Association of Single Nucleotide Polymorphisms in the Cyclooxygenase-2 (COX-2) Gene with Periodontal Disease—A Systematic Review with Meta-Analysis and Implications for Personalized Dentistry

Background: Genetic polymorphisms in the cyclooxygenase-2 (COX-2) gene may contribute to individual susceptibility to periodontal disease. A meta-analysis assessed the association between three COX-2 single-nucleotide polymorphisms (SNPs) namely, −765 G/C (rs20417), −1195 G/A (rs689466), and 8473 T/C (rs5275), and the risk of CP. Methods: Following the PRISMA 2020 guidelines, we conducted a comprehensive search of five electronic databases and additional sources. The eligible studies were observational (case–control or cohort) with genotypic data comparing individuals with periodontal disease and periodontally healthy controls. Methodological quality was assessed using the Newcastle–Ottawa Scale (NOS), and the certainty of evidence was evaluated via the GRADE framework. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated under dominant genetic models. Results: Seven studies (n = 1467 participants) met the inclusion criteria. No eligible studies evaluated the 8473 T/C SNP. The meta-analysis of the −765 G/C variant revealed a significant association with periodontal disease (OR = 1.61; 95% CI: 1.12–2.32, p = 0.03; I2 = 0%). For the −1195 G/A variant, the pooled OR was 1.86 (95% CI: 1.00–3.43, p = 0.05; I2 = 35%), suggesting a borderline significant association. The certainty of evidence was graded as moderate for −765 G/C and low for −1195 G/A. Conclusions: The COX-2 −765 G/C polymorphism is significantly associated with increased CP risk, while the −1195 G/A variant shows a potential, though less certain, link. Larger, high-quality studies using standardized classifications are needed to confirm these associations.