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RO0211

I 17 special _ laser I roots2_2011 Intra-canallasertherapy The final stage of root-canal preparation and disinfectioniscompletedwiththeWaterlaseMDlaser (Er,Cr:YSGG) using radial-firing tips (Biolase Tech- nology). The laser tips are available in two sizes: RFT2 and RFT3 with diameters of 275 and 415µm, respectively (Fig. 5). The RFT2 tip is inserted 1mm short of WL, requiring canal preparation sizes of ISO 30 or more while the RFT3 tip is inserted to the junction of mid- dleandapicalthirds,requiringcanalsizesofISO45or more. These sizes fall well within typical working widthpreparationsizespreparedwithLSXfiles.Intra- canal laser therapy is performed in two phases, the Cleaning Phase for smear layer and debris removal, and the Disinfection Phase for tissue ablation and bacterial elimination. Cleaningphase(1.25W;50Hz;24%air;30%water) This phase uses water and removes smear layer and debris without using chemical irrigants. It takes two to three minutes per canal and uses Hydro- Photonicstocreateapowerfulmicro-agitationeffect throughout the canal system. It is generally accepted that smear layer removal facilitates the cleaning and disinfecting of the denti- naltubulesandimprovesthesealingoftherootcanal. When merging results of two studies, the Er,Cr:YSGG with radial-firing tips produced significantly better smearlayerremovalintheapical,middleandcoronal thirds than two rotary techniques.16,17 This extremely efficient action opens the dentinal tubules, lateral canals and isthmuses in preparation for disinfection (Figs. 6–8). Technique for cleaning phase after completion of access, working width preparation and negative pressure irrigation: _use the RFT2 to perform apical and partial coronal two-thirds cleaning; _select the recommended laser settings in the wet mode; _fill canal with sterile solution; _insert RFT2 tip 1mm short of WL; _activate laser on withdrawal of tip coronally at approximately 1mm/s and maintain tip in contact with the side surface of the canal wall during the entire apical to coronal pass; _repeatsteps4and5oneortwomoretimestoensure that the entire inner canal has been cleaned (Fig. 9); _place the RFT3 tip in handpiece to perform final cleaning of the coronal two-thirds; _fill canal with sterile solution; _insert the tip to the junction of apical and middle third of the root canal; and _repeat steps 5 and 6. Disinfectionphase(0.75W;20Hz;10%air;0%water) As stated previously, the laser energy emitted fromtheEr,Cr:YSGGlaserishighlyabsorbedbywater in tissue and micro-organisms, resulting in instan- taneous photo-ablation. In addition, the resulting micro-pulse expansion and collapse of intratubular water produce acoustic waves sufficiently strong to Fig. 10_Upper premolar treated with laser protocol. Fig. 11_Lower molar treated with laser protocol. Fig. 10 Fig. 11