The purpose of this study was to investigate the influence of thickness on the degree of cure of dual-cured composite core.

2, 4, 6, 8 mm thickness Luxacore Dual and Luxacore Self (DMG Inc, Hamburg, Germany) core composites were cured by bulk or incremental filling with halogen curing unit or self-cure mode. The specimens were stored at 37℃ for 24 hours and the Knoop's hardness of top and bottom surfaces were measured.

The statistical analysis was performed using ANOVA and Tukey's test at p = 0.05 significance level.

In self cure mode, polymerization is not affected by the thickness. In Luxacore dual, polymerization of the bottom surface was effective in 2, 4 and 6 (incremental) mm specimens. However the 6 (bulk) and 8 (bulk, incremental) mm filling groups showed lower bottom/top hardness ratio (p < 0.05). Within the limitation of this experiment, incremental filling is better than bulk filling in case of over 4 mm depth, and bulk filling should be avoided.