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Dental Tribune Middle East & Africa Edition | 6/2016 13 mCMESELFINSTRUCTIONPROGRAM CAPPmea together with Dental Tribune provides the opportunity with its mCME - Self Instruction Program a quick and simple way to meet your continuingeducationneeds.mCMEoffersyoutheflexibilitytoworkatyour own pace through the material from any location at any time. The content is international, drawn from the upper echelon of dental medicine, but also presentsaregionaloutlookintermsofperspectiveandsubjectmatter. Membership YearlymembershipsubscriptionformCME:1,100AED OneTimearticlenewspapersubscription:250AEDperissue.Afterthe payment,youwillreceiveyourmembershipnumberandallowingyouto starttheprogram. 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Formoreinformationpleasecontactevents@cappmea.comor +97143616174 FORINTERACTIONWITHTHEAUTHORSFINDTHECONTACTDETAILSAT THEENDOFEACHARTICLE. laser are highly efficient in disinfect- ing the root canal surfaces and the dentinal walls (up to 750 microns 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 morpho- logical alterations of the dentinal wall. The smear layer was only par- tially removed and the dentinal tu- bules 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 debrid- ing and cleaning root canal walls.9, 10 The bacterial load reduction after er- bium laser irradiation, demonstrat- ed high on the dentin surfaces, but low in depth of penetration because of the high absorption of laser en- ergy on the dentin surface.7 Also the laser activation of commonly used irrigants (LAI) resulted in statistically moreeffectiveremovalofdebrisand smear layer in root canals compared with traditional techniques (CI) and ultrasound (PUI).11, 12 Additionally the laser activation method resulted in a strong modulation in reaction rate of NaOCl significantly increas- ing production and consumption of available chlorine in comparison to ultrasoundactivation.13 A recent study has reported how the useofanEr:YAGlaser,equippedwith a newly designed radial and stripped tip, in combination with 17 per cent EDTA solution, using very low pulse duration (50 microseconds) and low energy (20 mJ) resulted in effec- tive debris and smear layer removal with minimal or no thermal dam- age to the organic dentinal structure through a photoacoustic technique called photon induced photoa- coustic streaming or “PIPS.”14, 15 Also the same photoacoustic protocol in combination with 5.25 per cent sodium hypochlorite solution has been investigated and shown to re- ducethebacterialloadanditsassoci- ated biofilm in the root canal system threedimensionally.16 Other similar studies are in progress for publication and the results are promising and suggest a three-di- mensional positive effect of this la- seractivated decontamination (LAD) method. The purpose of this article is to pre- sent briefly the experimental back- groundofthislasertechniqueandto introducetheclinicalprotocol. Scientificbackground The microphotographic recording of the LAI studies suggested that the erbium lasers used in irrigant-filled root canals generate a streaming of fluidsathighspeedthroughacavita- tion effect.17 The laser thermal effect generates the expansion-implosion ofthewatermoleculesoftheirrigant solution, generating a secondary cavitation effect on the intracanal fluids. To accomplish this streaming, it is suggested the fiber be placed in the middle third of the canal, 5 mm from the apex and stationary.18 This concept greatly simplifies the laser technique,withouttheneedtoreach the apex and to negotiate radicular curves. Also, the recorded video of the new technique,PIPS,showedastrongagi- tationoftheliquidsinsidethecanals. It differs from the already cited LAI technique by activating the irrigant solutions in the endodontic system through a profound photoacoustic and photomechanical phenomena. The use of low energy (50 microsec- ond pulse, 20 mJ at 15 Hz, 0.3 W av- erage power, or less) generates only a minimal thermal effect. The study with thermocouples applied to the radicular apical third revealed only 1.2°Cofthermalriseafter20seconds and 1.5 °C after 40 seconds of contin- uousradiation.14 When the erbium laser energy is de- liveredatonly50microsecondpulse duration through a special designed tapered and stripped 400 microns tip(FotonaLightWalker,Technology- 4Medicine), it produces a large peak power of 400 watts when compared to a longer pulse duration. Each im- pulse, absorbed by the water mol- ecules, creates a strong “shock wave” that leads to the formation of an ef- fective streaming of fluids inside the canalwhilealsolimitingtheundesir- able 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 prepara- tion with less thermal damage as seen with those techniques placed intothecanalsystem. Therootcanalsurfacesirrigatedwith 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 dis- infecting action of PIPS is very effec- tive both on the root surface, the lat- eral 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 intro- duce the tip into the root canal sys- tem. Unlike traditional laser tech- niques requiring placement of the tip 1 mm from the apex, or even 5 mm from the apex as proposed for LAI18 , the PIPS tip is placed in the cor- onal portion of the pulpal chamber only and left stationary allowing the photoacoustic effect to spread into theopeningsofeachcanal.Anewtip design consisting of a 400-micron diameter,12mmlong,taperedendis usedforthistechnique(Fig.5).Thefi- nal 3 mm of coating is stripped from the end to allow for greater lateral emission of energy compared to the frontaltip. Thismodeofenergyemissionallows for improved lateral diffusion with low energy and enhanced photoa- cousticeffect. Discussion Laser irradiation is a common tech- nique used in endodontics to im- prove both the cleaning, the debrid- ingand disinfectionoftheroot canal system. Many wavelengths and pro- tocols are used. Near infrared lasers are used for the three-dimensional decontamination of the endodontic system. Nd:YAG and diode lasers use thermal energy to destroy bacteria. Observations reveal a certain grade of thermal injury to the root canal surface and create a typical morpho- logical damage. Moreover, they are not able to thoroughly remove the smearlayer. On the contrary, erbium lasers are used for their effective smear layer removal while their bactericidal ac- tivity is limited to the root surface. The placing of the tip close to the apex and its back movement during theactivationprocessisrelatedtothe riskofapicalperforation,ledgingand surface thermal damage, because of the ablation ability of this wave- length. Also a combination of the nearandmediuminfraredlasershas been proposed. A technique, called twinlight endodontic treatment (TET), uses the erbium laser energy first, to clean the root canal surface and remove the smear layer, and the Neodimium:YAG laser second, used in dry mode as the final disinfect- ing step. All these techniques utilize traditionaltipsandfibresplacedinto the canal, close to the apex (1 mm) with all the corresponding thermal disadvantages observed in long, nar- rowandcurvecanals. The erbium lasers are also used as a medium of activation of commonly used irrigants (LAI), avoiding the risk of thermal damage, while increasing the cleaning and disinfecting activ- ity of the fluids. PIPS, in particular, reduces all these risks and disadvan- tages, thanks to the position of the tip in the coronal orifice only and to theuseofminimallyablativeenergy levelsof20mJorless. The findings of our studies demon- strated that PIPS technique resulted in a safe and effective debriding and decontaminating the root canal sys- tem. Our clinical trials showed that PIPS technique greatly simplifies root canal therapy while facilitating the search for the apical terminus, debriding and maintaining patency. As a result of the efficacy of PIPS the final size required for canal shaping can be significantly reduced, often to a size 25/04, allowing for a more minimally invasive and biomimetic preparation which can then be obtu- ratedthreedimensionally. Conclusion Lasers are an extremely versatile ad- dition to the dental practice and can be used in many instances instead of the conventional methods em- ployed by the vast majority of den- tists.Incorporatingalaserintheden- tal practice should be viewed as an investment rather than a cost. When used with a good knowledge of laser physics, training and safety, lasers provide our patients a new standard ofdentalcare. References [1] Weichman JA, Johnson FM. Laser useinendodontics.Apreliminaryin- vestigation. Oral Surg Oral Med Oral Pathol.1971Mar;31(3):416–20. [2] Pini R, Salimbeni R, Vannini M, Barone R, Clauser C. Laser dentistry: a new application of excimer laser in root canal therapy. Lasers Surg Med. 1989;9(4):352–357. [3] Shirasuka T, Wakabayashi H, Debari K, Kodaka T, Ahmed S, Mat- sumoto K. Morphologic changes in human tooth enamel by contin- uous-wave Nd-YAG laser irradia- tion. Showa Shigakkai Zasshi. 1990 Jun;10(2):206–215. [4]MyersTD.Lasersindentistry.CDS Rev.1991Sep;84(8):26–29. [5] Gutknecht N, Behrens VG. In- strumentation of root canal walls with Nd-YAG laser. ZWR. 1991 Oct;100(10):748–750,752,755. [6] Stabholz A, Moshonov J, Rotstein I. Lasers in endodontics. Rev Belge MedDent.1992;47(4):9–15.Review. [7] Schoop U, Kluger W, Moritz A, NedjelikN,GeorgopoulosA,SperrW. Bactericidal effect of different laser systems in the deep layers of dentin. LasersSurgMed.2004;35(2):111–116. The full list of references is available fromthepublisher. DrLawrenceKotlow,DDS,hasbeen inprivatedentalpracticeinAlbany, NY,since1974.Heisboardcertifiedin pediatricdentistry.Heisarecognized standardproficiencycourseproviderfor theAcademyofLaserDentistry. DrEnricoDiVito,DDS,isanAdjunct Pro- fessorat theArizonaSchoolofDentistry andOralHealth.Heisinprivatepractice at theArizonaCenterforLaserDentistry inScottsdale,AZ,inconjunctionwith MDATGresearchgroup. DrGiovanniOlivi,MD,DDS,isaProfes- sorofendodonticsat theUniversityof GenoaSchoolofDentistry,whereheis directorfor theLaserinDentistryMaster CoursewithProf.S.Benedicenti.Heisin privatepracticeinRome,Italy. ◊Page12 mcme Dental Tribune Middle East & Africa Edition | 6/201613