不同方法建立实验性狗根尖周炎模型的比较

目的：对比研究不同根尖周炎致病菌、内毒素分组注入根管内制备动物根尖周炎模型的效果。方法：将80个犬牙根管失活牙髓后分成四个组,分别封混合菌（A组）,细菌内毒素（B组）,粪肠球菌（C组）,生理盐水（D组）,术后不同阶段拍摄根尖周X线片观察分析。结果：内毒素组术后30 d出现根尖周阴影;混合菌组术后45d出现根尖周阴影,进展迅速;粪肠球菌组术后90d有阴影出现;对照组在实验观察期间均未见根尖周异常表现。结论：犬牙失活牙髓后封内毒素或混合菌能较快有效形成根尖周炎症。     

Toll样受体4在大鼠实验性牙髓炎和根尖周炎中的表达

目的:建立大鼠实验性牙髓炎及根尖周炎模型,了解TLR4在大鼠牙髓和根尖周组织的表达情况。方法:采用单纯髓腔开放法建立大鼠实验性牙髓炎及根尖周炎模型,进行组织学及X线片观察。免疫组化检测TLR4在牙髓炎中的表达,RT-PCR检测TLR4在根尖周炎中的表达。结果:组织学及X线观察证实成功复制大鼠牙髓炎及根尖周炎模型,免疫组化结果表明大鼠正常牙髓组织成牙本质细胞层TLR4阳性表达,牙髓内部血管内皮细胞亦见表达,牙髓成纤维细胞未见表达。炎症牙髓组织TLR4表达较正常组增强。RT-PCR检测发现正常和炎症根尖周组织均有TLR4mRNA表达,炎症组表达较正常组增强。结论:TLR4在牙髓组织和根尖周组织均有表达并参与了牙髓根尖周炎症的发生和发展。     

替硝唑对诱发性大鼠根尖周炎的作用效应

目的：探讨替硝唑对诱发性大鼠根尖周炎的作用效应。方法：暴露磨牙牙髓，T组于术后每天腹腔注射4mL/L替硝唑液至处死，C组注射生理盐水。两组分别于术后0、3、7、14d处死作牙髓、根尖周组织学观察。结果：T组在3、7d时牙髓、根尖周炎症细胞浸润程度均较C组轻。结论：替硝唑可有效地抑制大鼠根尖周炎活动期的炎症细胞浸润。     

替硝唑治疗诱发性大鼠根尖周炎的组织学分析

目的 探讨替硝唑对诱发性大鼠根尖周炎的作用效应。方法 将26只大鼠随机分成T、C两组，暴露磨牙牙髓，T组术后每天腹腔注射0.4%替硝唑液至处死，C组注射生理盐水。两组分别于术后0天、3天、7天、14天处死作牙髓、根尖周组织学观察。结果 T组在3天、7天时牙髓、根尖周炎症反应和炎症细胞浸润程度均较C组轻。结论 替硝唑可有效地抑制大鼠根尖周炎活动期的炎症反应和炎症细胞浸润。     

实验性鼠根尖周炎组织学动态观察

目的 :观察大鼠磨牙牙髓在自然暴露状态下组织学动态过程。方法 :16只SD大鼠磨牙开髓 ,分别于术后 1、2、3、4周取下颌骨组织 ;拍根尖X线片 ,图像分析系统测根尖阴影面积 ;组织经固定、脱钙后作组织切片 ,HE染色 ,进行组织学观察。结果 :从术后 1周始根尖阴影面积逐渐增大 ,第 3周达峰值(1.2 5± 0 .15 )mm2 ,4周后相对稳定 ;组织学变化表现为非特异性炎症过程 ,术后 1周根尖区即可见炎细胞浸润及轻度骨吸收 ;2周后牙髓全部坏死 ,根尖炎症加重 ;3周后根尖周出现根尖脓肿 ;4周后炎症浸润减轻 ,并可见立方状成骨细胞。结论 :开放大鼠磨牙髓腔使口腔菌丛感染后 ,可建成实验性根尖周炎模型。 1～ 3周表现为急性炎症阶段 ,根尖周破坏逐渐加重 ,4周后转为慢性期     

维生素C对大鼠实验性根尖周炎影响的初步研究

目的：探讨维生素 C 对大鼠实验性根尖周炎形成过程的影响。方法：选用100只8周龄 Wistar雄性大鼠，髓腔直接暴露法建立根尖周炎模型，将大鼠分成维生素 C 干预组（0．1、0．5、1．0 mg/mL 维生素 C 灌胃）及对照组，术后1、3、7、14、21 d处死，通过 X线测量法和 HE 染色观察根尖周病变的大小和组织学变化。结果：维生素 C 干预组和对照组根尖透射区的面积从3 d开始增大，呈时间依赖性，21 d时透射面积到达高峰。术后7、14、21 d维生素C 干预组的根尖透射区的面积均小于对照组，差异具有统计学意义（P＜0．05），其中0．1 mg/mL组根尖透射区的面积明显小于其它各组（P＜0．05）。术后7、14、21 d 维生素 C 干预各组骨吸收陷窝数及牙槽骨破坏范围均小于对照组。结论：全身应用维生素 C 对抑制大鼠根尖周炎的进展有一定的作用。     

实验性根尖周病变的X线及组织学研究

本实验将三只实验狗的全部牙髓暴露于口腔环境内诱导根尖周病变的发生，术后第５，１４，１８周分别处死动物，Ｘ线片显示各组动物根尖周均有不同程度的密度减低影像，观察时间最长的动物其密度减低范围较前两组增大，且部分根尖周密度减低区周围存在密度增高的Ｘ线阻射带，组织学检查，１５７个牙根右的８６个根尖周出现不同程度的炎症或有肉芽肿形成，１３个根管内有活髓残留，其根尖周均无炎症，认为根尖周病主煌发生出现在牙髓感     

浓缩生长因子用于比格犬成熟恒牙牙髓再生的实验研究

目的:探讨浓缩生长因子(CGF)结合牙髓血运重建术在比格犬成熟恒牙牙髓再生中的作用。方法:选择6只18月龄比格犬的36颗上颌门齿,分为4组：阳性对照组不干预,阴性对照组建立根尖周炎并牙根吸收模型后不治疗,血运重建组建立同样模型后行牙髓血运重建术,血运重建加置CGF膜组建立同样模型后置CGF膜行牙髓血运重建术。术后拍摄X线片,HE染色观察各组牙组织学变化。结果:比格犬实验模型建立成功。血运重建组和血运重建加置CGF膜组根尖周阴影缩小,根尖部矿化组织中可见骨陷窝,但后者矿化组织更致密。结论:CGF结合牙髓血运重建术有促进犬成熟恒牙根尖周炎愈合和牙根发育的作用。     

不同氢氧化钙制剂对牙髓卟啉单胞菌的杀菌效果

目的:比较Endocal、Calxyl、国产氢氧化钙糊剂、Vitapex 4种氢氧化钙制剂对牙髓根尖周主要致病菌牙髓卟啉单胞菌(Porphyromonas endodontalis,P.e)活性的影响。方法:(1)通过动态比浊法比较在直接接触条件下不同氢氧化钙制剂不同作用时间对牙髓卟啉单胞菌的抑制作用。(2)选取新鲜拔除的人单根管牙85颗,经根管预备、高压消毒灭菌后,置入P.e菌悬液,建立牙髓卟啉单胞菌感染模型。将模型采用抽签法随机分为5组,即Endocal组、Calxyl组、国产氢氧化钙糊剂组、Vitapex组、无菌去离子水对照组。分别于封药前和封药7d后,用无菌纸捻在根管中取样,细菌培养计数菌落,并完成细菌24h回复实验。采用SPSS11.0软件包对数据进行统计学处理。结果:Endocal、Calxyl、国产氢氧化钙糊剂、Vitapex均能有效减少牙髓卟啉单胞菌的数量(P<0.05),细菌清除率均达95%以上。动态比浊法检测结果显示,Endocal、国产氢氧化钙糊剂抑菌作用优于其他组,有显著性差异(P<0.05);细菌培养法结果显示,Endocal组细菌清除率显著大于Vitapex组(P<0.05)。结论:Endocal、Calxyl、国产氢氧化钙糊剂、Vitapex 4种药物对牙髓卟啉单胞菌均有较好的抑制作用,其中,Endocal的抗菌作用优于Vitapex。     

大鼠根尖周炎的细胞组成及其对药物治疗反应

目的 :探讨诱发性大鼠根尖周炎活动期的细胞组成变化规律及替硝唑的治疗机制。方法 :将 14只大鼠随机分成2组。A、B两组各 7只 ,每只暴露 2颗受试牙牙髓 ,A组于术后每天腹腔注射 0 4%替硝唑液 (5 0mg/kg) ,B组注射生理盐水直至处死。分别于术后 0、3、7、14天处死作根尖周组织学观察。结果 :B组根尖周炎症组织中中性多形核白细胞 (PMNs)在活动期始终是最优势的炎症细胞 ,成纤维细胞密度在一定程度上反映了炎症的程度 ;A组在 3天、7天时的根尖周炎症、炎症细胞浸润和骨破坏程度均较B组轻。结论 :PMNs和成纤维细胞密度是评价根尖周炎症程度的两个重要方面 ;替硝唑通过抑制厌氧菌生长、PMNs炎性浸润 ,从而控制炎症反应和骨破坏。     

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提要：牙髓卟啉单胞菌是根尖周病变中的重要致病菌之一,牙髓卟啉单胞菌可产生多种毒力因子,其中内毒素尤为重要。研究证明,在根尖周病变的发展过程中,根尖部炎症反应以及骨吸收的发生等都与牙髓卟啉单胞菌内毒素密切相关。本文针对牙髓卟啉单胞菌内毒素的致病性研究进展加以综述。     

大鼠实验性根尖周炎中肿瘤坏死因子α的免疫组化测定

目的测定大鼠实验性根尖周炎病损大小及肿瘤坏死因子α(TNF-α)表达量的变化。方法采用髓腔直接暴露法建立SD大鼠根尖周炎模型,分别通过X线测量法和免疫组化染色观察对照组、术后1、3、7、14、21d时根尖病损的大小和TNF-α免疫组化光密度值的变化。结果①根尖病损面积自术后3d开始增大,呈时间依赖关系,21d达到峰值。②TNF-α表达量在开髓术后1d即有少量增加,7～14d增强,14d达到峰值,在21d降低。结论大鼠实验性根尖周炎急性炎症性破坏中TNF-α的表达量与根尖病损发展呈正相关,提示TNF-α和根尖周炎骨质破坏关系密切。     

Stimulation of Fusobacterium nucleatum biofilm formation by Porphyromonas gingivalis

BACKGROUND/AIMS: Bacterial infection is a major cause of periapical periodontitis. Eradication of these microorganisms from apical lesions is essential to the success of endodontic treatment. The aim of this study was to clarify the molecular interaction between Fusobacterium nucleatum, Porphyromonas gingivalis and other microorganisms associated with periapical periodontitis. METHODS: Microorganisms isolated from periapical lesions were inoculated into type-I collagen-coated polystyrene microtiter plates and maintained at 37 degrees C under anaerobic conditions for 2 days, after which, the quantity of organized biofilm on the plates was evaluated by crystal violet staining. Growth enhancement via soluble factor was evaluated by separated coculture using a 0.4-mum membrane filter. RESULTS: F. nucleatum exhibited strong adherence to type-I collagen-coated polystyrene microplates. Biofilm formation by F. nucleatum was significantly enhanced by P. gingivalis. It was complemented by compartmentalized coculture with P. gingivalis. Enhancement of biofilm formation by P. gingivalis was only slightly reduced by inactivation of its autoinducer-2-producing gene luxS. CONCLUSION: The results suggest that P. gingivalis enhances biofilm formation by F. nucleatum by releasing diffusible signaling molecules other than autoinducer-2.     

雌激素缺乏对大鼠根尖周炎病变区TLR4表达的影响

目的:探究雌激素缺乏对大鼠根尖周炎病变区TLR4表达的影响。方法:30只大鼠随机分为两组:OVX组、SHAM组,暴露下颌第一磨牙髓腔,分别于开髓后 0、7、14、21 d处死大鼠。HE染色、酶组织化学染色、免疫组织化学法观测根尖周组织骨吸收范围,破骨细胞数及TLR4的表达。结果:与SHAM组相比,OVX组根尖周炎病变区骨吸收范围增大、破骨细胞数升高、TLR4的表达增强。结论:雌激素缺乏可增强大鼠根尖周炎病变区TLR4的表达。     

Semaphorin 7A Accelerates the Inflammatory Osteolysis of Periapical Lesions

IntroductionSemaphorin 7A (SEMA7A), the only class VII semaphorin member, has been considered as a potent immunomodulatory regulator whose function in periapical lesions remains unclear. In our previous study, we found that SEMA7A was up-regulated in human periapical periodontitis and might be involved in the immune response and tissue destruction of periapical lesions. In this research, we aimed to further explore the specifical regulatory role of SEMA7A as well as its regulatory mechanisms in the inflammatory progression of periapical lesions.MethodsHuman periodontal ligament cells (hPDLCs) were collected from intact, caries-free, and healthy third molars and stimulated with recombinant human/mouse SEMA7A (rSEMA7A). Real-time quantitative polymerase chain reaction (RT-qPCR), Western blot analysis, and enzyme-linked immunosorbent assay were used to detect the messenger RNA and protein levels of inflammatory cytokines and matrix metalloproteinases (MMPs) in hPDLCs. Twenty C57BL/6 mice were randomly divided into 4 groups: the healthy control group, pulp exposure group, pulp exposure and saline treatment group, and pulp exposure and rSEMA7A treatment group. Twenty microliters of sterile saline or 4 μg rSEMA7A were injected respectively into the buccal mucosa around the root apex at day 0, 7, and 14. Mandibular tissues were collected at day 21. Micro–computed tomographic and immunohistochemical staining were used to identify the bone destruction and inflammatory infiltration in periapical areas. Finally, an AKT inhibitor (LY294002) was used to pretreat hPDLCs before rSEMA7A stimulation to determine the role of AKT signaling activation in this process.ResultsAfter treatment with rSEMA7A, the messenger RNA and protein levels of interleukin (IL)-1β, IL-18, cyclooxygenase-2, MMP-1, and MMP-3 were remarkably up-regulated in hPDLCs. For in vivo experiments, compared with the other 3 groups, the treatment of rSEMA7A aggravated the osteolysis of alveolar bone and promoted the infiltration of immune cells into the apex area, along with increased expression levels of IL-1β, IL-18, MMP-1, and MMP-3. Furthermore, we found that the proinflammatory role of SEMA7A could be inhibited by the application of the AKT inhibitor (LY294002).ConclusionsSEMA7A likely aggravates the inflammatory reaction and bone destruction of existing periapical lesions. The proinflammatory role of SEMA7A in hPDLCs could partially be mediated through the AKT signaling transduction pathway.     

NLRP3/Caspase-1炎性体通路在大鼠根尖周炎中表达的研究

目的:研究大鼠实验性根尖周炎中NLRP3/Caspase-1炎性体通路的表达。方法:30只大鼠双侧下颌第一磨牙开髓后封入PBS缓冲液棉球,玻璃离子封闭髓腔,分别于开髓后0、7、14、21d和28d处死大鼠,分离双侧下颌骨。组织学处理后HE染色观察根尖周组织炎症状况,免疫组织化学染色和实时荧光定量PCR分别检测NLRP3、Caspase-1和IL-1β的表达情况。结果:NLRP3、Caspase-1和IL-1β在炎性根尖周组织中均有表达;与对照组相比,三者表达水平均明显增高,差异有统计学意义(P<0.05);其中Caspase-1和IL-1β阳性细胞数与NLRP3阳性细胞数呈显著正相关(P<0.01)。结论:根尖周组织中存在着NLRP3/Caspase-1炎性体通路,提示该通路在根尖周组织固有免疫中可发挥重要作用。[关键词]炎性体NLRP3Caspase-1根尖周炎     

Periapical lesion progression and cytokine expression in an LPS hyporesponsive model

AIM: The purpose of this study was to compare periapical lesion progression and the expression of the bone modulating cytokines IL-1alpha, TNF-alpha, IL-4, IL-6 and IL-11 in periapical lesions of normal and C3H/HeJ (LPS hyporesponsive) mice. METHODOLOGY: Pulps of both mandibular first molars from C3H/HeJ and BALB/c (normal) mice were exposed and inoculated with normal mouse oral microorganisms for 2, 4, 6, and 8 weeks. After euthanasia, specimens were prepared for histological examination. A quantitative evaluation of the lesional area and immunohistochemical stain counts was performed. RESULTS: There were no statistically significant differences in progression of periapical lesions for both mouse strains with time (two-factor ANOVA, P > 0.05). The immunohistochemical staining revealed no overall differences between the two strains in levels of expression of the cytokines (P > 0.05). IL-11 expression did not change from control levels in BALB/c mice, but correlated with the expression of IL-6 and IL-4 in C3H/HeJ mice. CONCLUSION: Responsiveness to LPS may not be significant in the pathogenesis of periapical lesions and in cytokine expression within the lesions, when the lesions are induced by non-specific oral flora.     

Radiographic evaluation of the effect of endotoxin (LPS) plus calcium hydroxide on apical and periapical tissues of dogs

The aim of this study was the radiographic evaluation of the apical and periapical region of dog teeth submitted to intracanal bacterial endotoxin (lipopolysaccharide, LPS), associated or not with calcium hydroxide. After removal of the pulp, 60 premolars were divided into four groups and were filled with bacterial endotoxin (group 1), bacterial endotoxin plus calcium hydroxide (group 2), saline solution (group 3), or periapical lesions were induced with no treatment (group 4), for a period of 30 days. Similar periapical lesions were observed in groups 1 and 4. The lamina dura was intact in groups 2 and 3. Bacterial endotoxin (LPS) caused radiographically visible periapical lesions, but when associated with calcium hydroxide, this endotoxin was detoxified.     

Histologic Evaluation of the Effects of Emdogain Gel on Injured Root Apex in Rats

Introduction

This study investigated the effects of Emdogain gel (EMD) on the injured open apex within periapical lesions.

Methods

Periapical lesions were induced in rats by opening the pulp chambers of the mandibular first molars and filing the apical foramen through the distal root canal with #25 K-files to make an open apex. The teeth were exposed to the oral environment for 7 days. Then we irrigated the distal root canals and divided them into EMD-treated and propylene glycol alginate–treated groups. The rats were killed 7, 14, and 28 days after treatment and examined histochemically.

Results

In the EMD-treated rats, more cells expressed transforming growth factor-β1 or bone morphogenetic protein-2 at 7 days after treatment, and the regeneration of cementum and bone was observed around the root apex at 14 days after treatment. Conversely, in the propylene glycol alginate–treated group, few cells expressed transforming growth factor-β1 or bone morphogenetic protein-2, and apical periodontal tissue recovery was rarely seen within the periapical lesions throughout the experiment.

Conclusions

These results suggest that EMD does not irritate injured periapical tissue and may create a favorable environment that promotes the healing of destroyed periapical tissues.