**1. Introduction**

#### **1.1. Review of laser physics and tissue interaction**

LASER is an acronym for light amplification by stimulated emission of radiation, which is based on theories and principles first put forth by Einstein in the early 1900s [1]. Laser light has a single wavelength. The production of lasing occurs when an excited atom is stimulated to release a photon before it occurs spontaneously. The spontaneous emission results in random light waves alike to light emitted by a light bulb [2]. The stimulated emission of photons

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

produces a very coherent, collimated, and monochromatic radiation that is found nowhere else in nature [3]. Because laser radiation is so concentrated and focused, it may have an effect on target tissue at a much lower energy level than the other light sources [4]. The effects of laser radiation on the target tissue are dependent on its wavelength, power, and spot size

which is determined by the laser device [5]. If the laser radiation comes into contact with the tissue, it can reflect, scatter, absorbed, or be transmitted to the other surrounding tissues. In the biological tissue, the absorption of laser radiation occurs because of the presence of free water molecules, proteins, pigments, and even other organic matters [6, 7]. Thermal interactions caused by the laser radiation, the water molecules, and their absorption coefficient perform a strong role [1]. Laser beams (*Er,Cr:YSGG*, *Er:YAG*) are well absorbed by water which are able to mechanically ablate enamel, dentin, and alveolar bone, while laser beams (*diode*,

The first investigation of using the laser in dentistry was within the surrounding hard tissue, such as cavity preparation and caries removal as a replacement for the conventional drill. The ruby laser that was the focus of this investigation was invented in 1960 [10]. In succeeding years, many researchers examined the hard-tissue applications of the laser by using different types of

to enamel and dentin [11], while other researchers concentrated their attention on the laser applications on soft tissue of these early generation high-powered lasers. It was determined that

[12]. These studies enabled the periodontists to use these lasers for soft-tissue treatment, such as gingivectomies and frenectomies [13, 14]. Despite, these early studies profound a thermal effect on target tissues, including gingiva, periodontal ligament, cementum, and alveolar bone, that their using for periodontal hard tissue was not promising. Within the 1990s, the Nd:YAG laser was included that had a flexible and fiber-optic delivery system, which made it appropriate for periodontal pocket, including the root surface debridement and pocket curettage [15, 16].

Researchers concluded that the Er:YAG laser, which is highly absorbed by water and hydroxyapatite, had an effect in enamel cutting [17, 18]. Subsequently, Eversole and others published numerous distinguished researches on the Er,Cr:YSGG laser and its effectiveness in soft tissue application (enamel, dentin, and bone), which all play a significant performance in periodon-

Because of this versatility, the Er,Cr:YSGG laser was the first all-in-one laser that made an economics of providing a laser treatment and more feasible for the periodontist and general practitioner [21]. Over the time, the collective research has resulted in a laser that has a real and beneficial application for periodontal care. Laser types, wavelengths, and their applica-

One of the main difficulties of all starting dental laser using is the depth of penetration of laser to the tissue and its effects on the principal constituents of the tissue. In order to clarify

and the Nd:YAG lasers were capable of excellent soft tissue ablation and hemostasis

carbonization, charring, and melting of organic tissue [8, 9].

**1.2. Review of modern laser technology accessible in dentistry**

**2. Dental laser systems and the basics of the work**

**2.1. Basic processes of laser radiation and tissue interaction**

) are not well absorbed by water, resulting in strong thermal reactions, such as

Laser Dental Treatment Techniques http://dx.doi.org/10.5772/intechopen.80029 19

, and Nd:YAG. However, some studies resulted in major thermal damage

*Nd:YAG*, *CO2*

lasers such as Ar, CO<sup>2</sup>

the CO<sup>2</sup>

tal [19, 20].

tions are listed in **Table 1**.


**Table 1.** Lasers types, wavelengths, and their dental applications.

which is determined by the laser device [5]. If the laser radiation comes into contact with the tissue, it can reflect, scatter, absorbed, or be transmitted to the other surrounding tissues. In the biological tissue, the absorption of laser radiation occurs because of the presence of free water molecules, proteins, pigments, and even other organic matters [6, 7]. Thermal interactions caused by the laser radiation, the water molecules, and their absorption coefficient perform a strong role [1]. Laser beams (*Er,Cr:YSGG*, *Er:YAG*) are well absorbed by water which are able to mechanically ablate enamel, dentin, and alveolar bone, while laser beams (*diode*, *Nd:YAG*, *CO2* ) are not well absorbed by water, resulting in strong thermal reactions, such as carbonization, charring, and melting of organic tissue [8, 9].

## **1.2. Review of modern laser technology accessible in dentistry**

produces a very coherent, collimated, and monochromatic radiation that is found nowhere else in nature [3]. Because laser radiation is so concentrated and focused, it may have an effect on target tissue at a much lower energy level than the other light sources [4]. The effects of laser radiation on the target tissue are dependent on its wavelength, power, and spot size

1. Soft tissue ablation

8. Caries removal

13. Caries removal 14. Cavity preparation

11. Root canal preparation

16. Root canal preparation

ulcers or herpetic lesions 21. Frenectomy and gingivectomy

oral lesions or surgical wounds 23. Frenectomy and gingivectomy

18. Tooth bleaching

purposes

26. Treatment of oral lesions 27. Frenectomy and gingivectomy

2. Gingival contouring for esthetic purposes 3. Treatment of oral ulcerative lesions 4. Frenectomy and gingivectomy

erative periodontal surgeries

5. Elimination of necrotic epithelial tissue during regen-

microorganisms and debris from the root canal 7. Extensive periodontal surgery and scaling to eliminate necrotic tissues and pathogenic microorganisms

15. Bone ablation without overheating, melting, or chang-

19. Elimination of necrotic tissue and gingival contouring 20. Treatment of oral lesions such as recurrent aphthous

22. Proliferation of fibroblasts and enhancing the healing of

24. Correcting the gingival contouring for esthetic

10. Cavity preparation in enamel and dentin

ing the calcium and phosphorus ratios

17. Polymerization of restorative resin materials

**Laser type Wavelengths Delivery systems Applications**

Er:YAG 2940 nm Pulse 9. Caries removal

Er,Cr:YSGG 2780 nm Pulse 12. Enamel etching

continuous wave

continuous wave

HO:YAG 2100 nm Pulse 25. Gingival contouring

**Table 1.** Lasers types, wavelengths, and their dental applications.

continuous wave

Nd:YAG 1064 nm Pulse 6. Root canal therapy: helps eliminate pathogenic

CO<sup>2</sup> 10,600 nm Pulse or

18 Prevention, Detection and Management of Oral Cancer

Argon 572 nm Pulse or

Diode 810–980 nm Pulse or

The first investigation of using the laser in dentistry was within the surrounding hard tissue, such as cavity preparation and caries removal as a replacement for the conventional drill. The ruby laser that was the focus of this investigation was invented in 1960 [10]. In succeeding years, many researchers examined the hard-tissue applications of the laser by using different types of lasers such as Ar, CO<sup>2</sup> , and Nd:YAG. However, some studies resulted in major thermal damage to enamel and dentin [11], while other researchers concentrated their attention on the laser applications on soft tissue of these early generation high-powered lasers. It was determined that the CO<sup>2</sup> and the Nd:YAG lasers were capable of excellent soft tissue ablation and hemostasis [12]. These studies enabled the periodontists to use these lasers for soft-tissue treatment, such as gingivectomies and frenectomies [13, 14]. Despite, these early studies profound a thermal effect on target tissues, including gingiva, periodontal ligament, cementum, and alveolar bone, that their using for periodontal hard tissue was not promising. Within the 1990s, the Nd:YAG laser was included that had a flexible and fiber-optic delivery system, which made it appropriate for periodontal pocket, including the root surface debridement and pocket curettage [15, 16].

Researchers concluded that the Er:YAG laser, which is highly absorbed by water and hydroxyapatite, had an effect in enamel cutting [17, 18]. Subsequently, Eversole and others published numerous distinguished researches on the Er,Cr:YSGG laser and its effectiveness in soft tissue application (enamel, dentin, and bone), which all play a significant performance in periodontal [19, 20].

Because of this versatility, the Er,Cr:YSGG laser was the first all-in-one laser that made an economics of providing a laser treatment and more feasible for the periodontist and general practitioner [21]. Over the time, the collective research has resulted in a laser that has a real and beneficial application for periodontal care. Laser types, wavelengths, and their applications are listed in **Table 1**.
