Mandibular left first premolar with three roots and three canals:A case report

BACKGROUND The numbers of mandibular first premolar roots and root canals vary,and the incidence of three roots and three canals is 0.09%.CASE SUMMARY In this article,we review the root and root canal conditions for the mandibular first premolar and report the case of a mandibular left first premolar with three roots and three canals in a male patient,with suggestions for clinical diagnosis and treatment.The patient was referred by an orthodontist for the extraction of the tooth.Preoperative cone-beam computed tomography examination revealed that it had three roots.Under local anesthesia,the extraction socket was carefully expanded,and the tooth was successfully removed intact using forceps.The procedure was uneventful,with no root fractures,postoperative bleeding,or sensory abnormality observed.CONCLUSION The mandibular first premolar is characterized by multiple roots and canal variations that can increase the difficulty of treatment.

Complete resection of recurrent anal canal cancer using endoscopic submucosal dissection and transanal resection: A case report

BACKGROUND Early anal canal cancer is frequently treated with endoscopic submucosal dis-section(ESD)to preserve anal function.However,if the lesion is in the anal canal,then significant difficulties such as bleeding and challenges associated with scope manipulation can arise.CASE SUMMARY A 70-year-old woman undergoing follow-up after transverse colon cancer surgery was diagnosed with anal canal cancer extending to the dentate line.The patient underwent a combination of ESD and transanal resection(TAR).The specimen was excised in pieces,which resulted in difficulty performing the pathological evaluation of the margins,especially on the anal side where TAR was performed and severe crushing was observed.Careful follow-up was performed,and local recurrence was observed 3 years postoperatively.Because the patient had super-ficial cancer without lymph node metastasis,local resection was performed again.The second treatment attempt was improved as follows:(1)TAR and ESD were performed appropriately based on the situation by the same physician;(2)A needle scalpel was used during TAR to prevent tissue crushing;and(3)The lesion borders were marked using ESD techniques before treatment.Complete resection was performed without complications.CONCLUSION Anal canal lesions can be safely and reliably removed when ESD and TAR are used appropriately.

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.

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.

Three-dimensional inlay-guided endodontics applied in variant root canals: A case report and review of literature

BACKGROUND Root canal retreatment is common after root canal therapy in clinical situations.Especially,completing the retreatment of variant root canals can be challenging.This is particularly true for the molars located at the end of the dental arch.However,advancements in digital dental diagnosis and treatment techniques can solve these problems.Here,we describe a case of a maxillary second molar with a variant distobuccal root canal treated via a novel“inlay-guided endodontics”technique based on improved computer-generated programs.CASE SUMMARY A 63-year-old man complained of a defect in the maxillary left second molar.The tooth,diagnosed with post-treatment endodontic disease,was initially treated by conventional methods,which were ineffective.Our“inlay-guided endodontics”technique was subsequently adopted,with the establishment of a precise integrated three-dimensional(3D)plate model of cone-beam computed tomography data and a digital impression of the dentition.An optimal root canal approach was generated for the“virtual file”in the 3D model.The plate data were imported into a 3D printer and printed.With the help of the guide plate,the file was accurately placed into the cervical third of the distal root canal.The root canal and prosthodontic treatments successfully proceeded subsequently.CONCLUSION Our newly developed inlay guide plates may facilitate individualized and minimally invasive root canal treatment.

Study on Tissue Culture of Leucophyta brownii ‘Canal Rocks Form’

[Objective] This study aimed to establish a tissue culture technology for Leucophyta brownii ‘Canal Rocks Form’. [Method] Leucophyta brownii ‘Canal Rocks Form’ stems with axillary buds were selected as explants in vitro to investigate the effects of different concentrations of 6-BA and NAA on proliferation culture and the effects of IBA, NAA and subculture cycle on rooting culture. [Result] The results showed that Leucophyta brownii ‘Canal Rocks Form’ plantlets need low concentrations of phytohormones and the rooting culture was significantly affected by the subculture cycle; the optimal medium for proliferation culture was MS＋0.5 mg/L 6-BA＋0.05 mg/L NAA＋30 g/L sucrose＋5.5 g/L agar, with a proliferation coefficient of 4.25; the plantlets with a subculture cycle of 28 d were the most suitable for rooting culture, with a rooting rate of 95.9% in 1/2 MS＋0.1 mg/L IBA＋0.05 mg/L NAA＋20 g/L sucrose＋5.5 g/L agar, and the average number and length of roots were 4.69 and 1.68 cm, respectively. [Conclusion] This study laid the foundation for establishing sterile culture system of Leucophyta brownii ‘Canal Rocks Form’.

Comprehensive evaluation of water quality parameters in Tianjin Dagu Dainage Canal

In this paper, some indices of sulfide, organic carbon, oil and heavy metals （copper, lead, zinc, cadmium, mercury, arsenic and chromium） in the sediments from Dagu Dainage Canal at the Bohai Bay during four seasons in 2012 - 2013 are selected, and Water Quality Pollution Index （API） is applied to evaluate water quality indices, aiming for the systematic evaluation of the water quality of Dagu Dainage Canal. The results showed that four stations of D3, D6, D7and D9 for S2 had the type Ⅱand Ⅲ of water; others had the type Ⅰ ; the total level of TOC, TPH, Cu, Pb, Zn, Cd, Hg, As and Cr were type Ⅰ, Ⅳ, Ⅱ, Ⅴ, Ⅱ, Ⅴ, Ⅲ, Vand Ⅴ. Water Quality Pollution Index （API） was 3.28, which illustrated Dagu Dainage Canal was in the state of contamination and the degree of pollution exceeded the standard functional areas.

Post-inflammatory acquired atresia of the external auditory canal

Acquired atresia of the external auditory canal(EAC)is a rare cause of conductive hearing loss.It has been traditionally classified into 4 categories:traumatic,post-operative,neoplastic and inflammatory.Post-inflammatory acquired auditory canal atresia is thought to be the result of chronic and repetitive infectious bouts affecting the auditory canal.Nevertheless,the underlying pathophysiology of this disorder is yet to be fully elucidated.Current data fail to clearly state the impact that certain underlying systemic disorders may have on the EAC.The possible association to metabolic disturbances such as iron deficiency is also emphasized.In the light of these findings,this analysis can be used to improve the classification of this entity thereby standardizing the assessment of therapeutic approaches.

Root canal morphology and configuration of 123 maxillary second molars by means of micro-CT

The aim of this study was to investigate the root canal configuration, accessory canals and number of main foramina of 123 maxillary second molars by means of micro-computed tomography. The teeth were scanned and reproduced with 3D software imaging. The root canal configuration and number of main foramina were evaluated by means of a four-digit system. The morphological complexity of human maxillary second molars is depicted by the number of accessory and connecting canals. The most frequently observed root canal configurations in the mesiobuccal root were 2-2-2/2 （19.5%）, 2-2-1/1 （14.6%） and 2-1-1/1 （13.0%）. A 1-1-1/1 configuration was observed in 93.5% and in 96.7% in the distobuccal and palatal roots, respectively. The MB1 mot canal had one accessory canal （18.7%）, and 8.9% of the MB2 root canal had one or two accessory canals. The distobuccal （11.3%） and palatal （14.6%） root canals had at least one accessory canal, and connecting canals were observed in 16.3% of mesiobuccal roots. The MB1, MB2, distobuccal and palatal root canals had one main foramen in 99.2%, 43.1%, 98.4% and 99.2% of samples, respectively. In the mesiobuccal root, one accessory foramen was detected in 14.6%, two were detected in 7.3%, and three were detected in 5.7%. The distobuccal root showed one or two accessory foramina in 9.1% of samples. The root canal configuration of maxillary second molars is quite heterogeneous; the mesiobuccal root has predominantly two root canal entrances （58.4%, 1 in 41.1%） with one main foramen （54.4%）. Two main foramina were observed in 43.0%. Morphological variations, connecting and accessory canals were observed in all apical thirds.

Efficacy of Solution Form of Ethylenediaminetetraacetic Acid on Removing Smear Layer of Root Canal at Different Exposure Time In Vitro

Summary： This study was aimed to evaluate the effectiveness of solution form of 17% ethylenediaminetetraacetic acid （EDTA） on removing smear layer of root canals at different exposure time periods and to provide scientific basis for EDTA as a choice of root canal irrigation in clinical practice. Twenty-five single-rooted teeth were randomly divided into 5 groups： control group （group A） was given 2.5% NaOC1, and 4 experimental groups were given 2.5% NaOC1 and 17% EDTA, including groups B, C, D and E with exposure time of 1, 3, 5 and 7 min, respectively. After preparation of the root canals, the teeth were split along their longitudinal axis, and the root sections were examined under scanning elec- tron microscope for evaluation of smear layer removal and erosion on the surface of the root canal walls. The specimens in group B showed presence of smear layer on the walls of the root canal with no statistical difference from that in group A （P〉0.05）. In groups C and D, partial removal of smear layer was obtained, and there was no significant difference between the two groups （P〉0.05）, but there was significant difference in removal of smear layer between group C and group B （P〈0.05）. Root canal walls in group E specimens showed almost complete removal of smear layer, and the removal of smear layer was significantly different from that in group D （P〈0.01）. There was no significant change in the structure of the surface of root canal for each sample. It was concluded that combined irrigation with 17% EDTA and 2.5% NaOC1 could remove the smear layer with no significant alteration in dentinal structure when the chelating agent was applied for 7 min. At 3 and 5 min of application, partial removal of smear layer was observed and at 1 min negligible removal of smear layer was achieved.

Modified viscocanalostomy in the Chinese population with open angle glaucoma: a 10-year follow-up results

AIM: To study the long-term efficacy and safety of modified viscocanalostomy in Chinese people with open angle glaucoma(OAG).METHODS: This retrospective study included a total of 100 eyes from 100 Chinese patients with medically uncontrolled OAG. All the patients underwent modified viscocanalostomy with injection of viscoelastic material in the surgically created ostia of Schlemm's canal(SC). The modifications included peeling of the inner wall of SC and the juxtacanalicular meshwork, use of mitomycin C, and loosely suturing the superficial scleral flap. Intraocular pressure(IOP), visual acuity, number of medications, laser goniopuncture data and complications were recorded. The definition of complete(qualified) success was an IOP equal to or lower than 21, 18, 16 mm Hg without(with or without) anti-glaucoma medications. RESULTS: The mean IOP was 33.5±9.9 mm Hg before surgery, 15.2±3.6 mm Hg(mean IOP reduction of 51%) at 5 y after surgery, and 15.6±2.8 mm Hg(mean IOP reduction of 49.9%) at 10 y after surgery(P<0.001). The number of anti-glaucoma medications dropped from 2.39±0.5 preoperatively to 0.47±0.8 at 5 y and 0.67±0.8 at 10 y postoperatively(P<0.001). The follow-up period was 104.5±37.0 mo. The qualified success rate for an IOP of 21, 18 or 16 mm Hg or less was 84% [95% confidence interval(CI): 0.80-0.88], 73%(95%CI: 0.68-0.78), and 59%(95%CI: 0.52-0.66) after 5 y, and 80%(95%CI: 0.76-0.84), 69%(95%CI: 0.64-0.74), 51%(95%CI: 0.44-0.58) after 10 y, respectively. There was a relationship between age, preoperative IOP and success rate(P<0.01, P<0.05). A total of 31 eyes(31.3%)in 31 patients underwent laser goniopuncture, decreasing the IOP from 22.9±4.3 mm Hg to 16.3±2.5 mm Hg(P<0.01). Neither blebitis nor endophthalmitis occurred.CONCLUSION: Modified viscocanalostomy could be performed to lower IOP, decrease multiple anti-glaucoma drops use as well. It's a safe procedure with less complications over 10 y in Chinese individuals with OAG.

Schlemm’s canal结构和功能调控的研究进展及其在青光眼治疗中的应用

Schlemm管(Schlemm’scanal,SC)作为房水流出的主要通道,通过调节房水外排来维持眼内压的平衡,其结构和功能的异常与高眼压及青光眼的发生发展密切相关。对SC的研究有助于阐明房水外排阻滞的发生机制、探索新的途径以增加房水排出,从而为降低眼压和青光眼治疗的新药物开发提供基础。目前,对SC发育和功能的调节机制的认识仍然有限,缺乏针对SC的特异性治疗策略。近年来,关于SC细胞命运决定及其结构发育的细胞学机制逐渐被揭示,功能调控的关键分子靶标也相继被发现,这促进了对SC结构和功能调控的深入理解。此外,作为降眼压药物靶点和针对性手术的创新应用也在不断拓展。文章系统回顾SC的结构与功能研究,总结关键的分子和细胞学调控机制,归纳SC靶向药物和手术疗法的最新进展,为青光眼的临床诊治提供了新的思路。

Cone-beam computed tomography analysis of curved root canals after mechanical preparation with three nickel-titanium rotary instruments

Cone beam computed tomography is a 3-dimensional high resolution imaging method. The purpose of this study was to compare the effects of 3 different NiTi rotary instruments used to prepare curved root canals on the final shape of the curved canals and total amount of root canal transportation by using cone-beam computed tomography. A total of 81 mesial root canals from 42 extracted human mandibular molars, with a curvature ranging from 15 to 45 degrees, were selected. Canals were randomly divided into 3 groups of 27 each. After preparation with Protaper, Revo-S and Hero Shaper, the amount of transportation and centering ability that occurred were assessed by using cone beam computed tomography. Utilizing preand post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. Canals were metrically assessed for changes （surface area, changes in curvature and transportation） during canal preparation by using software SimPlant; instrument failures were also recorded. Mean total widths and outer and inner width measurements were determined on each central canal path and differences were statistically analyzed. The results showed that all instruments maintained the original canal curvature well with no significant differences between the different files （P=0.226）. During preparation there was failure of only one file （the protaper group）. In conclusion, under the conditions of this study, all instruments maintained the original canal curvature well and were safe to use. Areas of uninstrumented root canal wall were left in all regions using the various systems.

The structure of canalizing functions

The structure of a canalizing function is discussed. Using a new matrix product, namely semitensor product, the logical function is expressed in its matrix form. From its matrix expression, a criterion is obtained to test whether a logical function is a canalizing function. Then a formula is obtained to calculate the number of canalizing functions. Moreover, an algorithm is presented to generate canalizing functions. Finally, some results obtained are extended to seminested canalizing functions.

Non-surgical management of dens invaginatus type IIIB in maxillary lateral incisor with three root canals and 6-year follow-up:A case report and review of literature

BACKGROUND The presence of dens invaginatus(DI)complicates treatment of any tooth,from diagnosis to access cavity and biomechanical preparation and obturation.Reports of successful non-surgical management of DI type IIIB in maxillary lateral incisor are rare.Here,we report such a case,with three root canals and a long follow-up.CASE SUMMARY A 13-year-old female patient presented with mild pain in the maxillary right lateral incisor(#7)for 10-15 d.On examination,the tooth was slightly rotated,with slight tenderness on percussion and grade I mobility but with no caries,pockets or restorations and non-vital pulp(via vitality tests).Radiographic examination revealed unusual configuration of the tooth’s root canals,with an enamel-lined invagination extending to the apex,suggesting the possibility of DI Oehler’s type IIIB and a periapical radiolucency.Widening the access cavity lingually revealed one distinct buccal orifice and two distinct palatal orifices;under higher magnification of a dental operating microscope(DOM),the mesio palatal and disto-palatal orifices were observed as connected by a C-shaped groove.The root canals were prepared with hand K-files following a step-back technique,and obturated using a combination technique of lateral condensation and vertical compaction.At the 6-year follow-up,the patient was asymptomatic,and the periapical radiography displayed significant healing around the apical end of the root.CONCLUSION Proper knowledge of unusual root canal anatomy is required in treating DI.Conventional methods of root canal treatment can successfully resolve such complex cases,facilitated by DOM and cone-beam computed tomography.

Successful individualized endodontic treatment of severely curved root canals in a mandibular second molar:A case report

BACKGROUND The incidence rate of severely curved root canals in mandibular molars is low,and the root canal treatment of mandibular molars with this aberrant canal anatomy may be technically challenging.CASE SUMMARY A 26-year-old Chinese female patient presented with intermittent and occlusal pain in the left mandibular second molar.The patient had undergone filling restoration for caries before endodontic consultation.With the aid of cone beam computed tomography(CBCT),a large periapical radiolucency was observed,and curved root canals in a mandibular second molar were confirmed,depicting a severe and curved distolingual root.Nonsurgical treatments,including novel individualized preparation skills and techniques and the use of bioceramic materials as an apical barrier,were performed,and complete healing of the periapical lesion and a satisfactory effect were achieved.CONCLUSION A case of severely curved root canals in a mandibular second molar was successfully treated and are reported herein.The complex anatomy of the tooth and the postoperative effect were also evaluated via the three-dimensional reconstruction of CBCT images,which accurately identified the aberrant canal morphology.New devices and biomaterial applications combined with novel synthesis techniques can increase the success rate of intractable endodontic treatment.