Figure 3. Changes in relative transcript expression. The relative expressions of specific transcripts were compared for cells (either gingival fibroblasts [GF] or periodontal ligament fibroblasts [PDLF]) treated with root-end filling materials (HICR and MTA) with respect to control cultures grown on plastic. All cells were treated with 10 mM dexamethasone to stimulate differentiation to a mineralized phenotype. The RNA levels in all samples were first normalized to depict uniform expression of the S15 ribosomal subunit. The Fig. depicts the relative expression of differentially expressed transcripts as the mean ± standard deviation of 3 independent experiments. The relative levels of expression for a specific transcript are expressed as a ratio of the expression by cells grown in the presence of the material and those grown on plastic, where a value of 1 indicates identical levels of expression. The dashed rectangle represents the area in which relative expression values are not statistically different from one another. In this study, we determined statistically that expression levels were significantly different if there was a five-fold or greater difference in expression, based upon the average variance between samples with a group (40%), the number of independent samples evaluated (4), and a confidence level of greater than 99% by ANOVA analysis. Each point represents the mean of 3 samples. Error bars represent standard deviation from the mean. Ob Spec = osteoblast specific factor-1, Ob Cys = osteoblast cysteine-rich protein, Ob Stim = osteoblast-stimulating factor, Alk Phos = alkaline phosphatase, BSP-2 = Bone sialoprotein-2, MTA = mineral trioxide aggregate.