Search Results (112)

This study aimed to examine how downward load applied during instrumentation affects the stress generation and shaping properties in thermally treated and non-treated NiTi rotary instruments. ProTaper Universal (PTU; non-thermally treated) and ProTaper Gold (PTG; thermally treated) were used to prepare J-shaped canals in resin blocks. Load-controlled automated instrumentation and torque/force sensing devices were employed with preset downward loads of 1, 2, or 3 N (n = 10 each). The torque/force, instrumentation time, and canal-centering ratio were measured and analyzed using two-way or one-way analysis of variance with Tukey’s test (α = 0.05). In the PTU-1N group, instrumentation was not completed because a ledge was formed in all canals. The PTU-3N group showed significantly greater upward force (screw-in force) and clockwise torque, along with a significantly smaller canal-centering ratio (less deviation) at the apical 0 mm level, than the PTU-2N group (p < 0.05). The downward load did not influence the instrumentation time (p > 0.05). In the PTG groups, these effects of downward load on the force generation and canal-centering ratio were not significant (p > 0.05). In the non-thermally treated PTU instruments, greater downward loads enhanced screw-in force while decreasing apical canal deviation; however, these effects were abolished in the thermally treated PTG instruments. This study highlights the importance of adapting the instrumentation technique with instrument characteristics: thermally treated flexible instruments facilitate smoother use, while stiffer, non-thermally treated ones may require precise control of downward loads. Full article

This study evaluated the chemical composition and subcutaneous tissue biocompatibility of C-Point, a root canal filling material, compared to ProTaper gutta-percha cones (control). Material characterization was conducted using scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS). For biocompatibility assessment, both materials were implanted subcutaneously in the dorsal connective tissue of sixteen albino rats (n = 8 per group). Histological evaluation of inflammatory infiltrate intensity was performed at 30 and 60 days post-implantation, with statistical analysis (significance set at p < 0.05). SEM-EDS analysis revealed distinct elemental compositions: C-Point primarily contained zirconium and cobalt ions, while gutta-percha cones demonstrated a strong zinc signature with trace amounts of barium, aluminum, and sulfur. Both materials exhibited similar particulate morphology with radiopaque inclusions. Histologically, no significant difference in inflammatory response was observed between C-Point and gutta-percha at any time point (p > 0.05). All specimens developed a fibrous encapsulation. The inflammatory profile showed temporal dynamics, with lymphocyte predominance during early stages that progressively diminished by the study endpoint. These findings demonstrate that while C-Point possesses a unique elemental profile dominated by zirconium, its tissue biocompatibility parallels that of conventional gutta-percha obturation materials. However, due to the absence of mechanical testing and the limited in vivo follow-up period, the long-term stability of the material remains uncertain. Full article

Background/Objectives: The aim of this study was to investigate the effects of periodontal blood flow on the periapical region during various endodontic disinfection procedures. The hypothesis that periodontal blood flow reduces the increase in root surface temperature during disinfection procedures was tested. Methods: One hundred and twenty extracted human teeth were shortened to 11 mm and the root canal was prepared using the F4 ProTaper Gold system. The specimens were covered with wax and then sealed in a thermoforming sheet, leaving a gap of 0.2 mm. Cannulas were attached to simulate stable fluid circulation. Thermographic evaluation was carried out using an infrared camera. The following methods were chosen for disinfection: I, λ445 nm diode laser (0.6 W, cw); II, λ445 nm diode laser, 3 W, pulsed, duty cycle 50%, 10 Hz; III, λ445 nm diode laser, 3 W, pulsed, duty cycle 75%, 10 Hz; IV, λ970 nm diode laser, 2 W, pulsed, duty cycle 50%, 10 Hz; V, λ970 nm diode laser, 2 W, pulsed, duty cycle 75%, 10 Hz; VI, experimental plasma device (2.5 W, 3.7 V); VII, heat plugger (200.0 °C); VIII, NaOCl 3% (60 °C). The results were analyzed statistically using the Kruskal–Wallis test. When there were significant differences between the groups (p < 0.05), the pairwise Mann–Whitney test with sequential Bonferroni correction was applied. Results: The smallest temperature changes, with a median value of 0.82 °C (max. 2.02 °C, min. 0.15 °C, IQR 0.87 °C), were observed using the laser at a setting of λ445 nm, 0.6 W cw, and a circulation rate of 6 mL/min. The highest temperature changes were measured at a fluid circulation rate of 0 mL/min with a laser setting of λ445 nm, 3 W, pulsed, duty cycle 75% with a median value of 21.7 °C (max. 25.02 °C, min. 20.29 °C, IQR 2.04 °C). Conclusions: Disinfection procedures with laser, NaOCl, and an experimental plasma device can lead to an increase in root surface temperature. With the exception of the heat plugger, no significant temperature changes were observed. This study was conducted in vitro, which may limit the direct applicability of the results to clinical scenarios. Nevertheless, the simulation of blood flow showed a thermally protective effect, suggesting that clinical protocols should consider this variable when selecting thermal disinfection methods. These results support the hypothesis that periodontal blood flow may have a potentially positive influence on temperature changes during disinfection procedures. Full article

The aim of this study is to evaluate the apical sealing ability of novel bioceramic-based (BCB) and widely used resin-based (RB) root canal sealers in combination with traditional or bioceramic-coated gutta-percha points. A total of 92 human single-root extracted teeth were endodontically treated and divided into three groups (A, B, and C) of 30 samples based on the endodontic sealer/type of gutta-percha points/obturation method used. One tooth sample was used for the negative and positive controls (each). Group A: BCB sealer BioRoot RCS (Septodont, Saint-Maur-des-Fossés, France)/bioceramic-impregnated gutta-percha TotalFill BC points (FKG Dentaire, La Chaux-de-Fonds, Switzerland)/cold hydraulic single-cone. Group B: BioRoot RCS (Septodont, France)/traditional Protaper Gold Gutta-Percha Points (Dentsply Sirona, Charlotte, NC, USA)/cold hydraulic single-cone. Group C: RB sealer AdSeal (Meta Biomed, Cheongju, Republic of Korea)/traditional Protaper Gold Gutta-Percha Points (Dentsply Sirona, USA)/warm vertical condensation. A dye penetration method was applied, and the length of apicocoronal penetration was measured using a surgical microscope. The data were statistically analyzed to evaluate differences at the 0.05 significance level. A significant difference was found between groups A and C, p = 0.0003, and groups B and C, p = 0.003. The data analysis proved that the BCB sealer using the cold hydraulic single-cone method ensured a substantially better seal than the RB sealer using the warm vertical condensation method. The choice of the type of gutta-percha points (bioceramic-coated or regular) appeared to be unimportant. No statistical significance was found between groups A and B, which indicates that using bioceramic-coated gutta-percha points does not bring any considerable benefit in view of a no-gap root canal obturation. Full article

Background/Objectives: This study aimed to assess and compare the elimination of the smear layer and microhardness of dentin in root canals after sequential versus continuous chelation using different agitation techniques. Methods: Sixty-four palatal roots of upper first molars were instrumented to size X3 (Protaper Next files). According to the irrigant solution, samples were assigned to two groups (N = 32/group), 3% NaOCl irrigation followed by 17% EDTA (sequential chelation (SC)), or dual-rinse (3% NaOCl/9% HEDP) irrigation (continuous chelation (CC)). Each group has been divided into four subgroups (n = 8/subgroup), based on agitation techniques used: conventional needle (CN) (control group), EndoActivator (EA), ultrasonic agitation (UAI), and Er.Cr.YSGG 2780 nm (laser). SEM images assessed the smear layer, and Vicker microhardness (VHN) was performed at 50 and 100 µm depths. Data were analyzed using: Kruskal–Wallis, Wilcoxon, and the Mann–Whitney U test. Statistical significance was set at p < 0.05. Results: In the UAI and laser agitation, CC significantly reduced the smear layer presence compared to SC in the apical and coronal thirds, respectively (p < 0.05), and no significant differences were observed in the CN and EA groups between SC and CC (p > 0.05). There were significantly higher VHNs of dentine in CC groups than in SC groups in all sections and depths, except in the apical of the CN group at 50 µm and the coronal section of EA and UAI groups at 100 µm. Conclusions: CC was comparable to SC in smear layer removal. CC had a less detrimental effect on dentin compared with SC. Full article

Recently, the single-cone hydraulic canal filling technique using bioceramic sealers was found to hinder retreatment due to the mechanical properties of the bioceramic sealers. This study assessed the effectiveness of four nickel–titanium rotary files in removing gutta-percha and bioceramic sealer from molar root canals in vitro. Eighty-eight root canals from extracted molars were instrumented with Vortex Blue rotary files and filled with gutta-percha and bioceramic sealer using a single-cone technique. After 30 days, the filled canals were randomly divided into four groups according to the file used for re-instrumentation: ProTaper Gold (PTG), Endo ReStart (ERS), XP-3D Shaper (XPD), and HyFlex Remover (HFR). This study assessed whether root canal filling material removal and patency were achieved within a 10-min time frame, recording the time required in seconds. The rate of regaining patency and the time required to achieve patency were compared among groups using a generalized linear model. Scanning electron microscopy was used to evaluate the mechanical changes to the files after use. The patency rate of XPD and HFR was significantly higher than PTG. ERS and XPD demonstrated shorter patency times than HFR and significantly shorter patency times than PTG. SEM images revealed a varied range of reverse windings across file groups. PTG and ERS exhibited microcracks and fractured tips, while XPD and HFR did not display these mechanical alterations. The four file systems in this study displayed varying levels of effectiveness in the retreatment of root canals filled with bioceramic sealers. Full article

The present research compared the design, metallurgical properties, and mechanical characteristics of the ProTaper Ultimate instruments with five multifile systems. A total of 469 new nickel–titanium rotary finishing instruments, all 25 mm in length but varying in size, taper, and metal alloy composition, from six different multifile systems (ProTaper Ultimate, ProTaper Next, ProFile, Mtwo, EndoSequence, and GT Series X), were inspected for irregularities and analyzed for their spiral density (spirals per millimetre), blade design, surface finishing, alloy composition, phase transformation temperatures, and mechanical performance (microhardness, torsional, and bending resistance tests). Group comparisons were performed using Kruskal–Wallis and one-way ANOVA with post hoc Tukey’s tests (α = 5%). ProFile instruments exhibited a greater number of spirals and a higher density of spirals per millimetre compared to the other systems. Microscopic analysis revealed distinct tip geometries and blade designs among tested instruments. All of them displayed parallel marks from the machining process, but the EndoSequence system had the smoothest surface finish. The alloys of all instruments consisted of an almost equiatomic ratio of nickel to titanium. At the testing temperature, the ProTaper Ultimate system exhibited a complete R-phase crystallographic arrangement, while the ProFile and Mtwo systems were fully austenitic. The ProTaper Ultimate F2, F3, and FX instruments demonstrated the highest maximum torque values (1.40, 1.45, and 3.55 N.cm, respectively) and the lowest maximum bending loads (202.7, 254.9, and 408.4 gf, respectively). EndoSequence instruments showed the highest angles of rotation, while the highest microhardness values were recorded for GT Series X (407.1 HVN) and ProTaper Next (425.0 HVN) instruments. The ProTaper Ultimate system showed a high spiral density per millimetre and a complete R-phase crystallographic arrangement at room temperature, which significantly contributed to its superior flexibility and torsional strength when compared to the other tested systems. Full article

Background/Objectives: Nickel–titanium (Ni-Ti) rotary instruments have significantly enhanced the efficiency and safety of root canal shaping. However, the variety of Ni-Ti systems, characterized by differences in alloy composition, taper design, and heat treatment, may influence their usability, particularly for novice operators. This study aimed to evaluate the perceptions of dental students using four Ni-Ti rotary systems (MTwo, SlimShaper Pro, ProTaper Gold, and HyFlex EDM) in a simulated environment. Methods: Forty dental students from two universities participated in the study and completed a standardized preoperative training session. Root canal shaping was performed on resin teeth models, and an 11-item questionnaire was used to assess various parameters, including flexibility, ease of use, and the ability to maintain working length. Results: The results indicated significant differences in student feedback. SlimShaper Pro and HyFlex EDM were preferred for their flexibility, reduced resistance, and ease of instrument transitions, likely due to their smaller tapers and martensitic alloys. MTwo was rated the least flexible and more challenging to use. Conclusions: These findings underline the importance of user-friendly Ni-Ti systems in pre-clinical training to reduce procedural difficulties and operator stress. Further research should validate these findings in clinical settings to improve the training of novice operators. Full article

This study aimed to evaluate the efficacy of various nickel–titanium (Ni-Ti) root canal instrumentation systems in preserving root canal anatomy, focusing on their capacity to limit changes in canal angulation. One hundred canals in fifty extracted human molars were prepared with different techniques: Step-Back, Reciproc, MTwo, ProTaper Universal (PTU), and ProTaper Next (PTN). The curvature of each canal was measured before and after treatment using Schneider’s methodology, a widely accepted method for assessing canal curvature. Descriptive and statistical analyses, including the Kruskal–Wallis test, were employed to compare angular changes across the systems. The results indicated that all techniques effectively reduced canal curvature, with each system exhibiting a reduction in mean canal angle after instrumentation. Although the Reciproc system showed the smallest mean change in angulation, no statistically significant differences were identified between any of the systems (p = 0.182). This finding suggests that while minor differences in performance may exist, they do not translate into clinically meaningful distinctions in preserving root canal anatomy. The Reciproc system’s slight advantage aligns with other studies, highlighting its conservative design and minimal dentinal stress; however, its superiority was not statistically validated in this study. The results suggest that all five systems are clinically comparable in preserving root canal anatomy, highlighting that dentists can choose from these widely available techniques without compromising anatomical preservation. While this study had limitations, including a relatively small sample size and an in vitro design, it aligns with previous findings on the mechanical behavior of Ni-Ti systems in endodontic practice. Full article

Background/Objectives: This study investigates the temperature changes on the external root surface during root canal preparation using different rotary systems and assesses the impact of irrigation temperatures. Methods: Sixty extracted human maxillary incisors were divided into four groups based on the rotary system used: ProTaper Next (Dentsply Sirona, Ballaigues, Switzerland), Reciproc Blue (VDW GmbH, Munich, Germany), WaveOne Gold (Dentsply Sirona, Ballaigues, Switzerland), and TruNatomy (Dentsply Sirona, Ballaigues, Switzerland). These systems differ in cutting efficiency and design. Temperature measurements during instrumentation and irrigation were recorded using a FLIR E60bx thermal camera (Teledyne FLIR LLC, Hudson, NH, USA). Irrigations were conducted with sodium hypochlorite at room temperature and heated to 60 °C. Results: The ProTaper Next group exhibited the highest average temperature increase during instrumentation (5.2 °C), followed by WaveOne Gold (4.3 °C), Reciproc Blue (3.7 °C), and TruNatomy (2.8 °C). During irrigation with heated sodium hypochlorite, temperature rises recorded were 6.8 °C for ProTaper Next, 5.9 °C for WaveOne Gold, 5.2 °C for Reciproc Blue, and 4.1 °C for TruNatomy. Statistical analysis revealed a significant negative correlation between dentin thickness and temperature rise, with r-values ranging from −0.62 to −0.87 across the groups. No significant correlation was found between canal diameter and temperature change, indicating that the canal’s size does not influence the thermal impact as much as the properties of the rotary system and irrigation temperature. Conclusions: Different rotary systems produce varying levels of temperature increases on the external root surface, influenced significantly by the thickness of the dentin and the temperature of the irrigation solution. These variations necessitate careful selection of instrumentation and irrigation protocols to minimize potential thermal damage to surrounding periodontal tissues. Full article

Background: Adhesion within endodontic obturation material and root canal walls improves the efficacy of the endodontic treatment by establishing a barrier that inhibits reinfection and entombs residual bacteria. This study evaluates the push-out bond strength (POBS) of calcium silicate sealers compared to an epoxy-resin-based sealer. Methods: A total of 36 extracted mono-radicular teeth were prepared with Pro Taper Ultimate and irrigated with 5.25% sodium hypochlorite and 17% EDTA. The specimens were randomly split into three groups (n = 12) according to the endodontic sealer and filling technique used as follows: Ah Plus with the continuous wave condensation technique (CWC), Ah Bioceramic (Ah Bio) with the single-cone technique, and Total Fill Hi-Flow (FKG Hi-Flow) with the CWC technique. The material was allowed to set for 4 weeks, and afterwards, the roots were placed in acrylic resin and sectioned into 1 mm transverse slices. A POBS test was conducted using a universal testing machine, and the mode of bond failure was assessed at 4× magnification using a stereomicroscope. Six specimens from each group were selected for SEM-EDX examination to evaluate dentinal tubule penetration. The data were analysed using analysis of variance and Tukey and Bonferroni post hoc tests. Results: The POBS tests revealed higher values for Ah Plus in comparison to both calcium silicate sealers (p < 0.001), while FKG Hi-Flow showed superior results to Ah Bio (p < 0.001). The cohesive mode of failure was prevalent in all three groups. Conclusions: In conclusion, the resin-based sealer showed higher bond strength and better dentinal tubule penetration than the two calcium silicate sealers tested, while FKG Hi-Flow outperformed AH Bio. Full article

Background and Objectives: The access cavity design and instrumentation system could affect the remaining root canal obturation materials in root canal retreatment. This study aimed to evaluate the efficiency of two different multi-file systems in removing obturation materials with two different access cavities utilizing micro-CT scanning. Materials and Methods: Conservative access cavity (CAC) preparation was performed for 80 mandibular premolars. Then, root canal preparation was employed followed by obturation. The retreatment process began by dividing the samples into two separate groups: conservative (CAC) and traditional (TAC) access cavities. Subsequently, these groups were assigned to eight distinct subgroups (n = 10): Group 1; TAC and ProTaper retreatment system (PTR) with ProTaper Next (PTN); Group 2, TAC and PTR + ProTaper Ultimate (PTUL); Group 3, TAC and PTN; Group 4, TAC and PTUL; Group 5, CAC and PTR + PTN; Group 6, CAC and PTR + PTUL; Group 7, CAC and PTN; and Group 8, CAC and PTUL. The samples underwent micro-CT scans before and after the retreatment process, and the volume and percentages of remaining root canal filling material were calculated. Statistical analysis of the data was performed, and significance was determined at the 5% level. Results: The influence of the access cavity design (p = 0.500), the ProTaper system (p = 0.138), and the interaction of these variables (p = 0.513) was insignificant. However, group 3 (TAC and PTN) showed the highest percentage of remaining obturation materials at 29.53%, contrasting with group 6 (CAC and PTR + PTUL). Conclusions: Neither retreatment procedure succeeded in completely removing filling materials. Nevertheless, the impact of access cavity design, different multi-file systems, and their interaction on the remaining root canal obturation materials was deemed insignificant. Full article

Objectives: Apical extrusion of debris can affect the success of endodontic treatments, and the specific performance of certain retreatment systems has not been studied yet. Therefore, the aim of this in vitro study was to quantitatively assess the amount of apically extruded debris produced during retreatment procedures using three rotary NiTi retreatment systems in mature non-resorbed straight roots. Methods: Thirty extracted permanent human teeth with single straight roots were selected. The root canals were prepared with the ProTaper Next system up to size 30 and obturated with gutta-percha and AH Plus sealer using the continuous wave of condensation technique. The samples were stored for 30 days and randomized by computer sequence into three retreatment groups (n = 10): (1) ProTaper Universal Retreatment; (2) HyFlex Remover; and (3) VDW.Rotate Retreatment. Apically extruded debris was collected in Eppendorf tubes and weighed with a microbalance (10⁻⁵ g) before and after retreatment procedure. As the data were not normally distributed, the Kruskal–Wallis test was applied for comparing data among groups, with an alpha level set at α = 0.05. Dunn’s test was considered for post-hoc analyses, if appropriate. Results: Hyflex Remover was associated with the highest amount of extruded debris (0.85 ± 0.82 mg), followed by VDW.Rotate Retreatment (0.78 ± 0.41 mg) and ProTaper Universal Retreatment (0.62 ± 0.28 mg). However, the differences were not statistically significant (p > 0.05). Conclusions: All the retreatment systems tested were associated with apical extrusion of debris in vitro, with no significant quantitative differences between them, suggesting that clinicians can choose a retreatment system with features appropriate to the specific clinical situation without risk of increasing the amount of apically extruded debris. Full article

Background: The shaping of root canal space was completed using manual stainless steel files in earlier decades and with the advent of mechanical nickel–titanium (NiTi) instruments, there is potential for more efficient root canal preparation. Despite the advantages of NiTi instruments, their adoption in undergraduate dental education remains limited. The aim of this study was to evaluate three root canal instrumentation techniques, manual instrumentation using stainless steel hand files, continuous rotation employing ProTaper Gold (PTG) files, and reciprocation with WaveOne Gold (WOG) files, on endodontic resin blocks to assess the quality of preparation and the time required for instrumentation. Methods: A total of 36 third-year dental students, all lacking prior experience in root canal procedures, were divided into six groups to prepare 108 resin endodontic blocks with each student preparing 3 blocks. Images were captured at the preoperative, intraoperative, and postoperative stages to facilitate comparisons and measurements of the prepared blocks to assess the degree of resin removal, apical deviation, and mid-cervical wear. Furthermore, questionnaires were distributed to assess the students’ experiences and satisfaction with the techniques. The Friedman test, Wilcoxon test with Bonferroni correction, and Kruskal–Wallis test with Mann–Whitney U test were used to analyse and compare techniques, with the level of significance set at p < 0.05. Results: Instrumentation with PTG exhibited significantly reduced apical deviation (0.073 ± 0.003) compared to both the WOG and manual instrumentations (p < 0.001). Significant differences in mid-cervical wear were observed only between PTG and the manual instrumentation. In terms of resin removal, the manual instrumentation displayed greater variability and was five times slower to complete the instrumentation. In total, 90% of students favoured mechanical instrumentation, with substantial preferences for them over manual techniques. Conclusions: Mechanical instrumentation techniques, notably with the PTG system, were significantly faster and more effective in preparation quality. This highlights the potential for the inclusion of mechanical instrumentation in undergraduate dental curricula. Full article

Depending on the obturation technique, the tooth and surrounding tissues may heat up during root canal filling, particularly with warm methods. This study aimed to analyze the temperature increase in the periradicular and -apical region during various warm obturation techniques with a present simulated periodontal blood flow. Seventy-five extracted human teeth were shortened to 11 mm (cut-grinder Primus diamond cutting device; Walter Messner GmbH, Oststeinbek, Germany) and prepared using the ProTaper Gold system (Dentsply Sirona Inc., Charlotte, NC, USA) ISO size 40/.06. Specimens were prepared to ensure stable fluid circulation in an artificially created periodontal space, and the procedure was recorded with a thermal infrared camera (VarioCAM HD; InfraTec GmbH Infrarotsensorik und Messtechnik, Dresden, Germany). The following obturation methods were applied: I, cold single-cone obturation (control group); II, gutta-percha-coated rigid carrier technique (GuttaFusion); III, squirting technique (injection technique); IV, continuous wave technique; and V, Schilder technique. Statistical analysis was performed using the Kruskal–Wallis test, followed by the Mann–Whitney pairwise test using the sequential Bonferroni procedure for significant differences (p < 0.05). The Schilder technique with 0 mL/min showed the lowest temperature change, with a median of 0.00 °C (max. 0.00 °C, min. 0.00 °C, IQR 0.00 °C). In contrast, the continuous wave technique at a circulation rate of 2.6 mL/min exhibited the highest temperature change, with a median of 3.76 °C (max. 5.33 °C, min. 2.42 °C, IQR 1.46 °C). Although warm obturation techniques can increase surface temperature, none of the methods produced changes that were potentially damaging to the periodontium or surrounding bone. Full article