Root canal treatment of a mandibular first molar with three mesial root canals

The dynamic concept of the root canal system, describing a variable morphology of multiple root canals interconnected by anastomoses, has been established as the prevailing state in mandibular molars. This case report presents the treatment of a mandibular first molar with five root canals, of which three were located in the mesial root. A third middle root canal was found between the mesiobuccal and mesiolingual root canals. The morphological pattern of separate apical terminations of the three mesial root canals, as manifested in this case, is a very rare one and seldom encountered.     

伴靠近下颌神经管埋伏牙的种植修复1例

后牙种植术区伴有靠近下颌神经管的阻生牙临床病例报道少见。本文报道了1例右下颌区第二前磨牙缺失伴第一磨牙阻生的患者,并结合临床资料和文献资料,对其种植方案及铸造金属基台和聚合瓷的应用效果进行讨论。     

Differences between the chewing and non-chewing sides of the mandibular first molars and condyles in the closing phase during chewing in normal subjects

ObjectiveThis study aimed to assess differences between the closing paths of the chewing and non-chewing sides of mandibular first molars and condyles during natural mastication, using standardized model food in healthy subjects.DesignThirty-two healthy young adults (age: 19–25 years; 22 men, 10 women) with normal occlusion and function chewed on standardized gummy jelly. Using an optoelectric jaw-tracking system with six degrees of freedom, we recorded the path of the mandibular first molars and condyles on both sides for 10 strokes during unilateral chewing. Variables were compared between the chewing side and the non-chewing side of first molars and condyles on frontal, sagittal, and horizontal views during the early-, middle- and late-closing phases.ResultsOn superior/inferior displacements, the chewing side first molar and condyle were positioned superior to those on the non-chewing side during the early- and middle-closing phases. Conversely, the first molar and condyle on the non-chewing side were positioned significantly superior to those on the chewing side during the late-closing phase. On anterior/posterior displacements, the chewing side mandibular first molar and condyle were positioned significantly posterior to those on the non-chewing side throughout all closing phases.ConclusionOur results showed the differences between the mandibular first molars and condyles on both sides with respect to masticatory path during natural chewing of a model food. These differences can be useful for informing initial diagnostic tests for impaired masticatory function in the clinical environment.     

下颌第一磨牙根分叉病变治疗随访27年1例

下颌第一磨牙根分叉处解剖结构复杂,牙周破坏累及根分叉后,清洁困难,影响其临床预后.27年前患者因"右下后牙松动"就诊,X线根尖片显示46牙根分叉处牙槽骨破坏;经翻瓣术后,定期牙周维护治疗.3年前复诊,临床诊断为Ⅲ度根分叉病变,经过翻瓣术+隧道成形术治疗后,2、9、24和33个月复查显示牙周组织健康.本病例27年的随访结...     

双侧下颌第一恒磨牙融合根伴C形根管1例

下颌第一恒磨牙的牙根通常为2~3根伴2~4个根管,融合根伴C形根管较罕见。本文报道1例双侧均为融合根伴C型根管的下颌第一恒磨牙患者。     

锥形束CT在下颌第一磨牙桩道制备中的应用研究

 目的采用锥形束CT观测下颌第一磨牙牙根的解剖学形态,计算出桩道制备的合理空间,指导临床桩道的制备。方法对71例患者的121颗下颌第一磨牙的牙根采用锥形束CT进行扫描,在横断面、矢状面、冠状面重建三维数据图像,按照桩道制备的要求进行分析设计。结果下颌第一磨牙可以设计3个桩道：远中根桩道空间较大,有效可用长度为（7.19±0.91）mm,根尖上方4 mm处桩道直径为（0.80±0.12）mm;近中根有效可用长度为（6.92±1.02）mm,颊侧桩道在根尖上方4 mm处直径为（0.71±0.08）mm,舌侧桩道在根尖上方4 mm处直径为（0.71±0.07）mm。桩道应制备成一定的锥度。结论下颌第一磨牙桩道制备空间受到多种因素影响,变化较大;桩道制备应遵循个性化设计原则以达到最佳效果。锥形束CT可以提供可靠的影像学依据。     

Three independent canals in the mesial root of a mandibular first molar

Abstract Endodontic therapy was performed in a mandibular first molar with three canals in the mesial root. The mesiobuccal and the mesiolingual canals were found in their normal locations. The third was located in the middle of the distance between the other two. Radiographically, it ended in its own distinct foramen. Many reports deal with three orifices in the mesial root, but very few describe three independent canals, indicating a rare anatomical configuration. To locale the third possible intermediate canal it was suggested to reduce the mesial dentinal wall of the pulp chamber after instrumenting the main two canals.     

The interrelationship between bolus breakdown, mandibular first molar displacement and jaw movement during mastication

The purpose of this study was to clarify the interrelationship between food bolus breakdown, mandibular first molar displacement and jaw movement during mastication. Finite element models were constructed of the maxillary first molar crown, the mandibular first molar consisting of crown, root, periodontal ligament and alveolar bone, as well as the food bolus were constructed. Based on the actual measurement of the jaw movement pattern and the characteristics of food bolus, the patterns of mandibular first molar displacement and bolus breakdown on time course in the progress of mastication were simulated, to investigate the biomechanical significance of tooth displacement and jaw movement during mastication, using finite element non-linear dynamic analysis. The results showed that the patterns of tooth displacement and jaw movement and characteristics of food bolus changed with an interrelationship to each other as mastication progressed. Particularly at the initial phase, it was suggested that the patterns of mandibular first molar displacement and jaw movement worked inter-dependently to accomplish an efficient hard-bolus breakdown.     

不同投照角度X线根尖片诊断下颌第一磨牙远中舌根的临床研究

目的评价不同投照角度X线根尖片诊断下颌第一磨牙远中舌根的作用。方法选择需行根管治疗的205颗下颌第一磨牙为研究对象。术前拍X线正位根尖片及近中20°～30°偏位根尖片,对比分析是否存在远中舌根。术中根据根管的弯曲情况把远中舌根分为3类。记录下颌第一磨牙牙根和根管的数量。结果术前X线正位、近中偏位根尖片判断48颗(48/205)下颌第一磨牙存在远中舌根,临床治疗中均确定有远中舌根,其余157颗下颌第一磨牙术中均未见远中舌根。远中舌根发生率为23.41%。48颗下颌第一磨牙远中舌根中,Ⅰ类根管22颗(45.83%);Ⅱ类根管17颗(35.41%);Ⅲ类根管9颗(18.75%)。205颗下颌第一磨牙106颗(51.70%)为3根管;98颗(47.80%)为4根管;1颗(0.48%)为5根管。结论术前多角度根尖片能准确诊断下颌第一磨牙远中舌根。     

下颌第一磨牙近中三根管的临床观察

目的探讨12例下颌第一磨牙近中三根管的根管分型及与年龄、牙位、性别之间的关系。方法通过收集2014年8月—2015年8月共12例有近中第三根管的下颌第一磨牙记录根管分型、年龄、牙位、性别。结果 12例中融合型根管居多,年龄>30岁,独立型根管年龄<30岁;右侧牙位明显多于左侧;性别上无明显差异。结论年龄和牙位可能是影响下颌第一磨牙近中第三根管存在的主要因素。     

磨损对下颌第一磨牙形态影响的特点研究

目的 :探讨磨损对下颌第一磨牙形态特点的影响。方法 :选择磨损和基本无磨损的离体下颌第一磨牙各 15颗 ,通过实体测量与电子测量尺辅助下影像学测量相结合的方法分别测量牙体外形与髓腔的有关数据。结果 :①无磨损组近远中径显著大于颊舌径 ,但磨损组差异不显著 ;②无磨损组髓顶最低点到牙合面的垂直距离大于磨损组 ;③无磨损组远中两髓角到牙合面的垂直距离大于同侧近中髓角到牙合面的距离 ,但磨损组无此现象 ;④磨损组与无磨损组均显示远舌髓角到远中邻面的距离大于近舌髓角到近中邻面的距离 ,无磨损组远颊髓角到远中邻面的距离大于近颊髓角到近中邻面的距离 ,但磨损组无显著差异。结论 :磨损对于同一牙齿的不同部位影响不同 ,下颌第一磨牙牙合面远中及远中邻面颊侧是易被磨损的部位 ,这可能主要与牙齿的咬合特性及其生物力学承载特征有关     

下颌第一磨牙管间峡区清理技术的体外研究

目的探讨通过组织学方法观察和评价次氯酸钠与超声技术和（或）氢氧化钙联合应用对根管及管间峡区内有机碎屑的清理效果．为管间峡区清理技术的建立提供实验依据。方法收集新鲜拔除的下颌第一磨牙45颗，用ProTaper手用锉预备近颊和近舌两根管后，将45例近中根随机分为A、B和C三组．分别采用以下方法完成根管清理：A组5．25％NaOCl超声冲洗1min，B组和C组均先用Ca（OH）2糊剂处理根管24h．再分别通过超声冲洗和常规冲洗技术清理根管．冲洗液均为0．5％NaOCl.标本脱钙包埋后．取距根尖1、1．5、2、2．5、3mm处的切片各1张作为观察片，行HE染色。用图像软件分析根管及管间峡区内有机碎屑的含量．计算根管和管间峡区清洁度并对数据进行统计学分析。结果A组和B组的根管清洁度（根尖1～2．5mm水平）和管间峡区清洁度（根尖1～3mm水平）均优于C组（P〈0．05），A、B组间的差异不具有统计学意义。结论Ca（OH）2糊剂和0．5％NaOCl超声冲洗联合应用可获得较理想的根管及管间峡区清理效果．可替代5．25％NaOCl超声冲洗法成为一种安全、有效的根管及管间峡区清理技术。     

下颌第一磨牙斜向受力时下颌骨的有限元分析

目的：采用有限元方法分析下颌第一磨牙颊舌向45＆#176;受力时,下颌骨局部以及整体应力变化,为寻找下颌第一磨牙的最佳临床修复方法提供生物力学依据。方法：基于CT扫描1例正常的成年人的下颌骨, Mim-ics14.11软件建立下颌骨模型,下颌第一磨牙咬合面给予50N的颊舌向45＆#176;力,有限元分析软件ABAQUS6.9-3分析整个下颌骨应力应变的变化。结果：当下颌第一磨牙颊舌向45＆#176;受力时,下颌第一磨牙周围骨质应力应变最大处为底部偏向颊侧;整个下颌骨受力分析中,应力应变主要集中在受力的下颌第一磨牙处,其次在对侧的下颌角位置,应力应变也沿着下颌骨外斜线方向传导。结论：有限元分析方法可以用来进行下颌第一磨牙的受力分析,揭示引起局部以及整体因素导致的生理病理过程中生物力学机制。     

面磨耗对下颌第一磨牙牙体长轴倾斜程度影响的解剖测量研究

目的 :探索牙合面磨耗对下颌第一磨牙牙体长轴倾斜程度的影响和意义。方法 :从本教研室收藏的 34 18个下颌第一磨牙中 ,按下列标准选出 3组牙齿进行微机测量。Ⅰ组 :无磨耗组 ,18个 ,代表年轻组 ;Ⅱ组 :严重磨耗组 ,2 6个 ,代表年长组 ;Ⅲ组 :牙合面深龋组 ,18个 ,代表功能减弱组。样本中所有牙均选双根者 ,由三位作者遵三盲法进行。结果 :Ⅱ组牙冠相对于牙根更向近中倾斜 ,与Ⅰ组有明显差异 (P <0 .0 1) ,而Ⅲ组与Ⅰ组无明显差别。结论 :重度磨耗的下颌第一磨牙 ,牙体长轴的倾斜程度明显大于无明显磨耗组 ,其机制可能与咬合功能刺激有关。     

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目的 探讨伴有根分叉病变的下颌第一磨牙残根的修复方法。方法 选择2007年8 月至2008年8月济南市口腔医院修复科收治的32例患者（共计36颗患牙）,对其下颌第一磨牙残根行根管治疗术后应用分根术将近远中根分开,分别进行桩核冠修复,并制作连冠。随访观察1年。结果 1年后复查,33颗患牙咀嚼功能良好,修复体稳固,无松动;X线片示牙槽骨无继续吸收或有少量新生;成功率为91.7％。结论 伴有根分叉病变的下颌第一磨牙残根经完善的治疗后行分根术保存修复,可以行使良好的功能。     

下颌第一磨牙近中根管的根管口分型和临床疗效分析

目的探讨下颌第一磨牙近中根管的根管口形态特点和临床治疗方法。方法选取71颗临床进行根管治疗的下颌第一磨牙．在手术显微镜下观察并记录近中根管的根管口形态．分类计数;采用Protaper机用镍钛器械及超声器械进行根管预备,常规针式冲洗合并超声荡洗．热牙胶垂直加压充填技术充填根管;根据治疗前后临床检查及x线片评价根管预备和充填的效果。结果所有样本中单根管口出现率为2．82％（2例）、双根管口为91．55％（65例）、三根管口为5．63％（4例）。其中双根管口之间有峡区的为38例（53．52％）、无峡区的为27例（38．03％）。所有患牙根管治疗后均无根管内并发症发生．术后1年根管治疗成功率为92．9％。结论下颌第一磨牙根管形态复杂,手术显微镜有助于根管形态的探查．机用镍钛器械合并超声技术预备根管．超声冲洗和热牙胶垂直加压技术充填根管可获得良好的治疗效果。