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ePaper created 2016-07-29, 16:53:04 | version 1.38.0
23 2 2016 laser industry | quirement for the application was the minimum preparationsizeofISO60,whichresultedintheun- necessarysacrificeofdentalhardtissue.Becauseof the apical sealing, the apical cleaning effect was only low. Laser Activated Irrigation (LAI)— a revolution How can the major advantages of erbium laser ra- diation be maintained without having to accept the application-related drawbacks? In 2007, Blanken et al. described for the first time the intra-canal appli- cation of a pulsed erbium laser in the canal lumen filled with NaClO.51 They observed a few interesting effects:Eachlaserpulsecausedgreataccelerationof the fluid in the root canal. At the same time, they proved a strong cavitation effect in the root canal.52 Both effects combined resulted invitro in a cleaning effect, which is superior to the passive ultrasonic ir- rigation (PUI), the previous gold standard of clean- ing.53 LAI in root canals, however, had some disad- vantages too. Irrespective of the laser tip design, sometimes a lot of irrigation fluid was extruded through the apical constriction. This extrusion was significantly higher than in conventional irrigation systems.54 Addition- ally,theformationofgasbubblesbecauseofthelaser pulsemaycausetheirrigationfluidtovanishfromthe respectivecanalsectioncompletely,whichagainmay cause thermal damage of dental hard tissue.55 PIPS®—the evolution of revolution In2010,DeVitopresentedanoveltipdesignforthe first time, combining all advantages of erbium laser radiation, Laser Activated Irrigation (LAI) and the mi- nimisationoftheriskofirrigationfluidbeingextruded (Fig. 6).56 PIPS® is the abbreviation of Photon Initiated Pho- toacousticStreaming.Inthisprocedure,thePIPS®tip is inserted only into the pulp cavity filled with irriga- tion fluid. The pulsed laser beam generates shock- waves in the irrigation fluid and cavitation effects in the whole root canal system, intended to create a cleaning effect in the entire canal system, including isthmuses,lateralcanalsanddeepdownintotheden- tinal tubules, which is superior to any of the previous techniques. The almost complete elimination of bac- teria, smear layer, and biofilm was proven in the invi- tro experiment for NaClO and for EDTA.57 No indica- tion of irrigation fluid being extruded was noticed.58 What does the mechanism leading to this superior cleaning effect look like? When the laser pulse starts, the rapid heating of the irrigation fluid causes an ex- panding vapor bubble to form. The more the vapor bubble expands, the more it cools down, leading fi- nally to its implosion. This affects the root canal in the following ways: 1. The volume changes of the vapor bubble lead to heavy movement of the fluid in the root canal.59 2. The implosion of the bubble is a high-energy process. Shockwaves with large amplitudes and “micro- jets” develop. Shear stress builds up near surfaces (primary cavitation).60 Fig. 7 Fig. 7: Cavitation. Luther et al. 2001. AD 22016