Objectives. The present study was done to evaluate birefringence pattern of collagen fibres in different grades of oral squamous cell carcinoma using Picrosirius red stain and polarization microscopy and to determine if there is a change in collagen fibres between different grades of oral squamous cell carcinoma. Materials and Methods. Picrosirius red stained 5 μm thick sections of previously diagnosed different grades of squamous cell carcinoma and normal oral mucosa were studied under polarization microscopy for arrangement as well as birefringence of collagen fibres around tumour islands. Results. It was found that thin collagen fibres increased and thick collagen fibres decreased with dedifferentiation of OSCC (P < 0.0001). It was observed that there was change in polarization colours of thick fibres from yellowish orange to greenish yellow with dedifferentiation of OSCC indicating loosely packed fibres (P < 0.0001). Conclusion. There was a gradual change of birefringence of collagen from yellowish orange to greenish yellow from well to poorly differentiated squamous cell carcinoma, indicating that there is a change from mature form of collagen to immature form as tumour progresses. Studying collagen fibres with Picrosirius red for stromal changes around tumour islands along with routine staining may help in predicting the prognosis of tumour.

Picrosirius red stain has been increasingly used for collagen studies in dental and medical research. Sirius red is an acidic dye which binds specifically to collagen and distinguishes type I and type III collagen fibres. This review depicts earlier uses of picric acid, preparation of the picrosirus red stain, mechanism of action, hazards and safety protocols of handling picric acid in laboratory.

Introduction: In forensic science, the determination of age plays a vital role in the identification of bodies and persons associated with crimes. Teeth are frequently better conserved than any other human remains, so their use for identifying age at death is vital. The root portion of the teeth is covered by a thin calcified layer called cementum, the annulations of which is considered to be helpful in age estimation. The objective of the study was to ascertain and compare the accuracy and efficiency of age estimation between light, polarized, and phase-contrast microscopy in the ground and decalcified sections of the tooth stained with hematoxylin and eosin by light microscopy and picrosirius red (PSR) by polarized microscopy. Materials and Methods: Fifty extracted teeth were collected and stored in a solution of 10% formalin. The middle one-third portion of the root was used, later sectioned into two halves using carborundum disc. One-half of it was used to prepare ground sections, which was studied with light, polarized, and phase-contrast microscopy. The other half was decalcified with 10% formic acid, processed, and two sections of 5 -μm thickness were prepared. One was stained with PSR stain and the second section was stained with hematoxylin and eosin (H and E) stain, One was stained with PSR stain and the second section was stained with hematoxylin and eosin (H and E) stain. Statistical analysis was performed using Z -test and Karl Pearson's correlation coefficient. Results: No statistically significant difference was observed between actual and calculated age in the ground sections, while there was a statistically significant difference observed between actual and calculated age in decalcified sections stained with H and E and PSR. A strong positive correlation was observed between actual and calculated age by Karl Pearson correlation coefficient test. Conclusion: Cemental annulation and phase contrast microscopy can be reliably utilized in forensic science to establishing age, especially among young and middle age group individuals.

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