This study aimed to evaluate dentinal tubule penetration of the root canal filling material using various techniques such as cold lateral compaction, new generation thermoplastic core carrier and continuous-wave obturation. The root canals of premolar teeth were instrumented, and the teeth were allocated randomly to three groups (n = 15/group). After the obturation with three different techniques, three sections of 2-mm thickness at 2, 5 and 8-mm from the apex were examined under a confocal laser scanning microscope. The data were analysed of variance with a significance level of P < 0.05. There was no significant difference between techniques when parameters were evaluated in total (penetration depth P = 0.418, penetration area P = 0.701). The mean value of the cold lateral compaction group for maximum penetration depth was obtained higher than continuous wave (P = 0.004), whilst there was no significant difference between the thermoplastic core carrier and the other groups.