Impact of Endodontic Irrigant Activation on Smear Layer Removal and Surface Disintegration of Root Canal Dentine In Vitro

Abstract

The objective of this study was to compare the ability of different endodontic irrigation activation methods to enable irrigant penetration, remove the smear layer from root canal walls after preparation, and investigate surface effects on dentine. Root canals of 90 single-rooted teeth were prepared and irrigated with EDTA (17%) and sodium hypochlorite (5%), where both irrigants or sodium hypochlorite only were activated as follows: conventional needle irrigation, ultrasonic activation, sonic activation (EDDY), or laser-based activation (photon-induced photoacoustic streaming/PIPS). For the evaluation of irrigant penetration into dentinal tubules, methylene blue was injected and activated as well. Subsequently, teeth were sectioned horizontally, and dye penetration depths were measured. Alternating sections were split in halves and randomly selected for scanning electron microscopic analysis. Root canal dentine was assessed for smear layer removal and surface disintegration according to a defined scoring system. The data were analyzed statistically with nonparametric and chi-squared tests for whole teeth and separately for coronal, middle, and apical thirds. All the tested activation methods removed a thicker smear layer than needle irrigation only. Additional activation of EDTA improved penetration depths of the irrigants, but not the smear layer removal. Surface disintegration of root canal dentine was observed with the additional activation of EDTA and particularly after laser-based techniques. Additional activation of EDTA does not seem to offer any convincing advantages in terms of irrigant penetration or smear layer removal but disrupts the dentine surface. Especially laser-based activation resulted in undesirable destruction of root canal wall dentine.

Knowledge, Attitude, and Practice towards Chelating Agents in Endodontic Treatment among Dental Practitioners

“…This approach is recommended in several reports [24,[80][81][82]. However, this is not in agreement with the studies showing that EDTA should be used at the end of the shaping instead of alternating EDTA and sodium hypochlorite [18,41].…”

“…Different techniques may be used to enhance the action of EDTA, e.g., ultrasonic [7,36] or sonic activation [37], negative pressure irrigation [38], laser activation [39], and manual dynamic agitation [40]. At the same time, EDTA activation may also cause the surface disintegration of root canal dentin [41].…”

Principle and antimicrobial efficacy of laser‐activated irrigation: A narrative review

“…This is in agreement with Akbulut and Terlemez (2019), who found that root canal dentin microhardness was significantly affected by the irrigation solution, but not by the PIPS activation. Widbiller et al (2023) found that LAI activation of both NaOCl and EDTA led to pronounced surface disintegration of root canal dentine, which was higher than that of sonic (Eddy) or ultrasonic activation.…”

“…Widbiller et al. (2023) found that LAI activation of both NaOCl and EDTA led to pronounced surface disintegration of root canal dentine, which was higher than that of sonic (Eddy) or ultrasonic activation. Hancerliogullari et al.…”

Use of a Cellulase from Trichoderma reesei as an Adjuvant for Enterococcus faecalis Biofilm Disruption in Combination with Antibiotics as an Alternative Treatment in Secondary Endodontic Infection

“…The biofilms were irrigated by means of a blunt-ended 0.40 mm gauge needle (Endo-Eze, Ultradent, South Jordan, UT, USA). A soft ultrasonic device (tip 15) was used at frequencies of 20–30 kHz at 1 mm from the apical foramen during the final minute of irrigation in each group [ 25 , 26 ]. The antimicrobial activity was evaluated on three treated apices per group (as previously described).…”