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.

Three-dimensional computed topography analysis of a patient with an unusual anatomy of the maxillary second and third molars

We present a case of a patient with rare anatomy of a maxillary second molar with three mesiobuccal root canals and a maxillary third molar with four separate roots, identified using multi-slice computed topography （CT） and three-dimensional reconstruction techniques. The described case enriched/might enrich our knowledge about possible anatomical aberrations of maxillary molars. In addition, we demonstrate the role of multi-slice CT as an objective tool for confirmatory diagnosis and successful endodontic management.

Incidence of C-shaped root canal systems in mandibular second molars in the native Chinese population by analysis of clinical methods

The aims of the study were to investigate the incidence of C-shaped root canal systems in mandibular second molars in a native Chinese population using radiography and clinical examination under microscope and to compare the relative efficacies of these methods. For the recognition of C-shaped root canal system, 1 146 mandibular second molars were selected and examined. Teeth with C-shaped canal systems were categorized by using the radiographic classification criteria and the modified Melton＇s method. C-shaped canals were identified in 397 （34.64%） mandibular second molars by radiography （type I, 31.23%; type II, 38.29%; type III, 30.48%）. Clinical examination showed that 449 （39.18%） cases exhibited C-shaped canal systems （C1, 22.94%; C2, 48.11%; C3a, 15.59%; C3b, 13.36%）. As for the result of the radiographic and clinical combined examination, C-shaped root canals were found in 473 （41.27%） mandibular second molars （C1, 21.78%; C2, 45.67%; C3a, 16.70%; C3b, 15.86%）. The incidence of C-shaped root canal diagnosed by radiographic method was statistically different from that by clinical examination and the combined examination （P〈O.05）. The study indicated a high incidence of C-shaped canal system in a Chinese population. The combination of microscopic and radiographic examination is an effective method in identifying the C-shaped root canal system.

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.

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.

Maxillary Second Molar with Single Root and Single Canal—Case Report

The maxillary second molar contains three roots and three canals. Variations of the maxillary second molar are reported in numerous studies in vitro and in vivo. Dentists are required to have adequate knowledge related to root canal morphology and their possible variations. The aim of this study was to present a case report about a diagnosis and treatment in maxillary second molar with single root and single canal. It is concluded that the diagnosing of these unusual cases is of high importance for successful endodontic treatment of these teeth.

Anatomic Variation in Palatal Root of Maxillary Second Molar: Endodontic Management

The aim of the present clinical case report is to describe the singular root canal anatomy and endodontic management of a maxillary second molar with two palatal roots and two separate canal orifices. A 60 years-old female Hispanic/Latino patient attended the Endodontic Department at University of Buenos Aires School of Dentistry with acute pain in her maxillary left second molar. Clinical radiographs examination revealed unusual root morphology. Cleaning and shaping were completed with 5.25% NaOCl irrigation, 15% EDTA solution and hand/rotary instruments. Filling was performed with gutta-percha points and resin-based sealer. After one year follow-up periapical radiographs and CBCT images showed healing in the area and patient was asymptomatic.

Research on the Related Factors of the Second Molar Dislocation and Orthodontic Erect Method

The second molar dislocation is more common clinically.To investigate the related factors of the second permanent molar dislocation,and provide reference for the clinical diagnosis and treatment of orthodontics.From the current clinical research,the clinical methods of orthodontic erect secondary molars are also diverse and clinical.The narrower first molar alveolar arch width,smaller ANB angle,and crowded maxillary posterior segment arch are the factors that cause the maxillary second permanent molar dislocation.The narrow alveolar arch width,the smaller SNB angle,the larger ANB angle,and the crowded lower mandibular arch are the factors leading to the dislocation of the mandibular second permanent molar.In addition,for the second mandibular molar malposition,it is particularly important to select the corrective treatment plan.It is especially important to improve the treatment.

A Case Report of Kissing Molars Class II

Kissing molars (KMs) is a condition of occlusal molar surfaces in a single follicular space with roots extending in opposite directions. Here, we have reported a case of KMs in a 58-year-old woman. The patient complained of pain in the right mandibular molar region and was diagnosed with KMs consisting of the right mandibular second and third molars. Because of the patient’s pain having subsided at the time of the visit and her unwillingness to undergo tooth extraction, the patient was followed up. KMs is classified into three classes (I-III) and is either true-KMs or pseudo-KMs and presents with or without cystic variants of dental follicles. The presents as true-KMs class II without a cystic variant. With reference to the literature and based on our analysis, the mean age of patients affected by this specific case of KMs is 31.7 years and unilateral KMs is relatively more common (85.7%). Histopathological findings of dentigerous cysts are more often indicated (42.9%). The treatment policy for KMs should therefore be based on the classification of KMs. Importantly, the focus should be on preserving the first and second molars as much as possible. The treatment approach, such as the employment of surgical removal or orthodontics, should be determined by considering the associated factors such as the crowns, tissues, and age of the patient.

Bilateral maxillary fused second and third molars:a rare occurrence

This case report describes the diagnosis and endodontic therapy of maxillary fused second and third molars, using cone-beam computed tomography （CBCT）. A 31-year-old Chinese male, with no contributory medical or family/social history, presented with throbbing pain in the maxillary right molar area following an unsuccessful attempted tooth extraction. Clinical examination revealed what appeared initially to be a damaged large extra cusp on the buccal aspect of the distobuccal cusp of the second molar. However, CBCT revealed that a third molar was fused to the second molar. Unexpectedly, the maxillary left third molar also was fused to the second molar, and the crown of an unerupted supernumerary fourth molar was possibly also fused to the apical root region of the second molar. Operative procedures should not be attempted without adequate radiographic investigation. CBCT allowed the precise location of the root canals of the right maxillary fused molar teeth to permit successful endodontic therapy, confirmed after 6 months.

Endodontic management of a fused left maxillary second molar and two paramolars using cone beam computed tomography: A case report

BACKGROUND Fused teeth usually involve several complications,such as the development of caries in the groove between fused crowns,tooth impaction,diastemas,aesthetic and periodontal problems,and pulpal pathosis,due to the complex anatomical structure of fused teeth.A thorough diagnosis is paramount to forming an accurate treatment plan and obtaining a favourable prognosis.With the advent of cone-beam computed tomography(CBCT),accurate 3-dimensional images of teeth and their surrounding dentoalveolar structures can now be readily obtained,and the technology can accurately provide a minimally invasive approach to acquire detailed diagnostic information.Therefore,we utilize CBCT data herein to generate a digital model for the infected region in a patient,and this model enables us to better plan the management of his case.CASE SUMMARY This report details the diagnosis and endodontic treatment of a rare case involving a fused maxillary second molar and two paramolars with apical periodontitis.The patient experienced pain upon biting and cold sensitivity in the area of the maxillary left molar.No caries or other defects were identified in these teeth,and a normal response to a pulp electric viability test was observed.With the aid of CBCT and digital model technology,we initially suspected that the infection originated from the isthmus between the maxillary second molar and two paramolars.Therefore,we only treated the isthmus by an endodontic approach and did not destroy the original tooth structure;furthermore,the vital pulp was retained,and good treatment outcomes were observed at the 24-month follow-up.CONCLUSION This finding may provide new insights and perspectives on the diagnosis and treatment of fused teeth.

Concrescence of maxillary second molar and impacted third molar:A case report

BACKGROUND Morphological anomalies of teeth,including talon cusp,dens evaginatus,gemination,fusion,concrescence,root dilaceration,and taurodontism,always involve changes in the enamel,cementum and dentin.Diagnosing concrescent teeth through routine clinical examination alone is difficult,and most cases of concrescence are found accidentally during extraction.A definite preoperative diagnosis of concrescence would contribute to a better treatment plan and fewer undesirable complications CASE SUMMARY A 47-year-old woman who complained of left maxillary first molar loss for half a year presented to our department seeking treatment by dental implant restoration.Panoramic radiography and cone-beam computed tomography(CBCT)showed an unclear boundary between the distal root of the second molar and the mesial root of the third molar.The teeth were extracted under local anesthesia,and a definite diagnosis of concrescence was made by histopathological examination.CONCLUSION CBCT is a useful tool for diagnosing and planning the management of tooth concrescence and may be beneficial for reducing unnecessary complications.

Two Palatal Root Canals in a Maxillary Right Second Molar:One Case Report

牙根和根管的数目不是固定不变的,文献报道表明牙齿尤其是上颌磨牙根管存在着解剖变异。但是,上颌第二磨牙发生腭根双根管的可能性很低。在本文中,作者报道了一例右上颌第二磨牙腭根双根管的解剖变异。由于可能存在的上颌第二磨牙腭根管解剖变异,所以临床医生在牙髓病治疗过程中应注意术前对患牙进行影像学分析,术中可借助牙科手术显微镜等可视手段寻找可能存在的腭根解剖变异。

Two-stage extraction by partial grinding of impacted mandibular third molar in close proximity to the inferior alveolar nerve

BACKGROUND Extraction of impacted third molars often leads to severe complications caused by damage to the inferior alveolar nerve(IAN).AIM To proposes a method for the partial grinding of an impacted mandibular third molar(IMM3)near the IAN to prevent IAN injury during IMM3 extraction.METHODS Between January 1996 and March 2022,25 patients with IMM3 roots near the IAN were enrolled.The first stage of the operation consisted of grinding a major part of the IMM3 crown with a high-speed turbine dental drill to achieve sufficient space between the mandibular second molar and IMM3.After 6 months,when the root tips were observed to be away from the IAN on X-ray examination,the remaining part of the IMM3 was completely removed.RESULTS All IMM3s were extracted easily without symptoms of IAN injury after extraction.CONCLUSION Partial IMM3 grinding may be a good alternative treatment option to avoid IAN injury in high-risk cases.

Researching Creativity in Second Language Acquisition:Book Review

In the realm of psychology and language acquisition,the exploration of“individual differences”-encompassing attributes such as personality traits,motivation,and language aptitude-has long been a focal point of scholarly investigation.Within this sphere,the book“Researching Creativity in Second Language Acquisition”by Ashleigh Pipes offers a fresh perspective on the role of creativity as a significant individual difference in Second Language Acquisition(SLA).Positioned against the backdrop of extensive empirical research on individual differences,this book stands out by focusing on the often overlooked aspect of creativity,which Pipes argues,holds paramount importance in SLA.

Research on the Application of Second Language Acquisition Theory in College English Speech Teaching

The teaching of English speeches in universities aims to enhance oral communication ability,improve English communication skills,and expand English knowledge,occupying a core position in English teaching in universities.This article takes the theory of second language acquisition as the background,analyzes the important role and value of this theory in English speech teaching in universities,and explores how to apply the theory of second language acquisition in English speech teaching in universities.It aims to strengthen the cultivation of English skilled talents and provide a brief reference for improving English speech teaching in universities.

Research on Practical Teaching of Ideological and Political Courses in Colleges and Universities and Collaborative Education in the Second Classroom

In today’s society,the need for talent training is of utmost importance due to rapid development.To achieve high-quality talent training,we need to focus on building a collaborative education mechanism.Practical teaching and the second classroom,which serve as important carriers of educational talents,must align their educational goals and complement each other.This article explores the collaborative education mechanism of the second classroom and practical teaching for the ideological and political courses in colleges and universities.It proposes reasonable construction measures to provide some guidelines for teaching work.

The Convergence Rate of Fréchet Distribution under the Second-Order Regular Variation Condition

In this article we consider the asymptotic behavior of extreme distribution with the extreme value index γ>0 . The rates of uniform convergence for Fréchet distribution are constructed under the second-order regular variation condition.

Ectopic Molar Pregnancy with Coexistent Normal Intrauterine Pregnancy: A Report of an Unusual Diagnosis managed in Yaoundé Gyneco-Obstetric and Pediatric Hospital, Cameroon

Background: Heterotopic pregnancy is a very rare event in a natural cycle. Its incidence is rising mostly due to induction of ovulation or Assisted Reproductive Technique. Most ectopic in heterotopic pregnancies are localized in the fallopian tubes. The occurrence of molar tubal ectopic pregnancy coexisting with intrauterine pregnancy is uncommon and consequently not often considered a diagnostic possibility. Case Report: We report the case of a 25-year-old woman, gravida 4 para 1, who complained of vaginal spotting and lower abdominal pain after 6 weeks of amenorrhea following clomiphene citrate ovarian stimulation. Transvaginal Ultrasonography revealed an intrauterine pregnancy and an unruptured left tubal ectopic pregnancy. She underwent successful laparoscopic salpingectomy while the intra-uterine pregnancy was allowed to continue. The ectopic pregnancy tissue histology reported an ectopic partial molar pregnancy. She subsequently had a normal vaginal delivery at 39 weeks and 3 days and her follow-up was uneventful. Conclusion: Heterotopic pregnancy is a rare but life-threatening condition. It should be suspected in a pregnant woman with a risk factor of multiple gestations who presents vaginal bleeding and lower abdominal pain in the context of early pregnancy. Laparoscopic surgery is effective for confirming the diagnosis and treating the ectopic component. Routine histological examination of tubal specimens must be taken very seriously because some findings like molar pregnancies may require specific management.

Temporal electric field of a helium plasma jet by electric field induced second harmonic(E-FISH)method

Electric field is an important parameter of plasma,which is related to electron temperature,electron density,excited species density,and so on.In this work,the electric field of an atmospheric pressure plasma jet is diagnosed by the electric field induced second harmonic(E-FISH)method,and the time-resolved electric field under different conditions is investigated.When positive pulse voltage is applied,the electric field has a peak of about 25 kV cm-1at the rising edge of the voltage pulse.A dark channel is left behind the plasma bullet and the electric field in the dark channel is about 5 kV cm-1.On the other hand,when negative pulse voltage is applied,the electric field has a peak of-16 kV cm-1when the negative voltage is increased to-8 kV.A relatively bright channel is left behind the plasma head and the electric field in this relatively bright channel is about-6 kV cm-1.When the pulse rising time increases from 60 to 200 ns,the peak electric field at both the rising edge and the falling edge of the voltage decreases significantly.When 0.5%of oxygen is added to the main working gas helium,the peak electric field at the rising edge is only about 15 kV cm-1.On the other hand,when 0.5%nitrogen is added,the peak electric field increases especially at the falling edge of the voltage pulse,where it increases reversely from-12 to-16 kV cm-1(the minus sign only represents the direction of electric field).