Microhardness of Root Canal Sealers at Different Canal Thirds: a Pilot In Vitro Study

The aim of this in vitro study was to evaluate the microhardness of various root canal sealers in the coronal, middle and apical thirds of the simulated root canals.

The study analysed the bioceramic root canal sealers (RCS) TotalFill^® BC Sealer™, AH Plus^® Bioceramic Sealer and BioRoot™ RCS, the resin-based RCS AH Plus^® Jet™ and the bioceramic cement ProRoot^® MTA (positive control). Gypsum samples simulating root canals were prepared and divided into five experimental groups. The canals were filled with the respective RCS and incubated for 24 hours at 37 °C (95% humidity). The microhardness of the RCS in different thirds of the canal was evaluated using the Vickers microhardness (HV) test.

The microhardness ranged from 6.8 HV (AH Plus^® Bioceramic Sealer) to 70.3 HV (ProRoot^® MTA). TotalFill^® BC Sealer™ remained stable across all thirds (P > 0.05), AH Plus^® Bioceramic Sealer was significantly harder in the coronal third (P = 0.008), BioRoot™ RCS and ProRoot^® MTA were significantly harder in the apical third (P < 0.05), while AH Plus^® Jet™ showed significantly higher hardness in the middle and apical thirds (P = 0.008). BioRoot™ RCS showed no significant difference in microhardness compared to ProRoot^® MTA (P = 0.146). Other RCS were significantly less hard than the positive control (P < 0.05).

Sealer microhardness varied across canal thirds, with TotalFill^® BC Sealer™ showing stability, BioRoot™ RCS resembling the positive control and the others displaying regional variation.