The aim of the present study was to evaluate the agreements between the root canal length estimations using cone-beam computed tomography (CBCT) at different slice thicknesses, dedicated software, or ...an electronic apex locator (EAL) and the actual lengths (AL). In total, 111 extracted human molars with 302 root canals were chosen. Teeth were scanned using a CBCT device at a voxel size of 0.075 mm. Root canal lengths were estimated using CBCT software at different slice thicknesses (0.6, 1.2, and 2.4 mm) and dedicated software for proposed or operator lengths. The endodontic access cavities were created, and root canal lengths were estimated with an EAL for electronic length (EL) and a ruler for AL. Data were tested using paired t-tests and Bland-Altman plots to detect the differences between the methods in length estimation at a significance of 0.05. The accuracy in the range of ± 0.5 mm was 100% for the EAL. There was an agreement between the EL and CBCT at a slice thickness of 1.2 mm (p = 0.349). CBCT at the smallest slice thickness estimation was not the best modality in agreement with the AL. The EAL was an accurate and reliable method for root canal length measurement.
The aim of this study is to investigate the accuracies and the agreements of the 3D Endo software, conventional CBCT software Romexis Viewer at three voxel sizes, and the EAL ProPex Pixi in ...endodontic length measurements. Three hundred and twenty-nine root canals in 120 intact human extracted molars were accessed. The actual lengths (AL) and electronic lengths (EL) were measured using the ruler and electronic apex locator (EAL), respectively. Teeth were scanned using the CBCT at different voxel sizes (0.075, 0.10, and 0.15 mm). Root canal lengths were measured using 3D Endo with proposed length (3D-PL) by software, corrected length (3D-CL), Romexis Viewer. The Fisher's exact test, paired t-test and Bland-Altman plots were calculated to detect the agreements of the four methods with AL measurements. The ProPex Pixi measurements obtained the highest accuracy in the range of ± 0.5 mm. There was agreement between the 3D-PL and the 3D-CL with AL measurements at voxel size of 0.15 mm and at voxel size of 0.10 mm, respectively. The CBCT Romexis Viewer measurements agreed with AL at three voxel sizes. The conventional CBCT measurements using Romexis Viewer and dedicated software did not reach to the 100% accuracy in the range of ± 0.5 mm.
The present study aimed to measure the number of cycles to fracture (NCF) of different instruments using pecking motion at constant and varying distances of movement at body temperature. This study ...included 20 files from each brand: ProTaper Universal F2, ProTaper Next X2, and WaveOne Gold Primary (Dentsply Sirona, Maillefer, Ballaigues, Switzerland). Instruments from each brand were divided into two groups (ten files for each group) that experienced constant or variable distances in a stainless-steel artificial double-curved canal in a platform that ensured that the instrument rotated at a stable temperature with a minimum fluctuation of the environment. While running, the platform was programmatically controlled to move at any desired distance of instrument displacement to simulate the clinical pecking motion at variable distances. The files were rotated using proprietary programs. The times to fracture were recorded and then transformed into the number of cycles to fracture (NCF). Data were analyzed using Minitab with proper tests. All fragments were observed under a scanning electron microscope to capture and describe the characteristics of the fracture surface. The WaveOne Gold had the highest NCF, while the ProTaper Universal had the lowest NCF. The manufacturer brands and the modes of displacement of the experimental instrument showed interactive effects. The fracture surface revealed no striation. A new design, material, mode of rotation, and different distances of movement have certain effects on the cyclic fatigue resistance of the instrument.
The purpose of this study was to assess the effect of a calcium silicate-based sealers (CeraSeal) and an epoxy resin-based sealer (AH Plus) on cytotoxicity and cell migration of stem cell from the ...human apical papilla (hSCAPs) by using the Alamar Blue, Annexin V-FICT and wound healing assays. In Alamar Blue assay, hSCAPs exposed to undiluted CeraSeal extract had significantly higher cell viability compared with that observed when cells were treated with AH Plus in all experimental period (p < 0.001). The flow cytometry analysis confirmed the comparison on viable cells and indicated that AH Plus increased apoptosis compared to CeraSeal and the control groups (p < 0.001). Additionally, AH Plus exhibited significantly lower level of cell migration than CeraSeal and the control for up to 48 h observation (p < 0.01). In summary, calcium silicate-based sealer (CeraSeal) is less cytotoxic and more biocompatible than epoxy resin-based sealer (AH Plus).
The aim of the present study is to compare cone beam computed tomography and periapical digital radiography for the evaluation of root canal preparation. Nine extracted human molars were used in this ...study. Following access cavity preparation, mesio-buccal roots of maxillary and mesial roots of mandibular molars were prepared and the remaining roots were cut off. Three amalgam cavities were prepared on the coronal part of the teeth and were filled with amalgam to be used as landmarks. Specimens were scanned using cone-beam computed tomography and periapical digital radiograph images were obtained before and after root canal preparation. WaveOne Gold Primary was used for root canal preparation to full working length. Specimens were then scanned using CBCT and a periapical radiograph for the after-instrumentation images. The transportation and centering ratio were measured and calculated on the CBCT and periapical radiographic images. The Bland–Altman method was used for detecting the bias in the evaluation of agreement between the two methods’ measurements. There was agreement between the two methods’ measurements using CBCT scans and periapical digital radiographic images in the evaluation of transportation and centering ratio parameters. The two methods could be used interchangeably in measurements of transportation and calculating the centering ratio.
The present study aimed to evaluate the effectiveness of using platelet-rich fibrin (PRF) as the apical matrix for the placement of MTA in nonsurgical endodontic therapy for teeth with periapical ...lesions and open apices.
Twelve teeth from eleven patients with periapical periodontitis and open apices were enrolled in the study. Nonsurgical endodontic therapy was performed with the PRF used as an apical barrier and the MTA manipulated as an apical plug for further thermoplasticized gutta percha in the remaining part of the root canal. Clinical signs and periapical digital radiographs were recorded and analyzed to evaluate the curing progress after periodical follow-ups of 1, 3, and 6 months. The horizontal dimension of the periapical lesion was determined, and the changes in the dimensions were recorded each time. The Friedman test was used for statistical analysis, with P < .05 serving as the threshold for determining statistical significance.
All patients had no clinical symptoms after the first month of treatment, with a significant reduction in the periapical lesion after periodical appointments.
PRF is an effective barrier when combined with MTA for the treatment of teeth with periapical periodontitis and open apices.
To introduce a new method for measurement of surface roughness of the endodontic instrument, before and after instrumentation, using the Field Emission Scanning Electronic Microscope (FE-SEM) ...combined with the ImageJ software.
Twenty J-shape resin blocks were divided into two groups, ten blocks of each group. Simulated root canal inside the resin block was 16 mm length, 60
angle of curvature, and radius of 4.5 mm. Ten WaveOne Gold Primary and 10 Reciproc Blue R25 instruments were used for root canal instrumentation. The instruments were scanned before and after instrumentation with special molds made to ensure the same areas at the point located 3 mm from the tips of the instruments using the FE-SEM. These scanned images were analyzed using the ImageJ. The arithmetical mean roughness (R
), root mean square roughness (R
), and the average distance between the highest peak and lowest valley in each sampling length (R
) were calculated by ImageJ for quantitative analyses. The paired-t test was performed to analyze the data using the SPSS 22.0 at the significance of .05.
Almost all surface roughness values were decreased. However, these decreases were not statistically significant (P > .05).
The FE-SEM combined with the ImageJ was the reliable and appropriate modality for measurement surface roughness of instruments.
The present study aims to measure the number of cycles leading to fracture (NCF) of instruments in static and dynamic cyclic fatigue situations under body temperature in stainless steel double-curved ...canals. The framework was constructed to establish the movement of instruments occurring at a stable body temperature. A step motor, a holding system for an endodontic handpiece, created the movement in and out of the artificial canal of the file mounted on the handpiece. A total of 30 instruments of ProTaper Universal and ProTaper Next (Dentsply Sirona, Maillefer, Ballaigues, Switzerland) were divided into three groups of 10 per group. For group 1 (10 PTU F2), files were rotated in static cycles. For groups 2 (10 PTU F2) and 3 (10 PTN X2), files were rotated in dynamic cycles. Files were rotated using proprietary programs, and the times the files were rotated before fracture were recorded. Data were analyzed using survival probabilities and regression with life data. The ProTaper Next in the dynamic cycles had the largest NCF, and the ProTaper Universal in the static condition had the least. New modes of rotation, material, and design have affected the cyclic fatigue resistance of the instrument.
Abstract
Background
The transformation temperatures were important values, influencing the mechanical properties and clinical performance of nickel-titanium instruments. The aim of this study was to ...determine the transformation temperatures of three rotary nickel-titanium (NiTi) instruments: Reciproc, HyFlex CM Pro, and Neoniti before and after simulated clinical uses.
Methods
Ninety new NiTi instruments of three single-file instruments: Reciproc, HyFlex CM Pro, and Neoniti were divided into three groups. Thirty instruments of each group were divided into 3 subgroups (10 instruments for each subgroup): new, one-time simulated clinical used and sterilised, and three times simulated clinical used and sterilized subgroups. The instruments were in the as-received condition for the new subgroups, one time used in the plastic endo-training blocks and sterilised for the one-time subgroups, and three times used in the plastic endo-training blocks and sterilised for the three times subgroups. Each instrument in subgroups was cut into four small segments of 4–5 mm. All segments of instruments were analysed using Differential Scanning Calorimetry (DSC). Data was collected and analysed using SPSS version 20.0 with ANOVA test or Kruskal–Wallis test at the significant level of 0.05.
Results
There was not significant difference between before and after simulated clinical use with sterilised procedure in three NiTi instrument systems. The austenite-finish (A
f
) temperatures of three instrument systems were higher than that of the human body (37 °C), of these, the A
f
temperature of Neoniti was highest and that of HyFlex CM Pro was lowest.
Conclusions
The austenite-finish (A
f
) temperatures of three NiTi instruments were higher than that of human body temperature, therefore, material was in the phase transformation from martensite to austenite, gives the instruments more flexibility when used in the clinical situation.
This study examined the interrelations among vegetative cover and biomass, soil macronutrient levels, and soil erosion in northern Vietnam.
We selected ten dominant land-use types in a hilly area of ...western Hanoi including bare soil, agriculture (cassava or lemon grass), shrub land, five types of plantation forest, and indigenous forest. We measured the understory biomass, litter biomass, canopy openness, soil moisture content, soil pedestal height, soil hardness, soil bulk density, 137Cs and 210Pbex activities, and soil carbon and nitrogen on three 1m2 plots for each land-use type. Soil erosion was calculated from both pedestal heights and radionuclides. Multivariate statistical analysis was used to identify the key factors controlling soil erosion and nutrient accumulations.
Understory biomass ranged from 2 to 375gm−2, and this tended to be higher in most of the forest types and shrubland than in cassava and lemon grass. In contrast, the amount of ground cover varied more by forest type than between the agricultural land uses and forest lands. The height of soil pedestals indicated that short-term soil erosion was negligible when understory biomass was greater than 130 to 150gm−2. 137Cs was only detected in the cassava plots, whereas 210Pbex indicated widely different erosion rates across the land uses, with lower values in the agricultural lands and two types of forest plantations, although this may be due to soil management practices. Both the correlation and principal component analyses showed that soil organic carbon and nitrogen were positively correlated to understory biomass and strongly and inversely influenced by bulk density. Soil erosion as indicated by soil pedestal height was strongly and inversely controlled by ground cover, litter, and understory biomass. Soil erosion was also heavily influential to soil chemical richness and bulk density.
Ground vegetation cover and the resultant soil erosion processes altered the production and accumulation of SOC, while forest cover did not always result in high soil fertility or low erosion. A simple characterization of forest or non-forest is not sufficient to calculate carbon and nutrient stocks, or assess erosion risk.
Understory biomass of at least 130gm−2 and high ground cover are essential for reducing soil erosion and sustaining short- and long-term soil productivity.
Rapidly developing areas in Southeast Asia, including hilly areas in North Vietnam, need to maintain understory biomass and ground cover for soil and nutrient conservation.
•Variability among forest types was comparable to the variability between land uses.•Soil organic carbon and nitrogen increased with understory biomass.•Surface cover was an important control on short- and long-term erosion rates.•The interactions among vegetation, soil characteristics, and erosion are complex.•Vegetation and soil erosion may feedback into both SOC production and accumulation.
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