Estimation of MMP-8 Levels in GCF and Serum and Its Correlation With Wound Healing and Clinical Outcomes After Coronally Advanced Flap and Subepithelial Connective Tissue Graft for Root Coverage in Recession Defects: A CLINICO-BIOCHEMICAL STUDY

NEED FOR THE STUDY:

Coronally advanced flap with Subepithelial Connective Tissue Graft (CAF+SCTG) technique has proven to be one of the most successful modalities for root coverage.1 The success of any surgical procedure is dependent on wound healing.

Wound healing after surgical procedure is complex and highly orchestrated event that includes hemostatic phase, inflammatory phase, phase of new tissue formation and the final remodelling phase leaving behind collagen rich extracellular matrix (ECM) and a dense and stable tissue.2 During wound healing clot provides a foundation for the future ECM. ECM plays a vital role to prompt cellular migration, adhesion, wound contraction and epithelialization. This crucial role of ECM is maintained by a group of enzymes collectively known as Matrix Metalloproteinases (MMPs). MMPs plays a central role in wound healing.3,4 Failure of regulation of these MMPs has been correlated with faulty wound healing.3,4 MMPs (i.e. collagenases, gelatinases, matrilysins, stromelysins, and membrane type MMPs) are family of zinc dependent endopeptidases capable of cleaving extracellular matrix (ECM) in healing wounds.3 MMP-8 are primarly produced by neutrophils and are also produced by other cells such as oral epithelial cells, plasma cells and fibroblasts.7 MMP-8 is expressed during the myelocytic stage of development of PMN (Polymorphonuclear cell) precursors in the bone marrow29 and is stored as latent enzyme (pro-mmp-8) within the specific granules of PMN.30 Pro-MMP-8 is rapidly released from activated PMN undergoing degranulation31 and then is activated via cysteine switch mechanism to yield the active form of enzyme.29 MMP-8 (polymorphonuclear collagenase5) cleaves the triple helix of fibrillar collagen and has affinity for type I collagen and type III collagen5 that is abundantly found in connective tissue of gingiva. MMP-8 degrades gelatin type VII, VIII and X collagen.5 MMP-8 has been implicated to be important for acute wound healing.6 Assessment of wound healing progression after surgery is important. Currently blunt surrogate markers such as probing is used. Limitation of these markers is that it represents the history of healing and not the ongoing activity. As hallmark of healing is collagen remodeling, it is of interest to study the cytokine profile that relates to wound healing. Such knowledge may potentially lead to new diagnostic strategies to study wound healing in a better way reflecting the healing phenotype.

The function of collagenase during normal wound healing after periodontal surgery has been relatively ill-defined due to lack of studies in this area.10 Most of the research has concentrated on the characterisation of MMP-8 during pathogenesis of periodontal disease8 and the changes in MMP-8 level after periodontal treatment.

Nwomeh et al studied MMP-8 from dermal wound healing by collecting wound exudate from occlusive bandage. He noted that MMP-8 peaked at day 4 and persisted for about a week. MMP-8 over expression leads to faulty healing.5 Chronic wounds have 30 times greater MMPs than acute wounds. Inhibiting excessive protease expression in these wounds may allow a prospective wound healing treatment.5 Very less is known about the cellular aspects of soft tissue healing in the oral mucosa. The assumption that oral healing is similar to dermal wounds might provoke confusion, as there are certain subtle difference like reduced scar formation in the dermal wounds2, role of IL-1 in oral wounds and absence of IL-1 in dermal wounds11, faster healing in oral wounds, presence of saliva that aids in healing etc. Overall it is still a matter of speculation and ambiguity about the differences in the unique healing pattern of oral wounds.