What is typically the predominant inflammatory cell type in the established lesion of gingivitis, which occurs after 14-21 days?

In established gingivitis, typically occurring after 14-21 days of ongoing inflammation, plasma cells are found to be the predominant inflammatory cell type. This transition reflects the immune response progressing from an acute phase, characterized by neutrophil predominance, to a more chronic phase where the immune response shifts towards a humoral immunity.

Plasma cells, which are differentiated B-lymphocytes, are responsible for producing antibodies against the pathogens present in the periodontal tissue. Their presence indicates that the immune system is actively responding to longer-term infection and is associated with the development of chronic inflammation.

During earlier stages of gingivitis, neutrophils are indeed more prevalent as they provide the first line of defense against microbial invasion. However, as the condition progresses, the immune response evolves, leading to an increase in plasma cells. This indicates a change in the dynamics of the immune response in established lesions of gingivitis.