Sleep Problems, Salivary Biomarkers, Dental Caries and Periodontal Status in School-Aged Children

Assessed using the International Caries Detection and Assessment System (ICDAS II, codes 0-6) for each primary and permanent tooth. Higher codes indicate more severe lesions. 0 = sound, 1 = first visual change in enamel, 2 = distinct visual change, 3 = localized enamel breakdown, 4 = underlying dark shadow, 5 = distinct cavity, 6 = extensive cavity.

Assessed using the DMFT + dmft index to record the total number of decayed (D/d), missing (M/m) and filled (F/f) teeth in permanent and primary dentition.

Plaque accumulation assessed on all teeth using the Silness-Löe plaque index (score 0-3). 0 = no plaque, 1 = slight plaque visible, 2 = moderate plaque, 3 = abundant plaque. Higher scores indicate more plaque accumulation.

Gingival inflammation assessed on all teeth using the Silness-Löe gingival index (score range 0-3). Scores obtained from each tooth. Score interpretation: 0 = normal gingiva, 1 = mild inflammation (slight color change, no bleeding), 2 = moderate inflammation (redness, swelling, slight bleeding), 3 = severe inflammation (marked redness/swelling, bleeding on probing). Higher scores indicate more severe inflammation.

Bleeding on probing assessed on all teeth using the Ainamo & Bay index. Each site was gently probed; presence or absence of bleeding was recorded. Score interpretation: - = no bleeding, + = bleeding present. The percentage of bleeding sites relative to total sites was calculated per participant. Higher percentages indicate greater gingival inflammation.

Measured in unstimulated saliva as mL/min; reflects saliva production rate. Higher values indicate greater salivary secretion

Measured in unstimulated saliva using a digital pH meter; reported in pH units. Higher values indicate more alkaline saliva, lower values indicate more acidic saliva.

Salivary buffering capacity measured using the Ericsson method, reflecting saliva's ability to neutralize acids and maintain pH homeostasis. Reported as a score/units; higher values indicate greater buffering capacity.

Measured in unstimulated saliva using ELISA; reported in ng/mL. Melatonin is a hormone involved in sleep regulation and antioxidant defense. Higher values indicate higher melatonin levels.

Measured in unstimulated saliva using ELISA; reported in ng/mL. Cortisol is a hormone related to stress response and sleep regulation. Higher values indicate higher cortisol levels.

Measured in unstimulated saliva using ELISA; reported in pg/mL. IL-6 is a pro-inflammatory cytokine reflecting oral and systemic inflammation. Higher values indicate higher inflammatory status.

Measured in unstimulated saliva spectrophotometrically; reported in mmol H2O2 equivalent/L. Reflects overall oxidative stress in saliva. Higher values indicate higher oxidant levels.

Measured in unstimulated saliva spectrophotometrically; reported in mmol Ascorbic acid equivalent/L. Reflects total antioxidant capacity of saliva. Higher values indicate greater antioxidant defense.

Calculated as the ratio of TOS to TAS; unitless. Reflects the balance between oxidants and antioxidants in saliva. Higher values indicate higher oxidative stress relative to antioxidant capacity.

Assessed using the Sleep Disturbance Scale for Children (SDSC, total score ranging from 26 to 130) over the previous 6 months. Higher scores indicate greater risk or severity of sleep problems. A cutoff of 42 points is used; scores above this suggest an increased likelihood of sleep disturbances.

Assessed via parent-completed questionnaire. Categories: "Once daily", "Twice daily", "Irregular".

Assessed via parent-completed questionnaire. Categories: "Less than 2 minutes", "2 minutes or more".

Assessed via parent-completed questionnaire. Categories: "Yes", "Sometimes", "No".

Assessed via parent-completed questionnaire. Categories: "Yes", "Sometimes", "No".

Assessed via parent-completed questionnaire. Categories: "Yes", "Sometimes", "No".

Assessed via parent-completed questionnaire. Categories: "Male", "Female".

Assessed via parent-completed questionnaire. Categories: "Primary school", "High school", "University", "Master's degree".

Assessed via parent-completed questionnaire. Categories: "Primary school", "High school", "University", "Master's degree".

Assessed via parent-completed questionnaire. Categories: "Below minimum wage", "Up to 2x minimum wage", "Up to 3x minimum wage", "More than 3x minimum wage".