RERMOVING SMEAR LAYER DURING ENDODONTIC TREATMENT BY DIFFERENT TECHNIQUES - A INVITRO STUDY . A CLINICAL CASE - ENDODONTIC TREATMENT WITH ER : YAG LASER
advances in dental research have incorporated laser technology as an novel modality for use in endodontic therapy 10 . In 1917 , Albert Einstein wrote : “ a special kind of light could be created under the right conditions - a light nobody had seen before . The light would be a single color , it would not scatter the way normal light does and it would be very intense ”. This kind of light would later be called laser . The use of laser at different wavelengths has been proposed to supplement conventional endodontic cleaning procedures 11-14 . Lasers pulsed infrared have been shown to cause cavitation-bubbles and pressure waves within the root canal space when combined with irrigants 15-16 . The cleaning effect of LAI ( Laser Activated Irrigation ) is based on cavitation : when a pulsed erbium laser is emitting in a root canal brimful of irrigant , strong absorption of the laser energy by the irrigant results in the formation of vapor bubbles at the fiber tip . These vapor bubbles expand during the pulse and then collapse soon after termination of the laser pulse 17 . Erbium lasers are effective in activating irrigating solutions : the absorption coefficients for water at 2,940 nm ( Er : YAG laser ) and at 2,790 nm ( Er ; Cr : YSGG laser ) are 12,000 and 6,000 respectively 18 and cause formation of vapor bubbles at the fiber tip . For LAI to be effective , high absorption of laser energy into the irrigating liquid is necessary . The aim of this study was ( 1 ) to evaluate in vitro the effect of irrigation techniques , irrigation with syringe-needle and laser-activated irrigation with 17 % EDTA in root canals and ( 2 ) to demonstrate the effect of laser activated irrigation in a ppatient case .
2 . Materials and methods 2.1 . Tooth Samples Sixty single-rooted human teeth extracted for periodontal reasons were used . ( Ethics committee approval , Hadassah Hospital ( No 0118-14-HMO ). Root canal preparation was carried out using ProTaper™ ( Dentsply Maillefer , Baillaigues , Switzerland ) F3 Ni-Ti files with 2.5 % NaOCl irrigation . The apices of all teeth were sealed with
Super-EBA ( Harry J . Bosworth Co ., Skokie , IL , USA ) to prevent irrigant leakage . The teeth were randomly divided into three groups . Group 1 was treated with ProTaper™ F3 Ni-Ti files as described above , and served as a negative control . Group 2 was treated with ProTaper™ F3 Ni-Ti files , at the end of mechanical procedure , root canal was irrigated with 10 ml of 17 % EDTA using a syringe with a 27-G needle ( Navitip ) for 60 seconds . Group 3 was treated with ProTaper™ F3 Ni-Ti files , at the end of mechanical procedure , root canal was subjected to LAI with Er : YAG laser at a wavelength of 2940 nm ( LiteTouch™ , Light Instruments , Yokneam , Israel ) equipped with a 17 mm 400-μm plan-ended sapphire tip . Radiation was set to 0.5 W , 50 mJ , 10 HZ for 60 seconds . The water spray of the laser was closed . An irrigation solution of 17 % EDTA was injected during radiation . The laser tip was inserted 3 mm in the upper coronal third of the root canal . After the various treatments , two longitudinal cuts were made with a high speed bur and the teeth were split in half . 2.2 . Scanning Electron Microscopy ( SEM ) All samples were dried and mounted on stubs and then coated with Au / Pd using a Polaron SC7640 Sputter Coater ( Polaron , Hertfordshire , UK ). The effects of the irrigation treatments on the smear layer were examined by SEM at a magnification of 10,000X of the root canal . The samples were examined using FEI Sirion High Resolution SEM and FEI Magellan Ultra-High Resolution SEM ( FEI , Eindhoven , The Netherlands ).
3 . Results 3.1 . Examination of Surface Morphology Figure 1 shows SEM micrographs of the dentin wall at 10,000 magnification of the root canal present smear layer covered the root canal surface after endodontic preparation . In the second group , irrigation with 17 % EDTA through a syringe for 60 seconds removed only part of the smear layer , at the apical part smear layer is present no dental tubules can be seen ( Fig 2 ).
Figure 1 . SEM X 10,000 picture presents smear layer after cleaning and shaping the root canal system during endodontic treatment
Figure 2 . SEM X 10,000 picture presents smear layer at the apical part after irrigation with 10 ml of 17 % EDTA using a syringe for 60 seconds
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