Prevalence of sleep bruxism in children: a systematic review of the literature.

The aim of the present investigation was to perform a systematic review of the literature dealing with the issue of sleep bruxism prevalence in children at the general population level. Quality assessment of the reviewed papers was performed to identify flaws in the external and internal validity. Cut-off criteria for an acceptable external validity were established to select studies for the discussion of prevalence data. A total of 22 publications were included in the review, most of which had methodological problems limiting their external validity. Prevalence data extraction was performed only on eight papers that were consistent as for the sampling strategy and showed only minor external validity problems, but they had some common internal validity flaws related with the definition of sleep bruxism measures. All the selected papers based sleep bruxism diagnosis on proxy reports by the parents, and no epidemiological data were available from studies adopting other diagnostic strategies (e.g. polysomnography or electromyography). The reported prevalence was highly variable between the studies (3·5-40·6%), with a commonly described decrease with age and no gender differences. A very high variability in sleep bruxism prevalence in children was found, due to the different age groups under investigation and the different frequencies of self-reported sleep bruxism. This prevented from supporting any reliable estimates of the prevalence of sleep bruxism in children.