JCDP Zahed Mohammadi et al 10.5005/jp-journals-10024-2010 REVIEW ARTICLE Lasers in Apicoectomy: A Brief Review 1,2Zahed Mohammadi, 3Hamid Jafarzadeh, 4Sousan Shalavi, 5Jun-Ichiro Kinoshita, 6Luciano Giardino ABSTRACT the emission of identical photons from atoms that have 1 2 Since the invention of laser, various applications for lasers in been excited. Ladenburg in 1928 showed some indi- endodontics have been proposed, such as disinfection of the rect documents for the process of stimulated emission. root canal system, canal shaping, pulp diagnosis, and apico- Fabrikant3 in 1940 proposed that stimulated emission in ectomy. One of the major applications of laser in endodontics gas discharge may have the ability of amplifying the light is apicoectomy. The aim of this article is to review the benefits under suitable conditions. However, the weak point of and drawbacks of laser applications in apicoectomy, including effect on apical seal, effect on dentin permeability, effect on this study was no long-term follow-up. After the Second postsurgery pain, effect on crack formation, effect on root-end World War, Lamb and Retherford4 showed that nuclear morphology, effect on treatment outcome, and connective tissue magnetic resonance may produce population inversions. response to laser-treated dentin. Furthermore, the stimulated emission of radio waves was Keywords: Apical seal, Apicoectomy, Dentin permeability, shown by Purcell and Pound.5 Laser, Treatment outcome. The first laser was produced by Maiman6 by excitation How to cite this article: Mohammadi Z, Jafarzadeh H, Shalavi S, of a ruby rod with intense pulses of the light from a flash Kinoshita J-I, Giardino L. Lasers in Apicoectomy: A Brief Review. lamp. The first actual generating laser (633 nm) was built J Contemp Dent Pract 2017;18(2):170-173. using a combination of helium and neon.7 Source of support: Nil Potential uses of the ruby laser in dentistry were 8 Conflict of interest: None investigated for the first time by Stern and Sognaes and Goldman et al.9 As the initial studies were done with ruby INTRODUCTION laser, some clinicians started using other lasers including carbon dioxide (CO ; 10,600 nm), argon (Ar; 514 nm), In 1916, a German-born theoretical physicist, Albert 2 neodymium:yttrium-aluminum-garnet (Nd:YAG; 1,064 Einstein stated that photons have the ability of stimulating nm), and erbium (Er):YAG (2,940 nm).10 In the discipline of endodontics, for the first time Weichman and Johnson11 1Iranian Center for Endodontic Research, Research Institute in an in vitro study used a high power-infrared (CO2) of Dental Sciences, Shahid Beheshti University of Medical laser to help to get a better seal in the apical foramen Sciences, Tehran, Islamic Republic of Iran area. Subsequently, attempts were made to seal the apical 2Iranian National Elite Foundation, Tehran, Islamic Republic foramen using the Nd:YAG laser. of Iran 3Department of Endodontics, Faculty of Dentistry, Mashhad LASER’S CHARACTERISTICS University of Medical Sciences, Mashhad, Islamic Republic of Iran Light amplification by stimulated emission of radiation is 4General Dentist, Hamedan, Islamic Republic of Iran abbreviated to LASER. Laser light is a man-made single 1 5Department of Conservative Dentistry, Showa University Dental photon wavelength. According to Einstein, when an Hospital, Tokyo, Japan excited atom is stimulated to emit a photon before the 12 6Private Practice, Crotone, Italy process occurs spontaneously, the lasing process occurs. Spontaneous emission of a photon by one atom stimulates Corresponding Author: Hamid Jafarzadeh, Department of Endodontics, Faculty of Dentistry, Mashhad University the release of a subsequent photon, and so on. Laser is of Medical Sciences, Mashhad, Islamic Republic of Iran a single wavelength (monochromatic), collimated (very Phone: +985138829501, e-mail: [email protected]/ low divergence), and coherent (photons in phase) light. [email protected] Wavelength of the emitted photon depends on the state 170 JCDP Lasers in Apicoectomy: A Brief Review of the electron’s energy when the photon is released. produced some thermal damage. Relatively large spaces When the states of electrons of two identical atoms are between canal walls and gutta-percha were showed after identical, wavelengths of released photons are identical. Ho:YAG laser irradiation. 13 20 The characteristics of a laser depend on its wavelength. Moritz et al studied the CO2 laser effect in apical Wavelengths emitted at the ultraviolet portion of the surgery using color penetration tests and SEM. The root electromagnetic spectrum seem to be promising in end- canals and sections were irradiated with 0.5 W low power odontic therapy. It seems that the most appropriate laser in continuous wave mode for 20 seconds. Infrared spec- to slow selective removal of necrotic debris from the root troscopy showed that thermal stress for adjacent tissues canal and to leave smooth, crack-free, and fissure-free was moderate. Comparison with nonirradiated surfaces melted dentin walls are the ArF excimer laser (193 nm). showed that CO2 laser decreased color penetration at Further, the XeCl excimer laser (308 nm) can melt dentin the section. Furthermore, irradiation of the canal wall and close dentinal tubules.10,11,13 resulted in acceptable surface sealing. These results were Laser photons interact with tissue in four ways: They approved by SEM examination. Arens et al21 revealed that are transmitted through tissue, scattered within tissue, apicoectomy with laser may reduce the dentinal tubule reflected from tissue, or absorbed by tissue. Absorption of permeability. Application of Nd:YAG laser has been also laser beams by the tissues is mainly due to the presence of shown to have the ability of reduction in permeability of free water molecules, proteins, and pigments. The absorp- resected roots.22 tion coefficient strongly depends on the wavelength of the incoming laser. Absorption by water molecules plays CONNECTIVE TISSUE RESPONSE TO a significant role in thermal interactions. The absorption LASER-TREATED DENTIN coefficient for water is 0.020 for diode laser (800 nm), Maillet et al23 assessed the connective tissue response over 0.00029 for argon laser (514 nm), 860 for CO laser (10,600 2 time to implanted root segments with bur-cut or Nd:YAG nm), 12,000 for Er:YAG (2,940 nm), and 0.61 for Nd:YAG laser-cut surfaces. Results showed that tissue repair about (1,064 nm).14 the root surfaces resected with Nd:YAG laser was delayed EFFECT ON APICAL SEAL when compared with those resected with a bur. Marques et al15 assessed the influence of parameters of EFFECT ON POSTSURGICAL PAIN the Er:YAG laser on the apical sealing of apicectomized teeth. Findings revealed that the apicectomies carried Payer et al24 showed that low-level laser therapy had no out with 400 mJ/6 Hz showed the smallest infiltration significant effect on postsurgery pain. In a double-blind value. Karlovic et al16 showed that cavities prepared with randomized clinical trial, Kreisler et al25 evaluated the Er:YAG laser have significantly lower micro leakage for effect of low-level laser application on postoperative all tested materials. Wong et al17 compared the apical pain after endodontic surgery and found that it can be seals achieved using retrograde amalgam fillings or the beneficial for the reduction of postoperative pain. Nd:YAG laser. They reported that no statistically signifi- cant difference was found in bacterial leakage between EFFECT ON CRACK CREATION the laser-treated group and the retrograde amalgam Aydemir et al26 evaluated cracks on root end following group. resection and cavity preparation with a laser and two established techniques. They concluded that laser resec- EFFECT ON DENTIN PERMEABILITY tion and root-end preparation technique cannot affect the 18 27 According to Gouw-Soares et al, CO2 and Er:YAG lasers number of cracks formed on surfaces. Camargo Villela used for root-end resection and dentin surface treatment showed that ErCr:YSGG laser caused no crack on the showed a decrease in permeability to methylene blue. apical root surface. Rahimi et al28 compared the effect of Komori et al19 used different types of lasers [Er:YAG, Waterlase laser and ultrasonic root-end cavity preparation holmium:YAG (Ho:YAG) laser, and CO2 laser] on resected on the integrity of root end and showed no significant roots of extracted human teeth to investigate the clinical difference in crack formation. Batista de Faria-Junior et application of lasers on hard tissue. After resection by al29 evaluated the time required and quality of retrograde these techniques, morphological changes in the resected cavity preparations using ultrasonics or ErCr:YSGG laser surface were studied by both optical microscope and scan- and found that ultrasonics as better than laser. Wallace30 ning electron microscope (SEM). These studies have con- showed that Waterlase laser may induce no crack or even cluded that Er:YAG laser induced smooth clean surfaces very low percentage of cracks when used for root-end without thermal damage signs. Ho:YAG laser, however, cavity preparation. The Journal of Contemporary Dental Practice, Febuary 2017;18(2):170-173 171 Zahed Mohammadi et al EFFECT ON ROOT END MORPHOLOGY 10. Sulewski JG. Historical survey of laser dentistry. Dent Clin North Am 2000 Oct;44(4):717-752. 31 deMoura et al using Zekryaburs or Er:YAG laser, with 11. Weichman JA, Johnson FM. Laser use in endodontics. A pre- or without subsequent direct Nd:YAG laser irradiation liminary investigation. Oral Surg Oral Med Oral Pathol 1971 (apical and buccal surfaces) and indirect irradiation Mar;31(3):416-420. (palatal surface) showed that there were no differences 12. Aoki A, Sasaki KM, Watanabe H, Ishikawa I. Lasers in nonsurgical periodontal therapy. Periodontology 2000 2004 in cut quality between Er:YAG laser and burs or between Aug;36:59-97. two surfaces treated with Nd:YAG with direct irradiation.