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.

Methods

This study critically discusses the available peer-reviewed research concerning the formation and preservation of the HL, the mechanisms that lead to the degradation of the HL as well as the strategies to prevent it.

Results

The degradation of the HL occurs through two main mechanisms: the enzymatic degradation of its collagen fibrils, and the leaching of the resin from the HL. They are enabled by residual unbound water between the denuded collagen fibrils, trapped at the bottom of the HL. Consequently, endogenous dentinal enzymes, such as the matrix metalloproteinases (MMPs) and cysteine cathepsins are activated and can degrade the denuded collagen matrix. Strategies for the preservation of the HL over time have been developed, and they entail the removal of the unbound water from the gaps between the collagen fibrils as well as different modes of silencing endogenous enzymatic activity.

Significance

Although there are many more hurdles to be crossed in the field of adhesive dentistry, impressive progress has been achieved so far, and the vast amount of available research on the topic is an indicator of the importance of this matter and of the great efforts of researchers and dental material companies to reach a new level in the quality and longevity of resin–dentin bonds.

中文翻译：

---

牙本质粘合系统：从牙本质胶原蛋白结构到粘合保存和临床应用

目标

数十年来，人们一直在努力实现持久的树脂-牙本质键，包括了解杂化层（HL）降解的机理，制造改良的胶粘剂系统以及开发用于保存HL的策略。

方法

这项研究批判性地讨论了有关HL的形成和保存，导致HL降解的机制以及预防HL的策略的同行评审研究。

结果

HL的降解通过两个主要机理发生：其胶原原纤维的酶促降解，以及树脂从HL中的浸出。它们由残留在HL底部的裸露胶原蛋白原纤维之间的残留未结合水激活。因此，内源性牙本质酶，例如基质金属蛋白酶（MMP）和半胱氨酸组织蛋白酶被激活，可以降解裸露的胶原蛋白基质。已经开发出随着时间的流逝而保持HL的策略，它们需要从胶原原纤维之间的间隙中去除未结合的水以及使内源酶活性沉默的不同模式。

意义

尽管在粘合牙科领域还有许多障碍需要克服，但迄今为止已经取得了令人瞩目的进展，有关该主题的大量可用研究表明了该问题的重要性以及研究人员的巨大努力。牙科材料公司将树脂-牙本质胶的质量和寿命提高到一个新的水平。