**2. General principles of PIS grafting**

After transplantation to the recipient region, the soft tissue graft depends on plasmatic imbibition in order to receive sufficient nourishment. In the later stages, after 3–4 days, the soft tissue graft will be transvascularized with newly formed blood vessels. Blood vessel anastomoses will be formed between vessels of the recipient site and vessels already present in the graft [21, 25–29]. In order to achieve plasmatic imbibition and transvascularization certain factors must be met:


Most of the aforementioned conditions are met when the periosteum is used as a recipient site. The periosteum is well irrigated and it is immobile (**Figure 3**) [25, 30].

Likewise, to achieve those factors care must be taken while harvesting the soft tissue graft. The graft should be of uniform thickness to ensure even intimate contact of the inner surface of the graft and the recipient site [25, 26].

The composition of the graft can influence the nourishment of the graft—adipose and glandular tissue may hinder the nourishment of the rest of the graft so they should be dissected from the graft [26, 31].

#### **Figure 3.**

*Stabilization and intimate contact of the autologous soft tissue graft (free gingival graft) in the recipient site achieved with simple interrupted and cross mattress sutures. After the dissection and apical displacement of the mucosal flap, only the exposed periosteal surface is present in the recipient site. The periosteum is well irrigated and immobile surface, suitable for graft nutrition and stabilization.*
