Background To evaluate the completeness of reporting abstracts of systematic reviews (SRs) before and after the publication of the PRISMA-A checklist in 2013 and to assess if an association exists between abstract characteristics and the completeness of reporting. Methods A systematic search of the literature was conducted in the PubMed and Scopus databases in March 2020. The search focused on the SRs of evaluations of interventions published since 2002 in the field of periodontology. The abstracts of the selected SRs were divided into two groups before and after publication of the PRISMA-A checklist in 2013, and compliance with the 12 items reported in the checklist was evaluated by three calibrated evaluators. Results A set of 265 abstracts was included in the study. The total score before (mean score, 53.78%; 95% CI, 51.56–55.90%) and after (mean score, 56.88%; 95% CI, 55.39–58.44%) the publication of the PRISMA-A statement exhibited a statistically significant improvement (P = 0.012*). Nevertheless, only the checklist items included studies and synthesis of the results displayed a statistically significant change after guideline publication. The total PRISMA-A score was higher in the meta-analysis group and in articles authored by more than four authors. Conclusions The impact of the PRISMA-A was statistically significant, but the majority of the items did not improve after its introduction. The editors and referees of periodontal journals should promote adherence to the checklist to improve the quality of the reports and provide readers with better insight into the characteristics of published studies.