*2.6. Selection of Patients and the Control Group Participants*

Blood collection for the determination of hormones, antibodies and other clinical and oxidative stress parameters as well as ultrasound examination took place a day before saliva collection and dental examination, and included 70 patients and 70 control subjects. Based on the results of USG, thyroid hormone and TSH assays, the patients and the control group were qualified for further examinations (over 60 patients (10 patients had elevated TSH levels) and 59 control group participants (11 people from the control group had an abnormal ultrasound examination) were positively qualified for the experiment).

After the dental examination, 15 patients (PPD > 4 mm) and 5 control (gingival bleeding during probing) subjects were eliminated from the experiment due to the coexisting periodontal/gingival inflammation, and 9 additional participants were excluded from the control group as they did not match the other subjects in terms of BMI.
