Etiology
Etiology
Plaque-induced gingivitis is caused by supragingival and subgingival bacterial biofilm. The transition from healthy gingival flora to a dysbiotic, pro-inflammatory biofilm occurs within 10–21 days of cessation of oral hygiene. Classic gingivitis induction experiments (Löe et al., 1965) demonstrated complete reproducibility and reversibility of this process.
Local factors that promote plaque retention and thereby increase gingivitis susceptibility: calculus (mineralized plaque providing rough retention surface), overhanging restorations, ill-fitting crowns and dentures, orthodontic appliances, carious lesions, gingival anatomy variations, and mouth breathing causing gingival desiccation.
Systemic modifying factors amplify the gingival response to plaque: hormonal changes (pregnancy gingivitis from progesterone-driven capillary proliferation, puberty gingivitis, oral contraceptive-associated gingivitis); medications inducing gingival overgrowth (phenytoin, cyclosporin, calcium channel blockers — nifedipine, amlodipine); diabetes mellitus; hematological disorders (leukemia presenting as gingival hyperplasia); malnutrition especially vitamin C deficiency (scurvy).