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ePaper created 2018-02-14, 12:02:22 | version 1.38.0
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 Introduction A significant 3-D remodeling of the bone crest, especially horizontally, always occurs after the extraction of a tooth.1 This makes it difficult to insert an implant, especially in the frontal areas, where residual bone thickness is fundamental for optimal esthetic results. In order to reduce this contraction, a socket preservation technique entailing the insertion of a bone graft and of a resorbable membrane inside the socket, fol- lowed after 4–6 months by the positioning of a delayed implant, has usually been proposed.2, 3 However, such a technique does not always have predictable results, especially when the buccal plate of the alveolar socket is missing after tooth extraction. Guided bone regeneration (GBR) has been proposed as a possible alternative for patients with severe horizontal bone atrophy, to over- come the drawback of bone block techniques.4, 5 In order to protect the clot and prevent the inva- sion of the clot by nonosteogenic cells, main- taining an adequate biological space for the regeneration of bone tissue, the use of either nonresorbable or resorbable membranes has been proposed.6 Expanded polytetrafluoroeth- ylene (e-PTFE) membranes and resorbable membranes classically require soft-tissue cov- erage or primary closure to prevent soft-tissue ingrowth, bacterial contamination, infection, membrane migration, early membrane degra- dation, and graft exposure. The major feature of the e-PTFE membrane is macroporosity, which is believed to enhance regeneration by improving wound stability.7 Nevertheless, its main draw- back is that an early bacterial infection can occur, affecting the outcome of the regeneration. High-density polytetrafluoroethylene (d-PTFE) membranes offer an alternative to e-PTFE or resorbable membranes.8–11 A d-PTFE membrane is made of 100% pure medical-grade bio-inert PTFE, which is nonporous, dense, non- expanded and nonpermeable.3, 5 The thickness of the various commercially available mem- branes ranges from 0.13 to 0.25 mm and their low porosity ranges from 0.2 to 0.3 mm; e-PTFE membranes have a similar thickness, but a higher porosity (5–30 nm).12 The indications for d-PTFE membranes are similar to those for e-PTFE, but the different porosity of the first avoids any inflammation of the surrounding soft tissue in case of accidental exposure.13 There is limited clinical and histological evidence for the use of d-PTFE membranes at present, with some indications for guided tissue regeneration and GBR, especially in immediate implants and fresh extraction sockets.7 The aim of the present prospective study was to investigate the barrier effect of a d-PTFE membrane left intentionally exposed in post- extraction sockets grafted with an allograft biomaterial and removed after 5 weeks. This study is reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology statement for improv- ing the quality of observational studies.14 Materials and methods This prospective study was conducted in a pri- vate dental practice from February 2012 to March 2016. Forty-three patients of both sexes requiring 47 implant-supported single-crown restorations to rehabilitate an esthetic area with a hopeless tooth with an Elian type II socket (facial soft tissue was present, but the buccal plate was partially missing after extraction of the tooth),15 aged 18 years or older and able to sign an informed consent form, were enrolled and treated consecutively. This was provided that they fulfilled the inclusion criteria and gave their written consent to take part in the study. The buccal plate was defined as partially missing when the distance from the gingival margin to the most coronal part of the buccal plate was greater than 4 mm, even in only 1 of the 3 ref- erence points (mesial, distal and midpoint), while both the mesial, distal and the palatal bony walls were present at a distance of less than 4 mm from the palatal gingival margin. The exclusion criteria were positive medical findings (such as stroke, recent myocardial infarction, severe bleeding disorder, uncon- trolled diabetes, or cancer), psychiatric therapy, pregnancy or nursing, smoking more than 10 cigarettes per day, untreated periodontitis, acute or chronic infections of the adjacent tissue or natural dentition, previous radiotherapy of the oral and maxillofacial region within the last 5 years, absence of teeth in the opposing jaw, severe clenching or bruxism, severe maxilloman- dibular skeletal discrepancy, and poor oral hygiene (full-mouth bleeding and a full-mouth plaque index of higher than or equal to 25%). Patients were informed about the clinical pro- cedures, the materials to be used, the benefits, potential risks and complications, as well as any follow-up evaluations required for the clinical Journal of Oral Science & Rehabilitation Volume 3 | Issue 4/2017 09