Please activate JavaScript!
Please install Adobe Flash Player, click here for download
ePaper created 2018-03-23, 14:16:40 | version 1.38.0
Dental Tribune Middle East & Africa Edition | May-June 2015 9mCME < Page 8 used irrigants (LAI) resulted in statistically more effective re- moval of debris and smear layer in root canals compared with traditional techniques (CI) and ultrasound (PUI).11,12 Addition- ally, the laser activation method resulted in a strong modulation in reaction rate of NaOCl, sig- nificantly increasing production and consumption of available chlorine in comparison to ultra- sound activation.13 A recent study has reported how the use of an Er:YAG laser, equipped with a newly designed radial and stripped tip, in com- bination with 17 percent EDTA solution, using very low pulse duration (50 microseconds) and low energy (20 mJ) resulted in effective debris and smear layer removal with minimal or no thermal damage to the organic dentinal structure through a photoacoustic technique called photon induced photoacoustic streaming or “PIPS.”14,15 Also the same photoacustic protocol in combination with 5.25 per- cent sodium hypochlorite solu- tion has been investigated and shown to reduce the bacterial load and its associated biofilm in the root canal system three dimensionally.16 Other similar studies are in pro- gress for publication and the re- sults are promising and suggest a three-dimensional positive ef- fect of this laseractivated decon- tamination (LAD) method. The purpose of this article is to present briefly the experimental background of this laser tech- nique and to introduce the clini- cal protocol. Scientific background The microphotographic record- ing of the LAI studies suggested that the erbium lasers used in irrigant-filled root canals gener- ate a streaming of fluids at high speed through a cavitation ef- fect.17 The laser thermal effect generates the expansion implo- sion of the water molecules of the irrigant solution, generating a secondary cavitation effect on the intracanal fluids. To accom- plish this streaming, it is sug- gested 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, without the need to reach the apex and to negotiate radicular curves. Also, the recorded video of the new technique, PIPS, showed a strong agitation of the liquids inside the canals. It differs from the already cited LAI technique by activating the irrigant solu- tions in the endodontic system through a profound photoacous- tic and photomechanical phe- nomena. 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 thermocouples applied to the radicular apical third revealed only 1.2 degrees C of thermal rise after 20 seconds and 1.5 de- grees C after 40 seconds of con- tinuous radiation.14 When the erbium laser energy is delivered at only 50 micro- second pulse duration through a special designed tapered and stripped 400 microns tip (Fo- tona LightWalker, Technology- 4Medicine), it produces a large peak power of 400 watts when compared to a longer pulse du- ration. Each impulse, absorbed by the water molecules, creates a strong “shock wave” that leads to the formation of an effective streaming of fluids inside the ca- nal while also limiting the unde- sirable thermal effects seen with other methodologies. The place- ment of the tip in the coronal portion only of the treated tooth allows for a more minimally en- larged canal preparation with less thermal damage as seen with those techniques placed into the canal system. The root canal surfaces irrigated with 17 percent 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 Mac- edo,13 improving the disinfecting action of the sodium hypochlo- rite.16 The disinfecting action of PIPS is very effective both on the root surface, the lateral canals and the dentinal tubules, as con- firmed 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 tradition- al 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 tip is placed in the coronal portion of the pulpal chamber only and left stationary, allow- ing the photoacoustic effect to spread into the openings of each canal. A new tip design consist- ing of a 400-micron diameter, 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 com- pared to the frontal tip. This mode of energy emission allows for improved lateral dif- fusion with low energy and en- hanced photoacoustic effect. Discussion Laser irradiation is a common technique used in endodontics to improve the cleaning, the de- briding and disinfection of the root canal system. Many wave- lengths and protocols are used. Near infrared lasers are used for the three-dimensional decon- tamination of the endodontic sys- tem. Nd:YAG and diode lasers use thermal energy to destroy bacte- ria. Observations reveal a certain grade of thermal injury to the root canal surface and create a typical morphological damage. Moreo- ver, they are not able to thor- oughly remove the smear layer. On the contrary, erbium la- sers are used for their effective smear layer removal while their bactericidal activity is limited to the root surface. The placing of the tip close to the apex and its back movement during 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 me- dium infrared lasers has been proposed. A technique, called twinlight endodontic treatment (TET), uses the erbium laser en- ergy 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 disinfecting step. All these techniques utilize tradi- tional tips and fibers placed into the canal, close to the apex (1 mm) with all the corresponding thermal disadvantages observed in long, narrow and curve ca- nals. 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 particu- lar, reduces all these risks and disadvantages, thanks to the position of the tip in the coro- nal orifice only and to the use of minimally ablative energy levels of 20 mJ or less. The findings of our studies dem- onstrated that PIPS technique resulted in a safe and effective debriding and decontaminating of the root canal system. Our clinical trials showed that PIPS technique greatly simplifies root canal therapy while facilitating the search for the apical termi- nus, debriding and maintaining patency. As a result of the efficacy of PIPS, the final size required for canal shaping can be significantly re- duced, often to a size 25/04, al- lowing for a more minimally invasive and biomimetic prepa- ration that can then be obturated three dimensionally. Conclusion Lasers are an extremely versa- tile addition to the dental prac- tice and can be used in many instances instead of the con- ventional methods employed by the vast majority of dentists. Incorporating a laser in the den- tal practice should be viewed as an investment rather than a cost. When used with a good knowl- edge of laser physics, training and safety, lasers provide our patients a new standard of den- tal care. References 1. Weichman JA. Johnson FM. mCME SELF INSTRUCTION PROGRAM CAPPmea together with Dental Tribune provides the opportunity with its mCME- Self Instruction Program a quick and simple way to meet your continuing education needs. mCME offers you the flexibility to work at your 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 presents a regional outlook in terms of perspective and subject matter. Membership: Yearly membership subscription for mCME: 900 AED One Time article newspaper subscription: 250 AED per issue. After the payment, you will receive your membership number and Allowing you to start the program. Completion of mCME • mCME participants are required to read the continuing medical education (CME) articles published in each issue. • Each article offers 2 CME Credit and are followed by a quiz Questionnaire online, which is available on http://www. cappmea.com/mCME/questionnaires.html. • Each quiz has to be returned to events@cappmea.com or faxed to: +97143686883 in three months from the publication date. • A minimum passing score of 80% must be achieved in order to claim credit. • No more than two answered questions can be submitted at the same time • Validity of the article – 3 months • Validity of the subscription – 1 year • Collection of Credit hours: You will receive the summary report with Certificate, maximum one month after the expiry date of your membership. For single subscription certificates and summary reports will be sent one month after the publication of the article. The answers and critiques published herein have been checked carefully and represent authoritative opinions about the questions concerned. Articles are available on www.cappmea.com after the publication. For more information please contact events@cappmea.com or +971 4 3616174 FOR INTERACTION WITH THE AUTHORS FIND THE CONTACT DETAILS AT THE END OF EACH ARTICLE. Lawrence Kotlow, DDS, has been inprivatedentalpracticeinAlbany, N.Y.,since1974. He is board certified in pediatric dentistry. He is a recognized stan- dard proficiency course provider fortheAcademyofLaserDentistry. Enrico DiVito, DDS, is an adjunct professor at the Arizona School of DentistryandOralHealth. He is in private practice at the ArizonaCenterforLaserDentistry in Scottsdale, Ariz., in conjunction withMDATGresearchgroup. Giovanni Olivi, MD, DDS, is a pro- fessorofendodonticsattheUniver- sity of Genoa School of Dentistry, where he is director for the Laser in Dentistry Master Course with Prof.S.Benedicenti.Heisinprivate practiceinRome,Italy. About the Author Fig. 3. Representative sample image of root canal dentinal walls irrigated with 17 percent EDTA and PIPS for 20 sec- onds. Fig. 4. SEM image of clean lateral canal. Fig. 5. New tapered tip design for this technique. Laser use in endodontics. A preliminary investigation. Oral Surg Oral Med Oral Pathol. 1971 Mar;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 ca- nal therapy. Lasers Surg Med. 1989;9(4):352–357. 3. Shirasuka T. Wakabayashi H. Debari K. Kodaka T. Ahmed S. Matsumoto K. Morphologic changes in human tooth enamel by continuous-wave Nd-YAG la- ser irradiation. Showa Shigakkai Zasshi. 1990 Jun;10(2):206–215. 4. Myers TD. Lasers in dentistry. CDS Rev. 1991 Sep;84(8):26–29. Full list of references is available from the publisher. +97143616174