Abstract: Dental pulp tissue is loose connective tissue and can produce a series of cascade reaction to repair itself when meet external stimulation. The conservation treatment of vital pulp is becoming a hot spot of dental pulp biology, calcium hydroxide, MTA and composite pulp capping material mainly the capping agent. Matrix metalloproteinase 3 (MMP3) not only can degradate extracellular matrix components but also has close relation with tissue morphogenesis, damage repair, inflammation and other process. Along with the research of MMP3, it reveals its high expression in injured pulp tissue and promote the proliferation and differentiation of odontoblasts. Covered MMP3 on dental pulp and it contributed to the formation of hard tissues and angiogenesis, prompting that MMP3 may participate in the repairation of the injured pulp.This will provides a new idea for the development of new bioactive pulp capping material. This paper will make a review about the situation of conservation treatment of pulp and research progress of MMP 3 in the vital pulp conservation treatment

Key words: Dental pulp repair, Pulp capping agent, Matrixmetalloproteinases 3