Abstract
Objectives: To systematically review indexed literature that assessed the association between periodontal diseases and the ABO blood group. Method and materials: The addressed focused question was "Is there an association between periodontal diseases and the ABO blood group?" Indexed databases were searched without time and language restrictions using different key words. Original studies, case reports, and case series that assessed the association between periodontal diseases and the ABO blood group were included in a meta-analysis. The risk of bias was evaluated using the National Institutes of Health tool. Letters to the Editor, commentaries, and historical reviews were excluded. Results: A total of 17 studies including 8,543 individuals were included; periodontitis (n = 4,476), gingivitis (n = 1,582), and healthy (n = 1,610). The most frequent event rate of blood group phenotype in periodontitis was bloodgroup type O 39.0 % (95% CI 0.35 to 0.43). The event rate of positive Rh was 90.7% (95% CI 0.89 to 0.92) compared to 9.2% (95% CI 0.06 to 0.13) for negative Rh. Fixed effect analysis showed that blood group AB had a protective value to peri-odontitis; odds ratio 0.66 (95% CI 0.50 to 0.80; P < .001). How-ever, there was no significant association of blood group A, B, and O. In addition, there was no significant association between ABO blood group and gingivitis; odds ratios of blood group B and O were 1.18 (95% CI 0.80 to 1.67; P = .34) and 1.36 (95% CI 0.89 to 2.08; P = .16), respectively. Conclusion: There is a dis-crepancy among published observations regarding the effect of the ABO blood group on periodontium health. Further stud-ies are needed with a large sample population to build more robust evidence. (Quintessence Int2022;53:404-412;