Lasers in dentistry
Dental lasers were first introduced in the 1960s, but they were used mostly experimentally, until the 1990s when dentists started using lasers to treat different dental problems. The treatments provided by a dental laser are alternative treatments and the laser can be used in almost all of the fields in dentistry. The word LASER stands for ‘Light Amplification by the Stimulated Emission of Radiation’ and there are many different types of dental lasers on the market at the moment. In the last couple of decades, the studies and clinical trials about lasers in dentistry have grown immensely. It is considered that dental lasers provide a treatment that is much more comfortable for patients, less painful, more efficient, the recovery time is shortened, and the whole procedure is much faster.
How do lasers work?
Lasers produce a light that is of a single color, and every light wave has the same size and shape, in other words, lasers produce monochromatic and coherent light waves. This way, the laser can be used as a source of energy that is very precise and accurate. Once this energy gets in touch with hard or soft tissues it can be used for many different dental procedures.
There are four types of interactions that the laser light can have with tissues and it mostly depends on the optical properties that the tissue has. The laser light can be absorbed, transmitted, scattered or reflected.
Different types of lasers are differently absorbed by tissues. This depends on the composition of the tissue and the wavelength of the laser. Some lasers are able to penetrate deep into the tissues, while others can only penetrate the surface of the tissues. That is why lasers that can penetrate deeper are used for hard tissues, while the ones that have a limited penetration are mostly used for soft tissues.
The transmission also depends on the wavelength of the dental laser. There are laser lights that can go through tissues without causing any effects, but there are also wavelengths that can cause damage to surrounding tissues.
• Scattering of laser light
The scattered laser light might have no effect on tissues, but also if it is not used properly it might cause overheat and damage to surrounding tissues.
If the laser light is reflected from the tissues, the clinician must be very careful that the light will not be redirected to other parts of the body. This type of interaction is mostly used in caries detecting lasers.
Types of lasers
• Erbium: yttrium aluminum garnet (Er: YAG)
• Diode Semiconductor:
• Hybrid silicon laser
Lasers in dentistry
Lasers can be categorized by a lot of different methods including their wavelength, the type of tissue that is used for (hard tissue or soft tissue), the medium that is used (solid or gas laser) and more. The lasers that are most commonly used in dentistry are diode lasers, argon lasers, Nd-YAG lasers, carbon dioxide lasers, the Erbium lasers and more.
• Carbon dioxide lasers
The carbon dioxide lasers produce laser waves that are very well absorbed by water and are mostly used to treat soft tissues. These are the first lasers ever to be used in dentistry. The carbon dioxide laser produces light energy with a wavelength of 10,600 nm. This type of laser is used to remove soft tissue and it provides great coagulation, very clean and visible field. It does not have the ability to penetrate deep into the tissues and it provides a very painless recovery. Its main indication is treating mucosal lesions. The disadvantage of this laser is that it is very expensive, large and the recovery time might be prolonged.
• Nd-YAG lasers
The Nd-YAG laser is indicated also for soft tissues treatment because it is very well absorbed by pigmented tissue. It can penetrate much deeper than the carbon dioxide laser. Just like the one before, this type of laser is very good for cutting soft tissue, it provides a good hemostasis and a clean and visible operating field. It is mostly used for gingival and sulcular debridement in the treatment of periodontal disease, LANAP, and surgical treatments of soft tissues, but it can also be used for removing incipient dental caries, treating aphtous ulcers, root canal treatments and more. The wavelength of this laser is 1064nm.
• Argon lasers
These lasers can be very safely used for gingival tissues because they do not cause any damage to the hard tooth substances. They are used to treat the periodontal disease because they have a bactericidal effect. The main indication for argon lasers is curing composite resins, which makes the material much stronger. They can also find a use in diagnosing caries and vascular malformations. The wavelength of this laser is 488nm to 514nm.
• Diode lasers
The diode lasers are not absorbed by hard tissues and they are very safe to be used for soft tissue surgeries. Their main indication is intraoral surgery, sulcular debridement, gingivoplasty and more. It does not penetrate deep into the tissue so that is why it is not appropriate for deep periodontal pockets. A lot of surgeons use diode lasers for surgical procedures such as frenectomies, gingivectomies, biopsies and more. Some of the diode lasers can be used for caries and calculus detection, teeth whitening, and to stimulate fibroblastic proliferation. The wavelength of this laser is from 655nm to 980nm.
• The Erbium group of lasers
– Erbium: YAG: the main use of this type of laser is caries removal. It is considered that it is safe for the pulp because of the laser wavelength and the smaller penetration. The laser light provides an anesthetic effect, so tooth caries can be removed atraumatically. In most of the cases, there is no need for additional analgesia. The margins of the preparation are very precise and clean. The laser light disinfects and cleans the surfaces of the dentin and enamel and it provides a better bonding adhesion. The vibrations are barely noticeable which makes the whole procedure comfortable for the patient. This laser can also be used to disinfect root surfaces, and disinfecting before placing fissure sealants. The wavelength of the laser is 2,940nm.
– Erbium-Cr: YSGG: this laser is mostly indicated for hard tissues, but lately there have been a lot of attempts to use it for soft tissue procedures also. Its main indication is caries removal, with rough surfaces for great bonding. This is a very promising type of laser that might be the one that can be used for all types of tissue in the future.
Use of lasers in dentistry
Lasers for diagnostics
Lasers have been very successfully used for diagnostics in dentistry. The laser light can be used to detect incipient caries by using the ‘laser fluorescence’ method. Once the laser light is pointed towards the teeth, it is absorbed differently by different types of tissues. If there is caries, the bacteria in the cavity will absorb the laser light and that area will appear more fluorescent compared to the healthy tooth structure. It can be used to detect fissure caries, interproximal caries and even caries underneath fissure sealants. It is perfect for cavity lesions that can be easily missed by visual examination. Another use of lasers in diagnostics is diagnosing calculus that is located beneath the gums. This can be very helpful in the treatment of periodontal disease. Lasers also have a use in oral pathology, by helping in the diagnostics of oral cancer especially in the early stages. By using laser light the dentist will be able to locate any abnormal and pre-cancerous lesions that should be monitored closely.
Using lasers on hard tissues
• Lasers for caries removal:
The Erbium lasers have been very successfully used in treating teeth from caries. The laser is able to remove the cavity while forming clean margins and removing only the tooth substance affected by bacteria. The laser light is very accurate and precise and it also has an antibacterial effect. The laser can be applied to any class of cavity from I to V. It can be used for patients at any age, and the procedure is almost painless without any discomfort for the patients. It can also be used to remove old composite restorations.
• Lasers for calculus removal:
Lasers have also been used for removing calculus and removing the bacteria that are present on the root surface and have a role in the periodontal disease such as A. Actinomycetemcomitans and P. Gingivalis.
Lasers can be used to etch the surface of the enamel and dentine, and it provides a surface with micro-porosities and no smear layer.
• Teeth whitening
Laser assisted teeth whitening is becoming one of the most popular cosmetic procedures in dentistry. The laser light is used to excite the hydrogen peroxide or carbamide peroxide that is present in the bleaching agent and accelerate and improve the whitening process.
• Bone surgery
Lately the Er-Cr: YSGG lasers have been used to operate on bone in dentistry. These lasers have been proven safe when it comes to cutting bone, contouring and reshaping bone. They can be used for ostectomy, osteoplasty, crown lengthening and more, without any damage to the bone. The cuts that are made to the bone are very precise and the laser also provides an antibacterial effect and an aseptic environment. The only problem is that it requires a lot of expertise and experience.
• Hypersensitivity treatment
Lasers are a treatment option when it comes to dentin hypersensitivity. Most of the researches have provided results that lasers are effective in treating hypersensitivity, especially if they are combined with other conventional methods. The problem with this procedure is that it is more expensive than the other methods and it is more complex.
Using lasers on soft tissues
• Photodynamic therapy
Photodynamic laser therapy is used to treat malignancies in the oral cavity. The most common one that can be treated with a laser is the multifocal squamous cell carcinoma. It is considered that the laser light stimulates the immune response of the patient and it has a positive effect in treating the tumors.
• Lasers for biopsies
Both incisional and excisional biopsies can be performed with lasers. Once the laser light comes in touch with the soft tissue it causes necrosis.
• Disinfection with a photoactivated dye
The laser energy can activate dyes that are able to kill different types of microorganisms. This technique is able to destroy bacteria such as S. Aureus and a lot of other Gram-positive and Gram-negative bacteria, viruses, and fungi. All of these microorganisms can be found in root canals, biofilms, caries, periodontal pockets and more.
• Recurrent herpetic and apthous lesions
The laser has found its role in treating herpetic and apthous lesions. The laser light stimulates the healing of these ulcers and relieve patients from the pain.
• Soft tissue surgical procedures
Surgical procedures such as frenectomy, frenotomy, gingivectomy, gingivoplasty, vestibuloplasty, operculectomy, incisions of abscesses, removing benign tumors, inflamed and hypertrophic tissues, exposing unerupted or partially erupted teeth, can all be performed by lasers.
Laser in periodontics
Lasers offer a very promising advance in treating the periodontal disease. The YSSG laser is becoming more popular for treating both soft and hard dental tissues for a complete treatment of the periodontal disease. Other lasers can only be used to treat the soft tissues. Laser curettage is a procedure that can have a great influence on improving the outcome of periodontal treatment. The laser waves can impact the periodontal pathogen bacteria such as P. Gingivalis and A. Actinomycetemcomitans and fasten the healing procedure. Lasers can be used to remove the necrotic and infected tissue that is present in periodontal pockets, and also the inflamed tissue that can be found in bone defects. Lasers can perform different flaps that are used for periodontal surgery. They can also be used for hard tissues such as bone and removing calculus. Osteoplasty and ostectomy are the most common procedures to recontour the bone and restore the bone architecture when that is needed during the periodontal treatment.
Lasers in endodontics
A lot of endodontic procedures can be performed by lasers, starting from preparing the tooth to gain access to the root canal, debridement and cleaning the canal, canal enlargement, disinfecting the root canal and more. When it comes to disinfecting the root canal, lasers are very successful, they provide a very clean surface with almost no smear layer and debris. The lasers can also be used in endodontic surgery such as apicoectomy. The laser light can be used to create a flap and expose the bone, to cut the bone and gain access to the apex of the tooth’s root, perform the apicoectomy and remove all the pathologically changed tissue and prepare the root for retrograde filling. Lasers are efficient in removing cysts, abscesses, and granulomas that can be located around the teeth’s apexes.
Lasers in pedodontics
Lasers can be used for children for many procedures. They can have a very positive effect, since the procedures will be less painful, without any disturbing sounds and drills, no needles, and a better healing period.
Advantages of lasers
There are a lot of benefits of using a laser to perform dental procedures. All of the procedures carried out by a laser are less painful and less traumatic, which makes the experience much more comfortable for the patient. Lasers are very precise, so there is less damage to the surrounding tissues and the natural tooth substances are preserved. Lasers have the ability to cause analgesia, so in a lot of cases, there is no need for anesthesia. The bleeding during procedures is very reduced, there are better hemostasis and a better operating field. While working with the laser there is no vibration or unpleasant sounds of drills that can make a lot of patients anxious. The need for sutures is also very reduced when using a laser. The recovery period is shortened, there is less swelling of the tissues, less pain and decreased chances of bacterial infection. If lasers are used properly, they are completely safe.
Disadvantages of lasers
The main disadvantage is that lasers cost a lot and dentists need special training and education so that they are able to use them. Another disadvantage is that they cannot be used for gold, amalgam, and porcelain. They are of no use when it comes to preparing teeth for crowns and bridges yet, but there are some attempts to make this possible in the future. A lot of procedures that are performed with lasers will also need a drill. Lasers cannot be used to shape or polish a filling.