Olcay Özdemir

This study aimed to evaluate the effectiveness of energy-intensive irrigation activation systems for removing residual pulp tissue in completely uninstrumented oval root canals with different access cavity designs, using histological analysis. Seventy extracted human mandibular premolars with oval root canal morphology and organic tissue remnants were randomly assigned to five irrigation protocols: syringe-needle irrigation (control), Er: YAG laser (SWEEPS, Fotona), Er, Cr: YSGG laser (Waterlase iPlus, Biolase), multisonic high-speed irrigation (GentleWave G4 with ProControl, SonEndo, 5-min protocol), and an extended multisonic protocol (9-min). Each group was further divided according to access cavity design into ultra-conservative and traditional cavities (n = 7). Following irrigation with sodium hypochlorite and EDTA, serial histological sections from the apical third were prepared, and the percentage of residual pulp tissue was quantified using ImageJ software. Data were analyzed using two-way ANOVA with Bonferroni multiple comparisons (p < 0.05). The irrigation activation system significantly affected residual tissue percentages (p < 0.001; η²=0.736), whereas access cavity design showed no significant effect (p = 0.965). Syringe-needle irrigation demonstrated the highest residual tissue values (≈ 20%). Both laser activation systems significantly reduced residual tissue compared with needle irrigation but showed comparable performance (≈ 4–6%). Multisonic high-speed irrigation further improved canal cleanliness, with the 5-min protocol showing lower residual tissue values (≈ 2%), and the extended 9-min protocol achieving the lowest percentages (< 1%), approaching near-complete debridement. Within the limitations of this in vitro histological study, energy-intensive irrigation systems significantly improved the removal of residual pulp tissue in uninstrumented oval root canals. The extended multisonic irrigation protocol demonstrated the highest debridement efficiency under the tested conditions. These findings may inform future minimally invasive endodontic strategies; however, they should not be interpreted as supporting the clinical replacement of mechanical instrumentation.

This study evaluated the effect of calcium-rich nanohydroxyapatite (nano-HA) as an intracanal medicament on root fracture resistance compared with calcium hydroxide (CH). Forty-eight caries-free maxillary central incisors were instrumented and randomly assigned to a two-factor design (two medicaments × two sealers), yielding four experimental groups ( n = 12/group): CH + resin-based sealer, CH + bioceramic-based sealer, nano-HA + resin-based sealer, and nano-HA + bioceramic-based sealer. The medicaments were applied and stored in simulated body fluid at 37 °C and 100% humidity for 10 days. After removal, the canals were obturated with heated gutta-percha using either a resin-based or a bioceramic-based sealer, and were then stored for an additional 28 days. Vertical fracture resistance was measured using an Instron Universal Testing Machine. Data were analyzed using two-way ANOVA ( p < 0.05). The nano-HA groups showed a higher mean fracture resistance (924.04 N) than the CH groups (818.54 N). The highest fracture resistance was observed in the nano-HA + bioceramic-based sealer group (1020.38 N), whereas the lowest was observed in the CH + resin-based sealer group (665.83 N). The main effect of sealer type was statistically significant ( p < 0.001), while no significant interaction between medicament and sealer type was detected. Within the limitations of this in vitro study using static vertical loading, sealer type had a large, statistically significant effect on fracture resistance, with the bioceramic-based sealer yielding higher values than the resin-based sealer. Although the nano-HA groups exhibited numerically higher fracture resistance than calcium hydroxide, the main effect of intracanal medicament did not reach statistical significance. These findings are limited to laboratory conditions and should not be directly extrapolated to long-term clinical performance.

Aim: This in vitro study compared the mean and peak apical pressures generated by EDDY, GentleWave G4, and passive ultrasonic irrigation (PUI) in a standardized 3D-printed root canal model. Methodology: A standardized straight root canal model (apical diameter 0.25 mm, 4% taper, 16 mm working length) was fabricated by resin-based stereolithographic printing. Apical pressure was measured with a validated setup comprising a piezoresistive pressure transducer (PXM409-350; Omega), a DAQ board (USB6008; National Instruments), and LabVIEW software. Distilled water served as the irrigating medium. Twenty measurements were performed per group (n=20, 60 total), with each recording 12,020 data points over 12 seconds. EDDY was activated with a TA-200 air scaler (power level 2, #25/.04 tip); GentleWave G4 was operated per the manufacturer's protocol; and PUI was performed with a Newtron P5 XS ultrasonic unit (power level 6, IrriSafe #20 tip, 2 mm short of the working length). Normality was confirmed by the Shapiro-Wilk test, and group comparisons were performed using Welch ANOVA with Games–Howell post hoc comparisons. The study followed PRILE 2021 reporting guidelines. Results: Significant differences were observed across all groups for both mean and peak apical pressures (p < 0.001). EDDY produced the highest mean (16.03 ± 4.04 mmHg) and peak (35.53 ± 2.84 mmHg) apical pressures, exceeding the safety threshold in every measurement. GentleWave G4 yielded a negative mean apical pressure (−15.60 ± 7.96 mmHg) and a mean peak of 8.00 ± 6.76 mmHg, remaining below the threshold throughout. PUI generated near-zero mean apical pressure (−0.07 ± 0.05 mmHg) and a mean peak of 2.27 ± 0.05 mmHg, consistently below the critical threshold. All pairwise comparisons were significant (p < 0.001), including GentleWave G4 vs. PUI for peak pressure (p = 0.003). Conclusion: GentleWave G4 and PUI produced apical pressures below the established safety threshold, whereas EDDY exceeded it in all measurements, indicating a higher risk of periapical irrigant extrusion. Further ex vivo and in vivo studies with anatomically complex geometries are warranted.

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This study aimed to investigate the influence of multiple variations, such as different metallurgies available on the market in comparison with stainless steel, and simultaneously real-time reading and monitoring of apical sensing during instrumentation with various kinematic movements. Three stages of experiment on two allocated groups of artificial root canals were conducted for the study as follows: metallurgy experiment with passive measurement of working lenght, with a gold standard apex locator device, correlation analysis of the apex locator device and an apex locator integrated engine-driven motor with passive measurement, and kinematics experiment with dynamic monitoring. For the metallurgy and kinematics experiments, the same preshaped artificial root canals (n = 26) and for correlation analysis of the devices unshaped root canals were used (n = 15). Stainless steel, conventional NiTi, M wire, CM gold, CM blue, TM wire, C wire, CM EDM, special NiTi heat-treated wire, and R phase file systems were selected for the metallurgy experiment. For the apex locator integrated engine-driven instrumentation, test groups were arranged according to movements and metallurgy (M wire-reciprocating/rotational, CM gold-reciprocating/rotational) and conducted on the same 26-block set. Shapiro‒Wilk, Wilcoxon, Mann‒Whitney U, and Kruskal‒Wallis tests were performed for the statistical analysis (p < 0.050). All tested metallurgies presented correlated measurements (p = 0.139); however, tapered instrumentation affected the working length (p < 0,001). The dynamic measurements (rotational/reciprocating) presented a statistically significant difference compared to the passively established actual working length (p < 0.001). A statistically difference was also obtained between reciprocating and rotational CM gold (p = 0.003); however, there was no difference between reciprocating and rotational M wire (p = 0.084). Tapered instrumentation changes the initial working length. Different metallurgies have no variational impact on the determination of electronic working length. During apex locator integrated instrumentation, M wire files and rotational movement exhibit a more stable attitude; however, apical overextensions may be observed in all kinematics regardless of the metallurgies. Caution is recommended when using CM gold files with apex locator integrated engine-driven instrumentation, especially in reciprocating motion. Maintaining the real-time working length between preparation stages is essential to preserve the apical structure. Dynamic monitoring of apical limit, regardless of motion type, as a supporter may promote treatment outcomes; however, using apex locator integrated instrumentation as a primary way for working length determination, as well as preparation, may cause an extension beyond safe limits.

Objectives: This study aims to evaluate the effectiveness of current conventional and advanced irrigation techniques after minimally invasive instrumentation in necrotic oval root canals by histological analysis. Methods: Seventy extracted necrotic lower premolars with single oval canals classified utilizing bidirectional radiographs (mesiodistal diameter 2.5 times larger than buccolingual) were prepared up to 20.04 v. The samples were assigned to five experimental groups (n = 14) using the complementary irrigation technique: needle (control), passive ultrasonic, and shockwave-enhanced emission photo-acoustic streaming activation using Er:YAG laser (SWEEPS), Er,Cr:YSGG laser (Waterlase iPlus), and multisonic ultracleaning technology (GentleWave). After irrigation protocols, the roots were demineralized and the apical 5 mm was multi-sliced and processed for histologic examination. The residual necrotic tissue and debris percentage was calculated via image analysis software. One-way ANOVA and Tukey’s test were used to verify the variables influencing debridement (p < 0.05). Results: The mean value of the GentleWave group was the record low at 1.54 ± 1.46, and the utmost was needle irrigation with 15.64 ± 7.23. The main effect of techniques on the debridement was statistically significant (p < 0.001). The course of debridement effectiveness, according to the levels of significance between the groups, was as follows: Multisonic ultracleaning > Er:YAG > Er,Cr:YSGG > Passive ultrasonic irrigation > Needle irrigation (p <0.05). Conclusions: In necrotic oval-shaped canals after minimally invasive instrumentation, multisonic ultracleaning with updated software was considerably more effective in removing remnants in the apical level. Er:YAG and Er,Cr:YSGG lasers were highly promising, with results close to multisonic ultracleaning. It should be considered that needle irrigation and passive ultrasonic activation may not be able to provide competent debridement in treating such types of root canals.