How Stable is Dentin As a Substrate for Bonding?

Purpose of Review: This paper reviews the complexity of the composition of dentin, and the repercussions of this composition on the stability of dentin over time, particularly in relation to adhesive dental procedures. Recent Findings: Dentin is a complex and dynamic structure that comprises the major part of the tooth. Most adhesive procedures in dentistry involve bonding to dentin. The hybrid layer (HL) created on the very variable and dynamic organic dentin phase may fail over time, leading to the failure of dental restorations. Literature showed that the collagen fibers in the HL are prone to hydrolysis and mechanical strain, as well as endogenous proteolytic activity (collagenolytic activity of matrix metalloproteinases and cysteine cathepsins). Hydrolysis of the resin phase of the HL also occurs over time. Summary: Advancements in the area of dental adhesion have been huge. Silencing of collagenolytic enzymes (protease inhibitors and cross-linking agents) is one of the main strategies to decrease the degradation of the HL. In the following years, new techniques will also probably be available, and efficacy of some of the available techniques will perhaps be further clarified.