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Background: Oral cancer represents a significant component of the global cancer burden. It develops as a result of multiple risk factors. The main histological form of oral cancer is oral squamous cell carcinoma (OSCC). The disintegration of the extracellular matrix (ECM) is one of the key hallmarks of cancer progression, which stimulates the invasion of tumoral cells into the neighbouring tissue. Matrix metalloproteinases-9 (MMP-9) can degrade different elements of the ECM and basement membrane. Methods: A total of 35 histologically diagnosed cases of OSCC (n=25) and healthy individuals (n=10) as control were included. Immunohistochemical staining was performed on all cases. The results were analysed using SPSS version 20. Results: Increased expression of MMP-9 was observed in OSCC cases (n=23/25; 92%) as compared to healthy individuals. Statistically, a significant relation was observed while comparing the grade of staining intensity and MMP-9 expression among OSCC cases (p=0.001). Conclusion: The present study is planned to assess the immunohistochemical expression of MMP-9 in diagnosed cases of OSCC and healthy individuals. Increased expression of MMP-9 was observed in OSCC as compared to healthy individuals. Evaluation of MMP-9 could be of clinical importance in OSCC and can be used as a diagnostic predictive marker of OSCC. Keywords: Oral squamous cell carcinoma; Matrix Metalloproteinase -9; Immunohistochemistry

Mucopolysaccharidosis (MPS) is an inherited metabolic disorder that can affect the tooth structure leading to defects. Synchrotron X-ray diffraction being a state of the art technique has been used to determine the enamel crystallite orientation in deciduous enamel affected by Mucopolysaccharidosis Type I and Mucopolysaccharidosis Type IVA and comparing these with that of healthy deciduous enamel. Using this technique it was observed that there is a loss of texture in deciduous enamel affected by Mucopolysaccharidosis Type I and Mucopolysaccharidosis Type IVA when compared to the healthy deciduous enamel. Generally it was observed that the incisal surface of the deciduous teeth possessed a higher texture or preferred orientation of enamel crystallites and on progression towards the cervical region there was a decrease in the texture or preferred orientation of enamel crystallites. Scanning electron microscopy showed that the presence of a poorly calcified layer between the enamel and dentine at the enamel-dentine junction (EDJ) in MPS affected samples was likely to be responsible for rendering the tooth structure weak and prone to fracture as is often the case in MPS affected deciduous enamel.

Objectives To understand the pathology of the ultrastructure of enamel affected by systemic disorders which disrupt enamel tissue formation in order to give insight into the precise mechanisms of matrix-mediated biomineralization in dental enamel in health and disease. Methods Two-dimensional synchrotron X-ray diffraction has been utilized as a sophisticated and useful technique to spatially quantify preferred orientation in mineralized healthy deciduous dental enamel, and the disrupted crystallite organization in enamel affected by a systemic disease affecting bone and dental mineralization (mucopolysaccharidosis Type IVA and Type II are used as examples). The lattice spacing of the hydroxyapatite phase, the crystallite size and aspect ratio, and the quantified preferred orientation of crystallites across whole intact tooth sections, have been determined using synchrotron microdiffraction. Results Significant differences in mineral crystallite orientation distribution of affected enamel have been observed compared to healthy mineralized tissue. The gradation of enamel crystal orientation seen in healthy tissue is absent in the affected enamel, indicating a continual disruption in the crystallite alignment during mineral formation. Conclusions This state of the art technique has the potential to provide a unique insight into the mechanisms leading to deranged enamel formation in a wide range of disease states. Clinical relevance Characterising crystal orientation patterns and geometry in health and following disruption can be a powerful tool in advancing our overall understanding of mechanisms leading to the tissue phenotypes seen clinically. Findings can be used to inform the appropriate dental management of these tissues and/or to investigate the influence of therapeutic interventions or external stressors which may impact on amelogenesis.