Sleep bruxism: risk factors


Sleep bruxism (SB) involves repetitive jaw-muscle activity with clenching, grinding of the teeth bracing or thrusting of the mandible during sleep.  It can lead to tooth wear muscle tenderness and pain, headaches and temporomandibular disorders (TMDs) Prevalence peaks at around 13% in 18-29yr olds falling with age to around 3% in the over sixties.

The main aim of this review was to identify risk factors for sleep bruxism.


Searches were undertaken in the PubMed, Embase, Scopus, Cochrane Oral Health Group’s Trial Register and Cochrane Register of Controlled Trials, Web of Science, LILACs and SciELO databases.  Papers investigating risk factors for SB were included, papers that did not distinguish between awake bruxism (AB) and SB were excluded.

Two reviewers independently selected papers and abstracted data. The primary outcomes were risk factors associated to SB in adults, calculated as the standardized Odds Ratio (OR) effect size.


  • 9 studies (1 RCT, 2 case controlled, 6 cross-sectional) involving a total of 12,454 patients were included.
  • The age of the patients ranged from 18-89
  • SB diagnosis for all studies was based on questionnaires and/or clinical investigations.
  • Risk factors assessed included; genetic, depressive and stressed status, sleep disordered breathing, gastroesophageal reflux disease (GERD), morphological parameters, behavioural factors and personality traits, symptoms of TMDs and parafunctions, gender and age , chronic migraine, tinnitus and legal psychoactive substances intake such as smoke, alcohol and caffeine.
  • 26 different risk factors were presented. The strongest associations were found for Childhood sleep bruxism, GERD and C allele carrier of HTR2A single nucleotide polymorphism rs6313 (gene related to serotonergic neurotransmission).  The top 10 risk factors are shown in the table below
Risk factor Odds ratio (95% CI)
Childhood sleep bruxism 8.1 (5.4–12.2)
GERD 6.6 (1.4–30.9
HTR2A, rs6313 (102C > T) 4.3 (1.6–11.3)
Chronic migraine 3.8 (1.8–7.8)
Age 25–44 (≥65 Age ref.) 3.1 (2.3–4.1)
Age30–39 (> 60 Age ref.) 2.8 (1.4–5.5)
Age19–24 (≥65 Age ref.) 2.8 (2.0–3.8)
Current smoker 2.8 (2.2–3.5)
Age 45–64 (≥65 ref.) 2.7 (2.1–3.6)
Snoring 2.6 (1.5–4.4)


The authors concluded: –

The systematic review of the existing literature confirmed a probable multifactorial model for SB. History of SB during childhood, GERD and genetic polymorphisms seem to be important risk factors associated to SB in adults. Psychological and behavioural factors, smoke, age, chronic migraine, tinnitus, alcohol intake, snoring and OSA syndrome had a moderate association.

Interestingly, dry mouth on awakening seems to be a protective factor, even if this symptom needs to be further investigated. Association does not infer with causality. Even if the evidence emerged from the considered studies was clinically relevant, further studies are requested to better understand the biological mechanisms behind the described associations


The authors suggest that all of the studies included in this review met all the GRADE methodological criteria. However, looking at their quality assessment table none of the included studies reported allocation concealment, blinded personnel, patients or outcome assessors and all of this have the potential to introduce bias. Furthermore, 5 of the 9 studies only used questionnaires to diagnose SB and as highlighted in the review we looked at last week (Dental Elf- 13th Sept 2017) questionnaire may over diagnose SB by 2-29%.


Primary paper

Castroflorio T, Bargellini A, Rossini G, Cugliari G, Deregibus A. Sleep bruxism and related risk factors in adults: A systematic literature review. Arch Oral Biol. 2017 Jul 5;83:25-32. doi: 10.1016/j.archoralbio.2017.07.002. [Epub ahead of print] Review. PubMed PMID: 28692828.

 Other references

 Original review protocol on PROSPERO

Dental Elf- 13th Sept 2017

Sleep bruxism: validity of diagnostic tools

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