 Hello everyone, welcome back to another session on dentistry and model. Today we have wound healing. So how the wound is healed? There are various types of wounds and the process of wound healing is different in each type like healing by first intention, second intention or tertiary intention. So the process is different in each type of wound. So let's learn healing of wound. Healing of wound is nothing but this effort of injured tissues to restore their normal function and structural integrity after the injury. So the tissue is trying to get back to its normal structure and its integrity. So that is the generic definition of wound healing. So basically we have two types of wound. One is tidy wounds and another one is untidy wounds. Tidy wounds are like wounds which is caused by sharp objects like surgical incision which is a very clean healthy wound without any tissue loss and healing is very simple. The basic primary or first intention healing will be there. Whereas untidy wound it is due to the crushing, avulsion, devoidalization or vascular type or burns. So what is happening is there will be excision of tissue, there will be lots of tissue loss. So it will be healed by secondary intention. Though there are many other types of wounds but basically we have these two type tidy and untidy wounds. So tidy wounds are easy to get approximated or to get healed whereas untidy one it takes lot of time. So how does the wound heals? So we have basically two methods that is primary healing or first intention that is a wound healing, secondary intention or secondary healing. So first intention or primary healing it is the easiest wound. It means the wound is very clean, very sharp where the edges are very approximated just like a knife wound or a surgical wound. There will not be any infection, there will not be any much tissue loss. So these type of wound will be healed by primary intention that is epithelium will be approximated and there will be less granulation tissue and the scar will be very minimal and it heals very fast and there will be very less fibrous tissue, more of a granulation tissue present. So epithelial regeneration happens and there will be complete closure. So after that there will be complete closure. So it will be completely closed. So that is a wound healing by first intention or primary intention, okay first or primary intention or primary healing primary healing or first intention. But as a second one that is secondary healing or secondary intention that is different wound. It is most commonly associated with this untidy wound where it occurs in a wound with extensive soft tissue loss. There will be extensive soft tissue loss. There is no chance of the tissue edges are approximated because the tissue loss is very vast. This was like very close edges. So it is easy to get approximated but here the edges are very apart. There is lots of tissue loss. So in those cases the wound heals by secondary healing or secondary intention that is a heals very slowly there will be fibrosis rather than granulation tissue. So there will be lots of fibrosis tissue. So fibrosis happens and it results in scar formation, okay. Here it is scar is minimal but there will be irregular scar formation and there will be hypertrophied and there will be contraction of the tissue. It will not be as similar as the original tissue. In primary intention it will be almost like original tissue how it was before the injury but in this case it will not be how it was before the injury. There will be contraction of the wound area. So that is secondary intention. That is the basic difference between primary healing and secondary healing whereas the third one that is the healing by third intention or tertiary wound healing or delayed primary closure. This occurs in wounds which are left open for deep ride men. So if there is deep ride men we are leaving the wound for deep ride men. In those cases the tertiary healing happens. So after wound deep ride men and control of local infection then only the wound is closed with sutures or covered using a skin graft. So we need to use skin graft and sutures. Before that we need to do deep ride men and control of infection. So that is tertiary intention. That is a very extensive loss of tissues. So there should be a skin graft or suture in place of tertiary intention. So these are the basic difference between primary healing, secondary healing and tertiary healing. The clean wound not very clean. It is untidy wound and the tertiary it is delayed primary closure. So these are the three types. Now let us learn the phases of wound healing. So phases of wound healing basically it has a phase of inflammation then phase of proliferation and remodeling or we can say inflammation, granulation tissue formation, epithelization, scar formation and resorption and finally the maturation. So these are the steps of healing of wound. The first one is inflammatory state. So it is characterized by hemostasis increase to vascular permeability, then migration of cells into the wound by chemotaxis, secretion of cytokines and growth factors and activation of the other migrating cells. So all these chemical all these changes happens in inflammatory state. So after that there will be granulation tissue formation, then there will be epithelial changes and scar formation and resorption and finally the maturation and getting back to its normal anatomy. So factors affecting wound healing are it could be local factors such as infection, poor blood supply, tissue tension, hematoma or poor opposition of tissues or presence of any necrotic tissue and any foreign body and it could be general factors such as age, obesity, smoking, malnutrition, vitamin deficiency, anemia, malignancy, jaunt is, diabetes, steroids and other cytotoxic drugs and there could be many complications for healing of wound. If the scar formation that is deficient scar formation, so in deficient scar formation it is known as wound asens or there will be ulceration and excessive formation of the repair component like this is deficiency, this is excessive form like hyper trophic scar formation will be there or the cheloid, cheloid is important, cheloid could be there and there will be excess production of granulation tissue and there will be formation of contractures. So all these are the complications of wound healing. So the basic thing is types of wound healing, primary, secondary tertiary and the stages and the complications. So that is all about healing of wound. So I will come up with in your topic in pathology. Thank you.