牙髓再生的临床应用与未来

旨在修复牙髓牙本质复合体的牙髓再生治疗是近年来的研究热点,目前仅有牙髓血运重建技术已实现临床初步应用,而干细胞移植和细胞归巢等技术尚处于临床前阶段。经过多年的基础研究和临床实践,牙髓再生特别是牙髓血运重建技术在取得进展的同时也暴露出不少问题,包括概念混淆、适应证选择不当、评价标准不完善等。为此,本综述从牙髓血运重建技术出发,对牙髓再生临床应用的现状、存在的问题和未来的临床实践路径等进行分析和探讨。     

再生牙髓病学--牙髓再生的新方向

再生牙髓病学主要采用引导组织再生原理,通过组织工程学技术促进根管内牙髓再生,是牙髓再生治疗的新方向和新选择。在再生牙髓病学中,牙源性干细胞、生物支架以及生长因子是3个关键因素,逐渐成为学者们研究的热点。     

组织工程技术在牙髓组织再生中的研究进展

<正>外伤、感染等引起的牙髓炎症是临床上常见的口腔疾病之一,传统的牙髓炎治疗方法是对患牙进行根管治疗来保留患牙。但是经过根管治疗的牙齿失去营养代谢,丧失防御及保护功能,牙体组织变脆。对于根尖未完全发育成熟的恒牙而言,根管治疗仍然是一个临床上的挑战。尽管传统的根管治疗可以有效去除根管内牙髓感染,控制症状;但可能会造成牙根发育停滞,继而造成牙髓坏死,根管壁结构脆弱,牙根易折裂,降低牙齿存活率。因此,学     

牙髓再生的研究进展

活髓对于维持牙齿内稳态十分重要。理想的牙髓治疗方法应包括再生性牙髓治疗,即坏死或活力减退的牙髓被活髓所代替,最终牙齿活力恢复。随着组织工程的发展,牙髓再生成为可能,本文将从干细胞、支架、生长因子3个方面对牙髓再生相关的问题做一综述。     

富血小板血浆支架诱导牙髓再生的体内研究

目的：探讨不同浓度的富血小板血浆（PRP）支架在体内诱导牙髓组织再生的能力。方法将小型猪乳牙牙根段进行化学预备,采用二次离心法制备PRP,根据注入根管中的成分不同将研究分为4组：（1）阴性对照组,即全血组;（2）100％ PRP组;（3）50％ PRP组;（4）空白组,即空的牙根段;每组5个样本,分别植入裸鼠背部皮下,于术后5周处死动物,取出样本进行组织学观察。结果植入5周后,100％ PRP组根管内充满了炎性细胞,50％ PRP组根管内有少量牙髓样的组织生成。结论合适浓度的PRP作为生物支架在体内再生牙髓样的组织是可行的。     

牙髓再生的研究进展

尽管目前的根管治疗手段可有效地保存牙髓病变的牙齿,但其仍然存在诸多术后并发症.随着分子生物学、细胞生物学、发育生物学等生命前沿科学的发展,牙髓治疗由物理充填治疗向生物学治疗转变成为可能.本文就成牙本质细胞再生、牙髓血运重建、神经再生和支架移植等方面对近年来的牙髓再生研究作一综述.     

脱落乳牙牙髓干细胞聚合体再生牙髓实验研究

目的    利用动物实验模型证明使用小型猪脱落乳牙牙髓干细胞（stem cells from minipig exfoliated deciduous teeth, SPED）聚合体进行原位牙髓再生的可行性。方法    分离和培养SPED,检测和分析其细胞生物学行为,进而诱导制备SPED聚合体;建立年轻恒牙牙髓坏死的小型猪动物模型,设置SPED聚合体再生组和传统根尖诱导成形治疗组;术后4个月进行常规组织学取材,利用HE、免疫荧光染色等方法观察牙髓再生和牙根尖形成情况。结果    SPED聚合体再生组受试牙齿组织学HE染色检测发现,牙根继续发育并形成正常的根尖形态,此外全长根管内可见类牙髓结构的再生组织,免疫荧光染色可见组织中CGRP、TRPV1、TRPM8表达阳性细胞的规则分布;而传统根尖诱导成形治疗组受试牙齿仅在根管内形成不规则的钙化组织,未见牙髓组织形成。结论    SPED聚合体在小型猪体内可以实现牙髓再生,同时再生牙髓具有正常组织学形态,而且具有牙本质形成和诱导根尖形成的生理功能。     

细胞外基质支架及其在牙髓再生中应用的研究进展

实现全牙髓功能性再生是牙髓及根尖周疾病治疗的理想目标。以干细胞为基础的再生医学技术为牙髓再生带来了新的希望,而支架材料在其中发挥重要作用。通过化学、物理或生物学等方法去除组织、器官中的细胞及抗原,可获得天然脱细胞的细胞外基质支架。其具有良好的物理特性、生物相容性以及生物降解性,能够促进干细胞黏附、生长、增殖及分化,同时具有低免疫原性,避免过敏反应和疾病传播,被认为是再生医学一种新型的生物支架。文章就细胞外基质支架的制备、特性及其在牙髓再生中应用的研究进展做一综述。     

牙髓炎的活髓保存及再生治疗新进展:从基础到临床

近年关于牙髓炎治疗的研究取得了较大进展,这主要得益于牙髓炎治疗的基础和临床研究的飞速进展,一些基础研究已转化为临床实践。牙髓炎检测方法的研究进展可以帮助临床医师更准确地诊断牙髓炎的状态,并采取相应的治疗手段,包括间接或直接盖髓术、牙髓切断术、牙髓再生术和根管治疗术等。针对牙髓炎的诊断理念、牙髓免疫防御和修复功能研究以及新型盖髓剂材料研究均有了较大进展,牙髓炎的活髓保存治疗成功率显著提高。对于难以实现活髓保存治疗的弥漫性冠髓炎或根髓炎,除根管治疗术外,牙髓血运重建、细胞归巢和牙髓干细胞移植牙髓再生等牙髓再生术也可作为一种治疗选择。本文重点阐述牙髓炎治疗研究进展和相关的临床转化实践,旨在为牙髓炎的活髓保存和牙髓再生治疗提供参考。     

The Role of Small Extracellular Vesicles Derived from Lipopolysaccharide-preconditioned Human Dental Pulp Stem Cells in Dental Pulp Regeneration

IntroductionRegenerative endodontics has created a desirable shift in the treatment paradigm despite current limitations of regenerative outcomes. Mesenchymal stem cells (MSCs) facilitate tissue regeneration and repair in a mild inflammatory environment. Small extracellular vesicles (sEVs) derived from MSCs play an imperative role in the paracrine modulation of regenerative responses modulated by MSCs. However, it remains unknown whether MSCs enhance dental pulp regeneration or whether this enhancement is mediated by sEVs in a mild inflammatory environment. The present study aimed to elucidate the effects of sEVs originated from lipopolysaccharide (LPS)-preconditioned human dental pulp stem cells (hDPSCs) on dental pulp regeneration.MethodsAll sEVs were isolated from hDPSCs cultured with or without LPS (ie, N-sEVs and L-sEVs, respectively). The effect of N-sEVs and L-sEVs on proliferation, migration, angiogenesis, and differentiation of rat bone marrow MSCs was identified in vitro. Moreover, N-sEVs or L-sEVs were implanted into rat pulpless root canal models, and the regenerated tissue in root canals was assessed via hematoxylin-eosin staining, Masson staining, and immunohistochemistry after 30 days of transplantation.ResultsBoth N-sEVs and L-sEVs could modulate BMSC proliferation, migration, angiogenesis, and differentiation. Both kinds of sEVs enhanced the structure of the regenerated tissue closer to that of a normal dental pulp in vivo. L-sEVs had a more significant effect than N-sEVs.ConclusionssEVs released by hDPSCs in a mild inflammatory microenvironment are capable of facilitating the regeneration of dental pulp through functional healing instead of scar healing, which has potential applications in regenerative endodontics.     

Transplantation of Dental Pulp Stem Cells and Platelet-rich Plasma for Pulp Regeneration

Introduction

The loss of dental pulp may weaken teeth, rendering them susceptible to reinfection, fracture, and subsequent tooth loss. Therefore, regeneration of pulp is considered an ideal treatment to preserve teeth. The aim of this study was to explore the capacity of dental pulp stem cells (DPSCs) and platelet-rich plasma (PRP) to regenerate dental pulp in canine mature permanent teeth.

Methods

Pulpectomy with apical foramen enlarged to a #80 file was performed in 16 upper premolars of 4 beagle dogs. Four experimental groups were randomly established: (1) the blood clot group, (2) the autologous DPSCs group, (3) the PRP group, and (4) the DP + PRP group (a mixture of DPSCs and PRP). Four lower premolars without any further treatment after pulpectomy were used as the control group. All teeth were sealed with mineral trioxide aggregate and composite. Twelve weeks after transplantation, the teeth were subjected to radiographic and histologic examination.

Results

Twenty-four of 32 experimental root canals gained newly formed tissues. All canals with an introduction of a blood clot showed histologic evidence of vital tissue formation. Cementum-like and periodontal ligament–like tissues along the internal root canal walls were typical structures in most cases. There is no significant difference between groups with or without autologous DPSC transplantation (exact chi-square test, P < .05).

Conclusions

New vital tissues can be regenerated in permanent canine teeth after pulpectomy and enlargement of the apical foramen. Histologically, transplantation of DPSCs and/or PRP into root canals showed no enhancement in new tissue formation compared with inducement of a blood clot into the root canals alone.     

根尖孔大小对牙髓组织再生及牙齿抗压强度的影响

目的:探讨根尖孔大小对牙髓组织再生及牙齿抗压强度的影响。方法:收集因正畸拔除的牙根发育完成、 无牙根折裂的单根下前磨牙,离体牙截冠后,保留12 mm牙根,随机分为5组,每组25颗牙,根管预备至不同主锉号数,分别为30#、40#、60#、80#及100#主锉组,其中30#主锉组为对照组。体外培养人牙髓干细胞并接种于0.25%水凝胶支架中,将其分别注入不同主锉预备过的根管内,每组均取5颗牙,其牙根于Transwell小室分别培养14、21、28 d,提取水凝胶中细胞的总RNA,进行实时定量聚合酶链反应(real-time polymerase chain reaction,Real-time PCR)检测;每组余下的10颗牙,其牙根冠部封闭后植入裸鼠皮下,28 d后取出,5颗进行组织学观察,5颗进行静态载荷实验。结果:Real-time PCR检测牙本质涎磷蛋白(dentin sialophosphoprotein, dspp)、牙本质基质蛋白-1(dentin matrix protein-1, dmp-1)的表达,第28天时,各实验组均高于对照组(P<0.05),且40#主锉组高于其它实验组(P<0.05)。组织学分析表明,30#、40#、60#主锉组均未见连续的牙髓样组织形成,80#、100#主锉组可见组织形成,但未表现出典型牙髓样组织结构。静态载荷实验结果表明,40#主锉组的平均抗压载荷与对照组比较差异无统计学意义,其它实验组均低于对照组(P<0.05)。结论:根尖孔预备至100#(1 mm)以内时,根尖孔大小对牙髓组织再生没有明显影响,但根尖孔预备大于40#时,抗压强度明显下降。     

富血小板血浆对牙髓成纤维细胞附着、增殖的影响

目的 :探讨富血小板血浆 (PRP)对牙髓成纤维细胞附着、增殖的影响。方法 :利用原代细胞体外培养技术、PRP提取技术及四唑盐比色法 (MTT)检测 5 %PRP对牙髓成纤维细胞附着的影响和不同浓度PRP(5 %、10 %、2 0 %、30 %、4 0 %、5 0 % )对牙髓成纤维细胞增殖的影响。结果 :在附着实验中 ,5 %PRP组所测得的平均光密度值 (OD值 )明显高于空白对照组 (P <0 .0 1)。在增殖实验中 ,各不同浓度PRP组所测得的平均OD值均明显高于对照组 (P <0 .0 1)。结论 :PRP可促进牙髓成纤维细胞的附着及增殖     

EZH2, a Potential Regulator of Dental Pulp Inflammation and Regeneration

Introduction

Dental pulp has limited capability to regenerate, which happens in the early stage of pulpitis. An ambiguous relationship exists; inflammation may impair or support pulp regeneration. Epigenetics, which is involved in cell proliferation and inflammation, could regulate human dental pulp cell (HDPCs) regeneration. The aim of this study was to determine the role of the epigenetic mark, enhancer of zeste homolog 2 (EZH2), in the inflammation, proliferation, and regeneration of dental pulp. We used trimethylated histone H3 lysine 27(H3K27me3) and its lysine demethylase 6B (KDM6B) to monitor functional effects of altered EZH2 levels.

Methods

We detected epigenetic marks (EZH2, H3K27me3, and KDM6B) in pulp tissue by immunohistochemistry and immunofluorescence. EZH2 levels in HDPCs in inflammatory responses or differentiation were analyzed by quantitative polymerase chain reaction and Western blot. Quantitative polymerase chain reaction was used to assess the effects of EZH2 inhibition on interleukins in HDPCs upon tumor necrosis factor alpha stimulation. Cell proliferation was tested by cell counting kit-8, cell cycle, and apoptosis analysis. HDPC differentiation was investigated by quantitative polymerase chain reaction, alkaline phosphatase activity, and oil red O staining.

Results

EZH2 and H3K27me3 were decreased, whereas KDM6B was increased in infected pulp tissue and cells, which were similar to HDPC differentiation. EZH2 inhibition suppressed IL-1b, IL-6, and IL-8 messenger RNA (mRNA) in HDPCs upon inflammatory stimuli and impeded HDPC proliferation by decreasing cell number, arresting cell cycle, and increasing apoptosis. Suppressed EZH2 impaired adipogenesis, peroxisome proliferator-activated receptor r (PPAR-r), and CCAAT-enhancer binding protein a (CEBP/a) mRNA in adipogenic induction while enhancing alkaline phosphatase activity, Osx, and bone sialoprotein (BSP) mRNA in mineralization induction of HDPCs.

Conclusions

EZH2 inhibited HDPC osteogenic differentiation while enhancing inflammatory response and proliferation, suggesting its role in pulp inflammation, proliferation, and regeneration.