Imagine an army of enzymes working silently inside the mouth—building, remodeling, and destroying the tissues that support the teeth. This army is known as matrix metalloproteinases, or MMPs. For many people, the name may sound unfamiliar. For dental researchers and clinicians, however, MMPs are key to understanding why periodontitis can destroy the jawbone, why dentin caries can progress so aggressively, and even why tumors can invade the soft tissues of the mouth.
Prof. Dr. drg. Regina TC. Tandelilin, M.Sc., PBO., Professor in the Department of Oral Biology, Faculty of Dentistry, Universitas Gadjah Mada, together with her colleague Rajiv Saini from Pravara Institute of Medical Sciences, India, published an in-depth review of MMP dynamics in the oral environment. The article, titled Dynamics of Matrix Metalloproteinases in the Oral Environment, was published in the January–June 2015 edition of the International Journal of Experimental Dental Science.
The Guardians and Destroyers of the Extracellular Matrix
To understand MMPs, it is necessary to become slightly familiar with the extracellular matrix, or ECM. The ECM is the “invisible framework” that fills the spaces between cells, consisting of collagen, laminin, fibronectin, elastin, and proteoglycans. This structure provides strength, elasticity, and identity to connective tissues, the periodontal ligament, alveolar bone, and oral mucosa.
MMPs are a family of zinc-dependent endopeptidases. Their function is to degrade components of the ECM. Under normal conditions, this process is actually vital, enabling wound healing, embryological development, and bone remodeling. However, when the balance is disrupted, MMPs can become agents of tissue destruction.
To date, more than 24 types of MMPs have been identified and classified. They are divided into several major groups: collagenases (MMP-1, 8, and 13), gelatinases (MMP-2 and MMP-9), stromelysins (MMP-3, 10, and 11), matrilysins (MMP-7 and MMP-26), and membrane-type MMPs such as MMP-14. Each has different substrate targets, but they all share similar proteolytic mechanisms.
Interestingly, the body has a natural balancing system known as TIMPs, or tissue inhibitors of metalloproteinases. There are four types of TIMPs (TIMP-1, 2, 3, and 4), each of which specifically inhibits MMP activity. TIMP-2, for example, has been shown to be ten times more effective than TIMP-1 in inhibiting MMP-2 activity.
When the Balance Falters, the Periodontium Collapses
This is where the core clinical problem emerges. In patients with periodontitis, MMP levels—particularly the gelatinases MMP-2 and MMP-9—have been shown to be significantly higher than in healthy individuals. After periodontal treatment, the levels of these gelatinases decrease significantly. This is not merely a statistical coincidence; it reflects a strong causal relationship between MMP-TIMP imbalance and destruction of the tissues supporting the teeth.
“It is very important for dentists to understand the roles of several MMPs and TIMPs in the oral cavity, considering that these enzymes are involved in both normal and pathological conditions—from periodontal tissue destruction and dental caries to tumor invasion and temporomandibular joint disorders.” — Prof. Dr. drg. Regina TC. Tandelilin, M.Sc., PBO. & Rajiv Saini, in the International Journal of Experimental Dental Science, 2015
The damage does not stop at the periodontium. MMP-20, or enamelysin, for example, specifically breaks down amelogenin in newly formed tooth enamel. Gelatinases also contribute to dentin degradation caused by caries by activating collagenase-3 (MMP-13) and neutrophil collagenase. Even in the context of tumors, MMPs facilitate the direct invasion of cancer cells into the ECM—a mechanism that also occurs in tumors of the oral cavity.
Furthermore, MMP regulation occurs at several levels: transcription, secretion, activation, and inhibition. Some MMPs can even activate other MMPs, creating an interconnected proteolytic network in the pericellular space. MMP-14, 15, and 16 can activate MMP-2; MMP-3 activates MMP-9; and latent MMP-13 can be activated by MMP-2, 3, 10, and 14.
Why Do Dentists Need to Understand This?
This is a relevant and fundamental question. Dentistry is not limited to fillings and extractions. Every clinical procedure—from scaling and root planing to periodontal surgery, from caries treatment to soft-tissue reconstruction—involves ECM remodeling processes regulated by MMPs and TIMPs.
The review by Prof. Regina and Saini emphasizes that understanding matrix turnover in the periodontal ligament and surrounding structures, including in the context of embryology and craniofacial development, is a foundation that cannot be overlooked by anyone involved in basic dental research. Polymorphisms in MMP genes are also thought to contribute to differences in disease severity characterized by ECM degradation, suggesting that genetic factors may also play a role in an individual's susceptibility to periodontitis.
Moving forward, this review encourages the development of inhibitory factors that not only enhance our biological understanding of MMPs but also pave the way for new therapeutic interventions, particularly for diseases rooted in an imbalance of ECM degradation.
The mouth, as medical literature often describes it, is a window into the body as a whole. And behind that window, MMPs work relentlessly—sometimes building, sometimes destroying, and always operating within a balance that is more fragile than we might think.
Source DOI: http://10.5005/jp-journals-10029-1095
Authors: Anny Anggraini, drg. Achmad Zam Zam Aghasy, M.Kes.
Photo: Pexels