Background: Inflammation plays a key role in neointimal hyperplasia after an arterial injury. Chronic infectious disorders, such as periodontitis, are associated with an increased risk of cardiovascular diseases. However, the effects of a periodontal infection on vascular remodeling have not been examined. We assess the hypothesis that periodontal infection could promote neointimal formation after an arterial injury. Methods: Mice were implanted with subcutaneous chambers (n = 41). Two weeks after implantation, the femoral arteries were injured, and Porphyromonas gingivalis (n = 21) or phosphate-buffered saline (n = 20) was injected into the chamber. The murine femoral arteries were obtained for the histopathological analysis. The expression level of mRNA in the femoral arteries was analyzed using quantitative reverse transcriptase polymerase chain reaction (n = 19–20). Results: The intima/media thickness ratio in the P. gingivalis infected group was found to be significantly increased in comparison to the non-infected group. The expression of matrix metalloproteinase-2 mRNA was significantly increased in the P. gingivalis infected group compared to the non-infected group. Conclusion: These findings demonstrate that P. gingivalis injection can promote neointimal formation after an arterial injury. Periodontitis may be a critical factor in the development of restenosis after arterial intervention.