TIMP1 and periodontitis: The range of TIMP‐1 concentrations varied considerably between the included studies, from 0.32 ± 0.15 ng/mL to 719 ± 24 ng/mL in periodontitis/ gingivitis patients, and from 0.37 ± 0.20 ng/mL to 721 ± 24 ng/mL in healthy individuals (mean ± SD) (Table 2).