Normal Periodontium: Normal Periodontium -- Local Diseases and Conditions Affecting Periodontal Tissues: Periodontal and Gingival Health -- Gingivitis -- Periodontitis -- Necrotizing Periodontal Diseases -- Peri-Implant Diseases and Conditions -- Other Local Non - Dental Biofilm Induced Conditions Affecting Periodontal Tissues: Periodontal Abscesses -- Mucogingival Deformities and Conditions Αround Teeth -- Endodontic and Periodontal Lesions -- Traumatic Occlusal Forces and Occlusal Trauma -- Tooth and Prostheses Related Factors -- Developmental Disorders -- Heavy Metal and Foreign Bodies Depositions -- Mechanical Gingival Lesions -- Chemical and Thermal Gingival Lesions -- Drug Influenced Gingival Lesions -- Radiation and Chemotherapy-Induced Gingival Lesions -- Allergic and Inflammatory Reactions -- Pigmentary Disorders -- Bacterial Gingival Infections -- Viral Gingival Infections -- Fungal Gingival Infections -- Aphthous Ulcers -- Periodontitis as a Risk Factor for Systemic Diseases -- Gingivitis and Periodontitis as a Source of Malodor -- Systemic Diseases Affecting Periodontal Tissues: Genetic Diseases -- Bacterial Infections -- Viral Infections -- HIV Infection and AIDS -- Systemic Mycoses -- Protozoa Infections and Infestations -- Hematologic Diseases Non Neoplastic -- Mucocutaneous Diseases -- Paraneoplastic Mucocutaneous Diseases -- Autoimmune and Autoinflammatory Diseases -- Orofacial Granulomatosis -- Metabolic Diseases -- Endocrine Diseases -- Vitamin Deficiencies -- Potentially Malignant Disorders Affecting Periodontal Tissues: Leukoplakia -- Tumors Affecting Periodontal Tissues: Benign Tumors -- Malignant Tumors -- Hematopoietic and Lymphoid Tissue Malignancies -- Other Lesions, Tumors and Cysts Affecting Periodontal Tissues: Reactive Lesions -- Fibro Osseous Lesions -- Peripheral Odontogenic Tumors -- Soft Tissue Cysts -- Appendix. Classification of Gingival Lesions by Color and Morphology.