Efficiency of Removing a Novel Radiopaque Smear Layer Using Different Activation Instruments
Tyce A. Hebert, DDS1*, Thomas E. Lallier, Ph.D2, Dylan C. McMahan, B.S1, Annamari E. Farrar, B.S1, Albert F. McMullen III, DDS, FACD3
1Department of Endodontics, Louisiana State University Health Sciences Center School of Dentistry, 1100 Florida Ave., New Orleans, LA, USA 70119.
2Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center School of Dentistry, 1100 Florida Ave., New Orleans, LA, USA 70119.
3Department Head and Postgraduate Director, Department of Endodontics, Louisiana State University Health Sciences Center School of Dentistry, 1100 Florida Ave., New Orleans, LA, USA 70119.
*Corresponding Author: Tyce A. Hebert, DDS, Department of Endodontics, Louisiana State University Health Sciences Center School of Dentistry, 1100 Florida Ave., New Orleans, LA, USA 70119.
https://doi.org/10.58624/SVOADE.2025.06.026
Received: August 07, 2025
Published: September 13, 2025
Citation: Hebert TA, Lallier TE, McMahan DC, Farrar AE, McMullen AF. Efficiency of Removing a Novel Radiopaque Smear Layer Using Different Activation Instruments. SVOA Dentistry 2025, 6:5, 158-164. doi: 10.58624/SVOADE.2025.06.026
Abstract
Introduction: This study quantitively compared the efficiency of removing a novel radiopaque smear layer using different activation instruments.
Methods: 60 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, in order 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) EndoActivator (EA), (3) SmartLite Pro EndoActivator (SLPEA), and (4) an ultrasonic activator (UA) before taking final radiographs. Analysis of smear layer removal was performed radiographically using ImageJ for the entire canal, as well as its apical 3mm.
Results: Removal of the smear layer along the entire canal was significantly better for UA and manual agitation (p<0.05), 92% and 90% respectively. SLPEA was slightly better at removing smear layer (77%) than EA (71%), although this was not statistically significant. In the apical 3mm, no significant difference was observed in smear layer removal between all methods of activation.
Conclusion: Ultrasonic and manual agitation were significantly better at removing the smear layer along the entire canal than EA and SLPEA. In the apical 3mm, all irrigation techniques were equally effective at smear removal. Funding was provided by LSU Health Science Center.
Keywords: Ultrasonic; Sonic; Activation; Radiopaque; Smear Layer
