Please activate JavaScript!
Please install Adobe Flash Player, click here for download
ePaper created 2016-05-18, 11:28:18 | version 1.38.0
dual wavelength laser CE article | 13 roots 2 2016 the canals. It differs from the already cited LAI technique by activating the irrigant solutions in theendodonticsystemthroughaprofoundphoto- acoustic and photomechanical phenomena. The use of low energy (50 microsecond pulse, 20 mJ at 15 Hz, 0.3 W average power, or less) generates only a minimal thermal effect. The study with thermo- couples applied to the radicular apical third re- vealed only 1.2 °C of thermal rise after 20 seconds and 1.5 °C after 40 seconds of continuous radia- tion.14 When the erbium laser energy is delivered at only 50 microsecond pulse duration through a special designed tapered and stripped 400 microns tip (FotonaLightWalker,Technology4Medicine),itpro- duces a large peak power of 400 watts when com- paredtoalongerpulseduration.Eachimpulse,ab- sorbed by the water molecules, creates a strong “shock wave” that leads to the formation of an ef- fective streaming of fluids inside the canal while also limiting the undesirable thermal effects seen with other methodologies. The placement of the tip in the coronal portion only of the treated tooth allows for a more minimally enlarged canal prepa- ration with less thermal damage as seen with those techniques placed into the canal system. The root canal surfaces irrigated with 17 per cent EDTA and laser activated for 20 seconds showed exposed collagen matrix, opened tubules and the absence of smear layer and debris (Figs. 1-3). The rinsing with 5.25 per cent sodium hypochlorite and laser irradiation for 20 seconds produced a strong activation of the solution, as reported by Macedo,13 improving the disinfecting action of the sodium hypochlorite.16 The disinfecting action of PIPS is very effective both on the root surface, the lateral canals and the dentinal tubules, as confirmed with SEM and confocal studies (Fig. 4). The profound and distant effect of PIPS eliminates the need to introduce the tip into the root canal system. Unlike traditional laser techniques requiring placement of the tip 1 mm from the apex, or even 5 mm from the apex as proposed for LAI18, the PIPS tipisplacedinthecoronalportionofthepulpalcham- beronlyandleftstationaryallowingthephotoacous- tic effect to spread into the openings of each canal. Anewtipdesignconsistingofa400-microndiameter, 12 mm long, tapered end is used for this technique (Fig. 5). The final 3 mm of coating is stripped from the end to allow for greater lateral emission of energy compared to the frontal tip. This mode of energy emission allows for improved lateral diffusion with low energy and enhanced pho- toacoustic effect. Discussion Laser irradiation is a common technique used in endodontics to improve both the cleaning, the debriding and disinfection of the root canal sys- tem. Many wavelengths and protocols are used. Near infrared lasers are used for the three-dimen- sional decontamination of the endodontic system. Nd:YAG and diode lasers use thermal energy to de- stroy bacteria. Observations reveal a certain grade ofthermalinjurytotherootcanalsurfaceandcreate a typical morphological damage. Moreover, they are not able to thoroughly remove the smear layer. On the contrary, erbium lasers are used for their effective smear layer removal while their bactericidal activity is limited to the root surface. The placing of thetipclosetotheapexanditsbackmovementduring the activation process is related to the risk of apical perforation, ledging and surface thermal damage, because of the ablation ability of this wavelength. Also a combination of the near and medium infrared lasers has been proposed. A technique, called twin- light endodontic treatment (TET), uses the erbium laser energy first, to clean the root canal surface and remove the smear layer, and the Neodimium:YAG lasersecond,usedindrymodeasthefinaldisinfecting step. All these techniques utilize traditional tips and fibres placed into the canal, close to the apex (1 mm) with all the corresponding thermal disadvantages observed in long, narrow and curve canals. The erbium lasers are also used as a medium of ac- tivationofcommonlyusedirrigants(LAI),avoidingthe riskofthermaldamage,whileincreasingthecleaning and disinfecting activity of the fluids. PIPS, in partic- Fig.4: SEM image of clean lateral canal. Fig.4 22016