Efficacy of conventional cord versus cordless techniques for gingival displacement: A systematic review and meta-analysis

Statement of problem. Unsatisfactory adaptation of restorations with subgingival margins can cause problems such as accumulation of biofilm, secondary caries, and inflammation of the periodontal tissue. Therefore, special attention should be given to gingival displacement and impression procedures to optimize marginal fit. Purpose. The purpose of this systematic review and meta-analysis was to compare gingival displacement with conventional cords and cordless techniques and determine the reliability of the measurement methodologies. Material and methods. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and identified studies through September 2018. The studies were submitted to the Cochrane risk-of-bias assessment. The gingival displacement was evaluated by using the Review Manager Software. Results. Nine studies were selected, and the most common risks of bias were random sequence generation, blinding of outcome assessment, and absence of sample size calculation. Most of the studies reported obtaining a width greater than 0.2 mm. Conclusions. The cord technique resulted in increased displacement when compared with the cordless technique. The evaluation of sulcular width with digital microscope images obtained from sectioned gypsum casts is an adequate and versatile experimental methodology for measuring displacement.