目的研究根管预备、充填及纤维桩预备对根管壁微裂产生的影响。方法收集150颗离体前磨牙,并随机分为四个大组[1组(n=10)、2组(n=20)、3组(n=40)、4组(n=80)]及15个小组(1组,2组25#、2组40#,3组A25#、3组B25#、3组A40#、3组B40#,4组AX25#...目的研究根管预备、充填及纤维桩预备对根管壁微裂产生的影响。方法收集150颗离体前磨牙,并随机分为四个大组[1组(n=10)、2组(n=20)、3组(n=40)、4组(n=80)]及15个小组(1组,2组25#、2组40#,3组A25#、3组B25#、3组A40#、3组B40#,4组AX25#、4组AX40#、4组AT25#、4组AT40#、4组BX25#、4组BX40#、4组BT25#、4组BT40#,n=10)。1组:即对照组,不进行预备;2组:均分为两组,一组预备至WaveOne25#,另一组预备则预备至40#;3组:将样本与2组一样进行分组预备,之后进一步分为2个小组,进行冷牙胶侧压充填(A)及热牙胶连续波充填(B);4组:将样本与3组一样进行分组预备及充填,之后将不同方法充填后的样本进一步分为2小组进行RelyXTM(X)和RTD(T)纤维桩预备。将所有的样本从距离根尖3、5、7 mm处垂直于牙体长轴截断,在显微镜下观察微裂发生情况,并进行比较分析。结果1组及2组中均并未有裂纹存在。充填后,3组A与3组B的裂纹数目比较差异无统计学意义(P>0.05)。置入纤维桩后,4组A的牙本质裂纹明显较4组B多,且差异具有统计学意义(22/120 VS 10/120,P<0.05)。在与根尖距离7 mm处,相较于RelyXTM纤维桩,RTD纤维桩预备后牙本质产生更多裂纹,差异具有统计学意义(9/120 VS 23/120,P<0.05)。4组的裂纹总发生率高于1组、2组、3组(P<0.05),说明纤维桩置入后,牙本质裂纹较仅进行牙体预备和充填明显增多。结论纤维桩的预备主要导致根管壁裂纹的产生,冷侧压充填后进行纤维桩预备比热牙胶充填后进行桩体预备更容易产生根管壁裂纹。展开更多
Peanut root invasion by Bradyrhizobia is through a crack entry, which is different from many other legumes applying an infection thread entry in root hair. Understanding the role of root hair in the crack entry of Bra...Peanut root invasion by Bradyrhizobia is through a crack entry, which is different from many other legumes applying an infection thread entry in root hair. Understanding the role of root hair in the crack entry of Bradyrhizobia invasion of peanut root and subsequent peanut nodulation would facilitate improvement of biological nitrogen fixation in cultivated peanut. The objective of this study was to investigate the involvement of root hair in Bradyrhizobial invasion of peanut. Seedling roots of a nodulating peanut cultivar were observed for root hair emergence, its life span, and nodule formation at the base of the lateral roots with and without rhizobia inoculation for 14 days after germination (DAG). Scanning electron microscopy (SEM) was utilized to observe rhizobia accumulation at lateral roots at 24 hours after inoculation (HAI) before the emergence of root hair. Root hair emerged at 7 DAG with or without rhizobia inoculation. Two variations of rosette hair (RoH) were observed, the transient-thin RoH had life span of 3 days after root hair emergence and the thick and densely distributed RoH type stayed till the time of nodule emergence (9 days after inoculation). The lateral root devoid of root hair at the top 2 cm region was found to produce nodules. The SEM observation of seedling roots at 24 HAI showed that Bradyrhizobia invaded the roots at epidermis, protoplasm of cortical cell, and cortical cells of the main root near the newly emerged lateral root in the absence of RoH. The observations validated that root hair is not required in the Bradyrhizobia invasion of peanut root in the crack entry mode. Results from this study provided important morphological information for the hypothesis of close relationship between RoH and peanut nodulation for further genetic study of crack entry mechanism and signaling pathway of symbiosis between Bradyrhizobia and peanut.展开更多
文摘目的研究根管预备、充填及纤维桩预备对根管壁微裂产生的影响。方法收集150颗离体前磨牙,并随机分为四个大组[1组(n=10)、2组(n=20)、3组(n=40)、4组(n=80)]及15个小组(1组,2组25#、2组40#,3组A25#、3组B25#、3组A40#、3组B40#,4组AX25#、4组AX40#、4组AT25#、4组AT40#、4组BX25#、4组BX40#、4组BT25#、4组BT40#,n=10)。1组:即对照组,不进行预备;2组:均分为两组,一组预备至WaveOne25#,另一组预备则预备至40#;3组:将样本与2组一样进行分组预备,之后进一步分为2个小组,进行冷牙胶侧压充填(A)及热牙胶连续波充填(B);4组:将样本与3组一样进行分组预备及充填,之后将不同方法充填后的样本进一步分为2小组进行RelyXTM(X)和RTD(T)纤维桩预备。将所有的样本从距离根尖3、5、7 mm处垂直于牙体长轴截断,在显微镜下观察微裂发生情况,并进行比较分析。结果1组及2组中均并未有裂纹存在。充填后,3组A与3组B的裂纹数目比较差异无统计学意义(P>0.05)。置入纤维桩后,4组A的牙本质裂纹明显较4组B多,且差异具有统计学意义(22/120 VS 10/120,P<0.05)。在与根尖距离7 mm处,相较于RelyXTM纤维桩,RTD纤维桩预备后牙本质产生更多裂纹,差异具有统计学意义(9/120 VS 23/120,P<0.05)。4组的裂纹总发生率高于1组、2组、3组(P<0.05),说明纤维桩置入后,牙本质裂纹较仅进行牙体预备和充填明显增多。结论纤维桩的预备主要导致根管壁裂纹的产生,冷侧压充填后进行纤维桩预备比热牙胶充填后进行桩体预备更容易产生根管壁裂纹。
文摘Peanut root invasion by Bradyrhizobia is through a crack entry, which is different from many other legumes applying an infection thread entry in root hair. Understanding the role of root hair in the crack entry of Bradyrhizobia invasion of peanut root and subsequent peanut nodulation would facilitate improvement of biological nitrogen fixation in cultivated peanut. The objective of this study was to investigate the involvement of root hair in Bradyrhizobial invasion of peanut. Seedling roots of a nodulating peanut cultivar were observed for root hair emergence, its life span, and nodule formation at the base of the lateral roots with and without rhizobia inoculation for 14 days after germination (DAG). Scanning electron microscopy (SEM) was utilized to observe rhizobia accumulation at lateral roots at 24 hours after inoculation (HAI) before the emergence of root hair. Root hair emerged at 7 DAG with or without rhizobia inoculation. Two variations of rosette hair (RoH) were observed, the transient-thin RoH had life span of 3 days after root hair emergence and the thick and densely distributed RoH type stayed till the time of nodule emergence (9 days after inoculation). The lateral root devoid of root hair at the top 2 cm region was found to produce nodules. The SEM observation of seedling roots at 24 HAI showed that Bradyrhizobia invaded the roots at epidermis, protoplasm of cortical cell, and cortical cells of the main root near the newly emerged lateral root in the absence of RoH. The observations validated that root hair is not required in the Bradyrhizobia invasion of peanut root in the crack entry mode. Results from this study provided important morphological information for the hypothesis of close relationship between RoH and peanut nodulation for further genetic study of crack entry mechanism and signaling pathway of symbiosis between Bradyrhizobia and peanut.
