Effect of irrigant activation systems and dentine ageing on sealer penetration into dentinal tubules

This study aimed to assess the effect of dentine ageing and irrigant activation (ultrasonic activation (UA) and SmartLite Pro EndoActivator (SLP-EA)) on the penetration of endodontic sealer into dentinal tubules in the apical third. Eighty single-rooted teeth extracted from donors aged 30-40 years (n = 40) and 60-70 years (n = 40) were prepared using the ProTaper Gold system and randomly assigned to two irrigation protocols (UA or SLP-EA). Root canals were obturated with BC Universal Sealer labelled with sodium fluorescein using a single-cone technique. Roots were sectioned 3 mm from the apex and analysed using confocal laser scanning microscopy. Sealer penetration was quantified by total penetration area (PA), maximum penetration depth (MaxD), mean penetration depth (S-MeanD), and percentage of perimeter penetration at different depths. Data were analysed using 2-way ANOVA test (α = 0.05). No significant differences were observed between UA and SLP-EA, whereas donor age significantly affected sealer penetration. Younger teeth exhibited greater penetration than older teeth, with higher MaxD (1,458 µm vs. 698 µm), S-MeanD (738 µm vs. 183 µm), and perimeter percentages (p < 0.001). Within the limitations of this study, it may be concluded that dentine ageing affects the penetration of endodontic sealer into dentinal tubules in the apical third, regardless of the technique used to activate the irrigant. This finding should be considered when interpreting the results of experimental studies and emphasises the need to standardise donor age in tooth selection for in vitro studies.