Effect of calcium hydroxide removal protocols on push-out bond strength of hydraulic calcium silicate sealers: an <i>in vitro</i> study

Background and Objectives This study aims to evaluate the push-out bond strength of a hydraulic calcium silicate sealer (HCSS) (AH Plus Bioceramic; Dentsply Sirona, Tulsa, OK, USA), to dentin following calcium hydroxide (Ca(OH) 2 ) removal using different irrigation protocols and to assess the sealer-dentin adhesive interface. Materials and Methods Forty-four single-rooted human teeth were prepared, standardized to 16 mm in length, and instrumented with ProTaper Next to an X5 size. After final irrigation, the canals were filled with Ca(OH) 2 for two weeks. The specimens were divided into four groups according to the irrigation protocol: distilled water (control), ethylenediaminetetraacetic acid (EDTA) combined with NaOCl, citric acid, and glycolic acid. The canals were subsequently dried and filled with HCSS, a premixed hydraulic calcium silicate sealer, using an X5 gutta-percha cone. The specimens were stored at 37 °C and 100% humidity for 7-day before testing. Push-out bond strength was measured using a universal testing machine, and failure modes were evaluated under a stereomicroscope. Results Glycolic acid exhibited the highest overall bond strength, particularly in the coronal third ( p &lt; .05), compared to distilled water. EDTA + NaOCl and citric acid demonstrated similar bond strength values, both statistically superior to distilled water ( p &lt; .05), but not significantly different from glycolic acid ( p &gt; .05). Failure mode analysis revealed predominantly cohesive failures, with no statistically significant variation in failure modes among irrigation protocols or root canal thirds ( p &gt; .05). Conclusion The irrigation protocol used for Ca(OH) 2 removal significantly influenced the push-out bond strength of HCSS. Glycolic acid demonstrated the highest bond strength, particularly in the coronal third, while EDTA + NaOCl and citric acid also enhanced bonding compared to the control group.