Comparative evaluation of effect of N-acetyl cysteine, maleic acid, and ethylenediaminetetraacetic Acid on the depth of dentinal tubule penetration of an epoxy resin-based root canal sealer: A confocal laser scanning microscopy study.

Abstract

Background: Effective root canal irrigation removes the smear layer for optimal sealer penetration. While 17% ethylenediaminetetraacetic Acid (EDTA) is effective, concerns about dentin erosion exist. Alternatives like 7% maleic acid (MA) and 20% N-acetylcysteine (NAC) show promise with fewer adverse effects.

Aim: To compare the effects of 20% NAC, 7% MA, and 17% EDTA as final irrigating solutions on the depth of sealer penetration into dentinal tubules at coronal, middle, and apical thirds of root canals using confocal laser scanning microscopy (CLSM).

Materials and methods: Sixty-six single-canal mandibular premolars free of caries, fractures, or prior treatment were selected. The teeth were decoronated to 14 mm root length using a diamond disk under water spray. Working length was determined by inserting a size 10 K-file until visible at the apical foramen, subtracting 1 mm. Root canals were instrumented up to F3 using ProTaper Universal rotary files with 1 mL of 2.5% NaOCl irrigation between files. Based on the final irrigation protocol, samples were divided into three groups (n = 22): Group 1-20% NAC, Group 2-7% MA, and Group 3-17% EDTA. Each group was irrigated with 5 mL of the respective irrigant, followed by a final rinse with 10 mL of distilled water. AH Plus sealer with 0.1% Rhodamine B was applied using a #25 Lentulo, and an F3 gutta-percha cone coated with the sealer was placed to working length, trimmed, and sealed with Cavit. Samples were incubated at 37°C and 100% humidity for 7 days to allow sealer setting. Roots were sectioned at 2, 5, and 8 mm from the apex to obtain 1 mm thick sections. Sealer penetration into dentinal tubules was evaluated using CLSM at ×10 magnification, measuring the penetration depth in micrometers from the canal wall to the point of maximum sealer infiltration using ImageJ software, measuring the longest penetration depth from the canal wall to the point of deepest sealer infiltration.

Results: Sealer penetration was greatest in the coronal third, followed by the middle, with the least in the apical third (P < 0.0001). NAC demonstrated the highest mean in the coronal region (829.35 ± 85.36), while MA exhibited superior performance in the middle (522.92 ± 112.32) and apical (361.76 ± 49.03) regions. Intergroup comparisons showed superior penetration with 7% MA in the apical region (P < 0.0001). NAC and EDTA demonstrated comparable penetration across regions.

Conclusion: While all irrigants enhanced sealer penetration, 7% MA was most effective in the apical region. Both 7% MA and 20% NAC can serve as alternatives to 17% EDTA for final irrigation.