Methods: Forty-five roots of maxillary incisors with 17mm-length were endodontically treated. After 24h, gutta-percha was removed at 12mm and the canals were overprepared with diamond tips (Vortex, #4137; KG, #717). During reinforcement, the canals were filled with RC and light cured using DT Light Post with different times: G1 (control) - 40s; G2- 80s and G3- 120s. After 24h of posts cementation, the roots were horizontally cut at 2, 6 and 10mm in depth, which correspond the cervical, middle and apical region. CR microhardness was evaluated by the average of 3 indentations (100g/15s) in each depth at lateral distances of 50, 200 and 350ìm from the cement/post interface.
Results: The three-way analysis of variance (a = 0.05) indicated that time, depth and distance influenced in hardness (p<0.001), and the time X depth interaction was significant (p<0.019). Tukey test disclosed that VH values in G1 (76.37 ± 8.58) and G2 (74.89 ± 6.28) were statistically different (p<0.05) from G3 (79.55 ± 5.18).
Conclusions: In deeper regions and in the most lateral distant areas of the post, the hardness was significantly lower (p<0.001). However, light-curing time of 120s provided greater CR hardness when compared with 40 and 80s, mainly in the apical region.