Dimensional alterations in the post-extraction alveolar process in the esthetic zone : Il comportamento dell'alveolo post-estrattivo nel settore estetico

OBJECTIVES The alveolar process is a tooth dependent structure. After a tooth extraction, remodeling and resorption processes influence either hard and soft tissues, leading to a narrower and smaller edentulous ridge. The majority of remodelling process, both qualitative and quantitative, take place in the initial 6 months: in the mandible, bone remodeling occurs in the horizontal dimension, with a greater contraction on the buccal aspect of the crest than the lingual one, with a centripetal pattern, and therefore the crest will appear displaced in this direction. In the maxilla, on the other hand, bone reabsorption follows a centrifugal trend. MATERIALS AND METHODS The catabolic changes occurring after tooth extraction have been related to the interruption of blood supply by the periodontal liga ment, which can consequently lead to an important osteoclastic activity. Furthermore, the dimen sional variations can be linked to various additional factors, includ ing surgical trauma caused by the elevation of a flap, the lack of functional stimuli on the remaining bone walls, the lack of the periodontal ligament and the lack of genetic information given by the tooth itself. The density of vascular structures and macrophages has been shown to decrease slowly between 2 and 4 weeks, the level of osteoclastic activity slows down beyond the fourth week, where the presence of osteoblasts increases with a peak between the sixth and eighth week, remaining stable beyond this period. Post-extraction bone remodeling seems to be located mainly in the central part of the buccal bone wall of the alveolus 8 weeks after extraction, on the contrary of the neighboring areas that seem to remain supported by the periodontal ligament of the adjacent teeth and that do not show bone loss. As a consequence of crestal bone resorption, a loss of the natural convexity of the vestibular con tour can also occur, representing an esthetic problem, especially in the anterior zone, increasing also the future risk of mucosal recessions after implant placement. Furthermore, the absence of an adequate band of keratinized mucosa at implant site might lead to future implant biologic complications, as a consequence of the greater plaque accumulation due to bleeding and discomfort while performing tooth brushing. RESULTS AND CONCLUSIONS It is now accepted that the first possible way to minimize cortical bone loss is to perform a non-surgical atraumatic tooth extraction, with a “flapless” procedure. This method allows the reduction of healing times, patient discomfort, as well as local and systemic inflammation. Increasing keratinized mucosa width and mucosal thickness in post-extraction sites can offer ad vantages for future guided bone regeneration (GBR) and implantol ogy procedures, especially in the esthetic zone, which represents always a demanding challenge for prosthodontists. Hence, according to recent studies, a minimum thickness and width of 2 mm around the implant are mandatory to improve peri-implant health and the longterm esthetic and functional results of future implant-supported restoration. The use of ridge preservation procedures seems to be more effective, compared to spontaneous healing, in reducing dimensional alterations at future implant site. CLINICAL SIGNIFICANCE Knowledge of bone and soft tissue remodelling process and performing atraumatic extractions can allow clinicians to obtain predictable results while performing implant prosthetic rehabilitations in the esthetic zone.