Biomaterials for the Reconstructive Treatment of Periodontal Intrabony Defects. Part I. Bone Grafts and Bone Substitutes

Regeneration is defined as a reproduction or reconstruction of a lost or injured part in a way that both form and function of lost tissues are completely restored (Wikesjö and Selvig, 1999; Caton and Greenstein, 1993; Machtei, 1997; World Workshop in Periodontology, 1996). Regenerative periodontal therapy aims to predictably restore the tooth’s supporting apparatus which has been lost following periodontitis or dental trauma. Histologically, these treatment procedures should lead to the formation of new root cementum with inserting collagen fibers, new periodontal ligament and new alveolar bone (Wikesjö and Selvig, 1999; Caton and Greenstein, 1993; Machtei, 1997; World Workshop in Periodontology, 1996). Non-surgical and conventional surgical periodontal therapy may usually result in successful clinical outcomes such as probing depth reduction and gain of clinical attachment. However, histologically these types of treatment are characterized by a long junctional epithelium along the treated root surfaces and no formation of cementum and periodontal ligament (Caton and Greenstein, 1993). Although in some cases a conventional periodontal therapy may result in bone regrowth, histological studies clearly demonstrated that an epithelial lining was interposed between the root surface and the newly formed bone (Caton and Greenstein, 1993). Consequently, histology represents the only way to definitively demonstrate periodontal regeneration (Caton and Greenstein, 1993; World Workshop in Periodontology, 1996). Within the last decades many treatment modalities have been performed in order to predictably obtain periodontal regeneration. Generally, these modalities consisted of various types of surgical techniques involving conditioning of the root surfaces, implantation of various types of bone grafts, guided tissue regeneration (GTR), enamel-matrix-proteins, and growth factors. There is consensus that in order for a procedure to be considered as an approach which facilitates periodontal regeneration the following criteria must be fulfilled (World Workshop in Periodontology, 1996): 1. Controlled histological animal studies demonstrating formation of new cementum, new periodontal ligament and new alveolar bone. 2. Controlled clinical studies demonstrating gains of clinical attachment level and alveolar bone. Biomaterials for the Reconstructive Treatment of Periodontal Intrabony Defects. Part I. Bone Grafts and Bone Substitutes