The effect of different irrigation activation methods on the penetration of the irrigation solution into the dentinal tubules in teeth with calcium hydroxide applied and oval-shaped canals: Confocal laser scanning microscope analysis.

This study aimed to evaluate the efficacy of different irrigation techniques including standard needle irrigation (SNI), passive ultrasonic irrigation (PUI), EndoActivator (EA), XP-Endo Finisher (XPF), photon-induced photoacoustic streaming (PIPS), and shock wave enhanced emission photo-acoustic streaming (SWEEPS) systems on the penetration of irrigation solutions into dentinal tubules in teeth with calcium hydroxide (CH) applied and oval-shaped canals by confocal laser scanning microscope (CLSM). Ninety mandibular incisor teeth with oval-shaped canals were included in this study. After the preparation of teeth using Resiproc Blue R25 (VDW, Munich, Germany) canals were filled with a paste based on CH. The teeth were stored in 100% humidity at a temperature of 37°C for 14 days. According to the irrigation activation systems, the teeth were divided into six groups (n = 15); SNI, PUI, EA, XPF, PIPS, and SWEEPS. In each group, 3 irrigation/activation cycles of 20 s of irrigation and 20 s of activation were performed with the relevant activation method. The root canals were filled with fluorescein sodium (Sigma, Alldrich Co., St. Louis, MO, USA) and activated with the relevant activation method for 30 s. Specimens were sectioned horizontally to 1 ± 0.1 mm at 2, 5, and 8 mm from the apex and then examined under the CLSM. Maximum penetration depth, maximum penetration area and penetration percentage were measured by using Image J software. Data were analyzed using a two-way analysis of variance (ANOVA) and posthoc Tukey tests (p = .05). No difference was found between the activation systems in terms of maximum penetration depth and maximum penetration area of irrigation solutions in the apical section (p > .05). The penetration percentage of irrigation solutions was higher in PUI and PIPS compared with EA and XPF at the apical section (p < .05). No difference was found between SNI, PUI, PIPS, and SWEEPS in terms of the penetration percentage of irrigation solutions in all sections (p > .05). The penetration percentage of irrigation solutions was higher in the middle and coronal sections compared to the apical section in EA and XPF (p < .05). Tubule penetration of irrigation solutions in SNI was similar between sections. The Tubule penetration area of irrigation solutions in PUI, EA, XPF, PIPS, and SWEEPS was lower in the apical section than in the middle and coronal sections. RESEARCH HIGHLIGHTS: The tubule penetration depth and area of the irrigation solutions were similar between the activation systems tested in the apical sections. The Tubule penetration area of irrigation solutions in middle and coronal sections was higher in PUI and PIPS than in SNI.

Evaluation of the effects of different photosensitizers used in antimicrobial photodynamic therapy on tooth discoloration: spectrophotometric analysis.

BACKGROUND: Tooth discoloration is a common concern in antimicrobial photodynamic therapy (aPDT) using various photosensitizers (PS). Toluidine Blue (TB), Methylene Blue (MB), Phthalocyanine (Pc), and 2-mercaptopyridine-substituted zinc phthalocyanine (TM-ZnPc) are among those studied, but their relative impacts on tooth discoloration remain unclear. AIM: This study aimed to compare the effects of TB, MB, Pc, and TM-ZnPc in aPDT on tooth discoloration, utilizing a controlled experimental setup. MATERIALS AND METHODS: The study comprised seventy-five single-rooted incisors with root canals. Following meticulous preparation, a standardized area on the crown surface was designated for examination, and precise measurements of the initial tooth colors were recorded. Samples were randomly divided into five groups: Negative control, MB, TM, Pc, and TM-ZnPc. Photoactivation was performed using LED light, and color measurements were taken at multiple time points up to 90 days. Data were converted to Lab* color values of the CIE Lab* color system (International Commission on Illumination, Vienna, Austria), and ΔE values were calculated. Statistical analysis was performed using Two-way ANOVA and Post-Hoc Tukey tests (p < 0.05). RESULTS: At day 7 and 30, TM-ZnPc and Pc caused less discoloration compared to MB and TB. TM-ZnPc caused more tooth discoloration compared to Pc (p < 0.05). Compared to baseline, MB and TM-ZnPc caused more tooth discoloration at 30 days and TB caused more tooth discoloration at 90 days (p < 0.05). No significant difference was observed in terms of tooth discoloration at all periods evaluated after Pc application (p > 0.05). All photosensitizers tested in the study caused tooth coloration. CONCLUSION: All PS induced clinically detectable tooth discoloration, with TB and MB causing more significant discoloration compared to Pc and TM-ZnPc at certain time points. TM-ZnPc and Pc demonstrated more stable coloration levels over time, suggesting their potential reliability in aPDT applications. This study highlights the importance of selecting appropriate PS to minimize tooth discoloration in aPDT, with Pc showing promise in this regard.

Spectrophotometric analysis of the effectiveness of different dentin tubule occlusion techniques in preventing discoloration caused by photosensitizers used in photodynamic therapy.

AIM: The efficacy of Copal Varnish (CV), dentin bonding agent (DBA), Nd:YAG laser and Er:YAG laser, which occludes dentin tubules by different mechanisms, was investigated in order to prevent unwanted coloration caused by methylene blue (MB) and phthalocyanine used in photodynamic therapy (PDT). MATERIALS AND METHODS: 165 upper incisors included in the study. Root canals were prepared up to 30/0.6 size for all teeth using Protaper Next rotary files. Then the teeth were randomly divided into 2 main groups (n = 60); MB and phthalocyanine. Each main group was randomly divided into 5 subgroups (n = 15); Positive control, DBA, CV, Er:YAG and Nd:YAG. Root canals were filled with photosensitizers (PS) and activated after the dentin tubule occlusion method was applied to all teeth. Then, the residual PSs were removed by irrigation. Color measurements of the samples were carried out 5 different time periods. RESULTS: Clinically detectable color change was observed in all groups except for the negative control (ΔE≥3.3). It was determined that the positive control using MB caused more unwanted coloration in the CV on the 30th and 90th days compared to the phthalocyanine used in the 90th day (p < 0.05). While none of the dentin tubule occlusion methods were superior to each other in preventing undesirable coloration caused by phthalocyanine, Er:YAG caused less unwanetd coloration than CV only on the 90th day in preventing unwanted coloration caused by MB (p < 0.05). CONCLUSIONS: All dentin tubule occlusion methods used in the present study were effective in preventing some degree of unwanted discoloration. However, it was found that no technique could completely prevent unwanted coloration.

Microcomputed Assessment of Transportation, Centering Ratio, Canal Area, and Volume Increase after Single-file Rotary and Reciprocating Glide Path Instrumentation in Curved Root Canals: A Laboratory Study.

INTRODUCTION: The aim of this study was to compare the transportation and centering abilities of the ProGlider (PG; Dentsply-Sirona, Ballaigues, Switzerland), WaveOne Gold Glider (WOGG; Dentsply-Sirona), and R-Pilot (RP; VDW, Munich, Germany) file systems and the changes in the structure model index (SMI), surface area, and root canal volume (after creating the glide path in the mandibular first molar teeth's mesial canals with moderate curvature) using the micro-computed tomographic (micro-CT) method. METHODS: In the present study, 24 mandibular first molar teeth with 2 separate mesial canals and moderate (10°-20°) curvature were used. After scanning with micro-CT imaging before the procedure, the teeth were divided into 3 groups, PG, WOGG, and RP (n = 10/each group), followed by the glide path procedure. After the root canal preparation, changes in the root canals regarding the volume, surface area, SMI, transportation made by the files, and the change of their centering ability in the apical, middle, and coronal third were analyzed by micro-CT imaging. The data were statistically evaluated using 1-way analysis of variance and the Kruskal-Wallis test with a significance level set at 5% (P < .05). RESULTS: The WOGG and RP file systems showed better centering abilities at all thirds compared with the PG file system (P < .05). No significant difference was found in the apical third between the groups in terms of canal transportation degree (P > .05). However, in the WOGG and RP groups, less transportation was observed in the middle and coronal thirds compared with the PG group (P < .05). When the SMI changed, after the root canal preparation was compared, no significant differences were found between the groups (P > .05). Nevertheless, the changes in volume and surface area of the root canal in the WOGG and RP groups were significantly lower than in the PG group (P < .05). CONCLUSIONS: The WOGG and RP file systems caused similar levels of change in the root canal systems based on all parameters. Moreover, it was determined that the PG file system caused a significantly higher volume and surface area increase than the WOGG and RP file systems.

Effect of chitosan nanoparticle, QMix, and EDTA on TotalFill BC sealers' dentinal tubule penetration: a confocal laser scanning microscopy study.

The aim of the present study was to compare the effect of chitosan nanoparticle, QMix, and 17% EDTA on the penetrability of a calcium silicate-based sealer into dentinal tubules using a confocal laser scanning microscope (CLSM). Sixty mandibular premolar teeth were selected and randomly divided into three groups (n = 20) before root canal preparation according to the solution used in the final rinse protocol: chitosan, QMix, and EDTA groups. Twenty teeth of each group were filled with a TotalFill BC sealers' single gutta-percha cone and with 0.1% rhodamine B. The specimens were horizontally sectioned at 3 and 5 mm from the apex, and the slices were analyzed in CLSM (4×). Total percentage and maximum depth of sealer penetration were measured using confocal laser scanning microscopy with using Image J analysis software. Dentinal tubule's penetration depth, percentage, and area were measured using imaging software. Kruskal-Wallis test was used for statistical analysis. The level of significance was set at 5%. Results of Kruskal-Wallis analysis showed that there was a significant difference in the percentage and depth of sealer penetration among all groups at 3 and 5 mm level sections (P < 0.05). Within the groups, the minimum sealer penetration depth was recorded for chitosan nanoparticle group. Greater depth of sealer penetration was recorded at 5 mm as compared to 3 mm in all the groups. Within the limitation of the present study, it can be concluded that QMix and EDTA promoted sealer penetration superior to that achieved by chitosan nanoparticle.