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When selecting an instrument for canal preparation, it is important to consider several parameters that influence the shaping efficiency, including instrument design, metallurgy, and operating motion. This study aimed to evaluate the shaping ability of the ProTaper Next (PTN), WaveOne Gold (WOG), and XP-endo Rise Shaper (XPRS) rotary systems in severely and abruptly curved root canals using cone beam computed tomography (CBCT) and ImageJ software. Forty-eight mesial root canals of the mandibular first molars were assigned equally to three groups: PTN, WOG, and XPRS. Using ImageJ software, CBCT images were acquired pre- and post-instrumentation to assess dentin removal, remaining dentin thickness (RDT), canal transportation, and centering ratio at the coronal, middle, and apical levels. Statistical analyses were conducted on all numerical data. All rotary systems removed significantly more distocoronal dentin in the danger zone (DZ), than the mesiocoronal area. PTN removed significantly more dentin and caused less RDT than XPRS (p < 0.05). However, there were no significant differences between PTN-WOG and WOG-XPRS. In the DZ, the highest percentage of specimens with an RDT < 0.5 mm was observed when using PTN (50%), followed by WOG (31.3%), and XPRS (6.3%). Compared with PTN and WOG, XPRS demonstrated less coronal transportation. Among all rotary systems, there was no significant difference in apical transportation or centering ratio. Based on our observations, all rotary instruments exhibited a tendency to remove dentin in the DZ, but to different degrees. XPRS demonstrated better results in terms of coronal transportation and dentin thickness in the DZ. Comparable centering abilities and minimal apical transportation were demonstrated using all rotary instruments. [ABSTRACT FROM AUTHOR]

Proactive prevention and fighting fire at industrial facilities, often located in urbanized clusters, should include the use of modern methods for modeling danger zones that appear during the spread of the harmful combustion products of various chemicals. Simulation modeling is a method that allows predicting the parameters of a danger zone, taking into account a number of technological, landscape, and natural-climatic factors that have a certain variability. The purpose of this research is to develop a mathematical simulation model of the formation process of a danger zone during an emergency at an industrial facility, including an explosion of a container with chemicals and fire, with the spread of an aerosol and smoke cloud near residential areas. The subject of this study was the development of a simulation model of a danger zone of combustion gases and its graphical interpretation as a starting point for timely decision making on evacuation by an official. The mathematical model of the process of danger zone formation during an explosion and fire at an industrial facility presented in this article is based on the creation of a GSL library from data on the mass of explosion and combustion products, verification using the Wald test, and the use of algorithms for calculating the starting and ending points of the danger zone for various factor values' variables, constructing ellipses of the boundaries of the distribution of pollution spots. The developed model makes it possible to calculate the linear dimensions and area of the danger zone under optimistic and pessimistic scenarios, constructing a graphical diagram of the zones of toxic doses from the source of explosion and combustion. The results obtained from the modeling can serve as the basis for making quick decisions about evacuating residents from nearby areas. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Petrochemical Universities / Shiyou Huagong Gaodeng Xuexiao Xuebao is the property of Journal Editorial Department Of Liaoning Shihua University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: Injury to the radial nerve in the arm is very frequent following fractures of the shaft of the humerus and may also occur during surgery on the arm. These iatrogenic injuries can be prevented by predicting the point at which the nerve penetrates the lateral intermuscular septum during its course from the posterior-to-anterior compartment of the arm. Aims and Objectives: Our study aims to find out the point of penetration of the radial nerve in the lateral intermuscular septum (radial nerve risk zone [RNRZ]). Materials and Methods: The study was conducted on 30 upper limbs of adult formalin-embalmed cadavers during MBBS undergraduate dissection at the department of anatomy. The posterior aspect of the arm was dissected to expose the radial nerve, and measurements of parameters were recorded. Results: The mean humeral length was 29.91 ± 2.66 cm. The mean distance from the lateral epicondyle of the humerus to the point on the lateral intermuscular septum where radial nerve pierces during its course from posterior-to-anterior compartment was 11.42 ± 1.042 cm, r = 0.368, and P < 0.05 which was statistically significant. The mean (standard deviation) humeral length of both left and right side difference was statistically significant with P = 0.009 (P < 0.05). Conclusion: We believe that our study will help orthopedic surgeons to estimate the point of penetration of radial nerve into the lateral intermuscular septum which is the RNRZ. This minimizes the risk of radial nerve damage during the fixation of the fractured shaft of the humerus.

The supratrochlear artery (STA) demonstrates anatomical variability that impacts facial reconstruction with a paramedian forehead flap. STA branching patterns and the distance to the midline have been reported, but the STA pedicle has not been characterized. Our aim was to triangulate the STA pedicle relative to known anatomical landmarks and identify a danger zone to aid surgeons in creating viable tissue flaps. The upper facial region was dissected bilaterally on 38 cadaveric donors. Measurements from the supraorbital neurovascular bundle, orbital rim, and medial canthus to the STA pedicle were collected. Data were tallied and statistically analyzed. Measurement means, range, and standard deviations were calculated; no significant differences were found in the laterality of the measurements (p > 0.05). Statistically significant, sex-based differences were identified for all measurements collected among male and female donors. This study characterizes a surgical danger zone for the STA pedicle specific to a paramedian forehead flap and identifies important differences within this danger zone among male versus female donors that surgeons should consider to prevent pedicle violation and enhance surgical success while maximizing flap length and mobility. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to evaluate six files on the pericervical dentin (PCD) and the smallest dentin thickness zones (SDTZ) in mesial root canals of mandibular molars. Materials and methods: Sixty mandibular molars with two mesial canals and Vertucci configuration were aleatory allocated in 6 experimental groups of 10 molars and 20 root canals. Specimens were scanned before instrumentation using the SkyScan 1275 (Bruker microCT, Kontich, Belgium). Group 1 was treated with WaveOne Gold (WG), group 2 with Reciproc Blue (RB), group 3 with TRUShape (TS), group 4 with XP-endo Shaper (XP), group 5 with iRace (IR), and group 6 with TruNatomy (TN). After instrumentation, the molars were scanned again and the images recorded were reconstructed with the NRecon v.1.7 (Bruker micro-CT) and analyzed with CTAn v.1.20.8 software (Bruker micro-CT) quantifying the changes produced in the surface, volume, structure thickness, SMI, and centroids at the Pericervical Dentin area of the root canals (PCD) located from the root canal orifices at the floor of the pulp chamber to 4 mm in the apical direction, and the changes in the Smallest Dentin Thickness Zones (SDTZ) located (from the furcation to 4 mm and 7 mm in the apical direction. The data obtained were compared using Wilcoxon and ANOVA with a 5% significance level. Results: XP and TN were similar in all the parameters (P >.05) at the PCD, but TN showed significant differences from WG, RB, TS, and IR (P <.05), while XP showed significant differences from WG (P <.05) in volume, surface, and structure thickness. Regarding the changes in the SDTZ, the amount of dentin removed was similar between the groups in both canals at the middle 1/3, at the cervical 1/3 for MB canals, and in ML canals for RB, TS, XP, IR, and TN (P>.05). The action of WG was significantly different from that of XP and TN in the cervical 1/3 of the ML canal (P <.05). Conclusions: XP and TN rotatory files with small taper and volume maintained better with minor changes at the PCD and SDTZ, while WG reciprocation file produced the largest change. All the files were maintained centered at the PCD, and their performances were safe with a minimal thickness higher 0.5 mm at the SDTZ, and without risk of perforation. Trial registration: No clinical trials were indicated in this study. Clinical relevance: The choice of endodontic files is a relevant factor in the conservative performance of root canal treatments. [ABSTRACT FROM AUTHOR]

The supratrochlear artery (STA) demonstrates anatomical variability that impacts facial reconstruction with a paramedian forehead flap. STA branching patterns and the distance to the midline have been reported, but the STA pedicle has not been characterized. Our aim was to triangulate the STA pedicle relative to known anatomical landmarks and identify a danger zone to aid surgeons in creating viable tissue flaps. The upper facial region was dissected bilaterally on 38 cadaveric donors. Measurements from the supraorbital neurovascular bundle, orbital rim, and medial canthus to the STA pedicle were collected. Data were tallied and statistically analyzed. Measurement means, range, and standard deviations were calculated; no significant differences were found in the laterality of the measurements (p > 0.05). Statistically significant, sex-based differences were identified for all measurements collected among male and female donors. This study characterizes a surgical danger zone for the STA pedicle specific to a paramedian forehead flap and identifies important differences within this danger zone among male versus female donors that surgeons should consider to prevent pedicle violation and enhance surgical success while maximizing flap length and mobility.

The primary objective of this study is to evaluate the root canal diameter, wall thickness, and root concavity depth of human mandibular first molars' mesial roots across their coronal to apical thirds. By addressing these gaps in knowledge, this study aims to provide valuable insights for improved clinical decision-making and endodontic treatment outcomes. Ground sections of human mandibular first molars' mesial roots (n = 30) were cut horizontally at 0-, 2-, 4-, and 6 mm below the furcation and at 1 mm above the apex. Their root canal diameter, thickness, and root concavity depth were measured under a computer-aided stereomicroscope. The concavities of the root were considerably deeper on the distal aspect and at 0- and 2-mm below the furcation than they were on the mesial and other levels, respectively. The root's distal aspect, particularly its coronal third area, was considered the danger zone. The thinnest wall thicknesses were 20.0% in MB- and 16.7% in ML-canals, with their frequent mesial aspect toward the apical third area. The root canal's buccolingual diameter was significantly greater than its mesiodistal one. Furthermore, all canal shapes observed at all levels were oval (70.0%), long oval (22.0%), flat (4.7%), and round (3.3%). The present findings may assist dentists in selecting the appropriate instruments and techniques to improve root canal instrumentation without causing iatrogenic damage, thereby improving clinical procedures and endodontic treatment outcomes. [ABSTRACT FROM AUTHOR]

Purpose: Due to its vulnerable structure in the danger zone, the selection of an endodontic instrument becomes very important to avoid excessive root canal preparation in this area. It was aimed to compare the effect of different retreatment file systems and solvents on the amount of removed dentin thickness in the danger zone of mandibular molar teeth using cone beam computed tomography (CBCT). Methods: A total of 120 mesiobuccal root canals were prepared and obturated with BioRoot RCS root canal sealer using the single cone technique. Specimens were divided randomly into three groups according to the retreatment system used (n = 40): ProTaper Universal Retreatment (PTUR), Reciproc Blue (RB), and XP-Endo Retreatment (XPR). Thereafter, each group was divided into two subgroups according to whether a solvent was used or not (n = 20). CBCT images were obtained from specimens before and after removing root canal filling materials. The removed dentin thickness was calculated in axial sections obtained from 4 mm below the furcation area. Data were statistically analyzed using two-way ANOVA and Bonferroni tests (p = 0.05). Results: In terms of removed dentin thickness, no significant difference was found between retreatment systems when used with solvent (p = 0.964), whereas a significant difference was found when they were used without solvent (p = 0.004). The removed dentin thickness in RB was lower than in XPR (p = 0.008) and PTUR (p = 0.018). Conclusion: Solvent did not affect the amount of removed dentin thickness of XPR and PTUR files. Removed dentin thickness of RB was less when used without solvent than with solvent. [ABSTRACT FROM AUTHOR]

Proactive prevention and fighting fire at industrial facilities, often located in urbanized clusters, should include the use of modern methods for modeling danger zones that appear during the spread of the harmful combustion products of various chemicals. Simulation modeling is a method that allows predicting the parameters of a danger zone, taking into account a number of technological, landscape, and natural-climatic factors that have a certain variability. The purpose of this research is to develop a mathematical simulation model of the formation process of a danger zone during an emergency at an industrial facility, including an explosion of a container with chemicals and fire, with the spread of an aerosol and smoke cloud near residential areas. The subject of this study was the development of a simulation model of a danger zone of combustion gases and its graphical interpretation as a starting point for timely decision making on evacuation by an official. The mathematical model of the process of danger zone formation during an explosion and fire at an industrial facility presented in this article is based on the creation of a GSL library from data on the mass of explosion and combustion products, verification using the Wald test, and the use of algorithms for calculating the starting and ending points of the danger zone for various factor values’ variables, constructing ellipses of the boundaries of the distribution of pollution spots. The developed model makes it possible to calculate the linear dimensions and area of the danger zone under optimistic and pessimistic scenarios, constructing a graphical diagram of the zones of toxic doses from the source of explosion and combustion. The results obtained from the modeling can serve as the basis for making quick decisions about evacuating residents from nearby areas.

Objective To explore the influence of a contracted endodontic access cavity on the risk of canal transportation in the danger zone of the mesial root canal of mandibular first molars (MFMs) using a one-curve preparation system, and to provide an experimental basis for the clinical selection of a better pulp approach. Methods Twenty MFMs extracted for severe periodontal disease that met the inclusion criteria, including intact coronal roots, mesial roots with two separate root canals, mesiobuccal canal (MB) and mesiolingual canal (ML), and a curvature of 0° to 20°, were selected. Subsequently, these MFMs were randomly divided into two groups based on the endodontic access design, including the traditional endodontic access cavity (TEC) group and the contracted endodontic access cavity (CEC) group. In the TEC group, the pulp chamber roof of the tooth was completely removed, while in the CEC group, the pulp chamber roof and peri-cervical dentin were preserved as much as possible. Then, the One Curve single file was adopted to conduct root canal preparation. Next, cone beam computed tomography (CBCT) was performed on extracted teeth before and after preparation, and the measurement sections were located at 0-7.0 mm below the root bifurcation of the mesial root canal at 1 mm intervals. The minimum wall thickness on the mesial and distal aspect of the root canal was measured in each section. Results ① Prepreparation CT measurements of 20 MFMs showed that the danger zone in the range 0-4 mm under root bifurcation, a mean thickness of 1.18 mm on the mesial aspect of the MB root canal and 1.08 mm on the distal aspect. The mean thickness of the ML root canal was 1.28 mm on the mesial aspect and 1.07 mm on the distal aspect. ② Compared with that of the traditional endodontic access cavity, no significant difference in the decrease of wall thickness was observed in the danger zone of mesial root canal of MFMs in the contracted endodontic access cavity (t = 1.319，P = 0.19). ③ In the mesiobuccal canal, compared with the apical transportation of the traditional endodontic access cavity, which tends to be more mesial side, the apical transportation of contracted endodontic access cavity tends to the distal side. In the mesiolingual canal, both apical transportation groups tended to be on the distal side. Conclusion When using the One Curve file, compared with traditional endodontic access, the contracted endodontic access cavity based on the minimally invasive concept does not increase the risk that the mesial root canal of mandibular first molars is transported.

Objective To classify the furcation involvement (FI) of endodontically treated mandibular first permanent molars based on cone beam computed tomography (CBCT), provide reference for individualized treatment of FI. Methods CBCT images of the FI of 164 endodontically treated mandibular first permanent molars from 163 patients in Nanjing Stomatological Hospital, Medical School of Nanjing University were collected retrospectively. On the CBCT images, the shape and extent of periapical and periodontitis bone resorption, the thickness of residual dentin in the pulp floor and root canal wall, and the periodontal bone resorption of the complete dentition were evaluated. The FI was classified into periodontal, periapical, perforated and mixed types. Results Among the 164 FIs of endodontically treated mandibular first permanent molars, the periapical type was the most common (41.5%), followed by the mixed type (26.2%), perforated type (18.3%), and periodontal type (14.0%). Among the 68 periapical-type FIs of endodontically treated mandibular first permanent molars, 48.5% were proper root canal filling, 44.1% were insufficient filling and 7.4% were overfilling. Among the 43 mixed-type FIs, the periodontal mixed periapical type was the most common (72.1%). Conclusion Detailed evaluation and classification of furcation involvement could be performed using CBCT images; therefore, the study has guiding significance for clinical treatment.

Aim: The article presents issues related to selected aspects of chemical and environmental rescue, their location in the legal norms in relation to the performed tasks and taking into account the needs of the society. In this respect, the legal acts relating to the operation of the system of identifying chemical and environmental rescue hazard, its transformation, and its impact on the safety and execution of tasks by the rescue entities were reviewed. Moreover the meaning of records relating to the identification of chemical hazards was analysed and clarified. The topics were based on new legal regulations on the detailed organization of the national rescue and firefighting system and guidelines covering the organization of chemical and ecological rescue in Poland. The reviewed area in this analysis relates to the identification of hazardous materials, the designation of danger zones, the ability of emergency responders to identify hazards in formal and legal conditions, and their identification by the functioning cooperating entities. The dependencies that exist in the identification system and the future directions of its development are indicated. Introduction: In today’s world, the expectations of the society for emergency services focus on the quick and efficient execution of an organized rescue operation. In chemical rescue, the primary factor affecting the course and success of the operation is the identification of the chemical threat. Conducting reconnaissance activities under conditions of changing threats requires skills and the fulfilment of a number of conditions that will affect the functioning of the rescue entities in the reconnaissance system. Experience from ongoing rescue operations shows that reconnaissance tasks are carried out to varying degrees. On the one hand, they depend on regulations, and on the other, on the capabilities of emergency responders and the difficulties arising from the resulting disasters and chemical accidents. Therefore, it is reasonable to review selected legal elements relating to the identification of hazardous materials – in particular, those that condition the efficient and effective operation of the rescue entities in terms of the existing risks. Methodology: The article was developed using analyses of legal acts and literature on improving the system of threat identification. Consideration was given to the existing threats, the current international situation, the possibility of uncontrolled action and the release of hazardous substances with chemical, biological or radiological properties, especially in the border area. In analysing the conducted research, publications on rescue law, legal norms of the national rescue and firefighting system, emergency management, guidelines from chemical and ecological rescue, articles from the area of reconnaissance and conference materials were used. Conclusions: The emergence of new regulations in the Principles of Chemical and Environmental Rescue has led to the need for a unified course of action in the area of identifying the chemical agent. Ongoing monitoring of the area for the presence of a hazardous substance – due to the frequently changing weather conditions at the scene – should be a permanent part of the competence tasks of the rescue units. In addition, continuous and effective analysis of the samples taken at the site of the hazardous substance would allow detection and identification of the hazard relatively early – so that further appropriate action could then be taken. Such a solution would allow the emergency manager to conduct a chemical rescue operation continuously and make accurate decisions at every stage of the operation, despite a possible sudden change in the weather conditions. The inclusion in the regulations of all possible elements of identification in terms of the existing hazards will affect the effectiveness of the rescue entities in the elimination of chemical, biological, radiological hazards. Keywords: hazardous substance, danger zone, chemical and environmental rescue, chemical reconnaissance

Aim: The present study aimed to determine and compare the dentine thickness around the root canals of maxillary molars with fusion using micro‐computed tomography (micro‐CT). Methodology: A total of 120 fused maxillary molars having more than a single canal with distinct canal orifices near the cementoenamel junction were selected from a pool of extracted maxillary molars, which were scanned on a micro‐CT device (SkyScan 1172, Bruker‐microCT). The minimum dentine thickness around the root canals in furcal direction was measured using CTAn software (v.1.18.8 Bruker‐microCT) at each millimetre. The specimens were grouped according to their fusion type, and dentine thickness around the canals was compared. The data were statistically analysed using anova and post hoc Tukey–Kramer tests following an assessment of the normality of their distribution with the Kolmogorov–Smirnov test (p <.05). Results: Dentine thickness showed a statistically significant decrease at 2 mm apical to the orifice level irrespective of fusion type. The minimum dentine thickness values were detected around the second mesiobuccal canal as 0.30 mm at 6 mm below orifice. Dentine thickness around the mesiobuccal canal was significantly greater in fusion type 1 than those of types 2 and 3 (p <.05), while those of distobuccal and palatal canals were significantly thinner in type 3 fusion compared with type 1 or 6 (pDentine thickness showed a statistically significant decrease at 2 mm apical to the orifice level irrespective of fusion type. The minimum dentine thickness values were detected around the second mesiobuccal canal as 0.30 mm at 6 mm below orifice. Dentine thickness around the mesiobuccal canal was significantly greater in fusion type 1 than those of types 2 and 3 (Conclusion: Minimum dentine thickness values at the danger zone of distobuccal and palatal canals change according to the fusion type in fused maxillary second molars. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of root canal enlargement on the danger zone (DZ) of mandibular molars. Thirty mesial roots of mandibular first molars were scanned in micro-computed tomography (S1). Canals were sequentially enlarged with rotary instruments up to sizes 30/0.04 (S2) and 30/0.06 (S3). The dentin thickness was measured at 0.1-mm intervals after each preparation step (n = 2964 slices). Root level and position of the DZ were also recorded. Data were compared using analysis of variance with Bonferroni pairwise comparison, Cochran's Q method, and Pearson's test (α = 5%). Comparing the specimens before (S1) and after (S2 and S3) preparations showed a significant reduction in the thickness of the DZ (P <.05), as well as between S2 and S3 steps (P <.05). At S1, the DZ was mostly located in the middle third of the root, but after preparation, it shifted toward the coronal direction (P <.05). Both S2 (P =.004, r = 0.508) and S3 (P =.004, r = 0.506) preparation steps showed a positive correlation between canal length and the root level of the DZ. At S1, the DZ was positioned toward the distal and mesial in 73.4% (n = 22) and 26.6% (n = 8) of the specimens, respectively. After S3, the number of specimens with DZ positioned toward the mesial aspect of the root significantly reduced to 3.3% (n = 1), whereas none of the specimens with DZ positioned toward the distal changed its position after root canal enlargements (P >.05). Overall, the enlargement of mesial canals of mandibular first molars with final instruments sizes 30/0.04 and 30/0.06 affected the thickness, root level, and position of the DZ. [ABSTRACT FROM AUTHOR]

The ongoing challenge is to find an effective and precise fire detection method for safety concerns of utility tunnels to predict the fire danger zone and take measures for firefighting and intervention promptly. A data-driven danger zone estimation method was established based on Bayesian inference. The probability distribution of the fire danger zone can be obtained by this method. In particular, the governing equation is a simplified physical model, in which only crucial parameters of the fire states are referred to, including the fire source location, the maximum temperature, and the attenuation coefficient. This task shows superiority because it can avoid additional workload to provide the forward database for Bayesian inference. A prototype experiment was conducted in the largest utility tunnel experimental platform in China to verify the validity of the proposed method. Results demonstrated that the fire danger zone could be estimated with high accuracy merely based on several sensor data, which are not limited to specific scenes. The temperature distribution of the whole tunnel could also be predicted according to the fire parameters. Moreover, analysis of the measurement noise and disturbance conditions shows the robustness of the proposed method. Low costs, low consumption, and universality make it have broad engineering application prospects. [ABSTRACT FROM AUTHOR]

Copyright of Safety & Fire Technology (2657-8808) is the property of Centrum Naukowo-Badawcze Ochrony Przeciwpozarowej and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: This study aimed to investigate radicular dentin thicknesses in mandibular second molars (MSMs), considering variations in root configuration and the morphology of the pulp chamber floor (PCF). The types of radicular grooves and potential danger zones were also identified., Methods: A total of 149 MSMs were scanned with micro-computed tomographic imaging and classified into 4 groups according to root fusion and PCF morphology as follows: (1) 45 with fused roots and C-shaped PCFs, (2) 45 with fused roots and non-C-shaped PCFs, (3) 14 with a single canal, and (4) 45 with separated roots. The first 2 groups were subdivided into Ω-shaped, U-shaped, and V-shaped radicular groove subgroups. Measurements included minimum and mean dentin thickness from the start of the radicular groove or root bifurcation extending 5 mm apically, the ratio of outer to inner dentin thickness, and the distribution of dentin thickness., Results: Ω-shaped and U-shaped subgroups showed significant thinner minimum inner wall thickness than V-shaped subgroups at 2-5 mm from the starting point of the radicular groove in both C-shaped and non-C-shaped pulp floor categories (P < .05). The mesial roots of separated rooted MSMs showed significant thinner dentin than a non-C-shaped floor regarding minimum and mean inner thickness and mean outer thickness (P < .05). Teeth with a single canal had significantly thicker walls compared with the other 3 groups., Conclusions: In MSMs, caution must be exercised, especially in the presence of Ω-shaped and U-shaped grooves in C-shaped roots and around the root furcation of separated roots., (Copyright © 2024 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

INTRODUCTION: The radial nerve danger zone (RNDZ) is an important anatomic consideration to anticipate or prevent injury in trauma assessment or surgical fixation. No published estimate currently exists for Filipinos. In this study, we sought to provide a local estimate and explore potential predictors of this anatomic region in Filipino adult cadavers. MATERIALS AND METHODS: Posterior dissection to expose and measure the radial nerve, from the lateral epicondyle to the lateral intermuscular septum, was performed in 60 upper limbs from 30 formalin-preserved cadavers in the laboratory of the Department of Anatomy, College of Medicine, University of the Philippines Manila. Univariate and multivariate linear regression modelling was performed with RNDZ as the dependent variable and age, sex, height and humeral length as potential independent variables individually and in combinations. RESULTS: The mean radial nerve length from the lateral epicondyle to the lateral intermuscular septum was estimated at 10.6 cm (95% confidence interval: 10.3 cm, 10.9cm). Height and humeral length were statistically significant univariate predictors in female cadavers, while only height was significant in male cadavers. In addition, all multivariate regression models were statistically significant and accounted for more than 57% of the variability in female RNDZ estimates. In comparison, only models that included height and age were statistically significant predictors of RNDZ and accounted for at most 22% of the variability of the estimate in males. CONCLUSION: The estimated length of the radial nerve danger zone generated in this study should be strongly considered over other published estimates in surgical fixation procedures performed in adult Filipinos.

The aim of this study was to measure the initial and remaining dentin thickness in the danger zone of the second mesiobuccal (MB2) canal of maxillary first molars after rotary instrumentation using cone beam computed tomography (CBCT) imaging. After determining initial dentin thickness, each sample was subjected to a standardized protocol of rotary instrumentation files: ProTaper Gold Sx Orifice Opener (maximum depth of 7 mm); Vortex Blue 15.04, 20.04, 25.04, ProTaper Gold S1, S2, F1, F2, and finally Vortex Blue 30.06. Subsequent CBCT measurements were made to compare changes in remaining dentin thickness in comparison to initial presentation. Preoperative dentin thickness in the danger zone had a mean of 0.82 ± 0.17mm. Significant levels of dentin removal in the danger zone were noted after all instrumentation groups when compared to the pre‐instrumentation mean (Sx P < 0.001, 25.04 P < 0.0006, F2 P < 0.0001, 30.06 P < 0.0001). It was concluded that a thin area of dentin exists along the distal wall of the MB2 (danger zone) from the furcation to 4 mm apically. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the shaping ability of several heat‐treated nickel–titanium systems used to prepare root canals with moderate and severe curvature, in extracted mandibular molars, by micro‐computed tomography, considering their variation in kinematics and design. Methodology: Curved‐mesial roots of mandibular molars were randomly selected and assigned into 4 balanced experimental groups (n = 10), established by determining homogeneous 3D parameters of volume and surface area: R‐Motion (RM) size 30, 0.04 taper (RM; FKG Dentaire), Reciproc Blue (RCB) size 25, 0.08 taper (RCB; VDW GmbH), HyFlex CM (HFX) size 30, 0.04 taper (HFX; Coltène Whaledent) and XP‐endo Shaper size (XPS) 30, 0.01 taper (XPS; FKG Dentaire). The volume of irrigation was established at 10 ml of 2.5% NaOCl. Throughout the entire root canal preparation procedures, the samples were fixed in a vice submerged in a container with water monitored at 37°C. Dimensional cross‐sectional measures of area, perimeter, roundness, major/minor diameters and 3‐dimensional (volume, surface area, structure model index – SMI) parameters as well as the smallest dentine thickness along the cervical and middle root thirds were evaluated by micro‐CT. Data were analysed using analysis of variance and post hoc Tukey tests (α = 5%). Results: Reciproc Blue and XPS had significantly greater mean increases in cross‐sectional area measurements, only in the middle third, when compared with RM and HFX (p <.05). RM, RCB and XPS had a similar increase in measurements of length and width of perimeter (p >.05), and HFX had significantly lower mean increases in perimeter values only when compared with XPS (p <.05). RCB and XPS had significantly greater mean increases in volume when compared with RM and HFX (p <.05). RM had a significantly lower difference in SMI after preparation, compared with RCB, HFX and XPS (p <.05). The smallest dentine thickness was observed after the use of RCB (p <.05), in the danger and safety zones. Conclusions: XP‐endo Shaper and RM had a shaping ability similar to that of instruments with larger tapers, achieved with less dentine removal in danger and safe zones in curved‐mesial canals of extracted molar teeth treated on a laboratory benchtop. [ABSTRACT FROM AUTHOR]

Background: Although single‐file rotary systems are accepted in the field of paediatric dentistry in terms of providing time advantage, research works continue due to the variable anatomical structure of the root canal. Aim: This study aimed to evaluate rotary systems in different kinematics in terms of microcracks and the shaping of the danger zone in primary molars by micro‐CT. Design: The mesial canals of primary molars (n = 30) were used. Root canals in each group (n = 10) were prepared with single‐file rotary systems (One Shape®, OS; XP‐endo® Shaper, XP‐ES; WaveOne Gold, WOG). The images were evaluated for dentin thickness in the danger zone and microcrack formation. Results: WOG caused the highest dentin reduction in the danger zone area. OS led to significantly less dentin reduction than XP‐ES and WOG (P <.05). The XP‐ES showed the highest number of microcracks (P <.05). No statistically significant difference was found between WOG and OS (P >.05). In all systems, more microcracks were observed in the middle third than coronal and apical. Conclusion: Within the limitations of this study, the rotary systems were superior to reciprocating in terms of shaping ability in the danger zone. It is thought that further studies with different systems should be designed considering the anatomical variations and chemical composition of primary teeth. [ABSTRACT FROM AUTHOR]

Abstract Background Better understanding of the danger zone anatomy in mesial roots (MRs) of mandibular first molars (MFMs) may serve to decrease the risk of mishaps. This study aimed to measure the minimal distal dentine thicknesses of danger zone in MRs of MFMs in a native Chinese population using cone-beam computed tomography (CBCT). Methods CBCT images of 1792 MFMs from 898 Chinese patients were analyzed. The minimal distal dentine thicknesses of the mesiobuccal (MB) and mesiolingual (ML) canals below the furcation 1, 2, 3, 4, 5 mm were measured. The association between the minimal distal dentine thicknesses and the root lengths, patient’s age and gender, side were assessed. Results The minimal distal dentine thicknesses of MB and ML canals are located 3 ∼ 4 mm below the furcation for both men and women. There are no differences between MB and ML canals, while the minimal distal dentine thicknesses of MB and ML canals were higher in men than women (P 0.05). The minimal distal dentine thicknesses of MB and ML canals increased with age in both men and women at each location (P 0.05). Conclusions The minimal distal dentine thicknesses of MRs in MSMs have close correlation with root length, patient’s age and gender.

Background: Mandibular first molars appear to be the most commonly tooth subjected to a root canal treatment, therefore a better understanding of the anatomy critical zones for resistance of this teeth may decrease the treatment’s failure rate. So, this study was conducted to evaluate the dentin thickness of the danger zone in mesial roots of mandibular first molars using cone beam computed tomography in an Iranian population. Methods: In this cross-sectional study, 210 Cone Beam Computed Tomography acquisition of the mandibular first molars were collected from a radiology center in Qazvin. The dentin thickness of the mesial roots (mesiobuccal and mesiolingual canals) was measured from the furcation to 5 mm below. The relationship between the dentin thickness in the danger zone and parameters, like age, gender, placement side, root length, the curvature of the canal, canal type, presence of middle mesial canal, and distance between the orifices of the mesial canals was investigated. Frequency, mean and standard deviation for variables were calculated, and data analysis was done by SPSS using simple and multiple linear regression and Pearson correlation coefficient. Also, two-sample t-test was used to compare mesiobuccal and mesiolingual on two sides. The significant level was also considered at (p < 0.05). Results: The average minimum thickness of danger zone dentin was found to be 0.885 ± 0.259 mm in the mesiobuccal canal and 0.906 ± 0.206 mm in the mesiolingualcanal. Also, the minimum thickness of dentin in the mesiobuccal and mesiolingual canals in the range of 0 to 1 mm from the furcation was more than in other areas. There was no significant relationship between the minimum dentin thickness of the danger zone with gender, placement side, root length, canal type, and mesial canal entrance distance. But with increasing age, the thickness of dentin in the danger zone in the mesiolingualcanal increased significantly (p = 0.008). It was also observed that with the increase in the curvature of the canal, the thickness of the dentin in the danger zone in the mesiobuccal canal decreased (moderately curved (p = 0.008), severely curved (p = 0.046)). In addition, the thickness of the dentin in the mesiobuccal and mesiolingual canal was less in the samples with the middle mesial canal (p = 0.047, 0.044). Conclusions: Less dentin thickness in the danger zone in the mesial roots of mesiolingual mandibular first molars was seen in younger patients in mesiolingual canal, with a greater degree of canal curvature in the mesiobuccal canal and teeth with a middle mesial canal. Therefore, it is suggested that large taper instruments should be used with more precision to prevent complications.

Purposes: To identify the anatomical relationship between neurovascular structures and screws and to evaluate the danger zone of screw placement during minimally invasive plate osteosynthesis (MIPO) technique following the volar approach for the radius and the subcutaneous approach for the ulna in diaphyseal forearm fractures. Methods: Sixteen cadaveric forearms were fixed with a 3.5-mm, 14-hole, locking compression plate (LCP) using the MIPO technique with a volar approach of the radius. Two locking screws were fixed at each end via two separated incisions, and the remaining ten screws were inserted percutaneously. The same MIPO technique was performed at the ulna with the subcutaneous approach. The forearms were then dissected to identify any damage to or direct contact between the screws and the radial artery (RA), the superficial branch of the radial nerve (SBRN), the posterior interosseous nerve (PIN), and the dorsal cutaneous branch of the ulnar nerve (DCBUN). The distances from the screws to the structures at risk, as well as the radial and ulnar length, were measured. Results: The average lengths of the radius and ulna were 24.74 cm and 25.93 cm, respectively. On the volar aspect of the radius, the danger zones of RA and SRN were between 15.26 and 81.24% of the length of the radius from the radial styloid. The zone of PIN injury at the posterior aspect of the radius was between 41.45 and 81.24% of the length of the radius from the radial styloid. Meanwhile, the danger zone of DCBUN was between 12.21 and 27.23% of the ulnar length from the ulnar styloid. Conclusion: Based on our study, the percutaneous screw fixation in MIPO for the treatment of diaphyseal fractures of the forearm is a dangerous procedure, especially for the volar approach of the entire radius and the subcutaneous approach of the distal ulna. [ABSTRACT FROM AUTHOR]

Objectives: This study evaluated the danger zone (DZ) in mesial roots of mandibular molars and the correlation between anatomical references of the DZ and some anatomical landmarks including tooth/root length, depth of mesial and distal grooves, and inter-canal orifices distance. Material and methods: Twenty-eight mesial roots of mandibular molars with 2 independent canals were scanned and divided into 2 groups according to root length. The anatomical landmarks were correlated (Pearson or Spearman coefficients) with root level, thickness, and position of the DZ and also compared (independent samples t or Mann-Whitney tests) between the 2 groups at α = 5%. Results: No statistical difference was observed between groups regarding DZ parameters and depth of mesial and distal grooves (P > 0.05). Orifice distance in group 2 (4.49 ± 0.75 mm) was significantly greater than group 1 (3.76 ± 0.89 mm) (P < 0.05). Significant correlations (P < 0.05) were found between (i) DZ level and root/tooth length (r = 0.54 and 0.49, respectively), (ii) DZ thickness and distal groove depth (r = − 0.45), and orifice distance (r = 0.38), and (iii) DZ position and depth of mesial (r = 0.39) and distal (r = 0.40) grooves. Other variables such as root length and distal groove depth (r = 0.28), and orifice distance and mesial groove depth (r = 0.36) were also correlated (P < 0.05). Conclusions: The length of tooth/root, the distance of canal orifices, and the depth of mesial/distal grooves of mesial roots of mandibular molars might be predictive factors for the root level, position, and thickness of the DZ. Clinical relevance: The length, distance of mesial canal orifices, and the depth of mesial and distal grooves of the mesial roots of mandibular molars might be moderate predictive factors for the root level, position, and thickness of the DZ. [ABSTRACT FROM AUTHOR]

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Aim: To evaluate, using micro‐CT, the remaining dentine thickness after preparation of the mesiobuccal (MB), mesiolingual (ML) and middle mesial (MM) canals of mandibular first molars with the ProTaper Next rotary system. Methodology: Eleven mesial roots of mandibular first molars having three independent canals from the furcation level up to at least 5 mm towards the apical direction were selected. Preparation of MM canals was performed in two steps using ProTaper Next X2 (step 1) and X3 (step 2) instruments, whilst MB and ML canals were prepared in a single step up to X3 instruments. The roots were scanned (pixel size of 10 µm) before and after each step, and the dentine volume was calculated. Postoperative models of the roots were coregistered with their preoperative dataset and colour‐coded cross‐sections of the roots were used to measure the smallest dentine thickness surrounding each canal at 1.0‐mm intervals from the furcation level up to 5 mm in the apical direction, in both mesial and distal aspects of the roots. Changes in the remaining wall thickness between mesial canals were analysed with repeated‐measures anova and post hoc Tukey test. Significance level was set at 5%. Results: Mean percentage reduction of dentine volume after steps 1 and 2 was 4.66% and 5.16%, respectively. Overall, pre‐ and postoperative dentine thickness of the MM canal walls, in both mesial and distal aspects of the root, were significantly thinner than those of MB and ML canals (P < 0.05). No significant difference was observed when comparing dentine thickness in the mesial and distal directions of MM canal after preparation step 1 (0.88 ± 0.18 mm and 0.73 ± 0.26 mm, respectively) or 2 (0.83 ± 0.17 mm and 0.67 ± 0.26 mm, respectively) (P > 0.05). Dentine thickness values less than 0.5 mm were observed mostly towards the distal aspect of the MM canal. Mesial roots were not associated with strip perforations after canal preparation procedures. Conclusions: A significant decrease in the thickness of canal walls at all levels evaluated in the mesial roots of mandibular molars suggests that files with small tapers should be used in preference to instruments with large tapers to prepare mesial canals in mandibular molars. [ABSTRACT FROM AUTHOR]

Background: Better understanding of the danger zone anatomy in mesial roots (MRs) of mandibular first molars (MFMs) may serve to decrease the risk of mishaps. This study aimed to measure the minimal distal dentine thicknesses of danger zone in MRs of MFMs in a native Chinese population using cone-beam computed tomography (CBCT). Methods: CBCT images of 1792 MFMs from 898 Chinese patients were analyzed. The minimal distal dentine thicknesses of the mesiobuccal (MB) and mesiolingual (ML) canals below the furcation 1, 2, 3, 4, 5 mm were measured. The association between the minimal distal dentine thicknesses and the root lengths, patient's age and gender, side were assessed. Results: The minimal distal dentine thicknesses of MB and ML canals are located 3 ∼ 4 mm below the furcation for both men and women. There are no differences between MB and ML canals, while the minimal distal dentine thicknesses of MB and ML canals were higher in men than women (P < 0.05), except at 1 and 3 mm of ML canals (P > 0.05). The minimal distal dentine thicknesses of MB and ML canals increased with age in both men and women at each location (P < 0.05). The minimum distal dentine thickness at every location were significantly different between long teeth and short teeth both in men and women (P < 0.05), with short teeth having the smallest mean values. There are no significant differences between two sides (P > 0.05). Conclusions: The minimal distal dentine thicknesses of MRs in MSMs have close correlation with root length, patient's age and gender. [ABSTRACT FROM AUTHOR]

A lot of drosses appear on surface of molten zinc in the process of continuous hot dip galvanizing. The drosses,if not cleared in time,adhere to the surface of hot galvanized sheet and lead to surface defect. The production of zinc dross is closely related to the physical fields of molten zinc and dross remove can change of the physical fields,so it is necessary to carry out systematic research on the physical fields. Through the standard k-ε turbulence model and the geometric model of galvanizing pot and molten zinc,the author finds out the distribution regularities of the physical fields（ such as speed,temperature and concentration field） and the laws of these physical quantities changing with time,and determines the distribution characteristics of the vortex. The theoretical calculations can be used to predict the distribution regularity of zinc dross and the danger zone of the dross removing operation,provide important theoretical basis for the design of dross removing robot,and ensure the quality of zinc coating and improve the efficiency of dross removing.

Aim: To investigate the smallest dentine thickness in mesial canals of mandibular molars along the cervical and middle thirds of the root by means of a micro‐computed tomographic (micro‐CT) technology and digital image analysis. Methodology: Fifty mesial roots of mandibular molars having two independent canals (mesiobuccal and mesiolingual), in the coronal and middle levels, were selected and scanned in a micro‐CT device. After reconstruction procedures, approximately 468 slices per root covering the 7 mm below the furcation area of the mesial root were analysed to measure the smallest dentine thickness (danger zone [DZ]) in each slice from both distal and mesial regions of the mesial canals by an automatic segmentation process. Results: The DZ values in the mesiobuccal canals varied from 0.67 to 1.93 mm, with an average of 1.13 ± 0.21 mm. For the mesiolingual canals, the DZ varied from 0.77 to 1.89 mm with an average of 1.10 ± 0.21 mm. There was no correspondence in the DZ between the mesiobuccal and mesiolingual canals at the same cross‐sectional level in 71% of the specimens. Moreover, the smallest dentine thickness was towards the mesial region of the roots in 22% and 18% of the mesiolingual and mesiobuccal canals, respectively. (Figs 1 and 2 Conclusions: The smallest dentine thickness was on the mesial plane of the roots in about 40% of the canals. The vertical location of the DZ in relation to the furcation area was in the middle third of the root. [ABSTRACT FROM AUTHOR]

Aim: To evaluate dentine thickness from both distal ('danger zone') and mesial ('safety zone') aspects of the MB1 and MB2 canals of maxillary first molars at the furcation level using micro‐CT imaging. Methodology: One hundred maxillary first molars with two canals in the MB root were selected from a Brazilian subpopulation and scanned at a resolution of 19.6 μm in a micro‐CT device. From each specimen, two axial cross‐sectioned images were selected at 2 and 3 mm apical to the furcation level of the MB root and evaluated for the smallest dentinal thickness. Measurements were made from the outer perimeter of the MB1 and MB2 canals towards the external root surface from both distal (danger zone) and mesial (safety zone) aspects of the root. The influence of an isthmus was also considered in the analysis, and samples were classified according to the presence or absence of an isthmus in the axial sections. Non‐parametric Wilcoxon signed‐rank tests were used to compare dentinal thickness between MB1 and MB2 canals with a significant level set at 5%. Colour‐coded 3D models of dentine thickness throughout the MB root were created and evaluated qualitatively. Results: At both levels, median dentine thickness of the MB2 canal was significantly lower in both distal and mesial aspects of the root in comparison with the MB1 canal (P < 0.01). The presence of an isthmus was not a variable that influenced dentinal thickness. Colour‐coded models indicated that dentine thickness was dependent on the cross‐sectional shape of the MB root. At least 50% of the sample had <1 mm of dentine thickness at the danger zone of the MB2 canal. Conclusions: Danger zones in the MB roots of maxillary first molars were not symmetrical. MB2 canals had less dentine thickness on both aspects of the root compared to the MB1 canal. [ABSTRACT FROM AUTHOR]

Treating the lips to increase facial attractiveness and youthfulness is challenging when trying to consider ethnic differences in an increasingly more diverse society. Multiple injection techniques are currently available for treating lip contour and volume, but a validation in the cadaveric model under the aspects of safety has not been performed yet. The injection techniques presented in this study are based on the experience and personal selection of the authors. The authors have assessed, treated, and evaluated for more than 20 years patients from the Middle East and Central Europe. Cadaveric verification was performed for each of the presented techniques to identify the positioning of the injected product inside the lips and its relation to the superior/inferior labial arteries. The results of the anatomic analyses revealed that in 58.3% of the performed injections, the product was placed close to the superior/inferior labial arteries. In 60.0% of the cases, applications using a needle placed the injected product in endangered locations, whereas 57.1% of the cases using cannulas placed the product in endangered locations (i.e., in the vicinity of the superior/inferior labial arteries). This anatomic study revealed that injected material into the lips is frequently placed in close proximity to labial arteries representing a high risk for intra-arterial applications, leading to tissue loss (necrosis) and potential end-arterial embolism (potential blindness). Nevertheless, treatment of the lips should be a multistep approach focusing first on the far (upper and middle face) and close (labiomandibular and labiomental) perioral regions. [ABSTRACT FROM AUTHOR]

Background Iatrogenic or traumatic injury to the spinal accessory nerve is a rare but debilitating injury. An effective treatment, known as the Eden-Lange modification triple-tendon transfer procedure, involves the transfer of the rhomboid major (RM), rhomboid minor (Rm), and levator scapulae (LS). Careful detachment of their insertions is necessary to avoid injury of the dorsal scapular nerve (DSN). This study evaluated the surgical anatomy and safety of the DSN relative to this procedure. Methods The study used 12 cadavers (22 shoulders). The RM, Rm, and LS were detached from their insertions, and the DSN was dissected. Measurements were taken to evaluate the anatomy of each relative to the triple-tendon transfer procedure. Additional measurements were taken to identify "danger zones" for DSN injury, regarding detachment of RM, Rm, and LS from their respective insertions. Results Measurements of the 22 shoulders included in the study showed wide variation in anatomy. The minimum distance between the scapula and the DSN at the vertebral scapular border was 0.7 cm, suggesting that care and precision are needed to perform this technique. The region where the DSN crosses the superior border of the Rm was shown to be the greatest "danger zone" of this technique, with a mean distance to the scapula of 1.61 ± 0.53 cm Conclusions This study provides insight into the surgical anatomy of the DSN relative to a rare but successful procedure used to treat trapezius paralysis. The results of this study can inform the surgeon regarding potential anatomic considerations when performing the triple-tendon transfer. [ABSTRACT FROM AUTHOR]