Experimental polyethylene–hydroxyapatite carrier‐based endodontic system: an in vitro study on dynamic thermomechanical properties,sealing ability,and measurements of micro‐computed tomography voids

The dynamic thermomechanical properties, sealing ability, and voids formation of an experimental obturation hydroxyapatite‐reinforced polyethylene (HA/PE) composite/carrier system were investigated and compared with those of a commercial system [GuttaCore (GC)]. The HA/PE system was specifically designed using a melt‐extrusion process. The viscoelastic properties of HA/PE were determined using a dynamic thermomechanical analyser. Human single‐rooted teeth were endodontically instrumented and obturated using HA/PE or GC systems, and then sealing ability was assessed using a fluid filtration system. In addition, micro‐computed tomography (μCT) was used to quantify apparent voids within the root‐canal space. The data were statistically analysed using one‐way anova and post hoc tests. The HA/PE composite exhibited important modulus and damping changes with an increase of temperature. The HA/PE system was more flexible than GC as the modulus of GC appeared to be significantly higher than that of HA/PE as a result of the high positive glass transition temperature (T_g). However, HA/PE and GC presented similar sealing abilities. In conclusion, because sealing ability and voids formation were comparable between the tested materials, the experimental HA/PE system may be considered a suitable alternative material for root‐canal obturation. Moreover, HA/PE possesses specific viscoelastic behaviour and lower melting points, which may facilitate root‐canal retreatments.