(PO102) Efficiency of Removing a Novel Radiopaque Smear Layer using Different Activation Instruments

Abstract: This study quantitatively compared the efficiency of removing a novel radiopaque smear layer using different activation instruments. Sixty extracted human mandibular premolars with single canals were decoronated, accessed, instrumented with rotary files to the working length, and radiographed. The root canal was filled with a solution containing insoluble lead salts to impregnate the smear layer, making it radiopaque. All teeth were radiographed to confirm the presence of a radiopaque smear layer. Activation of 6% NaOCl was completed using one of four techniques on 15 teeth each: (1) manual agitation; (2) SmartLite Pro EndoActivator (SPE); (3) EndoActivator (EA); and (4) an ultrasonic activator before taking final radiographs. Analysis of smear layer removal was performed radiographically using ImageJ for the entire canal, as well as its apical 3 mm. Removal of the smear layer along the entire canal was significantly better for ultrasonic and manual agitation (p < .05), 92% and 90% respectively. SPE was slightly better at removing the smear layer (77%) than EA (71%), although this difference was not statistically significant. In the apical 3 mm, no significant difference was observed in smear layer removal between all methods of activation. In conclusion, ultrasonic and manual agitation were significantly better at removing the smear layer along the entire canal than EA and SPE. In the apical 3 mm, all irrigation techniques were equally effective at smear removal.