Association between orthodontic treatment and the occurrence of temporomandibular disorders: smoke and mirrors in the form of a systematic review?

Question: To investigate the association between orthodontic treatment and incidence of temporomandibular joint disorders (TMD) as a revision to the existing literature.

Data Sources: Electronic searches were performed in the following databases: PubMed/Medline, Scopus, Scielo, Google Scholar and Web of Science. Hand search of the references of the included studies was also conducted.

Study Selection: Two authors performed database search independently using the keywords to include case control and cohort studies in English or Spanish language. Systematic reviews and Randomized controlled trials (RCTs) were excluded.

Data Extraction And Synthesis: From the studies that met the inclusion criteria, investigators extracted the following data: authors, year, study title, number of patients, male/female ratio, mean age (range), follow up time, groups, number of patients per group, country and results. The Newcastle Ottawa scale was used for risk of bias assessment. All disagreements were resolved by consulting with a third reviewer.

Results: A total of 686 articles were found in the search and 28 duplicates were removed. After title and abstract screening, 648 articles remained. Ten articles were analyzed for full text and four studies were excluded in the process, leaving six articles that met all inclusion and exclusion criteria. Out of six studies, four were case control, one cohort and one prospective cohort. Authors found good quality on all categories of risk of bias assessment in the selected studies. For the meta-analysis, they considered Odds Ratio (OR) because of its presence in every included study. An association between orthodontic treatment and the occurrence of TMD was demonstrated with an odds ratio of 1.84.

Conclusions: The review authors conclude that the results of their systematic review indicate association between the orthodontic treatment and incidence of TMJ disorders.