AIMS: To perform a systematic review of the literature dealing with the prevalence of bruxism in adult populations.
A systematic search of the medical literature was performed to identify all peer-reviewed English-language papers dealing
with the prevalence assessment of either awake or sleep bruxism at the general population level by the adoption of questionnaires,
clinical assessments, and polysomnographic (PSG) or electromyographic (EMG) recordings. Quality assessment of the reviewed
papers was performed according to the Methodological evaluation of Observational REsearch (MORE) checklist, which enables
the identification of 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. For each included study, the sample features, diagnostic
strategy, and prevalence of bruxism in relation to age, sex, and circadian rhythm, if available, were recorded.
Thirty-five publications were included in the review. Several methodological problems limited the external validity of findings
in most studies, and prevalence data extraction was performed only on seven papers. Of those, only one paper had a flaw less
external validity, whilst internal validity was low in all the selected papers due to their self-reported bruxism diagnosis
alone, mainly based on only one or two questionnaire items. No epidemiologic data were available from studies adopting other
diagnostic strategies (eg, PSG, EMG). Generically identified "bruxism" was assessed in two studies reporting an 8% to 31.4%
prevalence, awake bruxism was investigated in two studies describing a 22.1% to 31% prevalence, and prevalence of sleep bruxism
was found to be more consistent across the three studies investigating the report of "frequent" bruxism (12.8% ± 3.1%). Bruxism
activities were found to be unrelated to sex, and a decrease with age was described in elderly people.
The present systematic review described variable prevalence data for bruxism activities. Findings must be interpreted with
caution due to the poor methodological quality of the reviewed literature and to potential diagnostic bias related with having
to rely on an individual's self-report of bruxism.