Periodontal ligament (PDL) fibroblasts play critical roles in the regeneration of periodontal tissues damaged by periodontitis. Histone deacetylase inhibitors (HDIs) have been suggested to be potential tools in tissue engineering. The feasibility of using the HDI, sodium butyrate (NaB) for periodontal regeneration was examined by evaluating its effect on the osteogenic differentiation of human PDL fibroblasts and its modulation of the inflammatory responses to lipopolysaccharide (LPS). NaB did not cause significant cell death at 100 mu M but promoted the expression of the osteoblast phenotype (Runx2, osterix, osteocalcin, and bone sialoprotein). NaB significantly inhibited the LPS-induced production of reactive oxygen species and the expression of pro-inflammatory cytokines (IL-1 beta and TNF-alpha). These results suggest that HDIs can offer a potential therapeutic agent for periodontal regeneration.