**4.4 Autogenous blood products**

Platelet-rich plasma (PRP) is defined as a portion of the plasma element of autologous blood having a platelet concentration above baseline [56, 57]. It is considered as a growth factor agonist [58] with both mitogenic and chemotactic properties [56].

It was found that intralesional injection is a newly described method for application of PRP and represents an effective therapeutic option when dealing with nonhealing wounds [59]. These findings open the door for using intralesional PRP in oral chronic ulcers. In 2015, El-K*omy* and his colleagues conducted a pilot study on seven patients suffering from resistant chronic oral pemphigus vulgaris (PV). All patients reported improvement in pain scores, ability to eat, and healing score [60].

In orthodontic therapy, significant improvement was reported following the introduction of local submucosal PRP injection in the pressure side. A single injection of PRP was enough during active orthodontic treatment (just 2 injections; pre and after 6 months). Acceleration of orthodontic tooth movement was reported 1.7-fold when compared to the conventional traction technique [61] (**Figure 8**).
