decongestant, fibrinolytic, thrombolytic, muscle relaxant, neurotropic, analgesic, regenerative, desensitizing, immunocorrective, improving regional blood circulation, hypocholesterolemic, bactericidal and bacteriostatic.

A significant place in the work is devoted to the study of the therapeutic effectiveness of low-intensity laser radiation. The possibility of using helium-neon (γ = 632.8 nm, power density 120-130 mW/cm2) and helium-cadmium (γ = 441.6, power density 80-90 mW/cm2) lasers to optimize the conditions of osteogenesis has been proven in the retention period of complex treatment of anomalies and deformations of the dental system in the formed bite.

Complex treatment includes the following stages: 1) creating conditions for faster restructuring bone tissue and prevention of relapses (compact osteotomy), 2) hardware orthodontic treatment, 3) optimization of the conditions of bone tissue opposition in the retention period, 4) prosthetic measures according to indications.

In order to optimize the conditions of bone tissue opposition, the areas of the jaws on which compact osteotomy was performed were exposed to laser radiation with the above parameters. The effectiveness of treatment was assessed by tooth mobility and oxygen tension in tissues (using polarography). After 1 month from the beginning of the retention period, tooth mobility in the group of patients treated with laser radiation was barely noticeable (0.78 ± 0.12 mm), while in patients in the control group it remained pronounced (1.47 ± 0.092 mm;r< 0,05). Применение лазерного излучения повышало напряжение кислорода в тканях (соответственно 39,1 ± 3,1 и 22,3 ±2,8 мм рт. ст.; p < 0,001). Полученные результаты позволяют утверждать, что лечение зубочелюстных аномалий и деформаций в сформированном прикусе должно быть комплексным, включающим все указанные выше этапы. Применение лазеротерапии способствует ускорению окислительно-восстановительных процессов в тканях альвеолярного отростка и позволяет сократить сроки лечения в 2,5—3 раза .

In recent years, there has been great scientific and practical interest in semiconductor laser emitters(laser diodes, LD), they have a number of advantages over gas diodes. The advantages of laser diodes include: 1) the ability to select wavelengths over a wide range, 2) compactness and miniaturization, 3) the absence of high voltage in power supplies, 4) the easily implemented possibility of creating equipment that does not require grounding, 5) low power consumption ( which makes it possible to operate them from a built-in autonomous power source - small batteries); 6) absence of fragile glass elements (an indispensable attribute of gas lasers); 7) easily implemented possibility of changing the influencing parameters (radiation power, pulse repetition frequency); 8) reliability and durability (which significantly exceed those for gas lasers and are continuously growing as new technologies are mastered); 9) relatively low price and commercial availability.

When developing laser therapeutic devices, the emphasis is on sources that generate radiation corresponding to the so-called “transparency window” of biological tissues: γ = 780–880 nm. At these wavelengths, the deepest penetration of radiation into the tissue is ensured. In addition, one of the main trends in the creation of modern emitters is the combination of optical influence with other physical factors (constant and variable magnetic field, ultrasound, electromagnetic fields in the range of millimeter wavelengths, etc.), as well as providing the ability to operate in continuous, pulsed and modulated modes.

Today, among laser therapeutic devices, one of the most popular in Europe are emitters with a power of P = 500 mW (808-810 nm). Just 4-5 years ago, therapeutic equipment with such radiation parameters was practically not produced, and one of the first devices in this class was the semiconductor magnetic laser device "Snag" (Fig. 4), developed by employees of the Institute of Physics of the National Academy of Sciences of Belarus, and used in our research.

Rice. 4. Portable laser therapeutic device "Snag"

In modern phototherapeutic installations, along with lasers, a new type of incoherent light sources is widely used - ultra-bright light-emitting diodes (LED - Light Emitting Diode). Unlike lasers, LED radiation is not monochromatic. Depending on the type of LED (the spectral range of its glow), the typical half-width of the emission spectrum is 20-25 nm. Despite numerous discussions about the biological and therapeutic effects of LED radiation, modern Western-made phototherapeutic equipment widely uses these incoherent sources. Moreover, both in matrix types of emitters (together with laser sources - LD), and as an independent physical factor.

A pressing issue in dentistry is the treatment of jaw anomalies and deformities in patients with cleft lip and palate. Determining the clinical effectiveness of low-intensity laser radiation with a wavelength of 810 nm in the complex orthopedic-surgical treatment of anomalies and deformities after end-to-end cleft lip and palate became the subject of one of the studies conducted at the department. The semiconductor magnetic laser device "Snag" was used as a radiation source. Low-intensity laser radiation was used to stimulate regenerative processes in bone tissue. The areas of the jaws on which the procedure was performed were exposed to irradiation. surgery(compact osteotomy). The diameter of the light spot on the mucosa was 5 mm, the radiation power was 500 mW. The effectiveness of laser therapy was assessed by tooth mobility and changes in the optical density of targeted radiographs. At the final stage of the study, the following results were obtained: after orthopedic surgical treatment using low-intensity infrared laser radiation, tooth mobility in patients was barely noticeable already 1 month from the beginning of the retention period, while in patients in the control group it remained pronounced. The optical density of bone tissue was almost the same (72.55 ± 0.24 in the control group; 72.54 ± 0.27 in the experimental group (p>0.05), and already a month from the beginning of the retention period in the group of patients who received a course of laser therapy was carried out, the optical density of bone tissue was significantly higher: 80.26 in the control group; 101.69 in the experimental group (p<0,05) . Это подтверждает значение лазеротерапии как важной составляющей в комплексном лечении пациентов с аномалиями и деформациями челюстей.

A special type of laser action on a pathological focus is photodynamic therapy. Its effectiveness is based on the ability of specific chemicals (photosensitizers) to selectively accumulate in bacterial cells and, under the influence of light of a certain wavelength, to initiate photochemical free radical reactions. The resulting free radicals cause damage and death of this cell. Chemical derivatives of chlorophyll (chlorins) or hematoporphyrin most often act as photosensitizers. The use of photodynamic therapy for the treatment of periodontal diseases is promising.

Contraindications to low-level laser therapy

Absolute: blood diseases that reduce coagulation, bleeding.

Relative: cardiovascular diseases in the sub- and decompensation stage, cerebral sclerosis with severe cerebrovascular accidents, acute cerebrovascular accidents, lung diseases with severe respiratory failure, liver and kidney failure in the decompensation stage, all forms of leukoplakia (as well as all proliferative phenomena) , benign and malignant neoplasms, active pulmonary tuberculosis, diabetes mellitus in the stage of decompensation, blood diseases, active pulmonary tuberculosis, first half of pregnancy, individual intolerance.

High intensity laser radiation

Having the ability to dissect, coagulate and ablate (evaporate) biological tissue, a high-intensity laser begins to gradually replace the scalpel and drill. The undoubted advantages of using a laser in surgery are the ability to work in a “dry field” due to reduced blood loss during surgery, a low likelihood of keloid scar formation, no need for sutures, reduced need for anesthesia, and absolute sterility of the working field (Fig. 5 - 8) .

Rice. 5. A frenectomy operation using a surgical laser (hereinafter, the figures are given from left to right): a - before the operation: a short powerful frenulum, which caused gum recession in the area of the upper incisors; b — condition after laser excision of the short frenulum. The operation was performed without the use of anesthesia and traditional methods of hemostasis; c — a week after surgical treatment.

Rice. 6. Obtaining a block bone graft using a surgical laser: a — view before surgery; b — after detachment of soft tissues, a graft of the required shape and size is cut out; c - laser “scalpel” allows you to obtain donor tissue with intact periosteum

Rice. 7. Increasing the height of the supragingival part of the tooth root for subsequent orthopedic treatment: a - before surgery (there are no clinical conditions for restoring the coronal part of teeth 11 and 21); b — increasing the height of the supragingival part of the tooth root by laser excision of adjacent tissues (including bone); c - to consolidate the results obtained, a direct prosthesis was made on the prepared teeth

Rice. 8. Removal of Schwannoma of the right lateral surface of the tongue using a diode surgical laser: a — schwannoma of the right lateral surface of the tongue (view before treatment); b — removal of the tumor through an incision on the surface of the tongue; c — gross specimen of the tumor; d — view of the surgical wound immediately after the intervention. There is a noticeable absence of bleeding; d — mucous membrane of the tongue two weeks after surgery

We, together with employees of the Institute of Physics of the National Academy of Sciences, have developed a laser surgical device “Spear” (Fig. 9) for use in the clinic of maxillofacial and plastic surgery.

Rice. 9. Laser surgical unit “Spear”

Medical tests were carried out at the 432nd Main Military Clinical Hospital in the presence of the developers of the device in order to ensure safety and make appropriate changes to the design of the device. 263 operations were performed on 76 patients aged 12-50 years with the following pathology: capillary hemangiomas of the face and neck - 45; papillomas of the face and neck - 83; fibroma - 1; fibrous epulis of the alveolar process of the jaw - 1; retention cyst of the minor salivary gland - 1; verrucous nevus - 1; skin pigmentation - 164; hyperkeratoses - 7. Surgical interventions included excision and coagulation with an Nd:YAG laser beam with a wavelength of 1064 nm, a “bare” light guide in contact and non-contact modes.

The best wound healing results (without keloid scar) were observed at a power of about 30 W.

With this mode of operation, there was no postoperative pain syndrome and perifocal hyperemia of the wound. There were no adverse effects associated with laser exposure on patients and medical personnel. At the end of the clinical trials, it was concluded that the Spear device meets its intended purpose and is recommended for use in medical practice in health care facilities of the Republic of Belarus.

The mechanism of laser preparation of dental and bone tissue

Using a pulse-periodic Nd:YAG laser as an example, we studied the mechanism of laser preparation of dental and bone tissue. Experimental studies used samples of cadaveric tissue from the mandibles of humans (dry bone) and dogs (bone preserved in formaldehyde). Bone preparation was carried out in air and water through direct contact of the output end of a flexible fiber light guide with the bone. The diameter of the light-conducting core was 0.6 mm, the holes being formed were arranged in a checkerboard pattern. During the preparation, we observed the following process: after several laser pulses, which did not lead to visible results, a bright flash appeared on the surface of the tooth or bone, which became brighter with each subsequent pulse. Then the bright flash began to be accompanied by the generation of a loud sound pulse. Finally, a bright flash and sound began to be accompanied by intense release of gas bubbles (in the case of treatment in water). As a result, small particles of tissue were ejected from the laser irradiation zone. Under the action of the laser beam, a certain proportion of particles burned, and there were significantly more particles in the case of processing in air.

After laser exposure both in air and in water, the following elements were determined on a microscopic section of tissue: (a) on the surface of the channel there was a thin blackened layer of charred tissue; (b) a layer of basophilic bone substance up to 1-1.5 mm thick, gradually turning into normal bone tissue; (c) structureless black-brown particles of partially burnt tissue; (d) bone fragments on the wall and in the lumen of the canal; (e) areas of torn bone fibers; (f) remains of burnt soft tissue. Elements (e) and (f) were observed in the area of the basophilic zone (b) or at its border with undestroyed bone tissue. An important feature should be noted that is not observed when forming holes with a conventional bur: on the histological specimen, thin collagen fibers are visible between the canal wall and the particles of burnt tissue in the interstitial substance of the tissue, while the basophilic zone smoothly passes into normal bone tissue. When processed in water, the proportion of retained collagen fibers increases significantly (Fig. 10).

Rice. 10. a, b - area of the fibrous structure of the homogeneous (light) zone, between the charring zones and the basophilic zone; c — thin collagen fibers between the wall of the laser channel and particles of charred tissue. Human cadaveric jaw; d - the beginning of the disintegration of the charring layer, the disappearance of the intermediate zone. The wall of the laser channel is formed predominantly by living bone tissue. Hematoxylin and eosin staining

This means that with laser preparation there is a basis for regenerative processes in living tissue. Thus, a significant reduction in injury rates can be expected compared to the use of a mechanical bur. Experimental data suggest the following mechanism for laser drilling of dental and bone tissue under the influence of infrared radiation from a Nd:YAG laser. It is known that bones and teeth are very complex biological structures consisting of organic and inorganic compounds with a high water content. In many cases, the initial absorption coefficient of tissue at γ = 1064 nm can be quite small. For this reason, the first few laser pulses do not lead to visible changes in the bone. When the local release of heat leads to an increase in temperature during the action of the laser pulse to 100°C and above, micro-boiling of the water that is part of the bone occurs (in the volume and on the surface of the bone). Finally, the increase in the temperature of bone structural elements during the laser pulse becomes sufficient for the appearance of a brightly emitting plasma in the laser irradiation zone. The pressure of the luminous gas in the cavity bounded by bone tissue exceeds the strength limit of the structural elements of the bone - and the cavity collapses with intense release of gas and generation of sound. After the cavity is destroyed, the plasma bubble continues to absorb the energy of the laser pulse and expand, overcoming the resistance of bone tissue and water (if the effect is carried out in an aquatic environment), limiting it. When treated in water, after the end of the laser pulse, as a result of plasma cooling, the bright glow disappears, the pressure in the vapor-gas bubble drops sharply, and its cavitation collapse occurs, which is accompanied by the generation of intense hydrodynamic and acoustic vibrations, which also leads to fragmentation of bone tissue.

Thus, the mechanism of laser preparation of bone and dental tissue consists of three sequential processes:

1)increase in tissue absorption coefficient as a result of laser exposure;

2)mechanical stresses that arise in the volume of dental and bone tissue during micro-boiling of water, which is part of living tissues;

3)the impact of hydrodynamic shock waves generated during the emergence and collapse of bubbles.

Today, the optimal laser for preparing hard dental tissues is an Er:YAG laser with a wavelength of 2940 nm. Its radiation has the highest percentage of absorption in water and hydroxyapatite. With the advent of a specially developed system for the temporal distribution of light pulses - VSP (Variable Square Pulsations i.e. rectangular pulses of variable duration) it was possible to reduce the pulse duration from 250 to 80 μs, and also create a new type of device (Fidelis, Fotona company) that allows this duration change. By adjusting three main parameters (duration, energy and pulse repetition frequency), any dental tissue can be removed with great efficiency. Moreover, the rate of removal of a particular tissue directly depends on the water content in it. Since the water content in carious dentin is maximum, its ablation rate is the highest. The sound generated during laser preparation of dentin, along with visual control, can also be a criterion in determining the boundaries of healthy tissue.

The main advantages of laser preparation of hard dental tissues (Fig. 11):

Rice. eleven. Laser tooth preparation: a - carious lesion of the occlusal surface of tooth 26; b — the cavity was prepared using an Er: AG laser; c - restoration of the defect with a composite material

· selective effect on carious dentin; high speed of tissue processing;

· no side thermal effects;

· sterility of the cavity after treatment;

· improved adhesion of filling materials due to the absence of a smear layer;

· preventive effect of enamel photomodification;

· psychological comfort of the patient and the possibility of treatment without anesthesia.

The Optima laser dental unit has been created in the Republic of Belarus, which includes neodymium and erbium emitters. A neodymium laser (γ = 1064, 1320 nm) has an average power of up to 30 W, a pulse duration of 0-300 μs, a range of energy emission per pulse from 50 to 700 mJ; and is designed for surgical interventions on soft tissues of the maxillofacial area. Erbium laser (γ=2780, 2940 nm) is intended for the preparation of hard dental tissues.

In 2004-2005 On the basis of the Department of Orthopedic Dentistry of the Belarusian State Medical University, clinical trials of the Optima laser system were carried out. During the tests, the following surgical interventions were performed: gingivectomy for hyperplasia of the interdental papillae, formation and de-epithelialization of a mucoperiosteal flap, sanitation of bone pockets, vaporization of subgingival dental plaque, smoothing of the craters of bone pockets. The sanitized bone pockets were filled with a mixture of the patient's blood clot and osteoconductor (CAFAM). Long-term observations (3-6 months after surgery) showed the absence or minimal recession of the gingival margin, remission of the disease, and radiographically - restoration of bone tissue in the area of the operated bone pockets.

Currently, clinical trials of the Optima laser dental unit on dental tissues in vitro using erbium laser radiation have been completed. It is planned to develop in the clinic methods and modes of using erbium laser radiation to remove carious tissue, as well as for other therapeutic measures in therapeutic and orthopedic dentistry.

The experience of medical testing of the new laser system has shown that it is quite competitive in its technical characteristics and medical application (i.e., not inferior to such foreign analogues as Opus Duo, Opus Duo E, Keylazer), and economically in terms of performance, service and cost more profitable.

In a therapeutic dentistry clinic, laser radiation can also be used to whiten teeth. Today, diode laser emitters with a wavelength of 810 nm are used for these purposes. Modern whitening systems include the use of a special photochemical gel, which minimizes the energy required for a full procedure. As a result, the procedure time is significantly reduced, heating of the teeth is eliminated and postoperative sensitivity is reduced. The effect of laser whitening is permanent (only minor changes invisible to the eye are possible) and lasts throughout life.

In addition to the physiotherapeutic and surgical effects of lasers, the auxiliary, or technological, use of laser radiation is of great importance in orthopedic dentistry and orthodontics. In particular, one of the most important issues is the connection of metal elements of orthopedic structures and orthodontic devices.

The relevance of this problem is determined not so much by technological problems (imperfections of existing methods of connecting metal parts of dentures and orthodontic devices), but by purely biological reasons associated with the adverse effects of PSR-37 solder on the oral cavity and the body as a whole. PSR-37 solder corrodes with the release of its ingredients (copper, zinc, cadmium, bismuth, etc.). Due to the heterogeneity of metals in the oral cavity, microcurrents arise, causing a pathological symptom complex, the so-called galvanism, and allergic phenomena are observed.

Advantages of laser welding of metal parts of dentures and orthodontic devices

1. Due to the low divergence, laser radiation can be precisely focused on small areas, obtaining high levels of power density (more than 100 MW/cm2), which allows the processing of refractory materials that are difficult to weld.

2. Non-contact exposure and the possibility of transmitting radiation energy through light guides makes it possible to carry out welding in hard-to-reach places.

3. Laser welds have a small heat-affected zone in the surrounding material, which leads to reduced thermal deformation.

4. No solders or fluxes.

5. The locality of the impact allows you to process areas of products in close proximity to heat-sensitive elements.

6. The short duration of the laser welding pulse allows you to get rid of unwanted structural changes.

7. High welding speeds.

8. Automation of the welding process.

9. The ability to quickly maneuver the duration, shape and energy of the laser pulse allows you to flexibly control the welding process.

An installation for laser welding of metal parts of dentures and orthodontic devices has been developed and created at the Institute of Physics of the National Academy of Sciences of Belarus.

Laser technologies occupy a strong position in the arsenal of modern dentistry. In conditions of increasing allergization of the population and the development of drug resistance, laser therapy is becoming a real alternative to drug therapy. The atraumatic nature and biocorrectness of laser surgery speak for themselves. Replacing the scalpel with a beam of light in many operations has made it possible to minimize the risk of side effects, and to perform some manipulations for the first time.

And in general, the development of laser technologies and the replacement of traditional chemical and mechanical effects with light are the most important trends in the medicine of the future.

Literature

1. Dosta A.N. Experimental and clinical rationale for optimizing osteogenesis in the retention period of orthodontic treatment using modern laser technologies: Abstract of thesis. dis. ...cand. honey. Sci. Mn., 2003. 15 p.

2. Lyudchik T.B., Lyandres I.G. , Shimanovich M.L. // Organization, prevention and new technologies in dentistry: Proceedings of the V Congress of Dentists of Belarus. Brest, 2004. pp. 257-258.

3. Lyandres I.G., Lyudchik T.B., Naumovich S.A. and others // Laser-optical technologies in biology and medicine: International proceedings. conf. Mn., 2004. P. 195-200.

4. Naumovich S.A. Ways to optimize complex orthopedic-surgical treatment of malocclusions and deformities in adults: Abstract of thesis. dis. ...Dr. med. Sci. Mn., 2001. 15 p.

5. Naumovich S.A., Berlov G.A., Batishche S.A. // Lasers in biomedicine: International proceedings. conf. Mn., 2003. pp. 242-246.

6. Naumovich S.A., Lyandres I.G., Batishche S.A., Lyudchik T.B. // Lasers in biomedicine: International proceedings. conf. Mn., 2003. P.199-203.

7. Plavsky V.Yu., Mostovnikov V.A., Mostovnikova G.R. and others // Laser-optical technologies in biology and medicine. M-ly international. conf. Mn., 2004. pp. 62-72.

8. Ulashchik V.S., Mostovnikov V.A., Mostovnikova G.R. and others. Int. conf. “Lasers in medicine”: Sat. articles and theses. Vilnius, 1995.

9. Baxter G.D. Therapeutic Lasers: Theory and Practice Edinburgh; New York, 1994.

10. Grippa R., Calcagnile F., Passalacqua A. // J. Oral Lazer Applications. 2005. V. 5, N 1. P.45 - 49

11. Lasers in Medicine and Dentistry. Basic science and up-to-date Clinical Application of Low Energy-Level Laser Therapy, ed. Simunovic, Grandesberg, 2000.

12. Simon A. Low Level Laser Therapy for Wound Healing: an Update. Edmonton, 2004.

Moderndentistry. - 2006. - №1. - WITH. 4-13.

Attention! The article is addressed to medical specialists. Reprinting this article or its fragments on the Internet without a hyperlink to the source is considered a violation of copyright.

"Lasers in dentistry"

Izhevsk 2010

Introduction

The word laser is an acronym for “Light Amplification by Stimulated Emission of Radiation.” The foundations of laser theory were laid by Einstein in 1917. Surprisingly, it was only 50 years later that these principles were sufficiently understood and the technology could be implemented practically. The first laser using visible light was developed in 1960, using ruby as the laser medium, generating a red beam of intense light. This was followed in 1961 by another crystal laser using neodymium yttrium aluminum garnet (Nd:YAG). In 1964, physicists at Bell Laboratories produced a gas laser using carbon dioxide (CO2) as the laser medium. In the same year, another gas laser was invented - which later proved valuable for dentistry - the argon laser. Dentists who studied the effects of ruby laser on tooth enamel found that it caused cracks in the enamel. As a result, it was concluded that lasers have no prospects for use in dentistry. However, in medicine, research and clinical use of lasers has flourished. In 1968, the CO2 laser was first used for soft tissue surgery. Along with the increase in the number of laser wavelengths, indications for use in general and maxillofacial surgery have also evolved. It was not until the mid-1980s that there was a resurgence of interest in the use of lasers in dentistry to treat hard tissues such as enamel. Although only some types of lasers, such as Nd:YAG, are suitable for treating hard tissue, potential hazards and lack of specificity for dental tissue limit their use.

1 . Laser beam principle

The main physical process that determines the action of laser devices is stimulated emission of radiation. This emission is formed during the close interaction of a photon with an excited atom at the moment of exact coincidence of the energy of the photon with the energy of the excited atom (molecule). As a result of this close interaction, the atom (molecule) passes from an excited state to a non-excited one, and the excess energy is emitted in the form of a new photon with absolutely the same energy, polarization and direction of propagation as that of the primary photon. The simplest principle of operation of a dental laser is to oscillate a beam of light between optical mirrors and lenses, gaining strength with each cycle. When sufficient power is reached, the beam is emitted. This release of energy causes a carefully controlled reaction.

2. Interaction of laser with tissue

The effect of laser radiation on biological structures depends on the wavelength of the energy emitted by the laser, the energy density of the beam, and the temporal characteristics of the beam energy. The processes that can occur are absorption, transmission, reflection and dispersion.

Absorption - The atoms and molecules that make up the tissue convert laser light energy into heat, chemical, acoustic or non-laser light energy. Absorption is affected by wavelength, water content, pigmentation and tissue type.

Transmission – laser energy passes through the tissue unchanged.

Reflection – reflected laser light does not affect tissue.

Scattering - Individual molecules and atoms receive the laser beam and deflect the beam's force in a direction different from the original one. Ultimately, the laser light is absorbed in a large volume with a less intense thermal effect. Scattering is affected by wavelength.

3. Lasers in dentistry

Argon laser (wavelength 488 nm and 514 nm): The radiation is well absorbed by pigment in tissues such as melanin and hemoglobin. The wavelength of 488 nm is the same as in curing lamps. At the same time, the speed and degree of polymerization of light-curing materials by laser far exceeds similar indicators when using conventional lamps. When using an argon laser in surgery, excellent hemostasis is achieved.

Diode laser (semiconductor, wavelength 792–1030 nm): radiation is well absorbed in pigmented tissue, has a good hemostatic effect, has anti-inflammatory and repair-stimulating effects. The radiation is delivered through a flexible quartz-polymer light guide, which simplifies the surgeon’s work in hard-to-reach areas. The laser device has compact dimensions and is easy to use and maintain. At the moment, this is the most affordable laser device in terms of price/functionality ratio.

Nd:YAG laser (neodymium, wavelength 1064 nm): radiation is well absorbed in pigmented tissue and less well absorbed in water. In the past it was most common in dentistry. Can operate in pulse and continuous modes. Radiation is delivered via a flexible light guide.

He-Ne laser (helium-neon, wavelength 610–630 nm): its radiation penetrates well into tissues and has a photostimulating effect, as a result of which it is used in physiotherapy. These lasers are the only ones that are commercially available and can be used by patients themselves.

CO2 laser (carbon dioxide, wavelength 10600 nm) has good absorption in water and average absorption in hydroxyapatite. Its use on hard tissue is potentially dangerous due to possible overheating of enamel and bone. This laser has good surgical properties, but there is a problem with delivering radiation to tissues. Currently, CO2 systems are gradually giving way to other lasers in surgery.

Erbium laser (wavelength 2940 and 2780 nm): its radiation is well absorbed by water and hydroxyapatite. The most promising laser in dentistry, can be used to work on hard dental tissues. Radiation is delivered via a flexible light guide. Indications for the use of a laser almost completely repeat the list of diseases that a dentist has to deal with in his work. The most common and popular indications include:

· Preparation of cavities of all classes, treatment of caries;

· Processing (etching) of enamel;

· Sterilization of the root canal, impact on the apical focus of infection;

· Pulpotomy;

· Treatment of periodontal pockets;

· Exposure of implants;

· Gingivotomy and gingivoplasty;

· Frenectomy;

· Treatment of mucosal diseases;

· Reconstructive and granulomatous lesions;

· Operative dentistry.

4. Use of laser in dentistry

Using laser systems, early stage caries is successfully treated, while the laser removes only the affected areas without affecting healthy tooth tissue (dentin and enamel).

It is advisable to use a laser when sealing fissures (natural grooves and grooves on the chewing surface of the tooth) and wedge-shaped defects.

Carrying out periodontal operations in laser dentistry allows you to achieve good aesthetic results and ensure complete painlessness of the operation. Laser treatment of gums and photodynamic therapy using a special laser device and algae eliminates bleeding gums and bad breath after the first session. Even with deep pockets, it is possible to “close” the pockets in a few sessions. This results in faster healing of periodontal tissue and strengthening of teeth.

Dental laser devices are used to remove fibroids without sutures, perform a clean and sterile biopsy procedure, and perform bloodless soft tissue surgeries. Diseases of the oral mucosa are successfully treated: leukoplakia, hyperkeratoses, lichen planus, treatment of aphthous ulcers in the patient’s oral cavity (nerve endings are closed).

In the treatment of dental canals (endodontics), a laser is used to disinfect the root canal for pulpitis and periodontitis. The bactericidal effectiveness is 100%.

The use of laser technology helps in the treatment of dental hypersensitivity. In this case, the microhardness of the enamel increases to 38%.

In aesthetic dentistry, using a laser, it is possible to change the contour of the gums, the shape of the gum tissue to form a beautiful smile; if necessary, tongue frenulums can be easily and quickly removed. Effective and painless laser teeth whitening with long-lasting results has gained the most popularity recently.

When installing a denture, the laser will help create a very precise micro-lock for the crown, which allows you to avoid grinding down the adjacent teeth. When installing implants, laser devices allow you to ideally determine the installation site, make a minimal tissue incision and ensure the fastest healing of the implantation area.

Laser dental treatment has other advantages - for example, when traditionally preparing a tooth for filling, it can be very difficult for a dentist to completely remove softened dentin without damaging healthy tooth tissue. The laser copes with this task perfectly - it removes only those tissues that have already been damaged as a result of the development of the carious process.

Therefore, laser dental treatment is much more effective than traditional technologies, because the service life of fillings largely depends on the quality of carious cavity preparation. In addition, in parallel with preparation, the laser provides antibacterial treatment of the cavity, which avoids the development of secondary caries under the filling. Laser treatment of caries, in addition to the listed qualities, provides dental treatment without pain and does not affect healthy tooth tissue. Thanks to such serious advantages of this technology, laser dental treatment is widely used not only in adult, but also in pediatric dentistry.

There are several types of dental laser: diode, argon, neodymium, erbium, carbon dioxide. The difference between the devices is in power, wavelength, point or constant flow of pulses. Each type of laser beam is used for specific procedures. It is used with equal success for therapeutic treatment and surgical intervention.

Therapeutic laser dental treatment

In therapeutic dentistry, laser therapy is used in the following cases:

Relieving inflammation. When treating gingivitis, stomatitis or herpes, electromagnetic waves are directed to the source of infection and destroy pathogenic bacteria.
Sterilization. Periodontal pockets and tooth canals are treated with a diode laser before installing a filling.
Treatment of caries. Affected tissues are effectively removed using an erbium apparatus.
Filling. Curing of light polymer fillings occurs under the influence of an argon laser.
Teeth whitening. The laser beam activates the hydrogen peroxide-based whitening gel without heating the tooth tissue, that is, without the risk of overheating or burning the pulp. Thanks to the local pulse effect, the patient does not experience discomfort during the procedure.

Application of laser in dental surgery

During surgery, a laser device is used for painless and bloodless tissue dissection - during the procedure, the beam instantly seals the vessels. The incision is smaller and thinner than with a scalpel, so no stitches are required during the operation, and after the wounds heal there are no scars or scars. In dental surgery, laser is used to solve the following problems:

Removal of tumors. The liquid inside the papilloma, cyst or fibroma is evaporated under the influence of electromagnetic waves.
Carrying out dental implantation. Thanks to the laser, implant installation is delicate. Thanks to laser implantation, the soft tissue contour is better preserved.
Plastic surgery of the frenulum of the lips and tongue. The fold is excised lengthwise or crosswise depending on the clinical case.
Gum correction. Excess tissue is trimmed before prosthetics, filling or orthopedic treatment. The laser is also used for gum surgery after implantation or if there are other indications.

Indications and contraindications

With the help of electromagnetic waves, it is possible to achieve positive therapeutic results even in the most difficult situations, and the absence of the need for anesthesia allows the device to be used for people with allergies to painkillers. The use of laser in dentistry is one of the safest and most effective methods of treatment, which is indicated for almost everyone. However, there is still a small list of contraindications.

Attention!

Insufficient qualifications of a specialist and failure to comply with safety rules significantly increase the risk to the patient’s health during laser treatment. Contact only trusted clinics, where your eyes are protected from radiation with special glasses, and the room is brightly lit during the procedure.

Advantages of the method

Today, laser dental treatment in Moscow is widespread in dentistry. Despite the high cost, it is deservedly popular among patients who appreciate the advantages of laser treatment.

Delicacy. The absence of unpleasant noise and vibrations makes the operation easier.
Short duration of procedures. Depending on the nature of the manipulations, the process takes from two to twenty minutes.
No need for anesthesia. The device does not touch the tissues of the teeth and gums, but acts at a distance, so there is no pain from mechanical action.
Accuracy. The rays are directed only at the affected tissues, healthy areas are not damaged.
Reduced injury rate. The laser seals the vessels and edges of the wound, so even complex operations do not require stitches and bandages to stop bleeding.
Fast rehabilitation. After treatment, the incision heals in a matter of hours and is not accompanied by swelling or pain.

Treatment of cysts and granulomas with laser

Granuloma usually occurs as a result of poor treatment of caries and pulpitis. The disease is asymptomatic at the first stage, and is later accompanied by swelling of the gums, pain and darkening of the enamel. When treating dental granuloma with a laser, the affected area is drilled and an electromagnetic beam is sent into the hole, destroying the contents of the cyst and sealing the vessels. The doctor then installs a filling.

Without timely treatment, the granuloma develops into a cyst, which can provoke even more serious complications. Gentle treatment of dental cysts with a laser is considered a good method, as it allows you to save the tooth. The procedure takes place without pain, stress and stitches. In addition, treatment of a dental cyst with a laser without removal eliminates the risk of re-development of inflammation. The patient’s comfort and the absence of complications justify the additional costs, because the price when treating a dental cyst with a laser is higher than when using other methods.

Painless laser dental treatment for children

Laser therapy is suitable for both adults and children aged 7 years and older. The technique is used to treat temporary and permanent teeth. It is possible to treat a tooth root cyst with a laser in a child and use electromagnetic waves to remove carious lesions at the initial stage of the disease. In general, laser dental treatment in children is often carried out in the presence of an allergy to anesthetics and is no different from therapy for adult patients.

How much does laser dental treatment cost?

As a rule, prices for laser dental treatment in Moscow depend on the type of dental disease and the severity of the pathology. You must be prepared for the fact that in any case it will be significantly higher than when using classical methods. Treatment of caries at the initial stage of the disease will cost from 800 rubles. The price for treating a dental cyst with a laser without removal will be approximately 1,500 to 2,000 rubles. For laser whitening you will have to pay from 8,000 to 11,000 rubles.

Obviously, the high cost of therapy is the only drawback of this technology. However, numerous rave reviews about laser dental treatment confirm the fact that patients are willing to pay for comfort, efficiency and peace of mind, the absence of irritating drill sounds and the frightening prospect of using anesthetics.