Intentional replantation for the retreatment of mandibular second molar: a case report / 华西口腔医学杂志

When the use of root canal retreatment and apical surgery experiences difficulty in treating endodontic diseases, intentional replantation is an optional clinical technique used to retain the tooth. A 28-year-old female complained of chewing discomfort at the mandibular second molar after undergoing root canal treatment 3 month ago. History record and radiographic examination revealed that a C-shaped root canal system was filled with gutta-percha in the mandibular second molar. A radiolucency area existed at the root furcal area with a thin canal wall in the distal and mesial roots. Intentional replantation was used to treat this tooth. The clinical and radiographic results showed that intentional replantation and nano-biomaterial application facilitated infection control, tooth retention, and periodontal tissue regeneration.

Comparison of panoramic radiography and cone-beam computed tomography images for detecting external root resorption of mandibular second molar associated with third molar impaction / 口腔医学

Objective@# To compare the diagnostic performance between panoramic radiography(PR)and cone beam computed tomography(CBCT)in the assessment of external root resorption(ERR)of mandibular second molars associated with impacted third molars. @*Methods@# A total number of 832 patients with 1 074 mesially and horizontally impacted mandibular third molars treated at our institution from January 2019 to December 2020 were retrospectively analyzed. Presence of ERR on the adjacent second molar was investigated with PR and CBCT. Factors affecting the diagnostic accuracy of PR were determined. @*Results@# The overall incidence of ERR in second molars was 33.15%(356/1 074)as detected by CBCT images. The accuracy of PR was 66.39%. Multivariate Logistic regression analyses further revealed that middle and Class Ⅲ impaction, crown contact or overlap with the root of adjacent tooth were risk factors for inaccurate diagnosis of PR(P<0.05). @*Conclusion@#The accuracy of detection on ERR of mandibular second molar associated with impacted third molar using panoramic radiography is lower. CBCT is recommended for this clinical scenario.

Radiological measurement and analysis of trans-inferior alveolar nerve implantation / 口腔医学

Objective@#To measure the position of the mandibular nerve canal at the mandibular second molar by CBCT image data, analyze the theoretical implantation range of trans-alveolar implantation, and provide a theoretical solution to insufficiency of posterior mandibular bone volume in clinical practice. @*Methods@#Eighty patients with missing mandibular second molars whose vertical bone height of the edentulous area was less than 9 mm were selected for CBCT image measurement, and the distances from the mandibular nerve canal to the buccal cortex, lingual cortex, and alveolar crest were measured to simulate trans-inferior alveolar nerve implantation. The angular range of the buccolingual inclination of the implant was also measured.@*Results@#The distances from the mandibular nerve canal to the buccal cortex, lingual cortex and alveolar crest at the mandibular second molar were(6.913±1.222)mm, (2.859±0.891)mm and (7.991±0.783)mm, respectively. The distance from the mandibular nerve canal to the buccal cortex was significantly greater than that to the lingual cortex. And, 75% of the patients could be implanted by the inferior alveolar nerve. The minimum angle of buccolingual inclination of the simulated implant was 19.360°±7.086°, and the maximum angle was 39.462°±6.924°. @*Conclusion@#The mandibular nerve canal at the mandibular second molar is inclined toward the lingual side, which ensures sufficient buccal bone volume. Most patients with severe mandibular atrophy can still adopt implants of conventional length by trans-inferior alveolar nerve implantation to keep a safe distance from the nerve canal.

CBCT study of the root and root canal morphology of mandibular second molars in a population in western Guangxi / 口腔疾病防治

Objective@#To observe the root and root canal morphology of mandibular second molars in Western Guangxi by CBCT, to provide a reference for clinical diagnosis and treatment.@*Methods@#In total, 564 patients′ 1 128 mandibular second molars that satisfy the inclusion criteria were analyzed with a planmecaromexis CBCT machine and its own image analysis software. The patients′ gender, age and ethnic differences in the root and canal morphology and the symmetry of the bilateral root and canal were statistically analyzed. @*Results@# Among the 1 128 mandibular second molars, 662 were the Zhuang ethnic group and 384 were the Han ethnic group, and 82 were other ethnic groups; the double root type and C-shaped root type accounted for a relatively high proportion: 73.94% and 24.47%, respectively. The detection rates of the double root type were higher in males than in females (P < 0.05); the detection rates of the C-shaped root type were higher in females than in males (P <0.05); the root type of the teeth was mainly double-rooted in the Zhuang ethnic group (P<0.01). The incidence of type IV in the mesial root of the double root type mandibular second molar was the highest (P < 0.01), and the incidence of type I in the distal root was the highest (P < 0.01). The C-shaped root canal is more continuous at the mouth of the root canal, more downward corresponds to a worse continuity: in three different levels of root canal orifice, root middle and root apex, the root canal orifice is dominated by the C1 type, and both root middle and root apex are mainly C3-type (P < 0.01). The difference in symmetry of bilateral roots and root canals was statistically significant among different gender groups, age groups, and ethnic groups (P < 0.05): there were more males than females, the results in the 18-35-year-old group and the Zhuang ethnic group were higher.@*Conclusion@# The root and root canal morphology of mandibular second molars in western Guangxi people are complex and changeable. The roots are mainly double root type in the Han ethnic group and the Zhuang ethnic group. C-shaped roots are also common. The detection rate of C-shaped roots in the Zhuang ethnic group was higher, and the symmetry rate of bilateral roots and that of bilateral root canals was higher in the Zhuang ethnic group than in the Han ethnic group.

Three-dimensional analysis of the mandible with impacted mandibular second molar / 华西口腔医学杂志

OBJECTIVE@#To study the developmental and morphological characteristics of the mandible in patients with impacted mandibular second molar and to predict the possible trend of mandibular development via three-dimensional (3D) measurement and analysis.@*METHODS@#A total of 88 cases of impacted group and 88 cases of control group were screened out. 3D measurements were performed by using Mimics software. A total of 23 landmark points and 17 measurements were determined. The measurements were analyzed by t-test.@*RESULTS@#The mandible length, the space between the first molars, the space between mandibular angles, and the width between the first molars in the impacted group were lower than those in the control group (P<0.05). Moreover, the value of the submandibular angle was higher than that in the control group (P<0.05).@*CONCLUSIONS@#The impacted mandible of patients with mandibular second molar showed lack of sagittal and width development, and the impacted mandibular second molar was a manifestation of its degeneration.

Anatomical morphology of the root and root canal system of the second permanent molar in the Uygur people / 口腔疾病防治

Objective @#To study the anatomical characteristics of the root and root canal system of the mandibular second permanent molar in the Uygur people and provide a reference for clinical practice.@*Methods @#A total of 125 mandibular second permanent molars were extracted from Uygur patients in hospitals in the Xinjiang Uygur Autonomous Region. Three-dimensional reconstruction was performed after micro-CT scanning. The number of root canals, the root canal type (Weine classification and Fan′s C-shaped canal classification) and the occurrence of lateral accessory canals were observed.@*Results @#A sex difference was not detected in the root number or root form (χ2 = 1.277, P = 0.259). The incidence of 2-rooted molars was 70.4% (n = 88); type 2-1 canals were most common in the mesial root, with an incidence of 29.5%, followed by type 1-1 and 2-2 canals (each with an incidence of 26.1%), and the distal root mostly had a type 1-1 canal (96.6%). The incidence of single-rooted molars was 28.8%, and the frequency of C-shaped (n = 28) and non-C-shaped (n = 8) single-rooted molars was 22.4% and 6.4%, respectively. A three-rooted molar was detected in one case. The incidence of accessory canals was 65.2%.@*Conclusion @# Uygur mandibular second molars are mainly composed of two roots, and the incidence of a single root and root canal fusion is low (including C-shaped canals). Two-rooted molars frequently have two mesial canals and one distal canal.

Cone-beam computed tomography evaluation of the distance between the root apex of mandibular molars and the inferior alveolar nerve canal in adults / 口腔疾病防治

Objective@# To evaluate the spatiotemporal relationship between the root apex of mandibular molars and the inferior alveolar nerve canal (IANC) in adults. @*Methods@#Cone-beam computed tomography (CBCT) images were collected in 236 patients, and the distances from the root apexes of mandibular molars to the IANC were measured in NNT 4.6 software. The relationship between distance and gender was evaluated. @*Results@#In two-rooted mandibular first molars, the distances from the mesial root and distal root to the IANC were 7.34 ± 2.07 mm and 6.69 ± 2.08 mm, respectively, in males and 6.47 ± 2.22 mm and 5.94 ± 2.11 mm in females. In three-rooted mandibular first molars, the distances from the mesial root, distobuccal root, and distolingual to the IANC were 7.29 ± 1.30 mm, 7.40 ± 2.33 mm, and 9.97 ± 2.19 mm, respectively, in males and 6.08 ± 2.57 mm, 6.35 ± 2.40 mm, and 9.01 ± 2.90 mm, respectively, in females. In one-rooted mandibular second molars, the distance from the root to the IANC was 4.09 ± 1.64 mm in males and 3.89 ± 1.76 mm in females. In two-rooted mandibular second molars, the distances from the mesial root and distal root to the IANC were 5.14 ± 2.08 mm and 4.39 ± 1.85 mm, respectively, in males and 3.78 ± 1.69 mm and 3.24 ± 1.72 mm, respectively, in females. There were no significant with in-gender differences between the left and right side in the distances from the root apexes to the IANC (P>0.05). The distances from the mandibular first molar were greater in males than in females. The longest average distance was from the distolingual root apexes of three-rooted mandibular first molars to the IANC, and the distances were longer from the distobuccal root apexes of three-rooted mandibular first molars to the IANC than from the distal root apexes of two-rooted mandibular first molars to the IANC (P<0.05). There was no within-gender difference in the distances from the root apexes of single-rooted mandibular second molars to the IANC (P>0.05), but the distances in two-rooted mandibular second molars were larger in males than in females (P<0.05). The distances from the root apexes to the IANC were smaller in mandibular second molars than in mandibular first molars (P<0.05). @*Conclusion @#There are significant differences between adult males and females in the distance from the root apex to the IANC for mandibular first molars and two-rooted mandibular second molars. The distances from the root apexes to the IANC were smaller in mandibular second molars than in mandibular first molars.

C-shaped root canals of mandibular second molars in a Korean population: a CBCT analysis

OBJECTIVES: The purpose of this study was to investigate the C-shaped root canal anatomy of mandibular second molars in a Korean population. MATERIALS AND METHODS: A total of 542 teeth were evaluated using cone-beam computed tomography (CBCT). The canal shapes were classified according to a modified version of Melton's method at the level where the pulp chamber floor became discernible. RESULTS: Of the 542 mandibular second molars, 215 (39.8%) had C-shaped canals, 330 (53%) had 3 canals, 17 (3.3%) had 2 canals, 12 (2.2%) had 4 canals, and 8 (1.7%) had 1 canal. The prevalence of C-shaped canals was 47.8% in females and 28.4% in males. Seventy-seven percent of the C-shaped canals showed a bilateral appearance. The prevalence of C-shaped canals showed no difference according to age or tooth position. Most teeth with a C-shaped canal system presented Melton's type II (45.6%) and type III (32.1%) configurations. CONCLUSIONS: There was a high prevalence of C-shaped canals in the mandibular second molars of the Korean population studied. CBCT is expected to be useful for endodontic diagnosis and treatment planning of mandibular second molars.

A case report of a geminated mandibular second molar / 实用口腔医学杂志

Geminated teeth is a double-tooth deformity which is rare in clinical practice. Geminated teeth are usually found in anterior dentition, more in deciduous and fewer in permanent dentition. This pater reports a case of a geminated mandibular second molar.

Diagnóstico de conducto radicular en C en segundos molares mandibulares mediante la evidencia del ángulo obtenido: estudio piloto de validación / Diagnosis of C-shaped root canals in mandibular second molars through the evidence of the obtained angle: a pilot validation study

Antecedentes: El estándar dorado para diagnosticar segundos molarescon conducto radicular en C antes del inicio de un tratamiento endodóntico restaurador es la tomografía cone beam. La difi cultad para accedera los servicios tomográfi cos y su baja distribución en los consultorios odontológicos nos han llevado a diseñar una técnica alternativa enradiografías panorámicas nombrada «evidencia del ángulo obtenido¼(EAO). Objetivo: El objetivo de este trabajo fue crear un punto de cortey estimar la precisión diagnóstica del mismo mediante un estudio pilotocuyo resultado será utilizado en una futura investigación de validación de pruebas diagnósticas...

Background: The gold standard to diagnose second molars withC-shaped root canals prior to beginning an endodontic and restorative treatment is cone-beam tomography. Tomographic services are hard to access and have a low distribution in dental clinics this has led usto design an alternative technique in panoramic radiographs named«evidence of the obtained angle¼ (EAO). Objective: The aim of thisstudy was to create a breakpoint and estimate its diagnostic accuracy through a pilot study; its results will be used in a future investigation of validation of diagnostic tests...

Bilateral mandibular second molar impaction with paradental cyst:A case report and literature review / 吉林大学学报(医学版)

Objective:To explore the etiology and treatment of one case of bilateral mandibular second molar impaction with paradental cyst, and to provide a reference for its diagnosis and treatment. Methods:Root canal treatment of the left mandibular first molar of the patient was performed before operation.The left mandibular second molar of the patient was removed;the residual dental follicle, the granulation tissue and the cyst wall were stroken off under local anesthesia.The diamond ball was used to polish the wound cavity and sharp bone edge, and to mill the distal apical part of left mandibular first molar.The tissue removed during the procedure was used for the pathological examination.Results:The X-ray image showed that the bilateral mandibular second molar was impacted with the left mandibular first molar root's absorption, and there was a clear round-like density reduction zone around the second molar crown.The pathologic result was paradental cyst.Conclusion:Dental impaction complicated with paradental cyst could occur in other tooth position except for the third molar.Its diagnosis should be combined with the clinical manifestations, the pathologic manifestations and the medical imaging.Multidisciplinary consultation is in favor of its diagnosis and treatment.

Clinical observation of the effects of CAD/CAM glass-ceramic onlay in the restoration of mandibular second molar / 实用口腔医学杂志

Objective:To evaluate the clinical effects of CAD/CAM glass-ceramic onlays in the restoration of mandibular second molar with distal caries.Methods:56 endodontically treated molars were restored with CAD/CAM glass-ceramic onlays after one-visit root canal treatment.The effects were evaluated by one experienced clinicians in accordanced with the modified USPHS-Criteria at baseline and after 6,12 18 and 24 months.Results:All teeth were completed 2-year-follow-up.Satisfactory effects were observed in retention,marginal adaptation,color match,the secondary caries and adjacency relation.Failure in 3 cases were noted.2 onlays were extracted and 1 fractured.Conclusion:CAD/CAM glass-ceramic onlays is an effective treatment in the restoration of permanent molars with serious caries.

Segundos molares mandibulares permanentes impactados en pacientes de 8 a 15 años del programa de presupuesto participativo de Medellín, Colombia / Impactation of Permanent Mandibular Second Molars in 8 to 15 Year-Old Patients from the Participative Budget Program in Medellín, Colombia

Antecedentes: La impactación de segundos molares mandibulares permanentes (2MM) se presenta con variaciones considerables según el grupo poblacional. Además de los problemas asociados a esta alteración, podrían requerir tratamientos múltiples y complejos. Por lo tanto, el diagnóstico temprano de una alteración en el proceso de erupción del 2MM es imperativo para reducir el riesgo de impactación, la dificultad de tratamiento y la aparición de problemas asociados en las poblaciones. Propósito: Describir las características de impactación del 2MM en pacientes de 8 a 15 años en una muestra de Medellin, Colombia. Métodos: En este estudio descriptivo retrospectivo se evaluaron 1756 radiografias panorámicas de las cuales 95 presentaron impactación de 2MM. Estas se analizaron según sexo, localización en la mandíbula y tipo de inclinación, y se realizaron 13 mediciones lineales y angulares para identificar parámetros dentoesqueléticos característicos del lado de la impactación. Para el análisis de los datos se utilizó estadística descriptiva y la prueba T (p < 0,05). Resultados: La prevalencia de impactación fue del 5,4 %. La impactación bilateral con inclinación mesial fue la más frecuente. El lado izquierdo predominó en impactaciones unilaterales. El único parámetro dentoesquelético característico de impactación fue el ángulo de inclinación del 2MM con respecto al plano oclusal, con mayor severidad en el lado izquierdo. Conclusiones: Un ángulo igual o mayor a 112,94° podría indicar riesgo de impactación contra el primer molar mandibular permanente. Por lo tanto, este parámetro debería incluirse en el análisis radiográfico para el diagnóstico temprano de impactación del 2MM.

Background: Impactation of permanent mandibular second molars (2MM) occurs with significant variations according to the population group. In addition to the problems associated with it, they could require multiple and complex treatments. Therefore, the early diagnosis of an alteration in the 2MM eruption process is a must to reduce the impactation risk, the treatment difficulty and the occurrence of related problems in the populations. Purpose: To describe the 2MM impactation characteristics in an 8 to 15 year-old patient sample in Medellin, Colombia. Methods: This retrospective descriptive study evaluated 1 756 panoramic radiographs and 95 of them showed 2MM impactation. The latter were analyzed based on the sex, location in the mandible and type of inclination; 13 linear and angle measurings were then carried out in order to identify dental-skeletal parameters characteristic in the impactation side. The data analysis used descriptive statistics and a T test (p < 0.05). Results: The impactation prevalence was 5.4% and the bilateral impactation with mesial inclination was the most frequently found. Unilateral impactations prevailed in the left side of the mandible/maxilla. The only dental-skeletal parameter of impactation was the 2MM inclination angle regarding the occlusal plane, with a greater severity on the left side. Conclusions: An angle of 112.94° or greater could indicate an impactation risk on the permanent mandibular first molar. Therefore, this parameter should be included in the radiographic analysis when diagnosing the early 2MM impactation.

Miniplacas como dispositivos de anclaje temporal (DAT) en la verticalización del segundo molar inferior impactado / Miniplates as temporary anchorage devices (TAD) for uprighting the impacted second mandibular molar

La impactación de los segundos molares inferiores permanentes es una patología con una incidencia del 0.03 or ciento a 0.04 por ciento del total de dientes retenidos, que en la mayoría de los casos debido a una posición impredecible del tercer molar, el resultado final es la exodoncia de ambas piezas dentarias.Dentro de los dispositivos de anclaje temporal, existen dos tipos, los minimplantes y las miniplacas. A través de este caso clínico se demuestra la eficiencia de las miniplacas en la verticalización de los segundos molares inferiores impactados sobre otras medidas terapéuticas debido a que su uso es un método predecible, rápido y seguro que no genera efectos secundarios indeseables. Además, estas miniplacas son colocadas a distancia de las piezas dentarias, por lo que no interfiere en los movimientos dentales.

Mandibular second molar impaction is a pathology with an incidence of 0.03% - 0.04% of the total of the impacted teeth due to animpredictible position of the third molar in most cases. As a consequence, where the final result is dental extraction of both teethThere are two types of temporary skeletal anchorage devices minimplants and miniplates. This case shows the miniplate efficiency in thesecond molar verticalization which is a predictible, fast and safe method without any side effects when compared with other treatments.In addition, miniplantes do not interfere with dental movements because they are placed far enough from the teeth.

Endodontic Management of Variants of C-Shaped Canal: Case Series

A thorough knowledge of the root canal morphology is required for successful endodontic therapy. One of the most important anatomic variations is the C-shaped configuration of the root canal system. The presence of high incidence of transverse anastomoses, lateral canals, and apical deltas makes it difficult to clean and seal the root canal system in these teeth and may complicate endodontic interventions. Meticulous mechanical and chemical debridement of the canal space with additional efforts is essential for complete elimination of pulpal pathology in the anatomical irregularities. Obturation of the canal space also requires special attention as obtaining a three dimensional fill of a C-shaped canal may prove to be a problem due to the various intricacies present within the root canal system. Hence, this case series presents various types of C-shaped canal morphologies of mandibular second molars and their management.

Healing outcomes of root canal treatment for C-shaped mandibular second molars: a retrospective analysis

OBJECTIVES: This study aimed to evaluate the healing rate of non-surgical endodontic treatment between C-shaped and non-C-shaped mandibular second molars. MATERIALS AND METHODS: Clinical records and radiological images of patients who had undergone endodontic treatment on mandibular second molars between 2007 and 2014 were screened. The periapical index scoring system was applied to compare healing outcomes. Information about preoperative and postoperative factors as well as the demographic data of the patients was acquired and evaluated using chi-square and multinomial logistic regression tests. RESULTS: The total healing rate was 68.4%. Healing rates for the mandibular second molar were 70.9% in C-shaped canals (n = 79) and 66.6% in non-C-shaped ones (n = 117). The difference was not statistically significant. CONCLUSIONS: The presence of a C-shaped canal in the mandibular second molar did not have a significantly negative effect on healing after treatment. Instead, proper pulpal diagnosis and final restoration were indicated as having significantly greater influence on the healing outcomes of C-shaped and non-C-shaped canals, respectively.

The treatment of mesially impacted mandibular second molar / 实用口腔医学杂志

The mesially impacted of mandibular second molar is one kind of common malocclusion in clinic.It can lead to damages to stomatognathic system.The looped uprightor is an effective tool in the treatment of this kind of malocclusion.

The correction of lingually inclined mandibular second molars / 实用口腔医学杂志

6 cases of lingually inclined mandibular second molar were treated by ring uprightor,the malposition was corrected in all the ca-ses in 3 months on average.

Relationships between mandibular second molar calcification stage and cervical vertebrae maturity / 实用口腔医学杂志

Objective:To investigate the relationship between mandibular second molar calcification stage and cervical vertebrae maturity.Methods:Samples were derived from panoramic radiographs and lateral cephalograms of 500 subjects (223 males and 277 females)aged 9 to 18 years.Demirjian Index(DI)and cervical vertebrae maturation indicators(CVMI)were used for the evaluation of dental and skeletal maturity.Results:A significantly association was found between DI and CVMI(P <0.001).DI stage E was associated with CVMI Ⅱ(pre-peak of pubertal growth spurt).DI stages F and G was associated with CVMI Ⅲ and Ⅳ(peak of pu-bertal growth spurt).DI stage H was associated with CVMI Ⅴ and Ⅵ(end of pubertal growth spurt).Conclusion:DI and CVMI are significantly associated.Mandibular second molar DI stage is a reliable indicator of skeletal maturity.

The correlation study of mandibular second molar root growth and bone age in male teenagers / 重庆医学

Objective To explore the relationship between cervical bone age and male juvenile mandibular second molar (Msm) root growth ,and to provide evidence for the development of bone and teeth in patients with orthodontic treatment . Methods The CBCT and lateral cephalometric radiographs of 114 cases of 9 .5 to 15 .5 years old children in Chongqing city and ad‐olescents cervical vertebral bone and MSM root length were measured ,using statistical analysis to explore the relationship between cervical vertebral bone ,tooth root length change of age and Msm .Results By Pearson correlation analysis ,Msm root length chan‐ges and cervical vertebral bone were positively correlated(r= 0 .737 ,P< 0 .01) .Msm root length changes showed a positive correla‐tion with age(r= 0 .681 ,P< 0 .01) .Msm root length changes was positively related with dental age(r = 0 .795 ,P< 0 .01) .Conclu‐sion The root growth of the mandibular second molar was highly correlated with cervical vertebral bone in male children .When the growth and development of patients were judged by orthodontic treatment ,we can adopt the mandibular second molar root length forecast growth level of male adolescents .