核因子κB激活受体的配体和骨保护素在小鼠下颌第一磨牙萌出中的免疫学定位

目的 研究小鼠下颌第一磨牙萌出过程中核因子κB激活受体的配体(receptor activator of nuclear factor-kappa B ligand,RANKL)和骨保护素(osteoprotegerin,OPG)的表达,并探索其表达与破骨细胞活动性之间的关系.方法 分离第1.5天～第14.5天小鼠的下颌骨,连续切片,抗酒石酸酸性磷酸酶染色显示磨牙萌出中破骨细胞的活动,免疫组化法显示RANKL和OPG的表达.结果 冠方骨组织中单位面积破骨细胞数在第1.5天和第9.5天分别出现两次高峰(分别为5.04和4.40),根方也在第1.5天和第9.5天出现两次高峰(分别为9.20和6.16),而侧方破骨细胞峰值出现在第3.5天和第9.5天(分别为7.48和5.75).RANKL表达越丰富,破骨细胞数量越多,破骨活动越活跃,OPG的表达越少.结论 磨牙牙胚的生长可出现两个生长高峰,在此过程中磨牙向冠方的发育速度相对平稳,而根向和侧向则可能出现一过性的加速生长态势;RANKL和OPG的表达与破骨细胞的活动参与了小鼠下颌第一磨牙萌出过程.     

低氧诱导因子1α在小鼠下颌第一磨牙萌出过程中的表达及意义

目的:研究小鼠下颌第一磨牙萌出过程中低氧诱导因子1α（hypoxia inducible factor-1alpha,HIF-1α）的表达,并探讨其表达与牙萌出及破骨细胞活性之间的关系。方法:分离出生后1.5~14.5 d小鼠的下颌骨,连续切片,对每组切片进行苏木精-伊红（H-E）染色、抗酒石酸酸性磷酸酶染色以及免疫组织化学染色。采用SPSS 25.0软件包进行统计学分析。结果:小鼠下颌第一磨牙萌出过程中,其冠方牙槽骨厚度逐渐减小,破骨细胞数量逐渐减少,HIF-1α在萌出过程中的表达逐渐减少。结论:小鼠下颌第一磨牙萌出过程中,HIF-1α表达越少,破骨细胞数量也越少。HIF-1α可能通过影响破骨细胞活性而参与小鼠下颌第一磨牙的萌出。     

牙齿萌出过程中 RANKL mRNA 的表达与破骨细胞的关系

目的:探讨核因子κB受体活化剂配体 RANKL 在大鼠下颌第一磨牙牙胚冠方组织中 mRNA 的表达及破骨细胞的分化情况.方法:运用原位杂交法检测大鼠下颌第一磨牙牙胚冠方组织中 RANKL mRNA 的表达;TRAP 染色观察破骨细胞分化情况.结果:出生1、3、5、7 d大鼠下颌第一磨牙牙胚冠方牙囊成纤维细胞、成釉细胞 RANKL mRNA的阳性表达强于对照组牙龈成纤维细胞(p<0.01).大鼠下颌第一磨牙牙胚冠方出生后1 d破骨细胞多为单核,3 d时多核破骨细胞增多.结论:RANKL mRNA 在大鼠出生后1、3、5、7 d下颌第一磨牙牙囊成纤维细胞、成釉细胞中有表达,可能通过促进破骨细胞的分化及成熟参与牙齿的萌出.     

儿童第一恒磨牙异位萌出的治疗及相关进展

异位萌出是指恒牙列形成过程中的局部萌出障碍.第一恒磨牙是异位萌出常见的牙位,多发生于上颌[1],Young[2]报道上颌第一恒磨牙异位萌出的发生率约为下颌的25倍,Dixon[3]报道异位萌出80％发生于上颌.     

Notch1在小鼠下颌第一磨牙牙胚发育中的表达

目的探讨Notch1在小鼠下颌第一磨牙胚胎发育过程中的组织学分布。方法制作ICR小鼠下颌第一磨牙不同发育阶段的冰冻组织切片,对小鼠下颌第一磨牙自牙胚发育起始期至出生后2天不同发育阶段组织的Notch1分布情况进行免疫组织化学染色。结果 Notch1在小鼠下颌第一磨牙牙胚发育起始期和蕾状期牙板上皮上方或其包绕的口腔上皮中表达,在牙板上皮中没有表达。自帽状期至钟状期,Notch1在牙胚的中间层表达,而在内釉上皮中无表达。至牙釉质和牙本质分泌期,Notch1仍在颈环部位的中间层表达。此外,Notch1还在牙胚发育不同时期的间充质、牙乳头和早期牙髓中表达。结论 Notch1可能在小鼠下颌第一磨牙发育过程中的牙上皮特别是内釉上皮的细胞分化,以及牙囊和牙乳头细胞分化及分化完成后的牙髓干细胞的稳定性方面有重要作用。     

第二磨牙拔除的问题

每当提到正畸拔牙这个名词时,立刻会想到的是第一双尖牙,这是因为以下原因:1.除了第一磨牙外,它常常在其它牙齿之前萌出;2.拔除第一双尖牙有利于恒尖牙萌出;3.它位于牙弓的中间,拔牙间隙可供前后牙解除拥挤。第二磨牙的大小及萌出时间上下颌第二磨牙在2(1/2)～3岁时钙化,牙冠完全形成是在7～8岁。下颌第二恒磨牙在11～13岁萌出,牙根在14～15岁仍未完全形成。上颔第二磨牙在     

骨折愈合中牙本质基质蛋白1与破骨细胞表达时间效应的观察

目的探讨骨折愈合过程中牙本质基质蛋白1（dentin matrix protein 1，DMP1）与破骨细胞的时间效应。为研究DMP1在体内矿化重建中的作用提供参考。方法将40只成年Wistar雄性大鼠左侧下颌支骨折，建立下颌骨骨折模型。骨折后5、7、14、21d处死大鼠，取骨痂和对侧正常骨组织（对照组），分别采用HE染色、TRAP染色和免疫组织化学链霉抗生物素．蛋白过氧化物酶（streptavidin perosidase，sp）法染色切片检测。结果在对照组正常下颌支组织中没有DMP1的表达，偶见破骨细胞；实验组在骨折后14～21d是破骨细胞活动高峰。结论DMP1与破骨细胞在骨折愈合过程中具有一定的时间效应。     

骨保护素对犬牙齿萌出过程(牙合)中方组织内破骨细胞的影响

目的:在体研究骨保护素对正常犬牙齿萌出过程中(牙合)方组织内破骨细胞的影响, 并分析其机制.方法:同一窝 6 只出生7 d本地犬随机分成对照组和骨保护素组, 后者皮内注射骨保护素每日1.5 mg/kg, 连续3 d.自注药起 5 d取其下颌骨, 制备石蜡切片,分别用酶组织化学和免疫组织化学的方法检测犬下颌第三前磨牙牙胚方组织中破骨细胞、RANKL阳性细胞的变化情况.结果:骨保护素组中平均破骨细胞数、RANKL表达较对照组明显降低(P<0.05).结论:骨保护素对正常犬牙齿萌出过程中(牙合)方组织内的破骨细胞可能有抑制作用,这可为牙齿萌出的研究提供一定参考.     

Immunolocalization of receptor activator of NF-kappaB ligand and osteoprotegerin during mouse mandibular first molar eruption

OBJECTIVE: To investigate the immunolocalization of receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin (OPG), and to explore the correlation between their expressions and activity of osteoclast during first mandibular molar eruption. METHODS: Mouse mandibles dissected from postnatal day 1.5 to 14.5 were stained respectively for multinucleated osteoclasts using tartrate-resistant acid phosphatase (TRAP) staining, and RANKL and OPG protein expression was examined by immunohistochemical staining. RESULTS: The two peak values of osteoclast/acrage in the occlusal and basal region were both observed on the P1.5 and P9.5; while the two peak values in the lateral region were on P3.5 and P9.5. During the mouse molar eruption, burst of osteoclastogenesis was associated with high expression of RANKL and low expression of OPG. CONCLUSIONS: RANKL and OPG could have a close relationship with the osteoclast activity and two developmental apexes were observed during the molar eruption. The occlusal movement was relatively stable, meanwhile the temporarily accelerative movement to the basal and lateral regions could occur.     

Nestin阳性细胞过表达DMP1对小鼠颌骨密度的影响

目的探讨Nestin阳性细胞中牙本质基质蛋白1(DMP1)的作用。方法 DMP1是牙齿和骨中重要的矿化蛋白,但是Nestin阳性细胞中DMP1的作用仍不清楚。我们构建了Nestin阳性细胞中过表达DMP1的转基因小鼠。以野生型(wild type,WT)小鼠为对照组,通过HE染色,Micro CT检测DMP1-Tg小鼠颌骨的变化,进一步通过TRAP染色检测DMP1-Tg小鼠颌骨破骨方面的变化。结果相对于WT小鼠,DMP1-Tg小鼠颌骨骨量下降;TRAP染色显示DMP1-Tg小鼠下颌骨破骨细胞增多。结论在下颌骨发育过程中,Nestin阳性细胞中过表达DMP1对骨形成发挥抑制作用。     

Delayed tooth eruption and suppressed osteoclast number in the eruption pathway of heterozygous Runx2/Cbfa1 knockout mice

Genetic studies have recently identified a mutation of one allele of runt-related gene 2 (RUNX2/CBFA1) as the cause for an autosomal-dominant skeletal disorder, cleidocranial dysplasia (CCD), which is characterised by hypoplasia of the clavicles and calvariae and widened sutures and fontanelles. In addition, CCD is frequently affected with multiple supernumerary teeth and the impaction and delayed eruption of teeth, the causes of all these dental abnormalities are still unknown. To clarify the cellular mechanism of the delayed tooth eruption in CCD, the process of tooth eruption was examined in heterozygous Runx2/Cbfa1 (mouse homolog of RUNX2/CBFA1) knockout mice, known to mimic most of the bone abnormalities of CCD. The timing of the appearance of maxillary and mandibular teeth into the oral cavity was significantly delayed in heterozygous mutant mice compared with wild-type mice. From postnatal days 8 to 10, an active alveolar bone resorption and a marked increase of the osteoclast surfaces was observed in the eruption pathway of both genotypes, but this increase was significantly suppressed in the mutant mice. In contrast, the osteoclast surfaces did not show a significant difference between the two genotypes in the future cortical area of femora. These results suggest that haploinsufficiency of Runx2/Cbfa1 does not effect the femoral bone remodelling but is insufficient for the active alveolar bone resorption essential for the prompt timing of tooth eruption. These results also suggest the possibility that impaired recruitment of osteoclasts is one of the cellular mechanisms of delayed tooth eruption in CCD patients.     

Gene expression of potential tooth eruption molecules in the dental follicle of the mouse

Tooth eruption requires alveolar bone resorption and the presence of the dental follicle, a loose connective tissue sac that surrounds each tooth. This bone resorption involves the follicle in that mononuclear cells enter the follicle to form osteoclasts which resorb bone to form the eruption pathway. In the rat first mandibular molar, probable eruption genes, CSF-1, c-fos, NFkappaB and MCP-1, are expressed maximally in the dental follicle at day 3 postnatally. This correlates with the time of peak influx of mononuclear cells into the follicle. In the mouse, the first peak influx of mononuclear cells into the first mandibular molar is at day 5 postnatally, and this study demonstrates that all four of the above resorption molecules are maximally expressed at this time in the dental follicle. Thus, this work suggests that these molecules may play a role in the cellular events of eruption (mononuclear cell influx and osteoclast formation) in the mouse molar at day 5 postnatally just as they do at day 3 in the rat molar. These results provide a standard for future studies on eruption in the mouse molar and extends the number of species in which putative eruption molecules are expressed at a critical time of eruption.     

二膦酸盐对骨质疏松大鼠下颌牙槽骨牙本质基质蛋白1表达的影响

目的 :观察二膦酸盐对去卵巢骨质疏松大鼠下颌牙槽骨内破骨细胞以及牙本质基质蛋白1(dentin matrix protein1,DMP1)表达的影响。方法 :取6月龄SD大鼠30只,随机分为假手术组(Sham)、去卵巢模型组(OVX)和二膦酸盐药物治疗组(RIS),每组10只。Sham组大鼠仅术中暴露卵巢不切除,OVX组大鼠行"双侧卵巢切除术+生理盐水皮下注射",RIS组行"双侧卵巢切除术+利塞磷酸钠(2.4μg/kg)皮下注射"。术后3个月取各组大鼠下颌骨常规脱钙,甲苯胺兰染色观察下颌第一磨牙(M1)区域牙槽骨组织学结构,抗酒石酸酸性磷酸酶(tartrate-resistant acid phosphatase,TRAP)染色观察M1区域牙槽纵隔破骨细胞的骨吸收情况,免疫组化染色观察各组M1牙槽骨DMP1分布表达情况,并进行相关半定量图像分析。结果:与Sham组相比,OVX组TRAP阳性细胞数增加;而较OVX组而言,RIS组TRAP阳性细胞数显著减少(P<0.05)。免疫组化染色显示,各组DMP1不仅表达在牙槽骨骨细胞内,牙槽间隔的松质骨骨基质、牙周韧带中均可见其表达,OVX组M1牙槽骨DMP1表达较Sham组减少(P<0.05),而RIS组表达较OVX组有升高。结论:二膦酸盐能减少骨质疏松大鼠下颌牙槽骨破骨细胞数量,并上调DMP1表达,从而影响下颌牙槽骨矿化。