A review on nature, role and functions of dentin non-collagenous proteins. Part II: enzymes, serum proteins and growth factors.

Part I was an overview of the role and function of proteoglycans and glycoproteins in the pulpo–dentin complex; part II will focus on enzymes, serum proteins, and growth factors. This review will discuss current knowledge regarding matrix metalloproteinases (MMPs), cathepsins, serum proteins, and growth factors in dentin and the related dentin–pulp complex in an attempt to better understand their nature, role, and function in the dentin extracellular matrix (ECM) environment. Dentin formation in physiological and pathological conditions has been widely studied. However, the regulation and involvement of non-collageneous enzymes, serum proteins, and growth factors are still not completely elucidated. MMPs, a family of 23 endopeptidases in humans, are collectively capable of degrading virtually all ECM components, and their specific tissue inhibitors (TIMPs: tissue inhibitors of matrix metalloproteinases) participate in organo- and morphogenesis, physiological tissue turnover, and pathological tissue destruction. Similarly, the lysosomal cysteine proteinases (cathepsins) are capable of degrading ECM proteins such as collagen, laminin, fibronectin, and proteoglycans. These enzymes are implicated in a variety of pathological conditions, especially in diseases involving tissue re-modeling states. Dentin also contains serum-derived proteins (such as albumin, immunoglobulins, and transferrin), and a variety of growth factors in the mineralized ECM are available for release during demineralization or other injury. A detailed description of the components of the above-mentioned dentin non-collageneous proteins will be summarized in this literature review.