We investigated the compensatory trends of mesiodistal angulation of first molars in malocclusion cases. We compared differences in the angulation of first molars in different developmental stages, malocclusion classi...We investigated the compensatory trends of mesiodistal angulation of first molars in malocclusion cases. We compared differences in the angulation of first molars in different developmental stages, malocclusion classifications and skeletal patterns. The medical records and lateral cephalogrammes of 1 403 malocclusion cases taken before treatment were measured to evaluate compensation of molar angulation in relation to the skeletal jaw. The cases were stratified by age, Angle classification and skeletal patterns. Differences in the mesiodistal angulation of the first molars were compared among the stratifications. We observed three main phenomena. First,angulation of the upper first molar varied significantly with age and tipped most distally in cases aged,12 years and least distally in cases aged.16 years. The lower first molar did not show such differences. Second, in Angle Class II or skeletal Class II cases, the upper first molar was the most distally tipped, the lower first molar was the most mesially tipped, and opposite angulation compensation was observed in Class III cases. Third, in high-angle cases, the upper and lower first molars were the most distally tipped, and opposite angulation compensation was observed in low-angle cases. These data suggest that the angulation of the molars compensated for various growth patterns and malocclusion types. Hence, awareness of molar angulation compensation would help to adjust occlusal relationships, control anchorage and increase the chances of long-term stability.展开更多
This case report is to present a maxillary first molar with one O-shaped root, which is an extended C-shaped canal system. Patient with chronic apical periodontitis in maxillary left first molar underwent replantation...This case report is to present a maxillary first molar with one O-shaped root, which is an extended C-shaped canal system. Patient with chronic apical periodontitis in maxillary left first molar underwent replantation because of difficulty in negotiating all canals. Periapical radiographs and cone-beam computed tomography （CBCT） were taken. All roots were connected and fused to one root, and all canals seemed to be connected to form an O-shape. The apical 3 mm of the root were resected and retrograde filled with resin-modified glass ionomer. Intentional replantation as an alternative treatment could be considered in a maxillary first molar having an unusual O-shaped root.展开更多
Objectives:Distolingual root of the permanent mandibular first molar(PMFM-DLR)has been frequently reported,which may complicate the treatment of periodontitis.This study aimed to assess the morphological features of P...Objectives:Distolingual root of the permanent mandibular first molar(PMFM-DLR)has been frequently reported,which may complicate the treatment of periodontitis.This study aimed to assess the morphological features of PMFM-DLR and investigate the correlation between the morphological features of PMFM-DLR and periodontal status in patients with Eastern Chinese ethnic background.Materials and methods:A total of 836 cone beam computed tomography(CBCT)images with 1497 mandibular first molars were analyzed to observe the prevalence of PMFM-DLR at the patients and tooth levels in Eastern China.Among them,complete periodontal charts were available for 69 Chinese patients with 103 teeth.Correlation and regression analyses were used to evaluate the correlation between the morphological features of DLR,bone loss,and periodontal clinical parameters,including clinical attachment loss(CAL),probing pocket depth(PPD),gingival recession(GR),and furcation involvement(FI).Results:The patient-level prevalence and tooth-level prevalence of DLR in mandibular first molars were 29.4%and 26.3%,respectively.Multiple linear regression analysis suggested that bone loss at the lingual site and CAL were negatively affected by the angle of separation between distolingual and mesial roots in the transverse section,while they were significantly influenced by age and the angle of separation between distobuccal and mesial roots in the coronal section.Conclusions:The prevalence of PMFM-DLR in Eastern China was relatively high in our cohort.The morphological features of DLR were correlated with the periodontal status of mandibular first molars.This study provides critical information on the morphological features of DLR for improved diagnosis and treatment options of mandibular molars with DLR.展开更多
THE purpose of root canal treatment is to thoroughly clean the root canal system and fill it in all its dimensions.I To achieve this goal, the entire root canal system must be adequately debrided and completely filled...THE purpose of root canal treatment is to thoroughly clean the root canal system and fill it in all its dimensions.I To achieve this goal, the entire root canal system must be adequately debrided and completely filled. In clinical practice, variations in the canal morphology pose a constant challenge to endodontists in deciding on accurate diagnosis and appropriate management. Knowledge of these variations is crucial for a successful endodontic treatment, especially in absence of an operating microscope or cone-beam computered tomography （CBCT）.展开更多
BACKGROUND As the complex anatomy of maxillary first molars is one of the major challenges in endodontic therapy,knowledge of the complicated root canal anatomy and configuration is crucial to ensure the success of en...BACKGROUND As the complex anatomy of maxillary first molars is one of the major challenges in endodontic therapy,knowledge of the complicated root canal anatomy and configuration is crucial to ensure the success of endodontic treatment and prognosis.This article presents an endodontically managed left maxillary first molar with an unusual palatal root morphology.The available literature on the anatomic variation of maxillary first molars is also reviewed.CASE SUMMARY A 36-year-old man with no medical history presented to the Stomatology Department of Peking University Third Hospital complaining of a toothache during mastication in the maxillary left posterior region for approximately 3 mo.He had a spontaneous and intermittent toothache that had worsened,particularly at night.The diagnosis based on clinical examination,X-ray imaging,and cone beam computed tomography(CBCT)was symptomatic irreversible pulpitis.Nonsurgical endodontic therapy was performed for the left maxillary first molar.Five root canals revealed by CBCT included a special palatal root canal(1-2-1-shaped),two mesiobuccal root canals,and one distobuccal root canal.Evaluation of the CBCT images confirmed the root canal morphology and the clinician performed more effective cleaning,obturation,and therapy.Finally,the tooth was restored using composite resin,and the patient was satisfied with the result.CONCLUSION CBCT and a complete review of the literature may be beneficial for investigating the root canal system to achieve a biological and functional therapeutic effect.展开更多
Aim: To confirm the effect of root canal treatment on radix entomolaris. Case: Radix entomolaris was an additional root that located on the distolingual of mandibular first molars. In this case, the radix entomolaris ...Aim: To confirm the effect of root canal treatment on radix entomolaris. Case: Radix entomolaris was an additional root that located on the distolingual of mandibular first molars. In this case, the radix entomolaris was detected clinically and radiographically with root canal configuration such as curves. An awareness and understanding of this unusual root and root canal morphology could contribute to the successful outcome of endodontic treatment. Conclusion: Root canal treatment on this case shows the lack of symptoms and normal radiographic presentation for two months follow-up.展开更多
BACKGROUND The complex anatomy of the maxillary first molars has always been a major challenge for complete root canal treatment in endodontic therapy. Here, we present two cases of maxillary first molars, each with o...BACKGROUND The complex anatomy of the maxillary first molars has always been a major challenge for complete root canal treatment in endodontic therapy. Here, we present two cases of maxillary first molars, each with only two root canals, which have been rarely reported. We also perform a literature review of maxillary first molar anatomy.CASE SUMMARY The two patients were referred to the hospital after 1) finding a cavity in their tooth with a color change and, 2) a toothache during mastication, respectively.Both of these cases were diagnosed as apical periodontitis by X-ray imaging and cone beam computed tomography(CBCT). Non-surgical endodontic therapy was performed with the assistance of a dental operating microscope(DOM). CBCT showed rare but accurate images of both patients, each with two root canals and two roots in their maxillary first molars. Both roots were located in the buccal in the palatal direction, and each root had only one clear root canal. In addition,each maxillary first molar in both patients was symmetrical to that on the opposing side with only two separate root canals. Non-surgical endodontic therapy was performed with the assistance of a DOM. Finally, the teeth were restored using composite resin and the patients were satisfied with the results.CONCLUSION Making full use of CBCT and DOM would contribute to helping dentists make correct diagnoses and successfully treat teeth with rare root canal morphologies.展开更多
Ectopic eruption is the abnormal eruption of a permanent tooth that often causes root resorption of an adjacent primary tooth which can be noted during routine dental radiographic evaluation. The mesial eruption of th...Ectopic eruption is the abnormal eruption of a permanent tooth that often causes root resorption of an adjacent primary tooth which can be noted during routine dental radiographic evaluation. The mesial eruption of the permanent first molar may be a local eruption problem or may indicate developmental arch circumference deficiency requiring further consideration. Early treatment is mandatory to move the ectopically erupting tooth away from the tooth it is resorbing to allow the tooth to erupt into its normal position, maintaining a normal arch circumference. Although much has been written about ectopic eruption of the maxillary first permanent molar, no case report mentions correction of ectopically erupted maxillary permanent first molar by using double loop stainless steel.展开更多
Maxillary first molar usually exhibits a radicular anatomy of three roots and three or four canals. However, different anatomic variations like extra number of roots and canals are possible. For a successful treatment...Maxillary first molar usually exhibits a radicular anatomy of three roots and three or four canals. However, different anatomic variations like extra number of roots and canals are possible. For a successful treatment, clinicians must have well equipment and a thorough knowledge of the external and internal anatomy of teeth and its variation. Using of CBCT may help to locate extra canals by giving a chance to clinicians to see the root canal anatomy in 3-D view. The aim of this study was to present a case report about a diagnosis and treatment in maxillary first molar with three roots and five canals. It is concluded that the diagnosing and the treatment of unusual cases are key factors for successful endodontic treatment of these teeth.展开更多
The first molar will play a key role in the formation of permanent dentition and also is easy to be caries. In this series, 7968 cases 4-6 yrs old children are investigated and the eruption and caries of first molar a...The first molar will play a key role in the formation of permanent dentition and also is easy to be caries. In this series, 7968 cases 4-6 yrs old children are investigated and the eruption and caries of first molar are analysed. The results are as follows: The eruption rate of first molar in 7968 cases 4-6 yrs old children is 22.13%. The mean number of molar erupted is 0.55+1.17. Both are in very signiflicant sexual difference. The eruption in girls is earlier than that in boys. The eruption rates are 1.01% in 4 yrs old group and 59.00% in 6 yrs old group. In the per centage of the molar erupted, (?) is 66.26% with symmetrical rate 69.31%, 6 is 33.74% with symmetrical rate 33.24%. The incidence rate of caries in 1763 cases 4-6 yrs old children with first molar erupted is 1.76% with dft 0.02±0.15. The dft in cases of caries is 1.26±0.63. There are two molars with caries of Degree IV in 5 yrs old group. The eruption and caries of the first molar in childhood are analysed. The importance of prevention dnd treatment of first permanent molar in childhood is indicated.展开更多
The first permanent molar as the first permanent tooth in the mouth and with a general insufficient oral hygiene of the children, is commonly subject to significant compromise which may arise due to caries or endodont...The first permanent molar as the first permanent tooth in the mouth and with a general insufficient oral hygiene of the children, is commonly subject to significant compromise which may arise due to caries or endodontic complication, or from developmental anomalies such as hypoplasia. Compromised teeth with questionable prognosis may result in short- and long-term clinical dilemmas. The aim of this research is to highlight the factors that require careful consideration when a compromised UFPM is detected and the importance of timely UFPM extraction to ensure the mesial drift of the upper second permanent molar (USPM) to fulfill the space of the extracted UFPM without any orthodontic intervention. For this purpose 52 heavily destructed UFPMs were extracted at age of 10.5 years old, 44 (84.6%) USPMs erupted exactly distal to the second premolar while only 7 (13.4%) USPMs erupted 1 mm distal to the second premolar. Clinically it is recommended to extract the heavily destructed upper first molars at age of 10.5 years old to ensure the complete closure of the extraction space by the passive mesial drift of upper second permanent molar.展开更多
摩尔体积的可靠预测对高熵合金设计具有重要意义。然而,由于受试验数据的限制,基于相图热力学计算(computational coupling of phase diagram and thermochemistry,CALPHAD)方法的多组元体系摩尔体积数据库的发展缓慢。为此,将第一性原...摩尔体积的可靠预测对高熵合金设计具有重要意义。然而,由于受试验数据的限制,基于相图热力学计算(computational coupling of phase diagram and thermochemistry,CALPHAD)方法的多组元体系摩尔体积数据库的发展缓慢。为此,将第一性原理计算与CALPHAD方法相结合,通过拟合第一性原理计算得到的摩尔体积确定模型参数,从而减少CALPHAD方法对试验数据的依赖,成功构建了Al CoCrFeMnNi六元系FCC溶体相的常温常压摩尔体积模型及数据库。在数据库构建过程中,通过试验数据对第一性原理计算结果进行校正以消除系统误差,校正结果与试验数据总体吻合较好。随后确定了模型参数,拟合了所有子二元系及部分子三元系的摩尔体积第一性原理校正结果和可用试验数据。最后,基于所构建的数据库对FeNiCoMn、CrNiCoMn和FeNiCoCrMn等原子比合金的摩尔体积进行预测,预测结果与第一性原理校正结果较吻合。展开更多
基金supported by the Specific Research Project of Health Pro Bono Sector, Ministry of Health, China (200802056)
文摘We investigated the compensatory trends of mesiodistal angulation of first molars in malocclusion cases. We compared differences in the angulation of first molars in different developmental stages, malocclusion classifications and skeletal patterns. The medical records and lateral cephalogrammes of 1 403 malocclusion cases taken before treatment were measured to evaluate compensation of molar angulation in relation to the skeletal jaw. The cases were stratified by age, Angle classification and skeletal patterns. Differences in the mesiodistal angulation of the first molars were compared among the stratifications. We observed three main phenomena. First,angulation of the upper first molar varied significantly with age and tipped most distally in cases aged,12 years and least distally in cases aged.16 years. The lower first molar did not show such differences. Second, in Angle Class II or skeletal Class II cases, the upper first molar was the most distally tipped, the lower first molar was the most mesially tipped, and opposite angulation compensation was observed in Class III cases. Third, in high-angle cases, the upper and lower first molars were the most distally tipped, and opposite angulation compensation was observed in low-angle cases. These data suggest that the angulation of the molars compensated for various growth patterns and malocclusion types. Hence, awareness of molar angulation compensation would help to adjust occlusal relationships, control anchorage and increase the chances of long-term stability.
文摘This case report is to present a maxillary first molar with one O-shaped root, which is an extended C-shaped canal system. Patient with chronic apical periodontitis in maxillary left first molar underwent replantation because of difficulty in negotiating all canals. Periapical radiographs and cone-beam computed tomography （CBCT） were taken. All roots were connected and fused to one root, and all canals seemed to be connected to form an O-shape. The apical 3 mm of the root were resected and retrograde filled with resin-modified glass ionomer. Intentional replantation as an alternative treatment could be considered in a maxillary first molar having an unusual O-shaped root.
基金The study protocol has been reviewed and approved by the Ethics Committee of the Stomatology Hospital,Zhejiang University School of Medicine(No.2023-031)and registered in Chinese Clinical Trial Registry(No.ChiCTR2300074445).
文摘Objectives:Distolingual root of the permanent mandibular first molar(PMFM-DLR)has been frequently reported,which may complicate the treatment of periodontitis.This study aimed to assess the morphological features of PMFM-DLR and investigate the correlation between the morphological features of PMFM-DLR and periodontal status in patients with Eastern Chinese ethnic background.Materials and methods:A total of 836 cone beam computed tomography(CBCT)images with 1497 mandibular first molars were analyzed to observe the prevalence of PMFM-DLR at the patients and tooth levels in Eastern China.Among them,complete periodontal charts were available for 69 Chinese patients with 103 teeth.Correlation and regression analyses were used to evaluate the correlation between the morphological features of DLR,bone loss,and periodontal clinical parameters,including clinical attachment loss(CAL),probing pocket depth(PPD),gingival recession(GR),and furcation involvement(FI).Results:The patient-level prevalence and tooth-level prevalence of DLR in mandibular first molars were 29.4%and 26.3%,respectively.Multiple linear regression analysis suggested that bone loss at the lingual site and CAL were negatively affected by the angle of separation between distolingual and mesial roots in the transverse section,while they were significantly influenced by age and the angle of separation between distobuccal and mesial roots in the coronal section.Conclusions:The prevalence of PMFM-DLR in Eastern China was relatively high in our cohort.The morphological features of DLR were correlated with the periodontal status of mandibular first molars.This study provides critical information on the morphological features of DLR for improved diagnosis and treatment options of mandibular molars with DLR.
文摘THE purpose of root canal treatment is to thoroughly clean the root canal system and fill it in all its dimensions.I To achieve this goal, the entire root canal system must be adequately debrided and completely filled. In clinical practice, variations in the canal morphology pose a constant challenge to endodontists in deciding on accurate diagnosis and appropriate management. Knowledge of these variations is crucial for a successful endodontic treatment, especially in absence of an operating microscope or cone-beam computered tomography （CBCT）.
基金Supported by the National Natural Science Foundation of China,No.81800983Beijing Natural Science Foundation,No.7164310.
文摘BACKGROUND As the complex anatomy of maxillary first molars is one of the major challenges in endodontic therapy,knowledge of the complicated root canal anatomy and configuration is crucial to ensure the success of endodontic treatment and prognosis.This article presents an endodontically managed left maxillary first molar with an unusual palatal root morphology.The available literature on the anatomic variation of maxillary first molars is also reviewed.CASE SUMMARY A 36-year-old man with no medical history presented to the Stomatology Department of Peking University Third Hospital complaining of a toothache during mastication in the maxillary left posterior region for approximately 3 mo.He had a spontaneous and intermittent toothache that had worsened,particularly at night.The diagnosis based on clinical examination,X-ray imaging,and cone beam computed tomography(CBCT)was symptomatic irreversible pulpitis.Nonsurgical endodontic therapy was performed for the left maxillary first molar.Five root canals revealed by CBCT included a special palatal root canal(1-2-1-shaped),two mesiobuccal root canals,and one distobuccal root canal.Evaluation of the CBCT images confirmed the root canal morphology and the clinician performed more effective cleaning,obturation,and therapy.Finally,the tooth was restored using composite resin,and the patient was satisfied with the result.CONCLUSION CBCT and a complete review of the literature may be beneficial for investigating the root canal system to achieve a biological and functional therapeutic effect.
文摘Aim: To confirm the effect of root canal treatment on radix entomolaris. Case: Radix entomolaris was an additional root that located on the distolingual of mandibular first molars. In this case, the radix entomolaris was detected clinically and radiographically with root canal configuration such as curves. An awareness and understanding of this unusual root and root canal morphology could contribute to the successful outcome of endodontic treatment. Conclusion: Root canal treatment on this case shows the lack of symptoms and normal radiographic presentation for two months follow-up.
文摘BACKGROUND The complex anatomy of the maxillary first molars has always been a major challenge for complete root canal treatment in endodontic therapy. Here, we present two cases of maxillary first molars, each with only two root canals, which have been rarely reported. We also perform a literature review of maxillary first molar anatomy.CASE SUMMARY The two patients were referred to the hospital after 1) finding a cavity in their tooth with a color change and, 2) a toothache during mastication, respectively.Both of these cases were diagnosed as apical periodontitis by X-ray imaging and cone beam computed tomography(CBCT). Non-surgical endodontic therapy was performed with the assistance of a dental operating microscope(DOM). CBCT showed rare but accurate images of both patients, each with two root canals and two roots in their maxillary first molars. Both roots were located in the buccal in the palatal direction, and each root had only one clear root canal. In addition,each maxillary first molar in both patients was symmetrical to that on the opposing side with only two separate root canals. Non-surgical endodontic therapy was performed with the assistance of a DOM. Finally, the teeth were restored using composite resin and the patients were satisfied with the results.CONCLUSION Making full use of CBCT and DOM would contribute to helping dentists make correct diagnoses and successfully treat teeth with rare root canal morphologies.
文摘Ectopic eruption is the abnormal eruption of a permanent tooth that often causes root resorption of an adjacent primary tooth which can be noted during routine dental radiographic evaluation. The mesial eruption of the permanent first molar may be a local eruption problem or may indicate developmental arch circumference deficiency requiring further consideration. Early treatment is mandatory to move the ectopically erupting tooth away from the tooth it is resorbing to allow the tooth to erupt into its normal position, maintaining a normal arch circumference. Although much has been written about ectopic eruption of the maxillary first permanent molar, no case report mentions correction of ectopically erupted maxillary permanent first molar by using double loop stainless steel.
文摘Maxillary first molar usually exhibits a radicular anatomy of three roots and three or four canals. However, different anatomic variations like extra number of roots and canals are possible. For a successful treatment, clinicians must have well equipment and a thorough knowledge of the external and internal anatomy of teeth and its variation. Using of CBCT may help to locate extra canals by giving a chance to clinicians to see the root canal anatomy in 3-D view. The aim of this study was to present a case report about a diagnosis and treatment in maxillary first molar with three roots and five canals. It is concluded that the diagnosing and the treatment of unusual cases are key factors for successful endodontic treatment of these teeth.
文摘The first molar will play a key role in the formation of permanent dentition and also is easy to be caries. In this series, 7968 cases 4-6 yrs old children are investigated and the eruption and caries of first molar are analysed. The results are as follows: The eruption rate of first molar in 7968 cases 4-6 yrs old children is 22.13%. The mean number of molar erupted is 0.55+1.17. Both are in very signiflicant sexual difference. The eruption in girls is earlier than that in boys. The eruption rates are 1.01% in 4 yrs old group and 59.00% in 6 yrs old group. In the per centage of the molar erupted, (?) is 66.26% with symmetrical rate 69.31%, 6 is 33.74% with symmetrical rate 33.24%. The incidence rate of caries in 1763 cases 4-6 yrs old children with first molar erupted is 1.76% with dft 0.02±0.15. The dft in cases of caries is 1.26±0.63. There are two molars with caries of Degree IV in 5 yrs old group. The eruption and caries of the first molar in childhood are analysed. The importance of prevention dnd treatment of first permanent molar in childhood is indicated.
文摘The first permanent molar as the first permanent tooth in the mouth and with a general insufficient oral hygiene of the children, is commonly subject to significant compromise which may arise due to caries or endodontic complication, or from developmental anomalies such as hypoplasia. Compromised teeth with questionable prognosis may result in short- and long-term clinical dilemmas. The aim of this research is to highlight the factors that require careful consideration when a compromised UFPM is detected and the importance of timely UFPM extraction to ensure the mesial drift of the upper second permanent molar (USPM) to fulfill the space of the extracted UFPM without any orthodontic intervention. For this purpose 52 heavily destructed UFPMs were extracted at age of 10.5 years old, 44 (84.6%) USPMs erupted exactly distal to the second premolar while only 7 (13.4%) USPMs erupted 1 mm distal to the second premolar. Clinically it is recommended to extract the heavily destructed upper first molars at age of 10.5 years old to ensure the complete closure of the extraction space by the passive mesial drift of upper second permanent molar.
文摘摩尔体积的可靠预测对高熵合金设计具有重要意义。然而,由于受试验数据的限制,基于相图热力学计算(computational coupling of phase diagram and thermochemistry,CALPHAD)方法的多组元体系摩尔体积数据库的发展缓慢。为此,将第一性原理计算与CALPHAD方法相结合,通过拟合第一性原理计算得到的摩尔体积确定模型参数,从而减少CALPHAD方法对试验数据的依赖,成功构建了Al CoCrFeMnNi六元系FCC溶体相的常温常压摩尔体积模型及数据库。在数据库构建过程中,通过试验数据对第一性原理计算结果进行校正以消除系统误差,校正结果与试验数据总体吻合较好。随后确定了模型参数,拟合了所有子二元系及部分子三元系的摩尔体积第一性原理校正结果和可用试验数据。最后,基于所构建的数据库对FeNiCoMn、CrNiCoMn和FeNiCoCrMn等原子比合金的摩尔体积进行预测,预测结果与第一性原理校正结果较吻合。
