1 Oral Wound Healing : An Overview

Wounds are common in oral cavity, caused by either trauma or surgery. Soft tissue wound healing in oral cavity proceeds along the same principles as in other areas of the body such as the skin. Wound healing always starts with the blood clotting that initially seals the wound (Chapter 2). Platelet activation during the primary hemostasis releases a number of important cytokines that start the healing process via chemotactic signals to inflammatory and resident cells. In addition, the fibrin-fibronectin clot provides a provisional matrix that both epithelial cells and fibroblasts can use to migrate to the wound space. If a wound continues to bleed, healing is delayed because of the disturbed formation of granulation tissue. Cytokines released during the clotting phase initiate the inflammatory reaction that provides wound debridement, removing damaged tissue and microbes. During this innate immune response, inflammatory cells that have been recruited to the wound site release more cytokines and chemokines which critically modulate wound-healing outcome (Chapter 3). Macrophages appear to be especially critical cells for wound repair. Interestingly, recent evidence suggests that wound macrophage populations shift over time and cells with different phenotypes orchestrate different phases of wound healing (reviewed in Brancato and Albina 2011). Among the cytokines and other regulatory factors that they release, macrophages secrete vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) and transforming growth factor-beta1 (TGF-ß1) which appear to be the most significant regulators of tissue repair. Persistent inflammation retards wound healing and can lead to the formation of chronic wounds and even to development of cancer (reviewed in Eming et al. 2007). In addition, inflammation seems to dictate the healing quality and outcome of the wound. Adult skin wounds heal with visible scars. Fetal skin wounds, however, heal without scars until late third trimester (Ferguson and O’Kane 2004). The most striking difference between fetal and adult healing is the lack of inflammation in fetal wound healing (Eming et al. 2007). It is 1 Oral Wound Healing: An Overview