Evaluation of effect of different irrigation solutions and activation systems on dentinal tubule penetration of root canal sealer with laser scanning confocal microscope

Aim of this study was to investigate effect of two different irrigation solutions (NaOCI/EDTA, Dual Rinse HEDP), three different activation techniques (conventional needle, irriflex, xp endo finisher) and single cone root canal filling techniques on penetration of root canal sealer into dentinal tubules and quality of root canal filling in single-rooted premolars using confocal laser scanning microscopy (CLSM). In this study; 96 extracted single-rooted human lower premolars were used with approval of Yeditepe University Clinical Research Ethics Committee. working length was standardized to 16mm. All specimens were shaped with Protaper Next rotary Ni-Ti files and divided into 8 groups. Group 1: NaOCI/EDTA – Conventional needle irrigation, Group 2 Dual Rinse HEDP – Conventional needle irrigation, Group 3: NaOCI/EDTA – Irriflex, Group 4: Dual Rinse HEDP – Irriflex, Group 5: NaOCI/EDTA – Xp Endo Finisher, Group 6: Dual Rinse HEDP – Xp Endo Finisher. According to final irrigation solutions, all teeth were divided into 2 main groups as 5 % NaOCI 17% EDTA, Dual Rinse HEDP. Each main group was divided into 3 subgroups according to conventional needle irrigation, Xp Endo Finisher and Irriflex irrigation techniques. After final irrigation and activation, teeth were filled with single cone filling techniques. AH Plus Bioceramic (Dentsply Sirona, USA) bioceramic-based canal sealer was used as a root canal filling sealer. specimens were kept in a humid environment in an oven for 1 week and fixed in cold acrylic (Self Cure, IMICRYL, Turkey) with apical foramen at tip. Each specimen was marked at intervals of 3-4 mm, 5-6 mm and 8-9 mm from apical. marked sections were cut perpendicular to long axis of root with a 0.3 mm thick diamond disc (Metkon A.Ş., Bursa Turkey) under water cooling using a low speed Isomet device (IsoMet, Buehler, Israel). Three horizontal sections (apical, middle, coronal) were obtained for each root (apical (3-4 mm), middle 5-6 (mm), coronal (8-9 mm), with a thickness of approximately 1 ± 0.1 mm. sections were formed as 3 horizontal dentin discs with a thickness of 1 mm perpendicular to long axis of tooth. thickness of each section was checked using a digital caliper (Macrona, Simetri Teknik, Izmir, Turkey) with an accuracy of 0.001 mm. sections were numbered according to relevant tooth and tooth regions. effect of interaction of irrigation solution and activation technique on penetration depth and percentage was evaluated by Two-way ANOVA test, Tukey HSD test was used in post hoc analyses. Repeated measures analysis of variance and post hoc Bonferroni test were used for in-group apical-mid- coronal region evaluations. Significance was evaluated at p<0.05 level. Statistically significant differences were observed between irrigation solutions and activation techniques in terms of both penetration area percentages and penetration depths (p<0.05). However, combined effect of irrigation solution and activation technique on parameters was not found to be significant (p>0.05). When HEDP solution was used, XPF technique achieved a higher penetration area percentage compared to Irriflex and conventional techniques (p<0.05), but no significant difference was found between Irriflex and conventional techniques. When NaOCl and EDTA combination was used, no significant difference was detected between activation techniques (p>0.05). In both conventional and XPF techniques, HEDP solution provided greater penetration depth compared to NaOCl/EDTA solution (p<0.05).