Comparison of 980 nm Diode Laser and Q-Mix Solution Alone and in Combination on Removal of Smear Layer from Root Canal Surface; a Scanning Electron Microscope Study

Aim: The aim of this study was to compare the efficacy of 980 nm diode laser and QMix 2in1 solution (DENTSPLY Tulsa Dental Specialties) alone and in combination, for smear layer removal from the root canals. Background: Smear layer is an amorphous layer formed on root canal walls following instrumentation. This layer should be removed as it can harbor bacteria and bacterial products and prevents the penetration of intracanal medicaments into the dentinal tubules. Irrigation agitation techniques have been proposed recently to remove smear layer from root canals more efficiently. The diode laser has the potential for irrigant activation and studies are needed to establish their efficacy for smear layer removal especially from apical thirds of canals. Methods: Forty extracted single-rooted permanent human teeth were used. Root canals were prepared to full working length using manual K-files (MANI) till 40K. Prepared teeth were divided into four groups (n=10): Group 1, no irrigation; Group 2, QMix 2in1 solution; Group 3, diode laser; Group 4, QMix 2in1 in combination with a diode laser. The roots were split longitudinally and prepared for scanning electron microscopic (SEM) investigation. The split roots were examined for remaining smear layer at the coronal, middle, and apical portion of each canal under a scanning electron microscope (JSM5910, JEOL, Japan) at 1000x magnification. Results: Smear layer removal was scored according to Guttman rating system for remaining smear layer scores (Gutmann et al.). Diode laser in combination with QMix solution had the least smear layer scores. Conclusions: Diode laser irradiation in combination with QMix 2in1 solution effectively removes smear layer from apical thirds of root canals.