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I n t e n t i o n a l l y e x p o s e d m e m b r a n e Fig. 6 Fig. 7 Fig. 8 Fig. 6 BPS: the distance from the inner part of the buccal gingival margin to the inner part of the palatal soft tissue at the mesiodistal midpoint of the socket 3 mm subgingivally at T0. Fig. 7 BPW: the alveolar ridge thickness from the buccal to the palatal side at the mesiodistal midpoint at T1. Fig. 8 BBT: the horizontal width of the ridge measured from the outer part of the implant platform to the buccal bone at T2. Table 1 Extracted teeth. Table 1 Tooth Maxillary central incisor Maxillary lateral incisor Maxillary canine Maxillary first premolar Maxillary second premolar Mandibular central incisor Mandibular canine Mandibular first premolar Mandibular second premolar Discussion No. 12 5 7 4 3 3 4 6 3 This study has presented the results of a new technique for the spontaneous regeneration of the missing buccal plate of a dental socket that avoids the ingrowth of soft tissue inside it and regenerates the previously resorbed buccal cor- tical bone. This technique may avoid invasive further regenerative techniques, thus notably reducing treatment time without impairing the esthetic results, the predictability of the implant treatment or patient satisfaction. A limiting situation for post-extraction implants, especially in areas of high esthetic concern, is the resorption of the buccal bone plate, which is fundamental for soft-tissue sta- bility in the area surrounding the fixture and therefore for long-term esthetic results. The reconstruction of such a bone wall almost always requires an additional regenerative sur- gery, usually invasive for the patient, and pre- cedes the prosthetically guided insertion of an implant. The use of a nonresorbable membrane intentionally left exposed inside the socket and removed after 4–6 weeks seems to work as a barrier in the separation of the soft tissue from the bone graft.17 The removal of the membrane after 4–6 weeks seems to give sufficient time to seclude fibroblasts from the gingival flap and to allow inside the socket the differentiation of mesenchymal cells into osteoblasts, leading then to bone. In a histological human study, a biopsy, taken at the moment of removal of a d-PTFE membrane left intentionally exposed for 28 days before, demonstrated the absence of epithelial tissue over a dense connective tissue matrix.12 This finding indicates that this connec- tive tissue seems to be a well-vascularized oste- oid matrix that needs some more maturation time to become a mineralized tissue and allow placement of an implant.18 This period can last from 3 to 6 months, depending on the size of the defect and the biomaterial used as a graft. In another histological study, a combination of 70% mineralized and 30% demineralized cor- tical allograft material placed in a post- extraction socket together with a d-PTFE membrane inten- tionally left exposed was compared with a group for which only a mineralized allograft material was used. The biopsy showed increased vital bone formation (36.16%) and a reduced residual graft (18.24%) compared with the 100% miner- alized bone allograft group (24.69% and 27.04%, respectively).19 In the present study, no infection of either the surrounding soft tissue or of the underlying graft was experienced owing to the low porosity of the d-PTFE membrane, which does not allow bacterial contamination. The nanoporosity of the d-PTFE membrane is about 0.2–0.3 μ, too small for the penetration of a bacterium, the size of which is about 5 μ. This was confirmed by a histological study in which a membrane, removed after 21 days, did not show any bacte- rial cell on the inferior border or surface.20 Journal of Oral Science & Rehabilitation Volume 3 | Issue 4/2017 13