Introduction
Materials and methods
Protocol and registration
Study eligibility criteria
Inclusion criteria | Studies evaluating the effect of sleep on early childhood caries (ECC) |
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Type of studies | Case–control studies, cross-sectional studies, longitudinal studies |
Population (P) | Children under 6 years of age with sleep disturbances |
Exposure (E) | Sleep disturbances which might include number of sleep hours, frequency of night-time waking (reported through subjective or objective parameters), bedtime routines |
Control (C) | Children under 6 years of age without sleep disturbances (either a parallel-group or in intervention studies, the same children treatment of sleep disturbances served as a control) |
Outcome (O) | ECC (prevalence or incidence or severity or progression of ECC) |
Information sources and literature search
Study selection
Data collection process
Data items
Risk of bias in individual studies
Summary measures and methods of analysis
Results
Study selection
Study characteristics and results
Cross-sectional studies
Author | Country | Sample size | Gender distribution | Age group | Method of assessing sleep (exposure) | Results |
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Kitsaras et al. (2018) | UK | 50 children | Males: 48% Females: 52% | Range: 3–5 years Mean age: 4 years (SD: 0.8 months) | Interactive text survey consisting of open-ended and closed-ended questions sent to mobile phones of parents. The main independent variable was optimal bedtime routines | Children in families with optimal bedtime routines presented lesser cavities and fewer missing or filled teeth (dmft = 0) (Median = 4) compared to children in families with suboptimal bedtime routines (dmft > 0) (Grand Median = 2), p = 0.011 |
Nishide et al. (2019) | Japan | 140 children (Only 38 were less than 7 years) | Males: 55% Females: 45% (gender distribution of children with primary dentition not mentioned) | Data of 38 children in primary dentition is extracted for the review | Recording form to record waking time, bedtime, mealtimes, snacking time, and tooth brushing time for 8 days at home | The number of caries was significantly correlated with the mean sleep onset time (r = 0.370, p = 0.022). No significant correlation was found between prevalence of caries and sleep duration (p = 0.094) and other sleep parameters |
Zhou et al. (2019) | China | 1591 children | Males: 51.6% Females: 48.4% | Range: 3–5 years | Structured questionnaire completed through interviews with parents or caregivers | Children who slept for 12 h or longer had lower caries prevalence. dmft scores were significantly lower (p < 0.05). The mean values of dmft were distributed as follows: ≥ 12 h (n = 130) = 3.37 ± 4.30 10–12 h (n = 912) = 4.24 ± 4.85 ≤ 10 h (n = 549) = 4.74 ± 4.72 |
Ogawa et al. (2021) | Japan | 332 children | Males: 53.6% Females: 46.4% | Mean age: 64.4 (SD = 10.1) months; range: 3 to 6 years | Questionnaire completed through parents | There was a significant negative correlation between the sleep duration the number of caries experienced by the children (r = − 0.17, p = 0.0016). In the multivariate analysis, the sleep durations [adjusted odds ratio = 0.54 (95% CI 0.36–0.80), p = 0.0012] was found to be independently associated with the development of dental caries in the children |
Longitudinal studies
Author | Country | Sample size | Gender distribution | Age group | Method of assessing sleep (exposure) | Results |
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Watanabe et al. (2014) | Japan | 31,202 children at 1.5 years follow-up | Males: 51.4%; Females: 48.6% | Age at baseline: 1.5 years | Self-administered questionnaire completed by parents or guardian | Multivariate logistic regression analysis showed that a late bedtime is an independent risk factor for caries development. The OR of developing caries if the child slept between 9 and 11 pm was 1.33 (95% CI 1.23, 1.45), after 11 pm was 1.85 (95% CI 1.61, 2.12) and irregular bedtime was 1.71 (95% CI 1.51, 1.93) |
Chen et al. (2018) | Japan | 71,069 children | Male: 51% Female: 49% | 18 months at baseline and 3 years of age at dental evaluation | Standardized parent-reported questionnaires to record child’s bedtime, wake time, and sleep duration | The risk of caries increased with bedtime becoming later in a dose–response manner, and children with irregular bedtime also had a greater risk of caries. The multivariable aORs were 1.26 (95% CI 1.19–1.33), 1.48 (1.38–1.58), 1.74 (1.58–1.92), 1.90 (1.58–2.29), and 1.66 (1.53–1.81) for bedtimes at 21:00, 22:00, 23:00, 0:00, and irregular bedtime, respectively The risk of caries was inversely proportional to sleep duration, but the associations were less pronounced than those of bedtime. Children with night-time sleep duration of ≥ 11 h had lesser caries compared to children with shorter (≤ 8 h) and irregular sleep duration (30% increased risk of caries). The multivariable aORs were 1.30 (95% CI 1.15–1.47), 1.16 (1.09–1.24), 1.11 (1.05–1.18), and 1.35 (1.25–1.46) for sleep durations of ≤ 8 h, 9 h, 10 h, and irregular sleep duration, respectively |
Risk of bias within studies
Cross-sectional studies
Author (year) | Selection | Comparability | Outcome | Total stars |
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Maximum 5 stars | Maximum 2 stars | Maximum 3 stars | Maximum 10 stars | |
(A) Cross-sectional studies | ||||
Kitsaras et al. (2018) | **** | * | ** | ******* (7) |
Nishide et al. (2019) | *** | – | *** | ****** (6) |
Zhou et al. (2019) | **** | * | ** | ******* (7) |
Ogawa et al. (2021) | ** | * | *** | ******(6) |
Maximum 4 stars | Maximum 2 stars | Maximum 3 stars | Maximum 9 stars | |
---|---|---|---|---|
(B) Longitudinal studies | ||||
Watanabe et al. (2014) | **** | ** | *** | ********* (9) |
Chen et al. (2018) | **** | ** | *** | ********* (9) |