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Volume 2 | Issue 1/2016 29 Journal of Oral Science & Rehabilitation Flaple ss so cke t pre se r vati o n pro ce du re tissue shrinkage after a tooth extraction: both thevertical and horizontal dimensions showed a minimal decrease. In particular, the vertical di- mension lost 0.2±0.7 mm at the mesial sites, 1.1 ± 0.9 mm at the buccal sites, 0.2 ± 0.8 mm at the distal sites and 0.9±0.9mm at the palatal/lingualsites afterfourmonths.These re- sults are in keeping with those reported in a re- cent systematic review that compared the out- comes after tooth extractions with and without ridge preservation procedures.27 In the case of the ridge preservation procedures, the vertical bonechangesrangedfromagainof1.3 ± 2.0 mm toalossof0.62 ± 0.51 mm,withfollow-uptimes rangingfromthreetoninemonths.27 In the current study, the ridge preservation procedures in all of the experimental sites were successful, and implants were placed after four months, with further augmentation procedures being necessary only in 7% of the cases at the time of implant placement. Moreover, bone cores were harvested for the histological analy- sisatthetimeofimplantplacement.Corroborat- ing the findings of other studies,28, 29 this study found that the cortico-cancellous porcine bone was effective in maintaining the architecture of post-extractionsocketsanddemonstratedsigns of active resorption at the same time. Iezzi et al. examined the use of various biomaterials and performed histological and histomorphometric analysesaftersixmonths.28 Amongthedifferent grafting materials, cortico-cancellous porcine bone gave rise to a rim of osteoblasts with signs of active bone matrix deposition; in some areas, bone apposition was observed directly on the particles’ surfaces.28 Similarly, the biomaterial used in this study showed a great percentage of newly formed bone. No inflammatory cells or foreign body reaction was observed in the bone samples, but new bone tissue and blood vessel growth. Active resorption signs were evident, since osteocytic lacunae were observed at the surface of the biomaterial granules. As found by another study,29 collagenated porcine bone was demonstrated to be resorbable, showing active resorptionsignsonthesurfaceoftheparticles. Another study investigated the effect of the exposureoftheresorbablemembranetotheoral cavityon bone healing, comparing a flapped and a flapless approach.14 The percentages of newly formed bone, residual graft particles and mar- rowspacesweresimilarforthetwogroups,sug- gesting that the exposure of the collagen mem- branehadnodetrimentaleffectontheregenera- tiveprocess.14 Similarly,inourstudy,thesecond- ary intention healing seemed not to affect the bone quality, as seen inthe bone cores.Thefind- ings of this study support the hypothesis that secondary intention healing and exposure ofthe collagen membrane do not jeopardize bone re- generation, but improve the amount of kera- tinizedgingiva.Theridgepreservationtechnique wasdemonstratedtobeeffectiveinmaintaining an adequate bone architecture, allowing the subsequent implant placement without adjunc- tive augmentation procedures in the majority of thecases Furtherstudiesarenecessarytoevaluatethe influence of early exposure of the membrane on theformationofnewboneandontheintegration ofthegraftingmaterialovertime.Furthermore,a longer follow-up period could be useful in order tomonitorthesuccessofthebiomaterialandthe qualityofthenewlyformedbone. Conclusion Within the limits ofthis prospective cohort study, ridgepreservationshowedadequateregeneration of the bone and stability of the facial soft-tissue level. The flapless ridge preservation procedure maintained the horizontal and vertical bone di- mensions, improving the amount of keratinized tissue. The exposure of the resorbable collagen membrane to the oral cavity seemed not to jeop- ardize the healing process or the quality of the newlyformedbone. Competinginterests The authors declare that they have no conflict of interestsrelatedtothisstudy. Volume 2 | Issue 1/201629