Artifact refers to an artificial structure or tissue alteration on a prepared microscopic slide—the result of an extraneous factor. It can result in alteration of normal morphologic and cytologic features that may occur as a result of the way the tissue has been handled, right from the time the biopsy, which is surgically obtained till the entire histopathological procedures of fixation, processing, embedding, sectioning and staining are performed on it. The procedures themselves subject to human and material errors resulting in an artifact may interfere with an adequate diagnosis or render the tissue to be undiagnosable. The present review provides in depth knowledge on the mismanagement of tissue during different biopsy sampling techniques and various processing procedures leading to the appearance of artifacts. Such familiarization in turn will contribute to knowledge of the material and instruments required for correct biopsy performance in dentistry, as well as of the material required for correct sample storage, transport and processing thereby necessitating stringent precision in technique at every step to enable an accurate diagnosis. How to cite this article Kumar K, Shetty DC, Dua M. Biopsy and Tissue Processing Artifacts in Oral Mucosal Tissues. Int J Head Neck Surg 2012;3(2):92-98.

Tooth enamel is a unique entity among all mineralized tissues because of the presence of high mineral content. It is non collagenous and does not undergo resorption and remodelling. Its formation occurs through a transient collaborating network of enamel matrix proteins which controls hydroxyapatite crystal growth and orientation. Amelogenins constitute about 90% of the total enamel matrix proteins and play a major role in enamel bio mineralization. Amelogenin isoforms coalesce into nanospheres thus dictating the width and thickness of apatite crystals. The X and Y copies of amelogenins do not undergo homologous recombination, thus preferring it for sex determination in modern forensics. Recently, it was discovered that application of amelogenin to diseased periodontal tissue surfaces enhanced the regeneration of all the periodontal tissues. Additionally, low molecular mass amelogenin polypeptides have also been thought to possess osteogenic potential. Recent data regarding usage of immunohistochemical markers for mesenchymal stem cells suggested that amelogenin has the capacity to induce the recruitment of mesenchymal stem cells directly or indirectly during regeneration of the supporting periodontal tissues. Thus, our current concepts of dental enamel formation should be reviewed thoroughly so that this information could be applied to clinical circumstances where this understanding may be particularly relevant.

Several tumors exhibit pH gradient reversal, with acidification of extracellular pH (pHe) and alkalinization of intracellular pH (pHi). The pH gradient reversal is evident even during the preliminary stages of tumorigenesis and is crucial for survival and propagation of tumors, irrespective of their pathology, genetics and origins. Moreover, this hallmark seems to be present ubiquitously in all malignant tumors. Based on these facts, we propose a new emerging hallmark of cancer "pH gradient reversal". Normalizing pH gradient reversal through inhibition of various proton transporters such as Na(+)-H(+) exchanger (NHE), Vacuolar-type H(+)-ATPase (V-ATPase), H(+)/K(+)-ATPases and carbonic anhydrases (CAs) has demonstrated substantial therapeutic benefits. Indeed, inhibition of NHE1 is now being regarded as the latest concept in cancer treatment. A recent patent deals with the utilization of cis-Urocanic acid to acidify the pHi and induce apoptosis in tumors. Another patent reports therapeutic benefit by inhibiting Lactate Dehydrogenase - 5 (LDH-5) in various cancers. Several patents have been formulated by designing drugs activated through acidic pHe providing a cancer specific action. The purpose of this review is to analyze the available literature and help design selective therapies that could be a valuable adjunct to the conventional therapies or even replace them.

The study supports the theory that POF develops from cells of periodontal ligament (PDL)/periosteum as undifferentiated mesenchymal cells having an inherent proliferative potential to form bone or cementum, whose nature can be confirmed by polarizing microscope.

Objective: To assess inter and intra observer variability in grading oral epithelial dysplasia (OED) using Smith and Pindborg grading system, WHO classification system and Brothwell DJ et al. classification system. Study design: In the study 45 histological tissues of dysplasia, 15 each of mild, moderate and severe dysplasia were coded and blindly graded by three observers in three grading systems. Further on the same observers graded 15 slides again of the previous 45 for analyzing the reproducibility in the three grading systems. The individual significance of various indicators of dysplasia among various grades of dysplasia was also assessed. Result: Inter observer agreement was significantly higher in Brothwell system as compared to WHO and Smith and Pindborg system. Intra observer agreement was significantly higher in Smith and Pindborg system, but the predictability and the probability index was distributed over a larger range in this system. Each indicator of dysplasia was also found to be statistically significant (P<0.05) for grading dysplasia. Conclusion: The present study puts forth the inherent intricacies in the grading of oral premalignant lesions. Key words:Carcinoma, dysplasia, grading systems, reproducibility.