Читать книгу The Art of Dental Suturing - A. Burak Çankaya - Страница 9

TYPES OF WOUND HEALING

Diverse biologic events such as hemostasis, coagulation, inflammation, granulation, connective tissue formation, and reepithelization occur during wound healing and continue upon remodeling of the wound site, even after wound closure. The healing model where the wound edges are well approximated is known as primary healing or primary intention, and that where a gap is left between the wound edges is called secondary healing or secondary intention. However, in case of injuries with significant tissue loss and in which the wound is contaminated with bacteria through contact with a foreign body, the wound is often left open for a couple of days to avoid the risk of infection, and then closed once this risk is eliminated. This is known as tertiary healing. In such cases, the wound should be irrigated with saline while it is left open.

In primary healing, the wound remodels rapidly with a very small amount of granulation tissue formation, whereas in secondary healing, a void exists between the wound edges, resulting in more granulation tissue formation. In these types of injuries, the epithelium needs to extend further to cover the wound surface by filling the gap between the wound edges due to tissue loss. This indicates prolonged epithelization compared with primary healing. In addition, healing becomes more complicated in contaminated wounds with the additional process of eliminating the infection.

Wound healing takes place through either regeneration or repair of damaged tissue. Healing through regeneration involves the recovery of lost tissue with that which is structurally and functionally similar to the original. In healing through repair of damaged tissue, however, structure and function are not of primary importance; the main goal in such cases is the closure of the wound using available onsite cells and/or mechanisms. Whether the tissues heal through regeneration or repair depends on the availability of the required cells, the existence of signals to be transmitted to stimulate these cells, and the distance between the wound edges. The duration of healing varies depending on local and systemic factors.

Wound healing is managed by inflammation resulting from the complex interaction between cells, soluble substances, molecules, and perfusion. The outcome and duration of healing is estimated by the timing of these interactions and associations as well as the magnitude, severity or duration of their mutual activities. Over the past decade, significant progress has been made in exploring some of these processes. Important insights have been provided by various models used to inhibit healing processes that yield poor outcomes (i.e. non-healing wounds, chronic wounds or wounds leaving scars) and in identifying underlying mechanisms that ensure wound healing. Regeneration is preferred to reparative tissue when it comes to healing, as the former is associated with no scars and with improved function. Recent research studies have therefore focused on regenerative healing.