Prevalence of temporomandibular disorders (TMD) in pregnancy: a systematic review with metanalysis.

BACKGROUND Over the past few years, researchers have investigated whether varying menstrual statuses and estrogen levels could affect the likelihood of temporomandibular disorders (TMDs), with conflicting results. While some studies suggest a potential link between increased estrogen levels and higher TMD risk, others have found no correlation. It is worth noting that estrogen levels can impact the structure and function of the temporomandibular joint (TMJ). In light of these findings, our study seeks to investigate the prevalence of TMDs among pregnant women. METHODS We searched in PubMed, Web of Science and Lilacs for articles published from the inception until January 20, 2023. We applied the Population, Exposure, Comparator, and Outcomes (PECO) model to assess the document eligibility: P) Participants: female human subjects. E) Exposure: pregnancy. C) Comparison: pregnant women compared to non-pregnant women in the childbearing age. O) Outcome: TMDs diagnosis. Only study providing data about the prevalence in both group (pregnant and non-pregnant) were included. We set the following exclusion criteria: 1) diagnosis of rheumatic diseases or chronic inflammatory disorders (e.g., rheumatoid arthritis, juvenile, idiopathic arthritis, psoriatic arthritis); 2) diagnosis of fibromyalgia; 3) congenital abnormality or neoplastic conditions in the TMJ region; 4) studies including subjects undergoing arthrocentesis or intra-articular infiltrations; 5) studies including local pressure pain assessment; 6) studies including women in menopause in the control group 7) cross-over study design; 8) language different from English; 8) full- text unavailability (i.e., posters and conference abstracts); 9) studies involving animals; 10) review (topical or systematic) article; 11) case reports/series; 12) studies evaluating TMDs prevalence in subjects not pregnant. The software Review Manager version 5.2.8 (Cochrane Collaboration, Copenhagen, Denmark; 2014) was used to perform the pooled analysis. We measured the risk ratio (RR) between the two group (pregnant and non-pregnant). RESULTS The included subjects in this review were 440. Among them, 244 were pregnant while the remaining 196 were age matched non-pregnant women. Among those pregnant 102 presented sign/symptoms of TMD or TMD diagnosis (41,8 %) whereas 80 of those not pregnant were diagnosed with (40,8%). The overall effect showed that there was no difference in TMD prevalence between pregnant and non-pregnant women in childbearing age (RR 1.12; 95% CI: 0.65- 1.93), suggesting that pregnant is neither a risk factor nor a protective factor for TMD. CONCLUSIONS Overall, we did not find an association between TMD and pregnancy, neither positive nor negative. Further studies on larger samples are needed to clarify our results.