半胱氨酸组织蛋白酶对牙本质粘接耐久性的影响

半胱氨酸组织蛋白酶是组织蛋白酶家族的主要成员.牙本质酸蚀脱矿后裸露的胶原纤维被内源性蛋白酶降解是影响牙本质粘接耐久性的主要因素之一.除基质金属蛋白酶外,半胱氨酸组织蛋白酶也在粘接过程中被激活并参与混合层中胶原的破坏.本文就半胱氨酸组织蛋白酶与基质金属蛋白酶的相互作用、在牙本质粘接中的作用以及半胱氨酸组织蛋白酶抑制剂对提高牙本质粘接耐久性的作用的研究进展作一综述.     

化学交联剂对树脂牙本质粘接稳定性的影响

随着粘接剂的发展口腔粘接修复在临床得到广泛应用。但牙本质粘接耐久性的问题仍然不容乐观。由于口腔各种酶、细菌等多种因素会导致粘接界面胶原纤维暴露,而裸露的胶原纤维极易降解和疲劳破坏,从而影响牙本质粘接稳定性。基质金属蛋白酶介导的对胶原纤维的降解是粘接界面破坏的主要因素。抑制基质金属蛋白酶活性、增强胶原性能是延长粘接寿命的关键。为此,针对口腔牙本质粘接难点的问题,基于牙本质生物改性的概念,通过使用胶原交联剂的生物活性介导的仿生方法,改变牙本质生物理化性能来强化牙本质胶原纤维强度,增加粘接稳定性。本文主要介绍牙本质生物改性及其相关的基质成分,并对化学胶原交联剂碳化二亚胺及戊二醛进行了综述。     

牙本质内基质金属蛋白酶的测定及其对牙本质胶原降解作用的研究

[摘要] 目的 检测并研究冠根部的牙本质内基质金属蛋白酶(MMPs)及其对牙本质胶原纤维降解的作用。方法 将牙本质粉经盐酸胍提取,然后经EDTA循环脱矿,再经盐酸胍提取。提取物经免疫印迹与酶谱分析检测基质金属蛋白酶-2,9(MMP-2,9)及酶的活性。扫描电镜观察脱矿及脱矿后置于人工唾液中的冠根部牙本质表面结构变化。结果 免疫印迹结果显示提取物中含有MMP-2,9。酶谱分析结果显示提取物中MMP-2,9均具有活性。扫描电镜结果表明,脱矿的冠根部表面胶原纤维较完整;而脱矿后置于人工唾液中的牙本质表而胶原纤维断裂,结构紊乱。结论 冠根部牙本质中含有活性的MMP-2,9。脱矿过程中的低pH值能使牙本质中的MMP活化,在中性时可降解胶原纤维。     

交联剂在抑制基质金属蛋白酶与提高粘接耐久性领域的研究进展

基质金属蛋白酶（MMP）能够降解牙本质胶原纤维,是影响牙科粘接修复耐久性的重要因素。因此,抑制牙本质MMP的活性是提高粘接耐久性的关键。作为一种MMP抑制剂,交联剂不仅能够抑制MMP活性,还具备促进牙本质胶原纤维交联的作用,上述双重作用使交联剂能够提高牙本质粘接的耐久性。本文就常见交联剂在抑制MMP与提高牙本质粘接耐久性方面的研究进展进行综述。     

基质金属蛋白酶介导牙本质粘接界面的生物降解及其拮抗剂的研究进展

随着牙本质粘接技术的不断发展,粘接效果也得到很大提高,但树脂牙本质粘接界面仍然受到诸多因素的影响。有研究表明,牙本质粘接剂中的亲水性和酸性单体可使粘接混合层具有较强的吸水性,容易引起聚合物的水解。同时,混合层内的不稳定聚合物可使胶原纤维受到侵蚀从而变得脆弱,容易被宿主源性的基质金属蛋白酶(MMP)降解。因此,MMP在降解Ⅰ型胶原的过程中发挥着重要作用,从而影响牙本质的粘接耐久性。本文就MMP介导的树脂牙本质粘接界面生物降解机理及其拮抗剂的应用做一简要综述。     

组织蛋白酶K在口腔疾病中的研究进展

组织蛋白酶K（cathepsin K）是一种半胱氨酸蛋白酶,主要存在于破骨细胞、破牙细胞中,该酶主要降解胶原纤维、骨连接素等多种骨基质蛋白。     

基质金属蛋白酶与龋病发生中有机基质降解的关系

近年大量的研究表明 :脊椎动物组织内基质的降解主要是由组织金属蛋白酶 (MatrixMetalloproteinassesMMPs)家族成员来完成的 ,MMPs能够降解几乎所有的基质蛋白[1] ,那么MMPs是否参与龋病发生时牙本质的机质的降解 ?越来越引起人们的兴趣 ,本文即对此方面的研究进行综述。一、基质金属蛋白酶的特性基质金属蛋白酶 (MMPs)是一组依赖二价金属阳离子 ,具有共同生化性质的 ,可降解细胞外基质的内肽酶 ,主要由成纤维细胞、软骨细胞、内皮细胞、巨噬细胞、粒细胞等细胞合成和分泌 ,其合成和分泌受许多因素的调控。近年一些研究发现人成釉细胞…     

宿主源性基质金属蛋白酶与树脂粘接

宿主源性的基质金属蛋白酶（MMP）是一类钙锌离子依赖的蛋白水解酶,其主要生物学功能是水解细胞外基质。树脂粘接时的酸处理往往会造成牙本质表层的酸碱度降低,而适度的弱酸环境则使MMP的活性增强,活性增强的MMP降解树脂-牙本质混合层底部的胶原纤维,破坏混合层,缩短粘接寿命。下面就MMP、酸处理对MMP的影响和MMP对混合层的破坏作用作一综述。     

牙本质和牙髓细胞外基质成分对牙髓细胞的集聚作用(英)

此项研究旨在确定牙髓细胞的迁移是否受牙本质组织、牙髓细胞外基质(pECM)、牙本质细胞外基质(dECM)及其降解产物的影响。趋化性Transwell实验和琼脂糖斑点实验表明,牙本质和牙髓的ECM成分对原发性牙髓细胞都具有化学吸引作用。dECM和pECM的化学吸引作用在酸、酶降解的环境中得到增强。这种活性增强及其相关降解产物可能和疾病环境相关。牙细胞外基质(ECMs)引起的牙     

牙本质粘接持久性的影响因素及解决对策

近20年来,随着牙本质粘接剂和粘接技术的快速发展,大大提高了牙本质的粘接性能。但是,口腔内环境的特殊性(如高湿度、温度变化、微生物、蛋白酶和咬合应力等)、粘接剂的自身降解、牙本质内胶原蛋白的纳米结构限制及其胶原纤维的降解是造成粘接失败和粘接难以持久的重要原因。迄今为止,牙本质粘接的持久性问题尚未完全解决。本文就影响牙本质粘接持久性的相关因素以及如何提高牙本质粘接持久性方面的对策作一探讨。     

Strategies to prevent hydrolytic degradation of the hybrid layer—A review

Objective

Endogenous dentin collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins, are responsible for the time-dependent hydrolysis of collagen matrix of hybrid layers. As collagen matrix integrity is essential for the preservation of long-term dentin bond strength, inhibition of endogenous dentin proteases is necessary for durable resin-bonded restorations.

Methods

Several tentative approaches to prevent enzyme function have been proposed. Some of them have already demonstrated clinical efficacy, while others need to be researched further before clinical protocols can be proposed. This review will examine both the principles and outcomes of techniques to prevent collagen hydrolysis in dentin–resin interfaces.

Results

Chlorhexidine, a general inhibitor of MMPs and cysteine cathepsins, is the most tested method. In general, these experiments have shown that enzyme inhibition is a promising approach to improve hybrid layer preservation and bond strength durability. Other enzyme inhibitors, e.g. enzyme-inhibiting monomers, may be considered promising alternatives that would allow more simple clinical application than chlorhexidine. Cross-linking collagen and/or dentin matrix-bound enzymes could render hybrid layer organic matrices resistant to degradation. Alternatively, complete removal of water from the hybrid layer with ethanol wet bonding or biomimetic remineralization should eliminate hydrolysis of both collagen and resin components.

Significance

Understanding the function of the enzymes responsible for the hydrolysis of hybrid layer collagen has prompted several innovative approaches to retain hybrid layer integrity and strong dentin bonding. The ultimate goal, prevention of collagen matrix degradation with clinically applicable techniques and commercially available materials may be achievable in several ways.     

Dentin Adhesion and MMPs: A Comprehensive Review

This review examines the fundamental processes responsible for the aging mechanisms involved in the degradation of resin‐bonded interfaces, as well as some potential approaches to prevent and counteract this degradation. Current research in several research centers aims at increasing the resin–dentin bond durability. The hydrophilic and acidic characteristics of current dentin adhesives have made hybrid layers highly prone to water sorption. This, in turn, causes polymer degradation and results in decreased resin–dentin bond strength over time. These unstable polymers inside the hybrid layer may result in denuded collagen fibers, which become vulnerable to mechanical and hydrolytical fatigue, as well as degradation by host‐derived proteases with collagenolytic activity. These enzymes, such as matrix metalloproteinases and cysteine cathepsins, have a crucial role in the degradation of type I collagen, the organic component of the hybrid layer. This review will also describe several methods that have been recently advocated to silent the activity of these endogenous proteases.     

Limitations in bonding to dentin and experimental strategies to prevent bond degradation

The limited durability of resin-dentin bonds severely compromises the lifetime of tooth-colored restorations. Bond degradation occurs via hydrolysis of suboptimally polymerized hydrophilic resin components and degradation of water-rich, resin-sparse collagen matrices by matrix metalloproteinases (MMPs) and cysteine cathepsins. This review examined data generated over the past three years on five experimental strategies developed by different research groups for extending the longevity of resin-dentin bonds. They include: (1) increasing the degree of conversion and esterase resistance of hydrophilic adhesives; (2) the use of broad-spectrum inhibitors of collagenolytic enzymes, including novel inhibitor functional groups grafted to methacrylate resins monomers to produce anti-MMP adhesives; (3) the use of cross-linking agents for silencing the activities of MMP and cathepsins that irreversibly alter the 3-D structures of their catalytic/allosteric domains; (4) ethanol wet-bonding with hydrophobic resins to completely replace water from the extrafibrillar and intrafibrillar collagen compartments and immobilize the collagenolytic enzymes; and (5) biomimetic remineralization of the water-filled collagen matrix using analogs of matrix proteins to progressively replace water with intrafibrillar and extrafibrillar apatites to exclude exogenous collagenolytic enzymes and fossilize endogenous collagenolytic enzymes. A combination of several of these strategies should result in overcoming the critical barriers to progress currently encountered in dentin bonding.     

Cysteine cathepsins in human carious dentin

Matrix metalloproteinases (MMPs) are important in dentinal caries, and analysis of recent data demonstrates the presence of other collagen-degrading enzymes, cysteine cathepsins, in human dentin. This study aimed to examine the presence, source, and activity of cysteine cathepsins in human caries. Cathepsin B was detected with immunostaining. Saliva and dentin cysteine cathepsin and MMP activities on caries lesions were analyzed spectrofluorometrically. Immunostaining demonstrated stronger cathepsins B in carious than in healthy dentin. In carious dentin, cysteine cathepsin activity increased with increasing depth and age in chronic lesions, but decreased with age in active lesions. MMP activity decreased with age in both active and chronic lesions. Salivary MMP activities were higher in patients with active than chronic lesions and with increasing lesion depth, while cysteine cathepsin activities showed no differences. The results indicate that, along with MMPs, cysteine cathepsins are important, especially in active and deep caries.     

Chlorhexidine inhibits the activity of dental cysteine cathepsins

The co-expression of MMPs and cysteine cathepsins in the human dentin-pulp complex indicates that both classes of enzymes can contribute to the endogenous proteolytic activity of dentin. Chlorhexidine (CHX) is an efficient inhibitor of MMP activity. This study investigated whether CHX could also inhibit cysteine cathepsins present in dentin. The inhibitory profile of CHX on the activity of dentin-extracted and recombinant cysteine cathepsins (B, K, and L) was monitored in fluorogenic substrates. The rate of substrate hydrolysis was spectrofluorimetrically measured, and inhibitory constants were calculated. Molecular docking was performed to predict the binding affinity between CHX and cysteine cathepsins. The results showed that CHX inhibited the proteolytic activity of dentin-extracted cysteine cathepsins in a dose-dependent manner. The proteolytic activity of human recombinant cathepsins was also inhibited by CHX. Molecular docking analysis suggested that CHX strongly interacts with the subsites S2 to S2' of cysteine cathepsins B, K, and L in a very similar manner. Taken together, these results clearly showed that CHX is a potent inhibitor of the cysteine cathepsins-proteolytic enzymes present in the dentin-pulp complex.     

Dentin bonding systems: From dentin collagen structure to bond preservation and clinical applications

Objectives

Efforts towards achieving durable resin–dentin bonds have been made for decades, including the understanding of the mechanisms underlying hybrid layer (HL) degradation, manufacturing of improved adhesive systems, as well as developing strategies for the preservation of the HL.

Co-distribution of cysteine cathepsins and matrix metalloproteases in human dentin

It has been hypothesized that cysteine cathepsins (CTs) along with matrix metalloproteases (MMPs) may work in conjunction in the proteolysis of mature dentin matrix. The aim of this study was to verify simultaneously the distribution and presence of cathepsins B (CT-B) and K (CT-K) in partially demineralized dentin; and further to evaluate the activity of CTs and MMPs in the same tissue. The distribution of CT-B and CT-K in sound human dentin was assessed by immunohistochemistry. A double-immunolabeling technique was used to identify, at once, the occurrence of those enzymes in dentin. Activities of CTs and MMPs in dentin extracts were evaluated spectrofluorometrically. In addition, in situ gelatinolytic activity of dentin was assayed by zymography. The results revealed the distribution of CT-B and CT-K along the dentin organic matrix and also indicated co-occurrence of MMPs and CTs in that tissue. The enzyme kinetics studies showed proteolytic activity in dentin extracts for both classes of proteases. Furthermore, it was observed that, at least for sound human dentin matrices, the activity of MMPs seems to be predominant over the CTs one.     

Photodynamically crosslinked and chitosan-incorporated dentin collagen

A lingering concern with restored root-filled teeth is the loss of structural integrity of the dentin and dentin-sealer interface over time. We hypothesized that crosslinking of dentin collagen with simultaneous incorporation of a biopolymer into collagen matrix would improve its structural stability. This study aimed to investigate the effects of combining chemical/photodynamic crosslinking of dentin collagen with the incorporation of carboxymethyl-chitosan (CMCS) on the resistance to enzymatic degradation and mechanical properties of dentin collagen. Ninety-six demineralized dentin collagen specimens (human, n = 72; and bovine, n = 24) were prepared and crosslinked chemically/ photodynamically, with/without CMCS. Glutaraldehyde and carbodiimides were used for chemical crosslinking, while rose Bengal activated with a non-coherent light (540 nm) at 20 J/cm(2) was applied for photodynamic crosslinking. The crosslinked human dentin collagen was subjected to chemical characterization, 7 days enzymatic degradation, and transmission electron microscopy (TEM), while the bovine dentin collagen was used for tensile-testing. Crosslinked collagen showed significantly higher resistance to enzymatic degradation (p < 0.01), stable ultrastructure, and increased tensile strength (p < 0.05). Crosslinking CMCS with collagen matrix as observed in the TEM further improved the mechanical properties of dentin collagen (p < 0.01). This study highlighted the possibility of improving the resistance and toughness of dentin collagen by chemically/photodynamically crosslinking collagen matrix with CMCS.