Assessing the Effect of Matrix Metalloproteinase-9 on the Growth of Mice Teeth by NMR.

A wide spectrum of mouse and human disorders affecting tooth and bone biomineralization shows that dentin and bone formation are under strict genetic control. Although the controlling mechanisms of dentinogenesis and osteogenesis require further study, a large body of evidence points to the importance of the matrix metalloproteinases (MMPs) participate in a wide variety of extracellular matrix degradation. Currently, we attempt to find that in MMP-9 knock out (KO) mice displayed severe attrition on teeth development. In this study a technique of low-field nuclear magnetic resonance (NMR) spin relaxation (T2) is applied for assessment of MMP-9 KO mice and wild-type (normal). Then, the spin relaxation decay curve is converted into T2 distribution spectrum. Here, we propose an NMR "calibration method" - the ratio of the amount of fluid in pulp component to the amount of fluid in dentin component obtained from NMR T2 distribution spectra. This ratio method can be used to calibrate the age-growth MMP-9 KO structural changes in teeth while eliminating any variations in size of teeth. Five MMP-9 KO groups from 10 days to 147 days were tested in this study. It is found that the ratio of dental pulp chamber to dentin greatly varies on the early age periods (1 month) than on the elder ages suggesting that MMP-9 is more involved in early stages of tooth development and formation.