Clinical and immunological aspects of gingival retraction systems in fixed dental prostheses: A systematic review

To describe the existing knowledge on the efficacy of the different gingival retraction systems (GRSs) in gingival displacement, to know their effects on biological functions of human gingival fibroblasts (HGFs), and on the expression of inflammatory mediators (TNF-α and MCP-1) in gingival crevicular fluid (GCF), and saliva. The protocol used for this systematic review was registered in INPLASY: 202410005. A digital search was performed in the databases PubMed/MEDLINE, Scopus, Science Direct, Web of Science, and Google Scholar of the literature published in the English language in the last 17 years (from December 10th, 2006, to May 15th, 2023), and included retrospective randomized clinical studies, prospective, and in vitro experimental studies. In addition, PRISMA criteria were followed. The methodological validity of the selected articles was assessed using Joanna Briggs Institute (JBI) critical appraisal tool, and the modified Consolidated Standards of Reporting Trials checklist (CONSORT). 27 articles published between 2006 and 2023 were evaluated. Six hundred 32 subjects, aged between 18 and 65, participated in the clinical studies. 93.7% of the studies assessed periodontally healthy patients, and only 6.3% evaluated patients with mild gingivitis. Also, 882 teeth were samples, of which the majority were posterior teeth (54%). The most commonly used GRSs was aluminum chloride gingival retraction paste (74%). The GCF samples were taken in 67% of the studies, and ELISA was used in all studies (100%) to determine inflammatory mediators. The most frequently analyzed marker was TNF-α (67%). The system Merocel Strips (Mystic, conn, USA) achieved the highest level of gingival displacement (1.66 ± 3.7 mm). In addition, the braided cords produced the lowest TNF-α levels (0.43 ± 0.08pg/mL). Astringent systems such as ferric sulfate had higher toxicity in HGFs.