Classification of Periodontal Diseases - Internationally agreed classification formulated in 1989 - Divided periodontal diseases into 5 groups: adult periodontitis, early-onset periodontitis, periodontitis associated with systemic disease, necrotizing ulcerative periodontitis, and refractory periodontitis - 1993 classification simplified and dropped categories of systemic disease and refractory periodontitis - New classification developed in 1999, reclassifying adult periodontitis to chronic periodontitis and early-onset periodontitis to aggressive periodontitis - Latest classification in 2017 addressed limitations of previous classifications, including defining the threshold between periodontal health and gingivitis, introducing staging and grading system, and introducing a new classification for peri-implant diseases

Gingival Diseases - Gingival diseases share common features such as inflammation, restricted to gingiva, and potential for return to health - Plaque-induced gingivitis is the most common form, caused by bacterial biofilm and characterised by red, swollen gums that bleed easily - Factors influencing plaque-induced gingivitis include hormonal fluctuations, drugs, systemic diseases, and malnutrition - Non-plaque-induced gingival diseases are less common and caused by bacterial, viral, fungal, genetic, or allergic sources - Specific bacterial species, such as Neisseria gonorrhoeae and Treponema pallidum, can cause gingival lesions, as well as herpes simplex virus and varicella-zoster virus

Non-plaque-induced Gingival Diseases - Non-plaque-induced gingival diseases are less common than plaque-induced lesions - Inflammation can be caused by allergic reactions, trauma, foreign bodies, toxic reactions, or genetics - Hereditary gingival fibromatosis is a genetic disease causing fibrous enlargement of the gums - Certain bacterial, viral, and fungal infections can cause gingival lesions - Systemic conditions like lichen planus and pemphigus vulgaris may manifest as gingival inflammation

Traumatic and Foreign Body Reactions - Trauma to the gingiva can be chemical, physical, or thermal - Traumatic lesions can be self-inflicted, iatrogenic, or accidental - Foreign body reactions can cause longstanding lesions or trigger chronic inflammatory responses - Dental materials can become impregnated in the gingival tissues and cause chronic inflammation - Granulomatous or lichenoid lesions may occur as a result of foreign body reactions

Periodontitis - Periodontitis is a type of periodontal disease characterised by extensive bone loss and soft tissue inflammation - It is a common condition affecting a significant portion of the population - Periodontitis can lead to tooth loss if left untreated - Risk factors for periodontitis include poor oral hygiene, smoking, diabetes, and genetic predisposition - Treatment for periodontitis involves professional cleaning, scaling, and root planing, as well as maintenance of good oral hygiene practices.

Subtopic: Aggressive periodontitis - Distinguished from chronic periodontitis by faster rate of progression - Loss of attachment may occur despite good oral hygiene - Can occur in younger individuals - Genetic aspect, may run in families - Risk factors may not include smoking

Subtopic: Manifestation of systemic diseases - Systemic diseases can be associated with development of periodontitis - Host immune response to plaque may be altered by systemic condition - Hematological disorders associated with periodontitis include acquired neutropenia and leukemias - Genetic disorders potentially associated include Down syndrome and Ehlers-Danlos syndrome - Other systemic diseases such as histiocytosis syndromes and glycogen storage disease may also be linked

Subtopic: Necrotizing periodontal diseases - Acute necrotizing ulcerative gingivitis is characterised by painful, bleeding gums and loss of interdental papillae - Necrotizing periodontal diseases are non-contagious infections - Predisposing factors include stress, poor oral hygiene, smoking, and immunosuppression - Necrotizing ulcerative periodontitis can lead to attachment loss - Necrotizing stomatitis (cancrum oris) involves tissue beyond the mucogingival junction

Subtopic: Abscesses - Abscesses are localised collections of pus - Periodontal abscesses do not arise from pulp necrosis - Gingival abscess involves the marginal gingiva or interdental papilla - Periodontal abscess involves a greater dimension of gum tissue, extending apically - Pericoronal abscess occurs around partially erupted and impacted mandibular third molars

Subtopic: Associated with endodontic lesions - Combined pulpal and periodontal pathology can occur in a tooth and surrounding periodontium - Developmental or acquired conditions can influence the outcome of periodontitis - Combined periodontic-endodontic lesions can occur when periapical lesion becomes continuous with a periodontal lesion - Vice versa, a periodontal lesion can become continuous with a periapical lesion - Certain conditions can affect the prognosis and treatment of periodontitis

Subtopic: Early Lesion - Infiltration and plasma cells at the edges of the area - Up to 15% of connective tissue occupied by the lesion - Altered fibroblasts with swollen mitochondria and rupture of cell membranes - Acute exudative inflammation with crevicular lymphocytes - Junctional epithelium may resemble a microabscess

Subtopic: Established Lesion - Overwhelming presence of plasma cells - Plasma cells clustered around blood vessels and between collagen fibers - Production of IgG and some IgA by plasma cells - Presence of complement and antigen-antibody complexes - Proliferation and apical migration of junctional epithelium

Subtopic: Advanced Lesion - Periodontal pocket formation - Gingival ulcer