Evaluation of the relationship between sleep disorders and salivary parameters with dental caries in school-age children

Dental caries are one of the most prevalent diseases among children globally. In addition to the primary etiological factors, secondary factors such as salivary composition, host-related characteristics, dietary habits, and oral hygiene practices also play an important role in it's development. This study aimed to evaluate the relationship between extensive stage dental caries and periodontal status with salivary flow rate, pH, buffering capacity, melatonin, cortisol, IL-6, total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI) and sleep disturbances in school-aged children. The study group is consisted of 39 children (17 girls, 22 boys; aged 6–12 years) with extensive stage caries (ICDAS codes 5 and 6), while the control group included 34 children (14 girls, 20 boys) with no caries or initial-to-moderate caries (ICDAS codes 0, 1, 2, 3, 4). All participants were evaluated for dmft index, plaque index, gingival index, and bleeding on probing scores. Unstimulated saliva samples were collected to measure salivary flow rate, pH, buffering capacity, melatonin, cortisol, IL-6, TAS, TOS, and OSI levels. Sleep problems were assessed by using the Sleep Disturbance Scale for Children (SDSC) which was completed by parents. For statistical analyses, IBM SPSS Statistics 22 software was used. For the comparison of quantitative data, Student's t-test was used for parameters with normal distribution, and the Mann-Whitney U test was used for parameters without normal distribution. The dmft and decayed tooth scores, gingival index scores and bleeding on probing index scores, were significantly higher in the study group compared to the control group (p < 0.05). No statistically significant differences were found between the groups regarding plaque index, SDSC scores, salivary pH, flow rate, buffering capacity, melatonin, cortisol, or IL-6 levels. In our study, no significant relationship was found between SDSC scores, salivary parameters, and advanced dental caries in children. However further researchs with larger population and different age groups are needed to evaluate the effects of sleep disturbances on the physical and chemical properties of saliva which has circadian rhythm, to assess whether melatonin — a major antioxidant that regulates the biological clock — has a protective role against dental caries and to better understand whether salivary cortisol, IL-6, TAS, TOS, and OSI levels — which are thought to be influenced by circadian rhythm alterations — are risk factors for dental caries.