Peat properties of a tropical forest reserve adjacent to a fire-break canal

Tropical peat comprises decomposed dead plant material and acts like a sponge to absorb water,making it fully saturated.However,drought periods dry it readily and increases its vulnerability to fire.Peat fires emit greenhouse gases and particles contributing to haze,and prevention by constructing fire-break canals to reduce fire spread into forest reserves is crucial.This paper aims to determine peat physical and chemical properties near a fire-break canal at different fire frequency areas.Peat sampling was conducted at two forest reserves in Malaysia which represent low fire frequency and high fire frequency areas.The results show that peat properties were not affected by the construction of a fire-break canal,however lignin and cellulose content increased significantly from the distance of the canal in both areas.The study concluded that fire frequency did not significantly influence peat properties except for porosity.The higher fibre content in the high frequency area did not influence moisture content nor the ability to regain moisture.Thus,fire frequency might contribute differently to changes in physical and chemical properties,hence management efforts to construct fire-break canals and restoration efforts should protect peatlands from further degradation.These findings will benefit future management and planning for forest reserves.

Steel bar penetrating cervical spinal canal without neurological injury:A case report

BACKGROUND We report a rare case of cervical spinal canal penetrating trauma and review the relevant literatures.CASE SUMMARY A 58-year-old male patient was admitted to the emergency department with a steel bar penetrating the neck,without signs of neurological deficit.Computed tomography(CT)demonstrated that the steel bar had penetrated the cervical spinal canal at the C6–7 level,causing C6 and C7 vertebral body fracture,C6 left lamina fracture,left facet joint fracture,and penetration of the cervical spinal cord.The steel bar was successfully removed through an open surgical procedure by a multidisciplinary team.During the surgery,we found that the cervical vertebra,cervical spinal canal and cervical spinal cord were all severely injured.Postoperative CT demonstrated severe penetration of the cervical spinal canal but the patient returned to a fully functional level without any neurological deficits.CONCLUSION Even with a serious cervical spinal canal penetrating trauma,the patient could resume normal work and life after appropriate treatment.

The Millennia-Old Canal Takes on a New Look Nihao!China——2024 China's Grand Canal Tourism Overseas Promotion Season

On the occasion of the 10th anniversary of the Grand Canal's application for the World Heritage status in 2024,with the strong support of the Department of International Cooperation of the National Radio and Television Administration and the International Tourism Alliance of Silk Road Cities.

Surgical Management of Lumbar Spinal Canal Stenosis with Instrumentation at the Yaounde Central Hospital: Comparison of Unilateral versus Bilateral Pedicle Screw Fixation Combined with Transforaminal Lumbar Interbody Fusion

Introduction: The choice of adopting unilateral pedicle screw fixation or using bilateral pedicle screw fixation in lumbar spinal stenosis remains controversial. In our context, very few studies have been performed comparing the clinical effectiveness of unilateral versus bilateral fixation in the surgical management of lumbar spinal canal stenosis. Objective: Evaluate the impact on quality of life and clinical efficacy of unilateral spondylodesis compared to bilateral spondylodesis in the surgical management of lumbar spinal canal stenosis at the Yaounde Central Hospital. Methods: This was a retrospective descriptive cross-sectional study for a period of 4 years, from June 2015 to June 2019. It involved all patients operated for lumbar canal stenosis and who underwent spondylodesis or spinal fusion at the neurosurgery department of the Yaounde Central Hospital. Results: A total of 68 participants were recruited during our study period. 32 (47%) of the study population were in the 50 - 60 age group, with a mean age of 56.98 years ranging from 41 to 75 years. Females, housewives and farmers were the most affected. In our study, 72% of patients had unilateral spondylodesis and 28% had bilateral fusion. Preoperatively, 71% of patients had insurmountable pain, refractory to medical treatment. At 3 months postoperatively, 73.7% of patients with bilateral setup had moderate pain compared to 69% of those with unilateral setup. At 6 months postoperatively, 79% of patients with bilateral fusion had mild pain compared to 82% of patients with unilateral setup. At 1 year postoperatively, all patients had mild pain. Preoperatively, 66.2% of patients were unable to walk and 19.1% of patients were bedridden according to the Oswestry score. At 3 months postoperatively, 10.2% of patients with unilateral setup were unable to walk compared to 10.5% of patients with bilateral fixation, while 67.3% of patients with unilateral fixation had moderate disability compared to 52.6% of patients with bilateral fixation. At 6 months postoperatively, 51% of patients with unilateral setup had moderate disability compared to 47.4% of patients with bilateral fixation, while 42.9% of patients with unilateral fixation had mild disability compared to 42.1% of patients with bilateral fixation. At 1 year postoperatively, 81.6% of patients who underwent unilateral fixation had only mild disability compared to 73.7% of patients with bilateral fixation. Conclusion: The assessment of quality of life according to the set-up used shows similar results at 3 months, 6 months and 1 year, with no statistically significant differences. Single-sided pedicle screw fixation combined with transforaminal lumbar interbody fusion or mounting has the advantage of being faster, with less bleeding and is less expensive compared to bilateral fixation.

Results Analysis of Surveys Made to Stakeholders in the Pacific Ports in the Panama Canal:A Study Focused to Improve the Efficiency of Loading/Discharging Operations

This research aims to analyze the communication process between the different participating actors in the port of Balboa,in the Panamanian Pacific.The starting hypothesis begins with the normal operation of the port itself.Considering which strategic actions have potential development and which specific strategic actions are proposed for their improvement,the article begins with a discussion of the nature of ports in Panama and their relationships with the Panama Canal,followed by a literary review of all the effects that climate change may have on navigation on the Panamanian Pacific coast.Next,the implication between the coordination and cooperation between the port,the Panama Canal pilots,and the other actors involved with the arrival and departure of vessels from the port will be analyzed.In a third part,the results of the perception of a significant sample of these actors who were surveyed,which are related to the process,are presented.The document concludes with recommendations on how the Panamanian Pacific port can improve its individual interests through the application of improvements derived from the results of the surveys,for more efficient inter-institutional coordination and cooperation.

Root Canal System Variation in Mandibular Second Molar: Middle-Mesial Canal

Middle-mesial canals in mandibular molars are present in the population depending on age, sex and ethnicity. However, limited literature alludes to its prevalence. Troughing procedures may enhance identification, cleaning and shaping. This case report expresses the recognition and management of middle-mesial canal in a mandibular second molar of 24 years old Hispanic-Latino male.

Investigation of serum calcium and vitamin D levels in superior semicircular canal dehiscence syndrome: A case control study

Objective: It remains unknown whether calcium metabolism has any effect on the clinical presentation of superior semicircular canal dehiscence(SSCD). Our aim was to analyse the adjusted calcium and vitamin D levels in SSCD patients compared to a control group.Methods: This was a prospective case-control study performed in a tertiary referral center, university teaching hospital in the UK. It included all new patients with SSCD seen in a dedicated skull base clinic over a 5-year period(2015-2019) compared to a gender and age matched control group. The main outcome of the study was adjusted calcium and Vitamin D levels between the two groups.Results: A total of 31 SSCD patients were recruited with a matched number of control patients. The mean Vitamin D level on the SSCD group was 44.8 nmoL/l(SD: 20.8) compared to 47.5 nmoL/l(SD: 27.4) on the control group(p = 0.702). Mean Adjusted calcium level was 2.34 mmoL/l(SD: 0.7) for SSCD compared to2.41 mmoL/l(SD: 0.11) for controls(p = 0.01), being within normal limits for both the SSCD and the control group.Conclusion: Our study did not identify a link between Vitamin D levels and presence of SSCD. Normal adjusted calcium values were found in both groups. Despite that a statistically significant lower calcium level was found in the SSCD group which could indicate that suboptimal levels of calcium may affect the micro-environment of the otic capsule at the SSC region.

An evidenced-based diagnostic tool for superior semicircular canal dehiscence syndrome

Purpose:To construct a symptoms-based prediction tool to assess the likelihood of superior canal dehiscence(SSCD)on high-resolution CT.Materials and methods:Mathematical modeling was employed to predict radiologic evidence of SSCD at a tertiary neurotology referral center.Results:A total of 168 patients were included,of which 118 had imaging-confirmed SSCD.On univariate analysis significant predictors of SSCD presence were:sound/pressure-induced vertigo(p?0.006),disequilibrium(p?0.008),hyperacusis(p?0.008),and autophony(p?0.034).Multivariate analysis enabled a 14-point symptom-weighted tool to be developed,wherein a score of6 raised the suspicion of SSCD(70%likelihood of being present),R2?0.853.Conclusions:The likelihood of SSCD on CT scan can be determined with a high degree of certainty based on symptoms recorded at presentation.Using the evidenced-based diagnostic tool validated herein,a score6 with any symptom combination justifies ordering a CT scan.

Nodular fasciitis of the external auditory canal: Clinical case report and review of the literature

Nodular fasciitis is a benign reactive soft tissue tumor arising from fibroblasts and myofibroblasts.Its incidence is low and misdiagnosis is frequent especially for malignant lesions.This can lead to inappropriate and unnecessary invasive treatment.Nodular fasciitis of the external auditory canal is extremely rare.So far,around fifteen cases have been reported.We present here the case of a 90-year-old patient with nodular fasciitis of the right external auditory canal.The lesion extends anteriorly for 6.5 cm and reaches the posterior wall of the maxillary sinus.To our knowledge,this is the first case in the literature of an external auditory canal nodular fasciitis presenting as an inflammatory ear polyp with such a wide extension.

Epithelioid trophoblastic tumor of the lower uterine segment and cervical canal:A case report

BACKGROUND Epithelioid trophoblastic tumor(ETT) is the rarest type of gestational trophoblastic tumor(GTT). It has been reported that more than 50% of ETTs arise in the uterine cervix or the lower uterine segment. Here, we report a case of ETT within the lower uterine segment and cervical canal and discuss its manifestations,possible causes, and related influencing factors.CASE SUMMARY A 35-year-old woman(gravida 7, miscarriage 3, induction 2 with 1 being twins,para 2 of cesarean section, live 2), who had amenorrhea for 9 mo after breastfeeding for 22 mo after the last cesarean section, was diagnosed with ETT. The lesion was present in the lower uterine segment and endocervical canal with severe involvement of the anterior wall of the lower uterine segment and the front wall of the lower uterine segment where the cesarean incisions were made.Laboratory tests showed slight elevation of serum beta-human chorionic gonadotropin. Intraoperative exploration showed the presence of a normal-sized uterus body with an enlarged tumor in the lower uterine segment. The surface of the lower uterine segment was light blue, the entire lesion was approximately about 8cm × 8 cm × 9 cm, with compression and displacement of the surrounding tissue.Histological examination diagnosed ETT. Immunohistochemical analysis showed positive expression of p63, with a Ki-67 proliferation index of 40%.CONCLUSION A search of the PubMed database using the search terms "cesarean section" and "epithelioid trophoblastic tumor" retrieved nine articles, including 13 cases of ETT and ETT-related lesions, all 13 cases had a history of cesarean section, and the lesions were all located at the cesarean section incision on the anterior wall of the lower uterine segment. The present case is the 14th reported case of ETT after cesarean section. Therefore, we deduced that cesarean section trauma had an important effect on the occurrence of ETT at this site.

Prevotella oris-caused meningitis and spinal canal infection:A case report

BACKGROUND Prevotella oris-induced meningitis and Prevotella oris-induced meningitis concomitant with spinal canal infection are extremely rare.To the best of our knowledge,only 1 case of Prevotella oris-induced central system infection has been reported.This is the second report on meningitis combined with spinal canal infection due to Prevotella oris.CASE SUMMARY We report a case of a 9-year-old boy suffering from meningitis and spinal canal infection.The patient presented to the neurosurgery department with lumbosacral pain for 1 mo and headache and vomiting for 1 d.He had been treated with cephalosporin and nonsteroidal anti-inflammatory drugs for fever,otalgia and pharyngalgia in a local hospital 2 mo prior to this admission.During hospitalization,magnetic resonance imaging suggested meningitis and L3-S1 lumbosacral dural sac infection.The cerebrospinal fluid and blood cultures were negative,but the cerebrospinal fluid specimen indicated the presence of Prevotella oris by metagenomic next-generation sequencing.Previous cases of Prevotella oris infection were retrieved from PubMed to characterize the clinicopathological features and identify the prognostic factors and related antimicrobial treatment of infection due to Prevotella oris.CONCLUSION This report shed light on the characteristics of Prevotella oris infection and highlighted the role of metagenomic next-generation sequencing in pathogen detection.

Root Canal Treatment Outcome and Restorative Condition of Teeth Treated by Undergraduates—A Clinical and Radiographic Evaluation

Background: The aim was to evaluate the nonsurgical Root Canal Treatment (nRCT) outcome, the restorative condition and the relationship between the coronal restoration quality and the outcome of teeth endodontic treated by undergraduates at the University of Caxias do Sul School of Dentistry (UCS-SD), Brazil, between 2019 and 2021. Materials and Methods: Data from the endodontically treated cases were retrieved, and the patients were recalled for a follow-up appointment at the university. The endodontic diagnosis, radiographs, and the presence of definitive restorations were analyzed in the clinical records. During the follow-up appointment, endodontically treated teeth were classified as present or absent. The nRCT was classified as successful (complete or incomplete healing) or failure (uncertain or unsatisfactory healing). Coronal restoration was classified as absent or present. When it was present, it was classified as permanent or temporary, and its quality as adequate or inadequate restoration. The results were presented as percentages. Results: A total of 257 teeth were endodontically treated. The most prevalent diagnosis was Chronic Apical Periodontitis (33.33%) and the most commonly treated teeth were premolars (46.15%). A total of 52 (21%) treated teeth were clinically and radiographically reexamined. The success rate for the nRCT was 98.08%. About 61.54% of this sample had a definitive composite resin restoration. Conclusion: The nRCT success rate was high. Special attention should be given to the presence and quality of the definitive restoration. Clinical Implications: There was no statistically significant impact between the coronal restoration and the nRCT success (P > 0.05).

Correlation study between the changes of motor evoked potential and the improvement of spinal canal volume in minimally invasive transforaminal lumbar interbody fusion

Objective:To analyze the correlation between the amplitude changes of motor evoked potential(MEP),the 3D volume changes of spinal canal measuring by postoperative CT and the improvement rate of clinical symptoms after the spinal canal decompression in minimally invasive transforaminal lumbar interbody fusion(MIS-TLIF),and to explore the predictive value of the changes of both MEP amplitude and spinal canal volume in the assessment of long-term clinical prognosis in MIS-TLIF.Methods:A retrospective study of 68 patients with L4/5 spinal stenosis treated with MIS-TLIF was performed.The changes of both intraoperative MEP amplitude and 3D spinal canal volume during the spinal canal decompression,as well as the visual analogue scale(VAS)and Oswestry dysfunction index(ODI)scores in the long-term follow-up were all recorded.Results:The values of intraoperative MEP amplitude was 159.04%higher in 68 patients with MIS-TLIF after spinal canal decompression(P<0.01).The 3 postoperative 3D spinal canal volume(4.89±1.27)cm increased by 31.22%in comparison 3 with preoperative date(3.78±1.08)cm(P<0.01).The VAS and ODI scores were improved to 78.55%and 80.60%,respectively at the last follow-up(P<0.01).The improvement rate of MEP amplitude on the decompression side was positively correlated with the improvement rate of postoperative spinal canal volume(r=0.272,P=0.025).The improvement rate of postoperative spinal canal volume was positively correlated with the improvement rate of VAS and ODI at the last follow-up(r=0.656,r=0.490,P<0.01).Moreover,the improvement rate of MEP amplitude on the decompression side was also positively correlated with the improvement rate of VAS and ODI at the last follow-up(r=0.322 and 0.235,respectively,P<0.05).Conclusion:The increase of MEP amplitude after spinal canal decompression in patients with lumbar spinal stenosis treated by MIS-TLIF was closely correlated with both of the increase of spinal canal volume and the improvement of clinical symptoms.Therefore,MEP amplitude monitoring was not only the one of the important monitoring methods for predicting the prognosis of MIS-TLIF but also the reliably predictive value in the long-term clinical prognosis in MIS-TLIF.

Resolving the“Matteo Ricci Puzzle”:Top-Level Design of the Grand Canal of China Based on the Ternary Leadership Theory

Guided by the ternary leadership theory from the perspective of social psychology,this paper explores the impacts of authoritarian,benevolent,and moral leadership on the top design of the Grand Canal of China in terms of its water management practice,while providing reference for resolving the“Matteo Ricci Puzzle”.The research findings are threefold:first,authoritarian as it is,the central government of China formulates relevant laws and regulations to provide legal system insurance for the construction of the Grand Canal Cultural Belt,thus providing the blueprint for constructing the“bright cultural belt,green ecological belt and colorful tourism belt of the Grand Canal”.Second,led by the Central Government,sticking to benevolent and moral leadership,China advocates scientific water management concepts and methods,and gives long-term and comprehensive care to the well-being of the people along the banks of the Grand Canal.Finally,the top-level design of the Grand Canal of China is based on the ternary leadership theory rooted in social psychology and has formulated a set of properly-scheduled,reasonably-coordinated,and flexibly-operated management system for the fundamental interests of the people and long-term goals of the country.

Review and Analysis: Fate of Arsenic Applied to Canal Shipping Lane Vegetation and United States Military Base Grounds in the Panama Canal Zone

The opening of the Panama Canal in 1913 increased the availability of internationally traded goods and transformed ocean-shipping by shortening travel time between the Atlantic Ocean and Pacific Ocean. The canal sparked the growth of port authorities and increased ship tonnage on both coasts of Panama. Since the construction of the Panama Canal, in the 1910s, pesticides, herbicides and chemicals, including arsenic, have been essential for controlling wetland vegetation, including hyacinth, which blocked rivers, lakes, and the canal as well as managing mosquitoes. Pesticides and chemicals flowed into Lake Gatun (reservoir) either attached to sediment or in solution during the monsoon season. Lake Gatun was the drinking water source for most of the people living in the Panama Canal Zone. The United States military base commanders had the ability to order and use cacodylic acid (arsenic based) from the Naval Depot Supply Federal and Stock Catalog and the later Federal Supply Catalog on the military base grounds in the Panama Canal Zone. Cacodylic acid was shipped to Panama Canal Zone ports, including Balboa and Cristobal, and distributed to the military bases by rail or truck. The objective of this study is to determine the fate of arsenic: 1) applied between 1914 and 1935 to Panama Canal shipping lane hyacinth and other wetland vegetation and 2) cacodylic acid (arsenic) sprayed from 1948 to 1999 on the US military base grounds in the Panama Canal Zone.

Gout: A Possible Cause of Lumbal Canal Stenosis. Cases Report in Sub-Saharan Area and Literature Review

Introduction: Gout is defined as an arthritic condition resulting from the deposition of monosodium urate crystals in and/or around joints, following long-standing hyperuricemia. This may cause gouty arthritis in joints and tophi in soft tissues. Spinal gout is rare and never mentioned in our context. It can appear as acute back pain, radiculopathy, spinal cord compression, spondylodiscitis or neoplasic/infectious epiduritis. Our aim was to share our surgical experience and proceed of a Literature review. Cases Presentation: Between January and August 2022, two patients male were surgically cared, aged of 42 and 60 years old. The gout was unknown in the youngest and poorly followed in the eldest. There was no past medical history of tuberculosis or immunodeficiency in both. The early diagnosis retained was unspecific lumbar spondylodiscitis due to clinical features: Patients complained both of lower back pain with initial fever. It was of a progressive left L5S1 deficit with erectile defect and dysuria in the first case and a progressive paraplegia without sphincter disorders in the second case. We proceeded with a lumbar laminectomy with a biopsy on both patients. The spinal tophus was ligamentous in one case and arthro-ligamentous in the other. There was a progressive motor recovery from postoperative Day-2 till postoperative Month-1. A probabilistic antituberculosis treatment was promptly initiated postoperatively based on radioclinic features while waiting for histologic proof. The Polymerase Chain Reaction (PCR) of Mycobacterium tuberculosis was negative and the histology was of a chronic calcified osteitis with dense fibrosis in both. The anti-gout treatment was implemented after 15 days with blood test evidence. A rheumatologic follow-up was also initiated and adjuvant physio-therapy. The results were very satisfactory from 4 - 6 months with independent walking. Discussion Conclusion: Spinal Gout may be suggested in 40-male-old faced with any acute rachialgia with neuro deficit with dubious neuro-imaging.

Review and Analysis: Did the United States Transport, Off-Load and Use Commercial 2,4,5-T Herbicides with Unknown Amounts of Dioxin TCDD on Military Base Grounds in Panama Canal Zone between 1948 and 1999?

The 84 km Panama Canal connecting the Atlantic and Pacific oceans has historically been a strategic waterway for shipping and the location of United States (US) military bases. Since the construction of Lake Gatun reservoir, canal locks and navigation channel through the Isthmus of Panama tropical forests in the 1910s, chemicals, pesticides, and herbicides have been essential for controlling upland and wetland vegetation as well as managing mosquito-borne diseases. Chemicals and pesticides flowed into Lake Gatun via land surface runoff and subsurface drainage either attached to the sediment or in solution during the rainy season. Lake Gatun and the Panama Canal was the drinking water source for most of the civilian and military population living in the Panama Canal Zone. Between 1948 and 1999, US military base commanders had the ability to order, from the Federal Supply Catalog, commercially available herbicide 2,4,5-T with unknown amounts of dioxin TCDD for use on the military base grounds in the Panama Canal Zone. The herbicide 2,4,5-T was transported to Panama Canal Zone ports, including the ports Cristobal on the Caribbean and Balboa on the Pacific, and distributed to the US military bases in Panama by rail or truck. The US National Toxicology Program and the International Agency for the Research on Cancer listed dioxin and TCDD as known human carcinogens. Dioxins are endocrine disrupters and can cause certain chloracne, cancers, developmental and reproductive effects. In 1985, the United States government banned the manufacture of the herbicide 2,4,5-T, with unknown amounts of dioxin TCDD, after it was shown to cause cancer in animals. The objectives of this study are to determine: 1) the fate of dioxin TCDD, a contaminant in the herbicide 2,4,5-T, sprayed on the US military base vegetation in the Panama Canal Zone from 1948 to 1999, 2) the transport of dioxin TCDD rich sediment via soil erosion and overland flow into Lake Gatun and Panama Canal waterways and 3) the human health impacts of dioxin TCDD, a known carcinogen, on US military and Panamanian civilians exposed to dioxin TCDD in the Panama Canal Zone.

Minimally Invasive 360 Degrees Decompression for Ligamentous, Bony and Discogenic Lumbar Canal Stenosis

Background: For decades, traditional open surgical techniques were used to treat lumbar disc herniation and lumbar canal stenosis (LCS). However, seeking for better outcomes for patients and avoiding extensive bony loss with its sequences had raised minimally invasive technique for treating these disorders as an alternative surgery. Methods: This is a retrospective study in which 54 patients of LCS were operated upon via unilateral minimally invasive technique to decompress the canal in a 360 degrees fashion through laminotomy, deroofing of opposite laminar side, sublaminar ligamintectomy, bilateral foraminotomies and discectomy. We used VAS scores and ODI to assess clinical outcomes with a period of one year follow-up. Results: Our results demonstrated that minimally invasive techniques for treating these disorders are effective procedures. Minimally invasive 360 degrees decompression for treating LCS had better outcomes regarding postoperative back pain, smaller incisions, less bony loss and early ambulation. Conclusion: Minimally invasive techniques for treating lumbar canal stenosis of different causes could be considered a better option instead of traditional full laminectomy with better outcomes as regards respecting the anatomical layers such as posterior spinal integrity and musculature, postoperative pain, accompanied with less blood loss, shorter hospital stays, and shorter recovery periods.

Solitary Neurofibroma of External Aural Canal

Neurofibroma is a benign tumor of the connective tissue of the peripheral nerves, developed mainly at the endoneurium. The most common localizations are the extremities of the limbs and the head and neck region. Neurofibromas are often associated with neurofibromatosis type 1. An isolated localization in the auditory canal is exceptional. We report the case of a 45-year-old female patient presenting with a neurofibroma of the auditory canal which had previously caused hearing loss. Examination revealed a tissue mass firm, painless and covered with normal skin obstructing the external auditory canal. The patient’s skin examination revealed no café-au-lait spots. A CT scan of the ear showed a hypodense tissue mass. Surgical removal via the ear canal gave good results. In conclusion, an isolated neurofibroma of the external auditory canal is a rare benign tumor with a good prognosis. The surgical approach depends on the exact location of the mass and the surgeon’s experience.

Tooth anatomy risk factors influencing root canal working length accessibility

The aim of this study was to analyze the specific influence of root canal anatomy on the accessibility of working length during root canal therapy. Four hundred seventy-six root canal therapy cases （amounting to a total of 1 005 root canals） were examined. The anatomy risk factors assessed in each case included： tooth type （tooth location）, root canal curvature, and root canal calcification, as well as endodontic retreatment. The investigation examined the correlation between each of these anatomic factors and the working length, with statistical analysis consisting of Chi-square tests and multiple logistic regression analysis. In an independent factor analysis, tooth type （tooth iocation）, root canal curvature, canal calcification, and endodontic retreatment were determined to be the primary risk factors. In a multiple-factor regression model, root curvature and canal calcification were found to most significantly influence root canal working length accessibility （P〈0.05）. Root canal anatomy increases the difficulty of root canal preparation. Appropriate consideration of tooth anatomy will assist in accurate determination of preparation difficulty before instrumentation. This study alerts clinical therapists to anatomical factors influencing the working length accessibility, and allows for a direct estimate of success rate given in situ measurements of tooth factors during the root canal treatment procedure.