Matrix metalloproteinases (MMPs) seem to play a important role in dentistry. While several MMPs have an important role to play in developmental defects of teeth and in caries, some MMPs also seem to have a defensive role. The main organic component of tooth structure is collagen and MMPs that degrade collagen and the extra cellular matrix have been implicated in progression of dental caries. MMPs have also been shown to be active in pulpitis and studies have shown that they can be used as diagnostic markers of pulpal inflammation. This book reviews the role of MMPs in restorative dentistry and endodontics. This book will describe MMP functions in caries and hybrid layer degradation and explore the potential therapeutic role of MMP inhibitors for the development of improved intervention strategies for MMP-related oral diseases like caries.