When a radiotracer is injected into a patient\'s body as part of a nuclear medicine investigation, the entire body is exposed to the ionizing radiation emitted, which can cause biological damage. Therefore, it is important to predict the internal radiation dose to properly balance the advantages of radiological examinations. Currently, various Monte Carlo tools, such as MCNP, Geant4, and GATE, are available to estimate internal radiation dosimetry-related quantities, such as S values (S) and specific absorbed fractions (SAF). Such codes make physics easier for physicists who are experienced with computer programming; however, programming and/or simulation inputs remain a time-consuming and intensive task. In this study, we present a newly developed Geant4-based code for internal dosimetry calculations, namely \"DoseCalcs\". To assess the performance of the geometrical methods and computational capabilities of our developed tool, we used the GDML, TEXT, STL, and C++ methods to model the ORNL adult phantom, and a voxel-based structure to construct the ICRP adult male. SAFs in the ORNL and ICRP adult male phantoms for eight discrete mono-energetic photons with energies ranging from 0.01 to 2 MeV are calculated with DoseCalcs and compared to ORNL and OpenDose reference data. The two phantoms showed good agreement with both references, which indicates the accuracy of DoseCalcs for subsequent use in estimating internal dosimetry quantities using a variety of geometrical methods.

To appraise the outcome of file systems and activation of the final irrigant on the push-out bond strength of root fillings in oval canals. Single-rooted mandibular premolars (n = 180) with oval canals were divided into three groups (n = 60) for instrumentation: ProTaper Next (PTN), WaveOne (WO), and Self-adjusting File (SAF). The specimens were further divided into subgroups (n = 20) and subjected to final irrigation with activation by EndoActivator or passive ultrasonic irrigation or without activation. Then, the specimens were again subdivided (n = 10) and obturated with gutta-percha and AH Plus (GP-AH) or C-Point with EndoSequence bioceramic sealer (C-EBC). One-millimeter-thick horizontal slices were cut from the apical third of the root, 5 mm from the apex, and subjected to push-out bond strength (BS) testing. Specimens for which SAF was used exhibited higher BS values than those for which PTN or WO was used (p < 0.05). Activation of the final irrigation did not affect the BS of the root fillings. Root fillings made of C-EBC presented a higher BS than those made of GP-AH (p < 0.05). Adhesive failure was more common with specimens instrumented using PTN and WO. Root canals instrumented with SAF, showed the highest bond strength values for both root filling materials. The C-EBC produced significantly higher bond strength values than those of the GP-AH.

Background. Pediatric endodontics is a field with constant evolution, resulting in the shifting of paradigms from the use of conventional hand files to rotary files for biomechanical preparation in primary teeth. Biomechanical preparation plays a crucial role in the success of root canal treatment. Primary teeth need special attention since they differ from permanent teeth in root canal morphology. Cleaning and shaping of the canals damage the root dentin, leading to dentinal cracks. Newer techniques for root canal preparation, including Ni-Ti rotary files and SAF system, have been developed for use in pediatric endodontics to overcome the drawbacks of conventional methods. The present study compared dentinal defects formed by rotary systems in primary teeth. Methods. Eighty primary teeth were included. The teeth were decoronated with a diamond disc. All the roots were inspected for any pre-existing cracks or craze lines under transmitted light under a stereomicroscope. The specimens were then divided into four groups (n=20): group 1: control, group 2: hand files (HF), group 3: ProTaper files, and group IV: SAF files. The samples were instrumented according to the group they were assigned to. Results. The HF and SAF groups exhibited fewer microcracks. Dentinal microcracks were observed in roots prepared with rotary ProTaper files. There were significant differences between HF/SAF and rotary files (P <0.05). Conclusion. Stainless steel hand K-files and SAF instruments resulted in fewer dentinal damage than the ProTaper Universal files. SAF exhibited satisfactory results with minimal or no crack formation.

UNASSIGNED: To compare the formation of dentinal defects using stainless-steel hand K-files (HFs), rotary files, reciprocating files, and Self-Adjusting File (SAF), when used for oval root canals.
UNASSIGNED: One hundred and forty extracted human mandibular premolar with single root and oval canal were selected for this study. Oval canals were confirmed by exposing to mesio-distal and bucco-lingual radiographs. Teeth with open apices or anatomic irregularities were excluded. All selected teeth were de-coronated perpendicular to the long axis of the tooth, leaving roots segments approximately of 16 mm in length. Twenty teeth were left unprepared (control), and the remaining 120 teeth were divided into 6 groups (n = 20) and instrumented using HF (size 40/0.02), Revo-S (RS; size 40/0.06), ProTaper NEXT (PTN; size 40/0.06), WaveOne (WO; size 40/0.09), RECIPROC (RC; size 40/0.06), and the SAF (2 mm). Roots were then sectioned 3, 6, and 9 mm from the apex, and observed under stereomicroscope, for presence of dentinal defects. \"No defect\" was defined as root dentin that presented with no visible microcracks or fractures. \"Defect\" was defined by microcracks or fractures in the root dentin.
UNASSIGNED: The control, HF, and SAF did not exhibit any dentinal defects. In roots instrumented by RS, PTN, WO, and RC files exhibited microcracks (incomplete or complete) in 40%, 30%, 55%, and 50%, respectively.
UNASSIGNED: The motor-driven root canal instrumentation with rotary and reciprocating files may create microcracks in radicular dentine, whereas the stainless-steel hand file instrumentation, and the SAF produce minimal or less cracks.

OBJECTIVE: The focus of this study was to find a correlation between the forces and vibrations during root canal shaping. This can be used to predict the fracture of the self-adjusting file (SAF) in root canal shaping.
METHODS: Forty J-shaped resin blocks were used in this study. Simulated root canals of resin blocks were prepared with the SAF. Force and vibration during root canal shaping were measured by dynamometer and accelerometer respectively. The recorded time domain signal of force and vibration were transformed to frequency domain signals. Frequency domain signals had been used for correlation study between force and vibration amplitude. The root mean square (RMS) value of force and vibration signature for new file and file just before failure were statistically compared using t-test at 95% confidence interval (CI).
RESULTS: Vibrations generated during root canal shaping exhibited positive linear correlation (r = 0.9173) with force exerted by the SAF on the root canal. It means vibration has strong correlation with force. The RMS values of force and vibration increase significantly (P < 0.05) just before the fracture.
CONCLUSIONS: From force and vibration analysis of SAF it was concluded that the vibration is well associated with force applied by the SAF on root canal. Therefore, the trend of force variation was reflected in the vibration signature. The sudden increment in vibration was the symptom of bulge formation and the end of useful life of the SAF.

OBJECTIVE: The objective of this study is to determine the potential for microcracks in the radicular dentin of first maxillary premolars using three different mechanized endodontic instrumentation systems.
METHODS: Eighty extracted maxillary first premolars with two root canals and no externally visible microcracks were selected. Root canal instrumentation was performed with either the ProTaper file system, the WaveOne primary file, or the self-adjusting file (SAF). Teeth with intact roots served as controls. The roots were cut into segments and examined with an intensive, small-diameter light source that was applied diagonally to the entire periphery of the root slice under ×20 magnification; the presence of microcracks and fractures was recorded. Pearson\'s chi-square method was used for statistical analysis, and significance was set at p < 0.05.
RESULTS: Microcracks were present in 30 and 20 % of roots treated with the ProTaper and WaveOne systems, respectively, while no microcracks were present in the roots treated with the SAF (p = 0.008 and p = 0.035, respectively). Intact teeth presented with cracks in 5 % of the roots. The intensive, small-diameter light source revealed microcracks that could not be detected when using the microscope\'s light alone.
CONCLUSIONS: Within the limitations of this study, it could be concluded that mechanized root canal instrumentation with the ProTaper and WaveOne systems in maxillary first premolars causes microcracks in the radicular dentin, while the use of the SAF file causes no such microcracks.
CONCLUSIONS: Rotary and reciprocating files with large tapers may cause microcracks in the radicular dentin of maxillary first premolars. Less aggressive methods should be considered for these teeth.

This study aims to compare the efficacy of different irrigation activation methods to remove smear layer and debris from oval-shaped root canals following retreatment. Ninety mandibular canines with oval-shaped root canals were selected. Retreatment was performed with R-Endo retreatment files. The samples were randomly divided into six groups (n = 15). Groups were assigned according to agitation technique: R-Endo with classic irrigation, with self-adjustable file, with passive ultrasonic irrigation, R-Endo + Er:YAG, R-Endo + PIPS and R-Endo + Nd:YAG. Compared with the classic irrigation (R-Endo + CI) group, all other groups were more successful in reducing smear layer and debris (P < 0.05). The least amount of residual smear layer and debris was detected in the Er:YAG laser group (P < 0.05). Additional use of different agitation methods contributes to removal of debris and smear layer following root canal filling removal with rotary instruments; however, none of the techniques tested render root canal walls completely free of smear layer or debris.

OBJECTIVE: The aim was to evaluate ex vivo apical debris extrusion associated with WaveOne and Self-Adjusting File instruments when used in oval canals.
METHODS: Twenty-four extracted human mandibular premolars with oval-shaped canals were assigned in two equal groups. Following coronal cavity preparation, a glide path was created. Group A was subjected to canal preparation using a WaveOne primary file, which was used along with syringe and needle irrigation and 10 mL of 2.4 % NaOCl solution, followed by flushing with 10 mL of 17 % EDTA solution, activation with EndoActivator for 1 min and final flushing with 10 mL of 2.4 % NaOCl solution, and activation for 30 s. Group B, the SAF system was used with continuous simultaneous irrigation, provided by the system\'s pump. The irrigant was supplied at 5 mL/min, alternating every minute between 2.4 % NaOCl solution and 17 % EDTA solution, over a total of 4 min followed by final flushing with 10 mL of 2.4 % NaOCl solution. Extruded apical debris from each root canal was collected into a preweighed glass vial and dried. The mean weight of the debris from each group was assessed and analyzed statistically. Both systems resulted in apical debris extrusion.
RESULTS: The WaveOne system was associated with a statistically significant greater mean mass of apically extruded debris (2.18 ± 0.44 mg) than the SAF system (0.49 ± 0.33 mg, permutation-based Wilcoxon test, p < 0.001).
CONCLUSIONS: Both WaveOne and the SAF systems were associated with apical debris extrusion. The amount of debris extruded by the WaveOne system was 4.4 times greater than that extruded by the SAF system.
CONCLUSIONS: The results of the present ex vivo comparative study cannot be directly applied to the clinical situation. Difference between both groups remains completely unclear; maybe the amount of extrusion is harmless in both groups or similarly deleterious for the periradicular tissues in both groups or may be dose-related to the amount of the extruded material.