MPO and myocardial infarction: The mean salivary levels of MMP-8 and MPO were significantly higher in non-MI subjects after adjustment for smoking, BOP, PPD 4–5 mm and ≥ 6 mm (MMP-8; 543 vs 440 ng/mL, p = 0.003) and MPO; 1899 vs 1637 ng/mL, p = 0.02), (Table 2).