The histochemical distribution of Matrix Metalloproteinase-2 (MMP-2) in the coronal dentin of exfoliated human upper deciduous teeth

Introduction: Matrix Metalloproteinase-2 (MMP-2) is an enzyme synthesized by odontoblast and acts as a proteolytic enzyme capable of digesting extracellular matrix protein gelatin/collagen of dentin and is involved in the pathogenesis of dental caries. Objective: To evaluate the histological criteria and the quantitative coronal immunohistochemical MMP-2 distributions in the various deciduous teeth and to compare coronal dentine in the anterior versus posterior maxillary exfoliated deciduous teeth. Materials and Methods: Fifty extracted non-caries deciduous maxillary teeth (20 incisors, 10 canines, and 20 molars) ready to be exfoliated were collected from healthy individuals aged (6-12years). Each tooth was placed in 10% formaldehyde and fixed for 72 hours at 4°C. Mesio-distal sectioning was done for each tooth and demineralized with 10% EDTA for 5 weeks, then paraffinized and sectioned to obtain 5μm sections, stained with hematoxylin and eosin stains for histological examination and labeled with MMP-2 immunohistochemical antibodies. The immunohistochemical reactivity was quantitatively evaluated using the Aperio Image-Scope software. Statistical analysis by One-way ANOVA was done to obtain immunohistochemical MMP-2 Results: The MMP_2 expression of secondary dentin was significantly (p < 0.05) more than the primary dentin in all deciduous teeth while there was no significant difference (p> 0.05) between deep and mantle parts of primary dentin. The MMP_2 expression of dentin in canines was significantly more than in incisors and molars (p < 0.05). While there were no significant differences between molars and incisors, also there were no significant differences between anterior and posterior teeth (p>0.05). Conclusion: The MMP-2 expression in the deeper part of dentin in all deciduous teeth was significantly more than in peripheral parts. There was no significant difference in MMP-2 expression between anterior and posterior teeth.