MATRIX METALLOPROTEINASES: ITS EFFECT ON DENTIN BONDING

Long term durability of the resin dentin bond still remains a challenge for the clinician. Micro mechanical retention for resin restoration is dependent on the formation of a stable hybrid layer. However, the hybrid layer created by most of the adhesive systems is highly susceptible to hydrolytic degradation caused by the aqueous environment. Studies have shown that the auto degradation of hybrid layer caused by the host-derived enzymes plays a significant role in the destruction of the bonded interface. Different types of matrix metalloproteinases (MMPs) and cysteine cathepsins have been isolated from dentin, and are found to be responsible for the digestion of exposed collagen fibrils within the hybrid layer. This degradation of collagen fibrils is clinically significant as it results in reduced bond strength and thus affecting the long term dentin bonding. The aim of this review is to summarize the role of dentinal host-derived MMPs in dentin matrix degradation and its effect on long term dentin resin bond strength. Also the role of various MMP inhibitors will be discussed as they provide a protective effect by inhibiting collagen degradation at the bonding interface, thereby increasing resin dentin bond durability.