# Modified Periosteal Inhibition (MPI) Technique for Extraction Sockets: _A Case Series Report_
## 3 Discussion  
All ARP techniques involving the filling of the extraction socket with biomaterials have shown results that were not always predictable. The volume shrinkage was often reduced but not completely eliminated [22]. Furthermore, the disadvantages deriving from the insertion of a biomaterial, such as the lengthening of the healing time and formation of vital bone, are much fewer than those resulting from spontaneous healing or from only using collagen [23; 24]. As put forward by [PERSON] et al. [25], the only ARP capable of preserving the internal osteo-gingival architecture seems to be the Socket Shield Technique, thanks to the preservation of the vestibular part of the root and periodontal ligament [26; 27; 28]. Complete preservation at 10 years has been achieved with this procedure. The Modified Socket Shield technique without implant placement with a concomitant extraction socket reconstruction was proposed by [PERSON] et al. [29]. The disadvantages of the technique include a difficulty to perform it and therefore the dependence on an operator, the fact that it takes a long time to perform, and the fact that the residual root occupies part of the implant space. The PI technique shifted attention to the outside of the extraction socket, working against the osteolytic activity deriving from the deep periosteum [17]. The preliminary results showed an almost total preservation of both hard and soft tissue volumes, without the need to either maintain root fractions inside the socket or resort to a biomaterial. The advantages therefore include extreme ease and speed of execution and a return to normality in 4 months, a relatively short time, not forgetting the most important aspect, which is the formation of only viable bone within the extraction socket. The PI technique's limits include having to remove the d-PTFE membrane later and not being able to increase alveolar volumes but only preserve them. The MPI technique aims to overcome these limitations. Thanks to the use of soft cortical lamina and human fibrin glue, nothing is removed during implant placement. Comparing the preoperative and postoperative ridge width of the present study, the radiographic measurement showed an increase equal to 0.41 \(\pm\) 0.21 mm (primary purpose), suggesting a good Periosteal Inhibition effect by the bone lamina. No biological complications occurred during the follow-up, and healing was uneventful (secondary purpose). The MPI technique could therefore be the first ARP technique to provide an extraction socket with an increased volume in only 4 months. OsteoBiol\({}^{\circledR}\) Lamina Soft (Tecnos\({}^{\circledR}\), Giaveno, Italy) is a membrane made of collagerated porcine cortical bone [30]. Several studies have shown its osteoconductive properties for both horizontal and vertical bone augmentation procedures [31; 32; 33]. [PERSON] et al. [34] demonstrated that the cortical membrane, positioned on the outer surface of the buccal bone, was able to maintain the ridge volume of the socket. The histological analyses at 4 months showed the formation of new bone below the membrane and the absence of resorption of the buccal bone. In cases of injury or inflammation, a portion of monocytes can differentiate into preosteoclast. Through the vessels of the periosteum, these precursors migrate to the affected bone cortex. Mononuclear precursors only fuse to form osteoclasts after attaching to the bone surface [18; 19; 20; 21]. Not only does the cortical lamina prevent this destructive process from affecting the bone cortex, but at the same time it allows the latter to increase or be recreated if partially damaged. Since the bone lamina is more resistant than the d-PTFE membrane, we can extend the indications for the technique to extraction sockets with partial deficits of the buccal bone, greatly increasing the range of cases that can be treated. [PERSON] et al.