Objective: To evaluate the effect of a light-transmitting post on the depth of cure of a resin composite.
Methods: Acetate resin molds were filled with resin composite in which a light-transmitting post was inserted into the center and photopolymerized to the manufacturer's recommendations. Identical molds without a light-transmitting post were photopolymerized in a similar matter and served as a control. Molds were sectioned on a water-cooled, diamond saw at prescribed distances and the depth of cure was determined using a Knoop Hardness bottom-to-top ratio criterion. Data within each group were analyzed using 2-way (depth-by-distance) repeated measure ANOVA. Between-group contrasts (post versus no post) were accessed by a 3-way (2 within-subjects and 1 between-subjects) ANOVA with critical p = 0.05.
Results: The presence of the post did increase (p < 0.001) Knoop Hardness values in simulated apical regions as compared to a control. However, there was no difference in the depth of cure between the groups (3-way analysis p = 0.2) and also when evaluated using an 80% bottom-to-top Knoop Hardness ratio.
Significance: The results suggest that these posts may have a limited utility when judged against a Knoop Hardness ratio criterion.