Figure 1: Micrograph of BPCM (a) and DFDBCBM (b). Collagen fibers of BPCM were seen to form loose structures giving impression of membrane porosities. On the other hand, DFDBCBM demonstrated dense collagen fibers with lacunas which were characteristic features of cortical bone. No retained cell was found in either type of membrane (Hematoxylin-Eosin, ×400 magnification). The result of MTT Assay (c). The percentage of viable cells after exposure of human gingival fibroblast culture to DFDBCBM-conditioned medium was 84.4%, 86.5%, and 89.7% after 24, 48, and 72 hours of exposure, respectively (CM = conditioned medium; non-CM = non conditioned medium).