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Matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPs) have been suggested to play a role in dental pulp destruction. This study examined the effects of interleukin (IL)-1 α on pulp fibroblasts. The ability of these cells to degrade collagen was determined with or without IL-1 α utilizing a cell-mediated collagen degradation assay. Reverse transcriptase-polymerase chain reaction was utilized to examine the mRNA expression of multiple MMPs and TIMPs with and without IL-1 α, while Western blot analyses and zymography were utilized to examine their protein expression. The collagen degradation mediated by these cells was stimulated by IL-1 α and inhibited by MMP inhibitors. IL-1 α increased the mRNA expression of MMP-1 and MMP-3, as well as induced MMP-7. Western blot analyses confirmed these results. IL-1 α increased the secreted protein level of TIMP-1, while only slightly affected the level of TIMP-2. These results suggest that IL-1 α can induce pulp destruction by differentially regulating MMPs and TIMPs.