Do bulk-fill resins decrease the restorative time in posterior teeth? A systematic review and meta-analysis of in vitro studies

The aim of the present study was to compare the restorative time for filling cavities in posterior teeth using bulk-fill and conventional resin composites through a systematic review and meta-analysis. A search for clinical trials and laboratory studies was performed in PubMed/MEDLINE, Scopus, the Latin American and Caribbean Health Sciences Literature database, the Brazilian Library in Dentistry, Cochrane Library, Clinical Trials, and ReBEC (Registro Brasileiro de Ensaios Clínicos) databases without publication year or language restriction. Two reviewers identified eligible studies according to the inclusion criteria: bulk-fill compared to conventional resin in class I or II, and the restorative time as an outcome. A meta-analysis of the restorative time mean difference between composites was performed (inverse variance method, random effects model; Z-test, P ≤ .05). From the 662 eligible studies, 133 were selected for full-text analysis; three were included in the systematic review and in the meta-analysis. Overall, the restorative time was lower when bulk-fill was used (P = .0007, Z = 3.37), as the subgroup full-body bulk-fill (P < .00001, Z = 21.00). There was no difference in restorative time between flowable bulk-fill and conventional resins (P = .08, Z = 1.76). Moderate-to-substantial heterogeneity was detected. Full-body bulk-fill composites decrease the restorative time in posterior teeth compared to conventional resins. Full-body bulk-fill resins require a shorter restorative time to perform restorations in posterior teeth than conventional resins, but the same is not valid for flowable bulk-fill resin composites.