Effects of Filling Technique and Light Irradiation Distance on the Push-Out Bond Strength of Dual and Light Cured Core Materials in a Direct Core Build-Up

This study evaluated the effects of filling technique and light irradiation distance on the push-out bond strength of dual-cured (DC) and light-cured (LC) core materials to the root canal dentin. DC and LC core materials were filled with a bovine root canal post space of 8mm deep, and polymerized under two different filling procedures, i.e., an 8mm bulk filling (I) and two times of 4mm incremental filling (II), multiplying two different light irradiation distances (0 or 5mm) from top of the root canal. After 24h water storage, specimens were horizontally sectioned to obtain 1±0.1mm thick core/dentin slices, and five slices were obtained for each root. After the slicing process, push-out tests were performed. Among all groups, the highest bond strength was observed in DCI5 (13.7 ± 4.3MPa), whereas the lowest was observed in LCI0 (10.3±3.7MPa). Consequently, the recommended curing procedure between DC and LC core materials differed. Combination of LC core material with incremental filling technique and of D...