N L Y A L S O N F E S SI O O R T A L P N E D PUBLISHED IN DUBAI www.dental-tribune.me March-April 2021 | No. 2, Vol. 11 Reducing microleakage with Er,Cr:YSGG and/or Nd:YAG lasers An evaluation By Drs Mina Mazandarani, Maziar Mir & Masoud Shabani, Iran; Prof. Norbert Gutknecht, Germany Introduction In endodontics, effective cleaning of the root canal system is essential for ensuring successful root canal therapy with long-lasting treatment outcomes.1–3 During endodontic instrumentation, various morpho- logical changes occur on the root canal walls, including organic and mineral debris4–7 and smear layer formation.2,4,7 Therefore, not only are conventional cleaning and re- moval of debris and the smear layer important steps in endodontic pro- cedures,1,2 but chemical irrigation is strictly recommended for use in conjunction with mechanical in- strumentation in order to dissolve debris and the smear layer.8,9 In fact, the methods employed to clean and shape root canal spaces create a smear layer, which may harbour microorganisms that ultimately re- sult in periapical pathosis.3,7 Many irrigant solutions, such as sodium hypochlorite and ethylenediami- netetraacetic acid (EDTA), are used. Sodium hypochlorite is effective in removing organic tissue remnants,8 while EDTA is effective in removing the inorganic portion of the smear layer.9 However, both irrigants are unable to remove the smear layer ef- fectively.1,3,10 A successful root canal therapy is based on a number of factors: reduc- tion of microorganisms to the mini- mum, sufficient and proper root canal instrumentation and disin- fection, as well as well-adapted root canal obturation.11 A crucial disad- vantage of irrigant solutions is that their bactericidal effect is limited to the main root canal. Because of the narrow diameter of the dentinal tu- bules and the high surface tension of the liquid solutions, they are able to penetrate only a small distance into the tubules. The penetration depth of chemical disinfection only reaches 100µm into the adjacent dentinal tubules.12,13 However, the bacteria can penetrate over 1,000µm from the canal lumen,12 as described by Kouchi et al.14 and Ando & Ho- shino.15 Therefore these bacteria are protected in the deeper layers of den- tine. In this protected area, we find Gram-negative bacteria, which are characterised by their unusual mi- gration qualities and their resistance to chemical irrigant solutions. They maintain their virulence against con- ventional endodontic techniques. And we find that, from this bacterial reservoir, the bacteria will spread to the periapical areas of the tooth, causing inflammation and infec- tion.12 Since conventional root canal therapy is not always successful, new methods could perhaps enhance the long-term prognosis and overcome the short- comings of conventional instrumentation methods.11 Today, lasers are used in endodontics to dramatically improve the progno- sis of root-filled teeth.12 Laser irradia- tion produces different effects on the same tissue, and the same laser can produce various effects in different tisues. Er:YAG and Er,Cr:YSGG lasers have been reported to ablate dental hard tissue16–21 with minimum in- jury to the pulp and surrounding tissue.17–19,22–25 The Er:YAG laser has been reported to ablate enamel and dentine effectively, because of its highly efficient absorption in both water and hydroxyapatite,16,20,21 and the Er,Cr:YSGG laser, which uses a pulsed beam system, fibre delivery and a sapphire tip bathed in a mix- ture of air and water vapour, has been shown to be effective for cut- ting enamel, dentine18,20 and bone.18 Moreover, this specific property, ÿPage A2 AD RECIPROCATION RECIPROCATION RECIPROCATION REDEFINED REDEFINED REDEFINED THE THE RACE ACE LEGACY LEGACY SAFE. EFFICIENT. SOFT CONTROL. SAFE. EASY. MINIMALLY INVASIVE. www.fkg.ch/race-evo www.fkg.ch/r-motion