MPO and Anxiety: Unpredictable variables, such as minor variations of the peroxidase enzyme components lactoperoxidase, myeloperoxidase, or GSH/H2O2-peroxidase [65], eventual anxiety behavior from participants [66], or even changes in oral hygiene or unknown fluoride treatment [36] could inadvertently cause the observed decreases in salivary peroxidase activity of participants herewith.