Push-out bond strength and fracture modes of MTA and bioactive glass-based sealers using different final irrigants: an in-vitro study

INTRODUCTION. The bond between gutta-percha and sealer is crucial for successful root canal (RC) filling, requiring sealers with optimal physical, chemical, and biological characteristics. Newer sealers aim to improve clinical outcomes, especially when smear layer removal enhances sealer flow and adhesion. This study compares the push-out bond strength (POBS) and failure modes of an MTA-based bioceramic sealer and a bioactive glass (BG)-based sealer using four different final irrigants. MATERIALS AND METHODS. Eighty single-rooted mandibular premolars were decoronated to a length of 16 mm and prepared using ProTaper Gold rotary files with intermittent irrigation using 5.25% NaOCl. Samples were categorised into two main groups depending on the sealer employed [ n = 40 (Nishika Canal Sealer BG and MTA Fillapex)] and further into four sub-groups according to the final irrigant [ n = 10 (10% glycolic acid, MTAD, 18% Etidronic acid and normal saline). Following obturation with gutta-percha, the specimens were incubated at 37°C and 95% humidity. POBS was evaluated using a universal testing machine, and failure modes were analysed under a scanning electron microscope. RESULTS. POBS obtained from the study were in the following order: Nishika Canal Sealer BG + Etidronic acid > MTA Fillapex + etidronic acid > Nishika canal sealer BG + glycolic acid > MTA Fillapex + glycolic acid > Nishika canal sealer BG + Normal saline > MTA Fillapex + MTAD > MTA Fillapex + normal saline > Nishika canal sealer BG + MTAD. CONCLUSIONS. All irrigants used allowed proper setting of both sealers. This study indicates that the choice of chelating agent affects bond strength, with etidronic acid showing the highest dislodgement resistance for both sealers, while MTAD showed the lowest.