Over time , classification systems have been changed in response to new scientific knowledge about the etiology and pathogenesis of periodontal diseases and condition.  1989 classification of inflammatory periodontal diseases : include five types : adults periodontitis , early-onset periodontitis , periodontitis associated with systemic diseases , necrotizing ulcerative gingivitis ( NUG) and refractory periodontitis “ABCSESS OF GIGIVAL DISEASE CLASSIFICATION “  1999 AAP classification of periodontal disease and condition .  Correct some 1989 classification system .  Based on the concept that plaque induced periodontal disease -bacterial infections.  Periodontal disease Gingivitis Reversible tissue damage Periodontitis Irreversible tissue damage 1. 2. 3. 4. 5. 6. 7. 8. Gingival Disease. Chronic periodontal disease . Aggressive periodontitis. Periodontitis as manifestation of systemic disease. Necrotizing periodontal disease. Abscess of the periodontium. Periodontitis associated with endodontic lesions. Deformities and conditions. 1-Gingival Diseases  Plaque-induced gingival diseases*  Non–plaque-induced gingival lesions 2-Chronic Periodontitis†  Localized  Generalized 3-Aggressive Periodontitis  Localized  Generalized 4-Periodontitis as a Manifestation of Systemic Diseases A-Necrotizing Periodontal Diseases  Necrotizing ulcerative gingivitis (NUG)  Necrotizing ulcerative periodontitis (NUP) B-Abscesses of the Periodontium  Gingival abscess  Periodontal abscess  Pericoronal abscess C-Periodontitis Associated with Endodontic Lesions  Endodontic–periodontal lesion  Periodontal–endodontic lesion  Combined lesion 5-Developmental or Acquired Deformities and Conditions      Localized tooth-related factors that predispose to plaqueinduced gingival diseases or periodontitis Mucogingival deformities and conditions around teeth Mucogingival deformities and conditions on edentulous ridges Occlusal trauma Gingival disease usually involve inflammation of the gingival tissues to bacterial plaque biofilm.  Sub-classification: I. Dental plaque induced gingival disease. II. Non-plaque induced gingival disease.   Definition: periodontal disease involving the gingiva in response to bacteria located at the gingival margin.  It is the most common form of gingival disease.  Subtypes: 1-Gingivitis associated with dental plaque biofilm only . Most common with no local or systemic complicating factors. 2-Gingival disease modified by systemic factors e.g. pregnancy associated gingivitis. 3-Gingival disease modified by medication – medication induced gingival disease e.g. phenutoin , cyclosporine. 4- gingival disease modified by malnutrition. Disease progression: Gingivitis may persist for years without ever progressing to periodontitis.  Dental Plaque–Induced Gingival Diseases These diseases may occur on a periodontium with no attachment loss or on a periodontium with attachment loss that is stable and not progressing. I. Gingivitis associated with dental plaque only A. Without local contributing factors B. With local contributing factors . II. Gingival diseases modified by systemic factors A. Associated with endocrine system 1. Puberty-associated gingivitis 2. Menstrual cycle–associated gingivitis 3. Pregnancy associated a. Gingivitis b. Pyogenic granuloma 4. Diabetes mellitus–associated gingivitis B. Associated with blood dyscrasias 1. Leukemia-associated gingivitis 2. Other  III. Gingival diseases modified by medications A. Drug-influenced gingival diseases 1. Drug-influenced gingival enlargements 2. Drug-influenced gingivitis a. Oral contraceptive–associated gingivitis b. Other IV. Gingival diseases modified by malnutrition A. Ascorbic acid deficiency gingivitis B. Other Less common type of gingivitis.  Not caused by bacterial plaque biofilm .  Causes: 1. Viral infection herpes simplex virus. 2. Fungal candidiasis, most common in immunocompromized individuals. 3. Systemic disease lichen planus. 4. Allergic reaction to tooth paste and mouth rinses, foods and chewing gum.  I. Gingival diseases of specific bacterial origin A. Neisseria gonorrhoeae B. Treponema palladiums C. Streptococcus species D. Other II. Gingival diseases of viral origin A. Herpesvirus infections 1. Primary herpetic gingivostomatitis 2. Recurrent oral herpes 3. Varicella zoster B. Other III. Gingival diseases of fungal origin A. Candida species infections: generalized gingival candidiasis B. Linear gingival erythema C. Histoplasmosis D. Other IV. Gingival lesions of genetic origin A. Hereditary gingival fibromatosis B. Other V. Gingival manifestations of systemic conditions A. Mucocutaneous lesions 1. Lichen planus 2. Pemphigoid 3. Pemphigus vulgaris 4. Erythema multiforme 5. Lupus erythematosus 6. Drug induced 7. Other B. Allergic reactions 1. Dental restorative materials a. Mercury b. Nickel c. Acrylic d. Other 2. Reactions attributable to: a. Toothpastes or dentifrices b. Mouth rinses or mouthwashes c. Chewing gum additives d. Foods and additives 3. Other VI. Traumatic lesions (factitious, iatrogenic, or accidental) A. Chemical injury B. Physical injury C. Thermal injury VII. Foreign body reactions VIII. Not otherwise specified SCIENCE TRANSFER Definition : A small rounded mass of inflamed, highly vascular granulation tissue on the skin, frequently having an ulcerated surface.  Clinical presentation :  1. 2. the labial maxillary gingiva being the most frequently affected site, especially anteriorly. other oral location may be affected, including the lips, buccal mucosa, and tongue. 3- The surface is smooth or rough and deep red in colour and the consistency is softer than the rest of the mucosa. 4- Ulceration is a frequent finding, sometimes covered by a fibrinous pseudomembrane, which imparts a whitish appearance . 5- The majority of PGs are asymptomatic . 6- Bleeding following mild trauma, or even spontaneously . 7- also complicated with specific periodontal alterations (bleeding, periodontal pocket formation, gingival retraction, and tooth mobility).  Diagnosis : clinical and histopathological characteristics.  Treatment : Surgical excision of PGs is the treatment of choice .