Future Dental Journal




Objectives: To evaluate and compare smear layer removal in root canals instrumented with two single Ni-Ti rotary instruments with two different irrigating systems. Materials and Methods: Sixty recently extracted single-rooted mandibular premolars teeth were decoronated to a standardized length of 14 mm. Roots were divided into two main groups (n=30) according to the rotary NiTi file used for instrumentation either with One Shape (OS) file or with One Curve file (OC). Each main group was subdivided into three subgroups according to the methods used to agitate the irrigating solutions either sonically or ultrasonically as following: Group A was subdivided into Subgroup A1: One Shape file and Endo Activator (EA) (n=10) Subgroup A2: One Shape file and Passive Ultrasonic irrigating (PUI) (n=10) Subgroup A3 (control group): One Shape file and passive needle irrigation (n=10) Group B was subdivided into: Subgroup B1: One Curve file and Endo Activator (EA) (n=10) Subgroup B2: One Curve file and Passive Ultrasonic Irrigation (PUI) (n=10) Subgroup B3 without activation: One Curve file and passive needle irrigation (n=10). During instrumentation: In all groups, 3 ml of freshly prepared 2.6% NaOCl irrigating solution was delivered using 30 G NaviTip closed end needle. The final irrigation protocol included 3 ml of freshly prepared 2.6% NaOCl followed by 3 ml of 17% EDTA solution then 3 ml of normal saline as final rinse. After dividing the roots in half, the specimens were analysed under SEM magnification at (X1000) to assess the smear layer and perform statistical analysis. Results: In all groups a statistically significant difference was found between (Apical) and each of (Coronal) and (Middle) groups, where apical third showed higher smear layer scores followed by middle third and the coronal third. As regards total mean scores of all canal thirds, passive needle irrigation had the highest smear scores followed by PUI then EA. OS file showed higher smear layer score than OC file and there was no statistically significant difference between them. Conclusions: Within the limitations of this study, it could be concluded that: Machine-assisted irrigant activation techniques are reliable and promising methods that improve the cleanliness of root canal. None of the techniques was able to remove smear layer completely from the root canal. Heat treatment of OS file did not have significant effect regarding the ability to remove the smear layer.