RO0211

I 09 special _ laser I roots2_2011 methodology, the traditional technique is to use a helical movement when retracting the tip (over a five- to ten-second interval), repeating three to four times depending on the procedure and alternating radiation with irrigation using common chemical irrigants,keepingthecanalwet,whileperformingthe procedure (NaClO and/or EDTA) with the integrated spray closed. The 3-D decontamination of the endodontic sys- tem with Erbium lasers is not yet comparable to that of near infrared lasers. The thermal energy created by these lasers is in fact absorbed primarily on the surface(highaffinitytodentinaltissuerichinwater), where they have the highest bactericidal effect on E. coli (Gram-negative bacteria), and E. faecalis (Gram- positive bacteria). At 1.5W, Moritz et al. obtained an almosttotaleradication(99.64%)ofthesebacteria.44 However, these systems do not have a bactericidal effectatdepthinthelateralcanals,astheyonlyreach 300µmindepthwhentestedinthewidthoftheradic- ular wall.8 Further studies have investigated the ability of the Er,Cr:YSGG laser in the decontamination of tra- ditionally prepared canals. Using low power (0.5W, 10Hz, 50mJ with 20% air/water spray), complete eradication of bacteria was not obtained. However, better results for the Er,Cr:YSGG laser were obtained with a 77% reduction at 1W and of 96% at 1.5W.42 AnewareaofresearchhasinvestigatedtheErbium laser’s ability to remove bacterial biofilm from the apical third,46 and a recent in vitro study has further validated the ability of the Er:YAG laser to remove endodontic biofilm of numerous bacterial species (e.g. A. naeslundii, E. faecalis, L. casei, P. acnes, F. nucleatum,P.gingivalisorP.nigrescens),withconsid- erable reduction of bacterial cells and disintegration of biofilm. The exception to this is the biofilm formed by L.casei.47 Ongoing studies are evaluating the efficacy of a new laser technique that uses a newly designed both radialandtaperedstrippedtipforremovalofnotonly thesmearlayer,butalsobacterialbiofilm.13 Theresults are very promising. The Erbium lasers with “end firing” tips— frontal emission at the end of the tip—have little lateral penetration of the dentinal wall. The radial tip wasproposedin2007fortheEr,Cr:YSGG,andGordon etal. and Schoop etal. have studied the morphologi- cal and decontaminating effects of this laser system (Fig. 6).48–50 The first study used a tip of 200µm with radial emission at 20Hz with air/water spray (34 and 28%) and dry at 10 and 20mJ and 20Hz (0.2 and 0.4W, respectively). The radiation times varied from 15 seconds to two minutes. The maximum bactericidal power was reached at maximum power (0.4W), with a longer exposure time, without water in dry mode and with a 99.71% bacterial eradication. The minimum time of radiation (15 seconds) with minimum power (0.2W) and water obtained 94.7% bacterial reduction.48 The second study used a tip of 300µm diameter with two different parameters of emission (1 and 1.5W,20Hz),radiatingfivetimesforfiveseconds,with acoolingtimeof20secondsforeachpassage.Thelevel of decontamination obtained was significantly high, withimportantdifferencesbetween1and1.5W,with athermalincreasecontainedbetween2.7and3.2°C.49 ThesamegroupfromViennastudiedotherparameters (0.6 and 0.9W) that produced a very contained thermal rise of 1.3 and 1.6°C, respectively, showing a high bactericidal effect on E.coliand E.faecalis.50 Fig. 17_Localisation 1mm from the apex of the fibre and tips of the near and medium infrared lasers. According to the LAI technique, the tip must be localised in the middle third of the canal, approximately 5mm from the apex (on the right). Fig. 18 Fig. 19 Fig. 20 Fig. 17 Figs. 18–20_PIPS tip, radial firing, in quartz, 400 µ. The 3 mm terminals were deprived of their outer coating to increase the lateral dispersion of energy.