Spin and Methodological Quality of Systematic Reviews and Meta-Analyses Comparing Single- and Multiple-Visit Endodontic Treatment: A Meta-Research Study

This study evaluated the methodological quality and presence of spin in systematic reviews with meta-analyses comparing single-visit and multiple-visit endodontic treatment, and investigated factors associated. Systematic reviews of randomised clinical trials were included without restrictions on language or publication year. Narrative reviews, reviews without meta-analysis, non-randomised or non-clinical studies, and conference abstracts were excluded. A comprehensive search was conducted in PubMed, Scopus, Web of Science, the Cochrane Library and grey literature in January 2025. Spin was classified using the Yavchitz et al. framework, and methodological quality was assessed with AMSTAR 2. Data extraction and spin assessment were performed independently and in duplicate. Thirteen systematic reviews were included. Spin was identified in 12 studies of abstracts and 10 of full texts, mainly as a misleading interpretation. Most reviews were rated as low or critically low quality. Positive results and absence of risk-of-bias assessment were associated with increased spin in full texts.