In Vitro Comparison of Void Formation Between Calcium Silicate-Based Sealers and AH Plus: A Systematic Review and Meta-Analysis

Background: Achieving a three-dimensional seal of the root canal system is considered essential for long-term endodontic success. Because no clinically acceptable threshold for void formation has been established, comparisons with clinically validated reference materials are needed to interpret the sealing quality of newer calcium silicate-based sealers (CSBSs). AH Plus is a well-established epoxy resin-based sealer (ERBS) with documented long-term clinical performance. This systematic review and meta-analysis compared the quality of root canal fillings produced with CSBSs and AH Plus using different obturation techniques in permanent mature extracted and artificial teeth. Methods: MEDLINE (PubMed), EMBASE, Cochrane Library, and Web of Science were systematically searched for randomized in vitro studies up to 1 July 2025. The primary outcomes were the percentages of void volume or area. Mean values and mean differences (MDs) with corresponding 95% confidence intervals (CIs) were calculated for the total filling volume and, where available, for the apical, middle, and coronal thirds of the root canal. Risk of bias and certainty of evidence were assessed. Results: Twenty-one studies met the eligibility criteria, and 18 articles were included in the quantitative analysis. No statistically significant differences were observed in total void volume between CSBSs placed with the single-cone technique and AH Plus used with either the single-cone or warm vertical compaction technique in extracted teeth. Similarly, no significant differences were observed between the investigated groups in the apical, middle, or coronal thirds of the root canal. Evidence for other obturation techniques and artificial teeth was limited. Conclusions: Within the limitations of the available in vitro evidence, no statistically significant differences in void formation were detected between the investigated sealer–technique combinations. Further standardized in vitro studies and well-designed clinical investigations are warranted.