1- initial, 2- Early, 3-Established (gingivitis), 4- Advanced (periodontitis)

2-4 days after stopping OH (plaque accumulation), changes identified in the coronal junctional epithelium (infiltrate), vasdodilation of adjacent blood vessels, loss of collagen around gingival blood vessels, Neutrophils migrate from blood vessels into JE and sulcus, Increased gingival fluid flow. NO CLINICAL SIGNS, REVERSIBLE, RESOLUTION, GINGIVITIS

4-14 days, exaggeration of initial lesion plus: Coronal junctional epithelial cells detach from enamel, stratum basale layer proliferates, T-lymphoctyes present in infiltrate, reduced number of pathological changes in fibroblasts. BOP, increased infiltrate area, increased pocket depth (poss false pocketing), REVERSIBLE, GINGIVITIS

2-3 weeks, Exaggeration of early lesion plus: B lymphocytes present producing immunoglobulins, infiltrate are spreads laterally and further into CT, further destruction of collagen fibres, continued proliferation thinning and ulceration of junction epithelium, further JE attachment. BOB, BOP, BOS, no pain or boneloss, false pocketing, Deep red, Odeama & fibrosis (frustrated repair), REVERSIBLE, GINGIVITIS- clinically visible at this point. MAY remain stable as chronic gingivitis, progress slowing to chronic periodontitis, or quickly to aggressive periodontitis

Exaggeration of established lesion plus: pocket extends apically past CEJ 'true pocket', Bone and ligament loss, fibrosis present, cytopathically altered plasma cells present, widespread inflammatory and immunological tissue reactions, period of quiescence and exacerbation. IRREVERSIBLE, PERIODONTITIS, true pockets, drifting, mobility, boneloss, abscess formation, suppuration, halitosis, recession, metallic taste (blood), infiltrate larger, red colour.