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roots - international magazine of endodontology No. 2, 2016

| CE article dual wavelength laser 12 roots 2 2016 Photoacoustic endodontics using PIPS Thegoalofendodontictreatmentistoobtaineffec- tivecleaninganddecontaminationofthesmearlayer, bacteria and their byproducts in the root canal sys- tem.Clinically,traditionalendodontictechniquesuse mechanical instruments, as well as ultrasonic and chemicalirrigation,inanattempttoshape,cleanand completely decontaminate the endodontic system but still fall short of successfully removing all of the infective microorganisms and debris. This is because the complex root canal anatomy and the inability for commonirrigantstopenetrateintothelateralcanals and the apical ramifications. It seems, therefore, ap- propriatetosearchfornewmaterials,techniquesand technologies that can improve the cleaning and the decontamination of these anatomical areas. Among the new technologies, the laser has been studied in endodontics since the early 1970s1-3 and has become more widely used since the ’90s.4–6 Different wavelengths have been shown to be ef- fectiveinsignificantlyreducingthebacteriainthein- fected canals, and important studies have confirmed these results in vitro.7 Studies reported that near in- fraredlaserarehighlyefficientindisinfectingtheroot canal surfaces and the dentinal walls (up to 750 mi- crons the diode 810 nm and up to 1 mm the Nd:YAG 1,064 nm). On the other hand, these wavelengths did not show effective results in debriding and cleansing the root canal surfaces and caused characteristic morphological alterations of the dentinal wall. The smear layer was only partially removed and the den- tinal tubules primarily closed as a result of melting of the inorganic dentinal structures.5, 8 Other studies reported the ability of the medium infrared laser in debriding and cleaning root canal walls.9, 10 The bacterial load reduction after erbium laser irradiation, demonstrated high on the dentin surfaces, but low in depth of penetration because of the high absorption of laser energy on the dentin surface.7 Alsothelaseractivationofcommonlyused irrigants (LAI) resulted in statistically more effective removal of debris and smear layer in root canals comparedwithtraditionaltechniques(CI)andultra- sound (PUI).11, 12 Additionally the laser activation method resulted in a strong modulation in reaction rate of NaOCl significantly increasing production and consumption of available chlorine in compari- son to ultrasound activation.13 A recent study has reported how the use of an Er:YAG laser, equipped with a newly designed radial and stripped tip, in combination with 17 per cent EDTAsolution,usingverylowpulseduration(50mi- croseconds) and low energy (20 mJ) resulted in ef- fective debris and smear layer removal with minimal or no thermal damage to the organic dentinal struc- ture through a photoacoustic technique called pho- ton induced photoacoustic streaming or “PIPS.”14, 15 Also the same photoacoustic protocol in combina- tionwith5.25percentsodiumhypochloritesolution has been investigated and shown to reduce the bac- terialloadanditsassociatedbiofilmintherootcanal system three dimensionally.16 Other similar studies are in progress for publica- tion and the results are promising and suggest a three-dimensional positive effect of this laseracti- vated decontamination (LAD) method. The purpose of this article is to present briefly the experimental background of this laser technique and to introduce the clinical protocol. Scientific background ThemicrophotographicrecordingoftheLAIstud- ies suggested that the erbium lasers used in irrig- ant-filled root canals generate a streaming of fluids athighspeedthroughacavitationeffect.17 Thelaser thermal effect generates the expansion-implosion of the water molecules of the irrigant solution, gen- erating a secondary cavitation effect on the intra­ canal fluids. To accomplish this streaming, it is sug- gested the fiber be placed in the middle third of the canal,5 mmfromtheapexandstationary.18 Thiscon- cept greatly simplifies the laser technique, without theneedtoreachtheapexandtonegotiateradicular curves. Also, the recorded video of the new technique, PIPS,showedastrongagitationoftheliquidsinside Fig.3: Representative sample image of root canal dentinal walls irrigated with 17 per cent EDTA and PIPS for 20 seconds. Fig.3 22016

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