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| ORIGINAL ARTICLE |
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| Year : 2018 | Volume
: 12
| Issue : 1 | Page : 2-13 |
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Er:YAG laser regarding its tissue interactions and future in dentistry
Mohammed Mohsen Abdelfattah1, Ahmed Rezk Abdelhay1, Mostafa Aboellil2
1 National Institute of Laser Enhanced Sciences, Cairo University, Cairo, Egypt
2 Faculty of Medicine, Cairo University, Cairo, Egypt
| Date of Web Publication | 27-Jun-2018 |
Correspondence Address:
Dr. Mohammed Mohsen Abdelfattah
Via camillo casarini 3, Bologna, Italy
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/jdl.jdl_4_17
Background: The advantage of laser use in medicine has been exciting and remarkable since its introduction in the 1960s. Several medical specialties use lasers in their daily practice; the excitement of this new technology has also reached dentistry, where over the past few years, the industry has developed lasers for intraoral use and has marketed them heavily, often relying on anecdotal evidence to support their claims of superior results with the use of lasers over conventional surgical treatment. Aim of Study: The study aimed to survey the attitude of dentists about laser and its interactions with tissue giving a near vision on the future of laser devices and its market in Egypt. Materials and Methods: A study carried on 15 dentists and they asked to answer a questionnaire of 22 questions about laser. Results: Regarding the question asked about knowing the dentists who have laser devices at their clinics in Egypt, all answered that they know 1–5 dentists only. Conclusion: Dentists have no enough motivation as they think that laser device in comparison with its limited uses in dental clinic is expensive and also spare parts are hard to gain or not available. Keywords: Dentistry, Er:YAG, laser
How to cite this article:
Abdelfattah MM, Abdelhay AR, Aboellil M. Er:YAG laser regarding its tissue interactions and future in dentistry. J Dent Lasers 2018;12:2-13 |
| Introduction | |  |
The advantage of laser use in medicine has been exciting and remarkable since its introduction in the1960s. Several medical specialties use lasers in their daily practice; the excitement of this new technology has also reached dentistry, where over the past few years, the industry has developed lasers for intraoral use and has marketed them heavily, often relying on anecdotal evidence to support their claims of superior results with the use of lasers over conventional surgical treatment [1] to study laser in medicine or dentistry; we should first learn about some general principles of laser.
The term “LASER” is an acronym for “Light Amplification by the Stimulated Emission of Radiation.” Laser light is a monochromatic light and consists of a single wavelength of light. It consists of three principal parts: an energy source, an active lasing medium, and two or more mirrors that form an optical cavity or resonator. For amplification to occur, energy is supplied to the laser system by a pumping mechanism, such as a flash lamp strobe device, an electrical current, or an electrical coil. This energy is pumped into an active medium contained within an optical resonator, producing a spontaneous emission of photons. Subsequently, amplification by stimulated emission takes place as the photons are reflected back and forth through the medium by the highly reflective surfaces of the optical resonator, before their exit from the cavity through the output coupler. In dental lasers, the laser light is delivered from the laser to the target tissue through a fiber-optic cable, hollow waveguide, or articulated arm. Focusing lenses, a cooling system, and other controls complete the system [Figure 1]a.
The wavelength and other properties of the laser are determined primarily by the composition of an active medium, which can be a gas, a crystal, or a solid-state semiconductor.
The light energy produced by a laser can have four different interactions with a target tissue: reflection, transmission, scattering, and absorption. When a laser is absorbed, it elevates the temperature and produces photochemical effects.
Depending on the water content of the tissues, when temperature of 100°C is reached, vaporization of the water within the tissue occurs, a process called ablation.
At temperatures below 100°C, but above approximately 60°C, proteins begin to denature, without vaporization of the underlying tissue. Conversely, at temperatures above 200°C, the tissues dehydrated and then burned, resulting in an undesirable effect called carbonization.
Absorption requires an absorber of light, termed chromospheres, which have a certain affinity for specific wavelengths of light. The primary chromospheres in the intraoral soft tissue are melanin, hemoglobin, and water and in dental hard tissues, water and hydroxyapatite. Different laser wavelengths have different absorption coefficients with respect to these primary tissue components, making the laser selection procedure - dependent [Figure 1]b.
Aim of study
The aim of this study is to survey the altitude of dentists about laser and its tissue interactions giving a near vision on the future of laser devices and its market in Egypt.
Review of literature
Er:YAG laser physics
Er:YAG lasers are solid-state lasers whose lasing medium is erbium-doped yttrium aluminum garnet (Er: Y3 Al5O12).[2] Er:YAG lasers typically emit light with a wavelength of 2940 nm, which is infrared light. Unlike Nd: YAG lasers, the output of an Er:YAG laser is strongly absorbed by water.[3] This fact limits the use of this laser in surgery and in many other laser applications where water is present.
In general, the active medium of a solid-state laser consists of a glass or crystalline “host” material to which is added a “dopant” such as neodymium, chromium, erbium, or ytterbium. Many of the common dopants are rare earth elements because the excited states of such ions are not strongly coupled with the thermal vibrations of their crystal lattices (phonons), and their operational thresholds can be reached at relatively low intensities of laser pumping.
Solid state lasing media are typically optically pumped, using either a flash lamp or arc lamp or by laser diodes. Diode-pumped solid-state lasers tend to be much more efficient and have become much more common as the cost of high-power semiconductor lasers has decreased.
Er:YAG tissue interactions and applications
Er:YAG lasers have been used for laser resurfacing of human skin.[4] For example, uses include treating acne scarring, deep rhytides, and melasma. In addition to being absorbed by water, the output of Er:YAG lasers is also absorbed by hydroxyapatite, which makes it a good laser for cutting bone as well as soft tissue. Bone surgery applications have been found in oral surgery, dentistry, implant dentistry, and otolaryngology.[5],[6],[7],[8] Er:YAG lasers are also safer for the removal of warts than are carbon dioxide lasers – because human papillomavirus DNA is not found in the laser plume.[9]
Erbium YAG lasers are effective for removing tooth decay a traumatically, often without the need for local anesthetic to numb the tooth. Eliminating the vibration of the dental drill removes the risk of causing micro fractures in the tooth. When used initially at low-power settings, the laser energy has a sedative effect on the nerve, resulting in the ability to subsequently increase the power without creating the sensation of pain in the tooth. Additional benefits are disinfection of the surface of the dentin and enamel before bonding the filling and etching the surface to increase surface area for improved bonding adhesion.
Depigmentation procedure using Er:YAG laser
Using Fotona's Er:YAG laser using long pulse with setting parameters of 85 mJ, 1.25 W, and 15 Hz for 4 s The beam was defocused to produce a 3-mm diameter circle, thus reducing the beam penetration to 2–4 μ/pulse while increasing the treated surface.[10] The laser beam was activated and used with “brush technique” as described by Tal et al., with continuous movement of the beam overlapping the laser spots by approximately 20%–30%. Postoperative follow-up was done after 24 h. There was no discomfort, teeth sensitivity, pain or bleeding, or any other complications. The patient experienced no interruption in performing daily activities.
The patient was recalled after 1 week; healing was uneventful without any postoperative complications and required no supportive therapy. The gingival appeared pink, healthy, and firm, giving a normal appearance. The results were very pleasing and the gingival appearance completely transformed. Esthetics have gained a lot of importance in today's dental practice. Clinicians are faced with cosmetic challenges as well as addressing biologic and functional problems.
Complaints of dark color of the oral mucosa and gingival surface are occasionally encountered in dental practice. Hard and soft tissues of oral cavity [11] contribute equally in having a “perfect smile.”
Dental hard substance ablation
Extracted human teeth, cut into facets about 2 mm thick and fixed in 4% formaldehyde, were used. The abrasion of enamel and dentin by pulsed 2.94 pm laser radiation was investigated in 5 carious and in 25 intact ground sections.
Measurements were performed using flash lamp-pumped Er:YAG laser (Quantronix 294). The duration of the total laser pulse was about 250 pHs at high energy level. Within this time, a pulse train of single spikes of about 1 pHs (FWHM) each was emitted. The number and height of the spikes depend on the flash lamp energy.[12]
Recently, it has been shown that bacteria can be sterilized by Er:YAG laser irradiation. By optical fiber transmission, the bactericidal effect can also be used in endodontic. Pulse energy: 50 mJ, repetition rate: 15 Hz, fiber withdrawal velocity: 2 mm/s. With these settings, four passes must be performed to accumulate the total dose for sterilization.[13]
Cavity preparation using lasers has been an area of major research interest since lasers were initially developed in the early 1960s. At the present time, several laser types with similar wavelengths in the middle-infrared region of the electromagnetic spectrum are used commonly for cavity preparation and caries removal. The Er:YAG, Er:YSGG, and Er, Cr: YSGG lasers operate at wavelengths of 2940, 2790, and 2780 nm, respectively.
These wavelengths correspond to the peak absorption range of water in the infrared spectrum although the absorption of the Er:YAG laser (13,000 cm −1) is much higher than that of the Er: YSGG (7000 cm −1) and Er, Cr: YSGG (4000 cm −1). Since all three lasers rely on water-based absorption for cutting enamel and dentine, the efficiency of ablation (measured in terms of volume and mass loss of tooth structure for identical energy parameters) is greatest forth Er:YAG laser.[14],[15]
These laser systems can be used for effective caries removal and cavity preparation without significant thermal effects, collateral damage to tooth structure, or patient discomfort.[16],[17] Normal dental enamel contains sufficient water (approximately 12% by volume) that a water mist spray coupled to an Er-based laser system can achieve effective ablation at temperatures well below the melting and vaporization temperatures of enamel. Err-based dental lasers can also be used to remove resin composite resin and glass-monomer cement restorations and to etch tooth structure.
A characteristic operating feature of Err-based laser systems is a popping sound when the laser is operating on dental hard tissues. Both the pitch and resonance of this sound relate to the propagation of an acoustic shock wave within the tooth and vary according to the presence or absence of caries. This feature assists the user in determining that caries removal is complete.[18]
An important theoretical extension to the principle of water-based laser ablation of tooth structure is the recently described effect of “laser abrasion,” in which Er:YAG laser energy is used to accelerate the movement of particles of sapphire 30–50 micrometers in diameter in aqueous suspension. In air abrasion, the impact of these particles causes brittle splitting, resulting in tooth substance removal. In the laser abrasion method, high-speed photography has documented particle velocities in the range of 50–100 m/s, which enable rate of enamel removal “higher than that of high-speed turbines” with a very low volume of abrasive particles.[19]
Er:YAG laser can effectively cut a variety of tissues, leaving thin zones of thermally damaged tissue.[20],[21] Bonner et al. found 3–10 pm further of damage at the ablation crater edge in cadaveric flu artery and bone, a result consistent with a simple thermal damage model.[22] More recent reports have demonstrated that normal-spiking-mode Er:YAG laser radiation can effectively cut bone and leave between 5 and 10 pm of damage.[23],[24]
Laser safety and precautions
The manufacturers have taken great measures to provide a wide margin of safety in the products recommended for dental use, with fail-safe default mechanisms to eliminate accidental exposure. However, certain safety measures must be strictly adhered to in the dental operatory.
When the laser is in use for any purpose, the access to the operatory should be restricted, a caution sign should be posted, and all personnel involved in the treatment, including the patient, must have eye protection.
Caution should also be taken near reflective surfaces since the laser beam may be reflected off dental mirrors or instruments and hit other intraoral sites.[25]
Additional safety standards for fire prevention become necessary when the laser is used in conjunction with general anesthesia and should be reviewed before use in the operating room.[26]
Laser vaporous byproducts (laser plume) are generated as smoke once the vaporization of the tissue surface occurs. The plume has been shown to contain particles with mean diameters of 0.1–0.3 pm, and within this plume of carbonized tissue, viable tumor cells and viral particles have been cultured. Baggish et al.[27],[28] have also demonstrated in vitro that human immunodeficiency virus proviral DNA was present in the laser smoke and collected in the evacuation tubing in their laboratory study. Wearing a surgical mask and using high-speed evacuation is essential for infection control, but the standard dental surgical mask does not filter out particles <0.5 pm.
A new generation of laser surgical masks is now available that will filter to 0.1-pm particles. There are also evacuation systems with filtration for submicron particles that will increase the safety of laser use for biohazards waste.[29]
The ad hoc Committee for the American Society for Laser Medicine and Surgery gives the following guidelines concerning hazards of laser plume:
- All laser personnel should consider the laser plume tube potentially hazardous both in terms of the particulate matter and infectivity
- Eva cuator suction systems with high-flow volume and frequent filter changes should be used at all times to collect the plume; the suction tip should be held within 2–5 comfy, the laser impact
- Eye protection, masks, gloves, and gowns should be always worn during laser use by all personnel, ensuring that the eyewear protects from splatter, the mask should have good effective filtration, and the gloves should preferably be latex.[30]
Laser safety should also include the protection of tooth structure adjacent to the impact site. As mentioned previously in this review, the effects of laser irradiation on enamel or root surfaces can be detrimental when the focused mode is used for soft-tissue ablation. Placing a periodontal retractor between the tooth and gingival while attempting to hit the surface at a 90° angle will afford the best protection during soft-tissue removal.[31]
| Materials and Methods | | |
A study carried on 15 dentists and they aside to answer a questionnaire of the following questions about laser
- When did you graduate from the college? From
a) 1–5 years b) 6–10 years c) 11–15 years d) More than 15 years
- Which university did you graduated from?
a) Cairo b) Ain Shams c) Private d) Other
- Do you know about laser in dentistry?
a) Yes b) No
- How do you know about laser?
a) Postgraduate b) Course c) Internet d) From friend
- Do you want to complete your postgraduate study or take a course in laser?
a) Yes b) No c) I do not know
- When was laser introduced in the medical applications of dentistry?
a) 1960–1970 b) 1970–1990 c) 1991–2000 d) 2001 till now
- How many dentists do you know that have laser devices at their clinics in Egypt?
a) 1–5 b) 6–10 c) 10–20 d) more than 20
- What do you think about laser device market in Egypt?
a) Great b) Good c) Acceptable d) Bad
- Where can you buy a good laser device?
a) China b) America c) Europe d) Other
- Which type of laser device do you prefer?
a) Er:YAG b) Diode c) Nd:YAG d) co 2
- How much is the laser device?
a) 2000–3000$ b) 3000–4000$ c) 5000–10000$ d) More than 10000$
- What is the most field in dentistry that you use laser in?
a) Surgery b) Endodontic c) Operative d) Periodontology
- How many patients did you treat by laser?
a) Zero b) 1–5 c) 6–10 d) 11–15
- How is the cost when you make a treatment by laser?
a) Acceptable b) Expensive c) Cheap
- How long is the appointment take time?
a) 15 min b) 15–30 min c) 30—35 min d) More than 1 h
- Which type of treatment do you prefer?
a) Laser b) Alternative c) Combined
- Comparing to traditional method, laser treatment is
a) Efficient b) Not efficient c) No difference
- The maintenance of device is every
a) Month b) 3–6 months c) 6–9 months d) 1 year
- The spare parts of device are
a) Available b) Not available c) Hard to gain
- Do you need special preparation when you use laser?
a) Yes b) No
- What is the organ of the body that mostly affected?
a) Skin b) Eye c) Hair d) Other
- What are the safeties that you should have when you use laser?
a) Eye protectors b) Skin protectors
| Results | | |
The answers of the questionnaire are mentioned in one table [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10], [Table 11], [Table 12], [Table 13], [Table 14], [Table 15], [Table 16], [Table 17], [Table 18], [Table 19], [Table 20], [Table 21], [Table 22], [Table 23] and [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15], [Figure 16], [Figure 17], [Figure 18], [Figure 19], [Figure 20], [Figure 21], [Figure 22], [Figure 23]. | Table 1: Results, the answers, are collected in the following table and then each question will discuss briefly
Click here to view |
 | Table 6: Q5. Do you want to complete your postgraduate study or take a course in laser?
Click here to view |
 | Table 7: Q6. When was laser introduced in medical applications of dentistry?
Click here to view |
 | Table 8: Q7. How many dentists do you know that have laser devices at their clinics in Egypt?
Click here to view |
 | Table 13: Q12. What is the most field in dentistry that you use laser in?
Click here to view |
 | Table 23: Q22. What are the safeties that you should have when you use laser?
Click here to view |
| Discussion | | |
The purpose of this study is to obtain knowledge of dentists about laser in dentistry. Fifteen dentists have answered 22 questions regarding to laser in dentistry.
About 85% of dentists are graduated in the past 10 years, and according to the study, they want to use laser in treatment.
Concerning to the third question, all dentists know about laser in dentistry and this is a good point. As they know from postgraduate studies and there are about 67% want to complete their study in laser, this refers to a great desire in learning about laser.
Analysis the question of the most field that laser used in dentistry we found that periodontology and surgery are the and most field that laser used in, this prove that surgery. periodontology will depend on laser
The questionnaire [13],[14] that about the patient mentality, a few patients was treated by laser and this may be according to patient mentality or the cost of treatment as it is. (expensive (93.33% according to questionnaire.
When we talk about the preferred type of treatment, we found that the combined method is the favorable method; this will take us to that laser and alternative method are complementary.
The part of questionnaire that about maintenance of device and its spare parts, unfortunately, spare parts are hard to make dentists have a cautious from buying a laser device.
The cost of the device is in the range of 3000–10000$; this makes a problem to dentist as it is expensive.
According to the question of safety, most of dentists know that laser is harmful to the patients and precautions should take to protect dentist and patient.
| Conclusion | | |
- Fresh graduate dentists have enthusiasm to use in treatment in dentistry as they think that it is the future of dentistry
- Surgery and periodontology are the most field uses laser till now
- There is a few or little knowledge about laser in dentistry, and the most of dentists have short knowledge about laser
- Most of dentists have a great fear of safety as it may be insufficient, especially in dental office and thus may cause harmful and have bad effect on eye and skin
- Dentists have no enough motivation as they think that laser device in comparison with its limited uses in dental clinic is expensive and also spare parts are hard to gain or not available.
Finally, this study will help in knowing about laser, its market, and importance of laser in dentistry.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15], [Figure 16], [Figure 17], [Figure 18], [Figure 19], [Figure 20], [Figure 21], [Figure 22], [Figure 23]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10], [Table 11], [Table 12], [Table 13], [Table 14], [Table 15], [Table 16], [Table 17], [Table 18], [Table 19], [Table 20], [Table 21], [Table 22], [Table 23]
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