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Dental Tribune Middle East & Africa Edition | 1/2017 ENDO TRIBUNE A3 LaserEnhancedEndodonticTreatment ByDrGregoriM.Kurtzman,USA Endodontic success is predicated on the ability to debride and clean the canal system. That canal system is a complex array of accessory and lat- eralcanals,finsandotheranatomical areasinaccessibletoendodonticfiles. (Figure1)Aspractitioners,weareable to clean the main canals with files, either hand or rotary. But can not mechanically remove pulpal tissue and debris from the canal anatomy present adjacent to the main canals. Treatment success requires elimina- tion of the pulpal tissue and associ- ated bacteria from this anatomy, so that it can be sealed during the ob- turation phase of treatment. As only one thing can occupy a space at a time, obturation material can not fill areas still occupied by pulpal tissue. Success is dependant on disinfection and debridement of the canal sys- tem so that it may be sealed during obturation. Irrigation has long been accepted as a key factor of treatment toachievethosegoals. Yet, complete clearing of residual bacteria especially in the apical por- tion of the canal system has been difficult to achieve with traditional methods using even sodium hy- pochlorite(NaOCL)solutions.(Figure 2) Studies have demonstrated that addition of an Er:YAG laser to acti- vate the irrigation solution greatly enhances not only the efficiency of the irrigation solutions advocated (NaOCLandEDTA)butalsoimproves disinfection of the canal system, clearing accessory so that it may be sealedduringobturation.(Figure3,4) Irrigationthekey toEndodonticsuccess Although,instrumentationwithfiles is important to enlarging the canals and ready them to be obturated, de- bris consisting of pulpal tissue and associated bacteria is not effectively removed by files. Irrigation with an appropriate solution is required to remove that debris from the canal walls. NaOCL is still the accepted irri- gantduetoitstissuedissolvingabili- tyandantibacterialnature.Yet,itcan not effectively reach far beyond the main canals to remove the residual tissue. Tissue dissolution can be en- hanced to more effectively remove pulpal tissue/bacteria and also reach further into the accessory anatomy to allow better sealing of the canal system improving treatment suc- cess. Smear layer within the canal system plays a factor in success in endodon- tic treatment. The smear layer con- tainsbacteriawhichwhenleftwithin the canal anatomy may lead to re- occurrence of infection endodonti- cally. When compared to traditional irrigation methods, laser enhanced irrigation has demonstrated better intracanal smear layer removal.1 As Enterococcus faecalis has been rou- tinely linked to endodontic failures, and is a common occupant of the oral cavity, elimination of this bacte- riaiscriticaltopreventionofreinfec- tionofthecanalsystem.NaOCLasan irriganthasnotshowntobeeffective ineliminationofE.faecalis,yetwhen combined with laser enhanced ir- rigation with NaOCL this bacteria has been eliminated in the canal anatomy.2 Laserenhancedirrigation Laser energy has been documented to enhance the known effects of NaOCL irrigation through both heat- ing the solution within the canal system and its distant antibacterial effects. But not all laser wavelengths have demonstrated to be equal in ef- fectiveness.Thebesteffectsarewhen NaOCL is combined with an Er:YAG laser as compared to NaOCL alone or whenutilizedwithothertypelasers.3 Antibacterial effects were reported to be the best with this combina- tion of irrigant and laser.4 The higher wavelength of the Er:YAG compared to the Nd:YAG or diode was more effective in smear layer removal, hence better at bacterial elimination within the canal system.5 Utilization of a EDTA as an irrigant alternated with NaOCL provides the best de- bridement of the canal system with enhancement with a Er:YAG laser, as these two solutions have a synergis- ticeffectcomplimentingeachothers effectsinthecanalanatomy.6 Additionally, the Er:YAG laser (Lite- Touch™, distributed in USA by AMD LASERS, Indianapolis, IN) creates hydrodynamic pressure following cavitation bubble expansion and collapsewhentheirrigationsolution is activated in the chamber.7-9 Place- mentofthelasertipdoesnotrequire entry into the canals to achieve the desired effects and activation of the irrigation solution in the chamber is sufficient to affect the entire canal system.TheLiteTouch™Er:YAGlaser energy is set at a sub-ablative power level which allows its use without structural changes to the hard tissue within the tooth. This eliminates the risks of ledging and perforation of the pulpal floor allowing safe usage withinthetooth. When the Er:YAG laser is activated a heat pulse is generated by the laser radiation delivered via a sapphire tip into an absorbing liquid (irrigant). Thisresultsintensilestresswithcav- itation being induced in the liquid in frontofthesapphiretipatadistance far below the optical penetration depth of the laser radiation. Bubble expansion and collapse cause the surrounding fluid to flow at a speed of up to 12 m/s traveling throughout the canal system. This causes rapid displacement of intra-canal fluid via radial and longitudinal pressures sufficient to drive irrigant into the canal anatomy and clean the dentin- al tubules significantly. This photo- mechanical activation of the irrigant includes a temperature rise in the irrigant increasing its effectiveness indebridementofdentinalwallsand its tubules and increases the chemi- calpropertiesoftheirrigants. LiteTouch™Induced Photomechanical Irrigation (LT-IPI™) Endodontic treatment is initiated with access to the pulp chamber, which may be performed by tra- ditional methods using burs or by ablation of the enamel and dentin with the LiteTouch™ Er:YAG laser. As the laser is ineffective in removal of ceramics and metals, such as those used in fixed prosthetics and also amalgam, carbides and diamonds are needed create access through these materials. Once dentin has been reached the laser may be uti- lized to unroof the pulp chamber (hard tissue mode). An additional benefit of the Er:YAG laser to ac- cess the pulp chamber is it provides decontamination and removal of bacterial debris and pulpal tissue to yield a cleaner chamber aiding it identification of the canal orifices (softtissuemode). Once the canal orifices are identified, hand files are utilized to establish a glide path to the apical working length in each canal. Canals are then enlarged to the desired ISO canal size with either hand or rotary files. (Figure 5A) Laser-assisted canal irri- gation requires canal preparation to an apical preparation ISO 25/30 at a minimum. A canal taper of 0.04 or 0.06 for the final instrumentation is recommended. Sodium hypochlo- rite (NaOCL) is utilized within the chamber and canals during instru- mentation both as a pulpal tissue dissolvent and to lubricate the files within the canal, decreasing the po- tential of file separation that can oc- cur when instrumenting a dry canal. (Figure5B) Photo-activationoftheirrigantwith- in the canal system is performed using the Er:YAG laser with a 0.4/17 or 0.6/17mm tip which assists in re- moval of the debris created by the files. Between each rotary file, the chamber is filled with NaOCL and the tip of the laser is placed into the chamber and the solution activated with the laser at 40mJ at 10Hz with anaveragepowerofonly0.5Wfor20 seconds. (Figure 5C) The chamber is suctioned and fresh NaOCL is placed into the tooth and the next file is used for instrumentation. It is un- necessary to place the lasers tip into the canals themselves, as activation of the solution within the chamber transmits down the irrigant into the canals to the apical aspect of the roots. Laser activation may also be performed with 17% EDTA solution alternated with NaOCL. The benefit of EDTA solution is its chelation ef- fect opening canal anatomy so that the next round of NaOCL can reach more pulpal tissue not accessible to the files in fins, as well as accessory and lateral canals. Following final instrumentation of the canals with rotaryfiles,thechamberisfilledwith NaOCL and the Er:YAG tip is placed into the chamber again and acti- vated for a minimum of 60 seconds. This allows the photo-activated ir- rigant to clear debris and remaining pulpal tissue from the complete ca- nal system. The irrigation solution Figure 1: Anatomy of the canal system demonstrating accessory canals, fins and lateral canals which are not accessible with endodontic files as shown in cleared teeth. Figure 2: SEM showing bacteria and pul- pal debris in the apical 1/3 that was not removed fully using standard irrigation protocol. (Courtesy Prof. Georgi Tomov, Plodiv,Bulgaria) Figure 3: SEM showing complete removal of bacteria and pulpal tissue in the apical 1/3 after irrigation using the LT-IPI™ pro- tocol.(CourtesyProf.GeorgiTomov,Plodiv, Bulgaria) Figure 4: SEM cross-section showing complete removal of bacteria and pulpal tissue in the apical 1/3 after irrigation us- ing the LT-IPI™ protocol leaving dentin tu- bules open. (Courtesy Prof. Georgi Tomov, Plodiv,Bulgaria) is suctioned from the chamber and fresh ir- rigant placed and pho- to-activation repeated until no visible debris (cloudiness) is noted in the chamber fluid. This indicated that all acces- sible debris has been re- moved from the canal system. Any remaining solution is suctioned from the tooth and the canalsaredriedwithpa- per points. Obturation is then accomplished using the practitioners preferred method and materials allowing ob- turation of anatomy in- Figure 5: LiteTouch™ Induced Photomechanical Irrigation protocol (LT-IPI™): Establish- ment of glide path with hand files (A), Canal and chamber filled with NaOCL (B) and Placement of the LiteTouch™ tip into the irrigant in the chamber and activation of the Er:YAGlaser.(Illustrations:courtesyofDrParvanVoynov,Plodiv,Bulgaria) Figure 6: Accessory anat- omy evident in the apical that has been filled with sealer accessible due to use of the LiteTouch™ Er:YAG laser. (Photo cour- tesy of Dr. David Guex, Lyon,France) Figure 7: Accessory api- cal anatomy filled with sealer due to use of the LiteTouch™ Er:YAG laser. (Photo courtesy of Prof. GeorgiTomov, Plodiv, Bul- garia) accessible by instrumentation with files.(Figure6,7) Conclusion The key to Endodontic success is two pronged, cleaning the system and sealing it. Although, rotary files have improved the efficiency of in- strumentation they are unable to reach any more of the anatomy that handfiles are able to reach. Cleaning ofthecanalsystemiskeyedtoirriga- tion of the canal system to improve debris removal in anatomy that the files are unable to contact. When anatomyisnotfullycleanedsealeris unable to fill this leaving bacteria to inhabit those areas which may lead to endodontic failure over time. La- ser enhanced activation of endodon- tic irrigants cleans more anatomy adjacent to the main canals so that a more complete obturation of the ca- nal system can occur. An added ben- efitisthelaserhasanantibacterialef- fect, killing bacteria within the canal anatomy as well as distant to where the irrigation solution may reach es- sentially sterilizing the entire tooth totheperiodontalligament. References 1. Takeda FH, Harashima T, Kimura Y, Matsumoto K.: A comparative study of the removal of smear layer by three endodontic irrigants and two types of laser. Int Endod J. 1999 Jan;32(1):32-9. 2. Meire MA, Coenye T, Nelis HJ, De Moor RJ.: Evaluation of Nd:YAG and Er:YAGirradiation,antibacterialpho- todynamic therapy and sodium hy- pochlorite treatment on Enterococ- cusfaecalisbiofilms.IntEndodJ.2012 May;45(5):482-91. doi: 10.1111/j.1365- 2591.2011.02000.x.Epub2012Jan14. 3. Asnaashari M, Safavi N.: Disinfec- tion of Contaminated Canals by Dif- ferent Laser Wavelengths, while Per- forming Root Canal Therapy. J Lasers MedSci.2013Winter;4(1):8-16. The full list of references is available fromthepublisher. Dr. Kurtzman is in pri- vate general practice in Silver Spring, Maryland and a former Assistant ClinicalProfessoratUni- versity of Maryland and a former AAID Implant Maxi-Course. Assistant program director at Howard University College of Dentistry. He has lectured internationally on the topics of Restorative dentistry, Endodontics and Implantsurgeryandprosthetics,removable and fixed prosthetics, Periodontics and has over 510 published articles. He has earned Fellowship in the AGD, AAIP, ACD, ICOI, PierreFauchard,ADI,MastershipintheAGD and ICOI and Diplomat status in the ICOI and American Dental Implant Association (ADIA). Dr. Kurtzman has been honored to be included in the “Top Leaders in Continu- ing Education”by DentistryToday annually since 2006 and was featured on their June 2012cover.Hecanbereachedat dr_kurtzman@maryland-implants.com