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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