Surgical Approaches Based on Biological Objectives: GTR versus GBR Techniques

Guided tissue regenerative (GTR) therapies are performed to regenerate the previously lost tooth supporting structure, thus maintaining the aesthetics and masticatory function of the available dentition. Alveolar ridge augmentation procedures (GBR) intend to regain the alveolar bone lost following tooth extraction and/or periodontal disease. Several biomaterials and surgical approaches have been proposed. In this paper we report biomaterials and surgical techniques used for periodontal and bone regenerative procedures. Particular attention will be adopted to highlight the biological basis for the different therapeutic approaches. 1. Introduction Guided tissue regeneration (GTR) and guided bone regeneration (GBR) are surgical techniques performed to regenerate, respectively, the tooth supporting tissues (GTR) and the alveolar bone in edentulous areas (GBR). Aim of GTR is the treatment of teeth affected by periodontal disease that induced loss of periodontal tissues and formation of infrabony defects. This procedure aims at the reconstruction of a periodontal ligament (PDL) with well oriented and organized collagen fibers inserted in newly formed cementum and newly regenerated alveolar bone [1]. The goals of GBR are (i) maintenance of the postextractive alveolar ridge volume that spontaneously reduces following tooth extraction, (ii) the reconstruction of the alveolar bone, that was lost following tooth extraction with the intent of realizing an implant supported prosthetic reconstruction or improved the aesthetics of edentulous areas, (iii) the correction of peri-implant dehiscences or fenestrations, and (iv) the reconstruction of the peri-implant bone that was lost following peri-implant disease [2]. From a biological and clinical standpoint, GTR and GBR share several important prognostic factors including stabilization of the blood clot [3, 4], ability to achieve primary intention wound healing, isolation of the defect from the gingival soft tissues, and space provision [5, 6]. Recently GTR techniques have progressed toward the use of minimally invasive approaches optimizing wound closure, limiting patient morbidity, and reducing need for regenerative materials including membranes [7–9]. Moreover, both GTR and GBR benefit from advances in regenerative medicine including the use of growth factors [10], gene therapy, and cell therapy approaches [11, 12]. The aim of the present paper is to review biomaterials (i.e., membranes, growth factors) and surgical techniques used for periodontal and bone regenerative procedures, with particular attention to