The variable shows the number of individuals registered with a BSI index in total (the sum of individuals with BSI 2–4, BSI 5–6, and BSI 7–8) in the relevant patient group. BSI index (plaque and mucosa index) for groups C1 and C2. The BSI index is the sum of two indices: Plaque Index (BI) + Mucosa Index (SI) = BSI. Each of these indices is graded from 1 to 4, where 1 describes the normal condition, meaning absence of plaque and absence of inflammation in the mucosa and gums.