Association between Apical Periodontitis and Interleukin Gene Polymorphisms: A Systematic Review and Meta-analysis

Introduction: Genetic polymorphisms may result in altered gene expression or functional changes of the encoded molecules and could possibly generate a deficient immunity. Consequently, individuals with specific genotypes could be more susceptible to disease or could present an increase in disease severity. Our study is aimed to verify, through a systematic review and meta-analysis registered in the PROSPERO database (CRD42016043905), whether currently available evidence supports a relationship between interleukin gene polymorphisms and apical periodontitis (AP). Methods: A broad search for studies was conducted. The following databases were used: PubMed, Scopus, Web of Science, and the Virtual Health Library (MEDLINE, SciELO, IBECS, and LILACS). The Medical Subject Headings (MeSH) terms "Periapical Periodontitis," "Periapical Abscess," "Polymorphism, Genetic," and "Polymorphism, Single Nucleotide" were used. MeSH synonyms, related terms, and free terms were included. After application of the eligibility criteria, selected studies were qualified by assessment of their methodologic quality. A fixed effects model was used for the meta-analysis. Results: The initial search identified 71 references. After excluding duplicate abstracts, 33 were selected. From these, 6 were eligible for quality assessment; 5 were classified as being of moderate quality, and 1 was classified as being of high quality. Conclusions: From these included studies, polymorphisms in IL1B, IL6, and IL8 were associated with AP. Polymorphisms in IL1A, IL10, or IL12B were not associated with AP regardless of the methodology used. The meta-analysis suggested that the genotype and allele distribution of IL1B (+3954 C/T) gene polymorphism was different in post-treatment AP. More research in this area is warranted to confirm these results.