Morphogenesis and Wound Healing in the Periodontium
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2015 Elsevier Inc. All rights reserved. The formation of new tissues during morphogenesis and wound healing involves similar processes, including cell proliferation, extracellular matrix synthesis, cell migration, and cell differentiation. However, the timing of events and the establishment of temporo-spatial boundaries between individual tissues are highly coordinated during morphogenesis, while the formation of the same tissues during wound healing appears to follow different parameters. This difference becomes especially obvious in the periodontal wound, in which differences in proliferation rate between epithelium and connective tissues cause junctional epithelium elongation, pocket formation, and a prevention of connective tissue attachment to the root surface. Moreover, the safe-guarding antimicrobial inflammatory response in adult periodontal wounds may also contribute to scar formation in periodontal tissues during wound healing [. 14].The present chapter highlights some of the tissue dynamics involved in periodontal development and then revisits the history of periodontal restoration and regeneration as a classic example of the implementation of developmental biology principles in clinical practice. These classic studies first established the periodontal ligament as the key tissue capable of periodontal regeneration, and then demonstrated the deleterious effect of direct contact between alveolar bone and root cementum, resulting in ankylosis and root resorption. Guided tissue regeneration and the development of a barrier membrane preventing the apical growth of the epithelium and facilitating periodontal ligament proliferation became a logical consequence of these early studies in periodontal tissue engineering. Together, these studies resulted in the development of a number of materials and procedures for the benefit of periodontal regeneration.