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.

Background:Oral submucous fibrosis (OSF) is a precancerous condition in which there is excessive deposition of collagen in connective tissue. The purpose of present study was to compare changes in birefringence of collagen fibers in histopathological stages of OSF.Materials and Methods:Collagen in connective tissue of 91 cases of OSF was studied by staining 5 μm thick sections with picrosirius red. The polarization colors of thin (0.8 μm or less) and thick (1.6-2 μm) collagen fibers were recorded.Results:The birefringence of thin collagen fibers showed no difference in both histopathological connective tissue stages and degrees of epithelial dysplasia. The polarization colors of thick collagen fibers showed a gradual change from predominantly yellow-orange to greenish-yellow in advancing connective tissue stages and degrees of epithelial dysplasia.Conclusion:The results of present study show a significant change in birefringence of collagen between connective tissue stages and between mild, moderate to severe degree of epithelial dysplasia. This change in birefringence colors and arrangement of collagen fibers may give an implication of impending neoplastic change in OSF.

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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.

BACKGROUND: A variety of prophylactic materials are used in the dental office for the removal of stains and calculus. OBJECTIVE: To evaluate tooth surface changes caused by the application of air abrasive powders (sodium bicarbonate, SBAP and glycine air powder, GPAP) along with scaling and root planing (SRP), under atomic force microscope (AFM) and to analyze the histological soft tissue changes caused by these agents, using light microscopy. METHODS: This study was conducted in two phases: in vitro and in vivo. In the in vitro phase, hard tissue analysis was done under AFM following air powder polishing. Eighteen extracted teeth were chosen. SRP and tooth sectioning were carried out. Subsequently, each section of the tooth was mounted on a glass plate with self-cure acrylic resin and air polished using SBAP and GPAP. In the vivo phase, the soft tissue was analyzed under a light microscope for surface roughness. A biopsy specimen was taken from patients who had received phase I therapy, and flap surgery was planned using a modified Widman flap technique. RESULTS: This study compared surface changes in enamel and cementum, under AFM, as indicated by RA after SRP, SRP and SBAP, and SRP and GPAP; comparisons were then drawn across the three groups. The mean AFM values were 108.5 and 144.7, 102.7 and 81.7, and 95.6 and 7.4, at the crown and root, for SRP, SRP and SBAP, and SRP and GPAP interventions, respectively. GPAP was the least rough on soft tissues. CONCLUSION: SBAP and GPAP were better than hand instrumentation as indicated by AFM and histological section analysis.