Is there association between dental malocclusion and bruxism? A systematic review and meta-analysis.

OBJECTIVES: Given that current literature largely dissociates dental malocclusion and bruxism, the objective of this study was to gather, through a systematic review, scientific evidence to support their relationship. METHODOLOGY: This study was performed according to the PECO strategy (where P = general population, E = dental malocclusion, C = no dental malocclusion, and O = bruxism). Literature searches were conducted without language or date restrictions in the following databases: PubMed, Scopus, the Web of Science, the Cochrane Library, LILACS/BBO via VHL, and the grey literature. The search strategy included Medical Subject Headings/DECs, synonyms, and free terms relevant to each database, with no age restrictions applied. Once the relevant data were extracted from the articles, the Fowkes and Fulton guidelines were followed to assess the quality and risk of bias. For quantitative analysis, dental malocclusions were divided into groups according to their type in order to perform odds ratio (OR) meta-analyses with 95% confidence intervals (CI) using the Review Manager software program (Cochrane, London, UK). The level of certainty of evidence was demonstrated through the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). RESULTS: After 1,502 studies found, 10 studies were included for qualitative analysis and nine for quantitative synthesis. Four studies presented high methodological quality. Five meta-analyses suggested a nonassociation between bruxism and Angle class I (OR: 1.05, 95% CI: 0.41-2.69; p = 0.92; I2 = 84%), Angle class II (OR: 1.49, 95% CI: 0.77-2.87; p = 0.23; I2 = 71%), or Angle class III (OR: 0.77, 95% CI: 0.31-1.93; p = 0.58; I2 = 0%). Bruxism was associated with children who did not present with a posterior crossbite (OR: 0.70, 95% CI: 0.51-0.96; p = 0.03; I2 = 27%) and present crowding (OR: 1.53, 95% CI: 1.03-2.26; p = 0.03; I2 = 0%). The GRADE analysis presented a very low quality of evidence. CONCLUSION: Individuals who present with bruxism have a greater chance of crowding. However, bruxism is not associated with the presence of any of the other malocclusions evaluated.