It is great timing for us to reevaluate periodontal therapy at the turn of the twenty-first century. There have been tremendous advancement in periodontal regenerative therapy, guided bone regeneration, endosseous dental implant, and plastic periodontal therapy in the last twenty years. Due to the demanding of modern people on esthetic, function, healthy, and quality of life, periodontal therapy has become the first line of oral care and plays a major role in oral environmental protection. As the invention of periodontal regeneration, the goal of periodontal therapy is not only to maintain teeth but also to regenerate and revive the lost periodontium and function. Moreover, based on the concept of guided tissue regeneration and the advanced development of biomaterial science, guided bone regeneration has made the reconstruction of oral and maxillofacial defects feasible. The purposes of this paper are to discuss 1) the development of periodontal surgery, 2) wound healing following various periodontal therapy, 3) the history and development of periodontal regeneration, 4) the history and development of guided bone regeneration, and 5) the future of periodontal reconstruction.