Critical Decisions in Periodontology, Fourth Edition, is designed to guide students and practitioners in applying their decision-making knowledge in a structured and logical manner. The decisions may be in diagnosis, treatment selections and options, procedures in various treatments, and evaluating outcomes. This new edition sees a section devoted to esthetics in periodontal treatment. New techniques such as minimally invasive surgery and effects of chemotherapy on periodontal therapy are presented. The contributors to the text represent both north American and international thinking.