Formaldehyde is the widely employed fixative that has been studied for decades. The chemistry of fixation has been studied widely since the early 20 ^th century. However, very few studies have been focused on the actual physics/chemistry aspect of process of this fixation. This article attempts to explain the chemistry of formaldehyde fixation and also to study the physical aspects involved in the fixation. The factors involved in the fixation process are discussed using well documented mathematical and physical formulae. The deeper understanding of these factors will enable pathologist to optimize the factors and use them in their favor.

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Toluidine blue is a basic thiazine metachromatic dye with high affinity for acidic tissue components, thereby staining tissues rich in DNA and RNA. It has found wide applications both as vital staining in living tissues and as a special stain owing to its metachromatic property. Toluidine blue has been used in vivo to identify dysplasia and carcinoma of the oral cavity. Use of toluidine blue in tissue sections is done with the aim to highlight components, such as mast cells granules, mucins, and cartilage. This article provides an overview on chemistry, technique, and the various applications of toluidine blue.

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Oral lichen planus (OLP) is a chronic inflammatory disease that affects the mucus membrane of the oral cavity. It is a T-cell mediated autoimmune disease in which the cytotoxic CD8+ T cells trigger apoptosis of the basal cells of the oral epithelium. Several antigen-specific and nonspecific inflammatory mechanisms have been put forward to explain the accumulation and homing of CD8+ T cells subepithelially and the subsequent keratinocyte apoptosis. A wide spectrum of treatment modalities is available, from topical corticosteroids to laser ablation of the lesion. In this review, we discuss the various concepts in the pathogenesis and current treatment modalities of OLP.

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Xylene is an aromatic hydrocarbon known for its wide usage in tissue processing, staining and cover slipping in the histology laboratory. The hazards of xylene are well documented, making it a potential occupational hazard for the histopathological technicians. As every other profession became cautious of the occupational hazards, the very speciality that identifies the illnesses became one of the last to become aware and remedy its own hazards. This review article aims to discuss the toxicity of xylene and safety measures to counteract the hazards and enlists the pros and cons of using various substitutes that claim to be much safer, better and faster.

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Recurrent aphthous ulcers are common painful mucosal conditions affecting the oral cavity. Despite their high prevalence, etiopathogenesis remains unclear. This review article summarizes the clinical presentation, diagnostic criteria, and recent trends in the management of recurrent apthous stomatitis.

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Histopathology is the science of slide analysis for the diagnostic and research purposes. However, sometimes the presence of certain artefacts in a microscopic section can result in misinterpretations leading to diagnostic pitfalls that can result in increased patient morbidity. This article reviews the common artefacts encountered during slide examination alongside the remedial measures which can be undertaken to differentiate between an artefact and tissue constituent.

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Histopathological examination is considered as gold standard procedure for arriving at a final diagnosis of various lesions of the human body. However, it is limited by a number of alterations of normal morphologic and cytological features that occur as a result of presence of artifacts. These artifacts may occur during surgical removal, fixation, tissue processing, embedding and microtomy and staining and mounting procedures. They can even lead to complete uselessness of the tissue. It is therefore essential to identify the commonly occurring artifacts during histopathological interpretations of tissue sections. This article reviews the common artifacts encountered during slide examination alongside the remedial measures which can be undertaken to differentiate between an artifact and tissue constituent.

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Candida is the shortened name used to describe a class of fungi that includes more than 150 species of yeast. In healthy individuals, Candida exists harmlessly in mucus membranes such as your ears, eyes, gastrointestinal tract, mouth, nose, reproductive organs, sinuses, skin, stool and vagina, etc. It is known as your "beneficial flora" and has a useful purpose in the body. When an imbalance in the normal flora occurs, it causes an overgrowth of Candida albicans. The term is Candidiasis or Thrush. This is a fungal infection (Mycosis) of any of the Candida species, of which Candida albicans is the most common. When this happens, it can create a widespread havoc to our overall health and well-being of our body.

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Pyogenic granuloma or granuloma pyogenicum is a well-known oral lesion. The name pyogenic granuloma is a misnomer since the condition is not associated with pus and does not represent a granuloma histologically. Pyogenic granuloma of the oral cavity is known to involve the gingiva commonly. Extragingivally, it can occur on the lips, tongue, buccal mucosa, palate, and the like. A history of trauma is common in such sites. The etiology of the lesion is not known, though it was originally believed to be a botryomycotic infection. It is theorized that pyogenic granuloma possibly originates as a response of tissues to minor trauma and/or chronic irritation, thus opening a pathway for invasion of nonspecific microorganisms, although microorganisms are seldom demonstrated within the lesion. Pathogenesis of pyogenic granuloma is still debatable. Medline and PubMed databases were searched under the following key terms: Pathogenesis of oral pyogenic granuloma, pyogenic granuloma, and oral pyogenic granuloma. This search was limited to articles on human/animal studies which were published in English language. After reviewing the searched articles, the relevant articles were selected for the present review. Through this article, we have tried to summarize and present all the concepts of pathogenesis related to this most common and most mysterious oral lesion.

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Cancer cachexia is a wasting syndrome characterized by weight loss, anorexia, asthenia and anemia. The pathogenicity of this syndrome is multifactorial, due to a complex interaction of tumor and host factors. The signs and symptoms of cachexia are considered as the prognostic parameters in cancer patients. This review gives an emphasis on the various mechanisms involved in cachexia and an insight into head and neck cancer cachexia.

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MicroRNAs are a highly conserved group of small, non-coding RNA molecules, which are 19-25 nucleotides in size. Previously thought to be evolutionary debris with no evident function, these small RNAs have been found to control gene expression primarily by silencing the gene. MicroRNAs are critical to cell physiology and development. They are also implicated in pathological processes such as autoimmune diseases, viral infections and carcinogenesis.

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Cancer is a disease involving complex multiple sequential irreversible dysregulated processes showing metastasis that results in morbidity and mortality. Metastasis is a complex biological course that begins with detachment of tumor cells from the primary tumor, spreading into the distant tissues and/or organs, invading through the lymphovascular structures followed by their survival in the circulation. Metastatic tumors to the oro-facial region are uncommon and may occur in the oral soft tissues or jawbones. The clinical presentation of metastatic tumors can be variable, which may lead to erroneous diagnosis or may create diagnostic dilemma. Therefore, they should be considered in the differential diagnosis of inflammatory and reactive lesions that are common to the oral region. Most of the literature on oral metastases involves either single case reports or reviews of these reported cases from scattered geographical areas. Hence this present article is an attempt to provide a detailed review of pathogenesis, epidemiological details including clinical and radiographic presentations, microscopic features and treatment of metastatic tumors to the jaws and oral cavity.

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Regenerative medicine encompasses new emerging branch of medical sciences that involves the functional restoration of tissues or organs caused by severe injuries or chronic diseases. Currently, there are two contending technologies that can repair and restore the damaged tissues, namely platelet-rich plasma (PRP)- and stem cell (SC)-based therapies. PRP is a component of blood that contains platelet concentrations above the normal level and includes platelet-related growth factors and plasma-derived fibrinogen. Platelets are the frontline healing response to injuries as they release growth factors for tissue repair. SCs, on the other hand, are the unspecialized, undifferentiated, immature cells that based on specific stimuli can divide and differentiate into specific type of cells and tissues. Differentiated SCs can divide and replace the worn out or damaged tissues to become tissue- or organ-specific cells with specialized functions. Despite these differences, both approaches rely on rejuvenating the damaged tissue. This review is focused on delineating the preparation procedures, similarities and disparities and advantages and disadvantages of PRP- and SC-based therapies.

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Mucormycosis is an opportunistic fulminant fungal infection which mainly affects the immunocompromised individuals. It begins in the nose and paranasal sinuses due to the inhalation of fungal spores. The common predisposing factors include diabetes mellitus and immunosuppression. Actinomycosis is a bacterial infection caused by nonspore-forming, anaerobic or microaerophilic bacterial species of the genus Actinomyces. It is a suppurative and chronic granulomatous disease characterized by abscess formation, tissue fibrosis and draining sinuses rarely diagnosed in humans. A case of rhinocerebral mucormycosis associated with actinomycosis of the maxilla involving the palate in an uncontrolled diabetic patient is reported.

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Oral squamous cell carcinoma (OSCC) is the most common type of oral neoplasm, accounting for over 90% of all oral malignancies and 38% of head and neck tumors. Worldwide, OSCC is the eighth most common human cancer, with more than 500,000 new cases being diagnosed every year with a fairly onerous prognosis, encouraging further research on factors that might modify disease outcome. Genetic and/or environmental risk factors associated with the development of oral cancer have been sufficiently understood (smoking, alcohol, betel, diet, living habits, etc.). Knowledge of the genetic basis in oral carcinogenesis is still a challenging task. To improve the diagnosis and prevention, a previously unknown type of chromatin modification, known as epigenetic, which is defined as heritable DNA changes that are not encoded in the sequence itself and which are reversible and increasingly appear to serve fundamental roles in cell differentiation and development are studied. Tumors shed their DNA into the blood and epigenetic changes that occur early during tumorigenesis, sometimes even in premalignant lesions, can provide valuable biomarkers. Key components involved in epigenetic regulation are DNA methylation, histone modifications and modifications in micro ribonucleic acids (miRNAs). Epigenetic modifications may contribute to aberrant epigenetic mechanisms seen in oral precancers and cancers. In the near future, epigenetic variations found in oral dysplastic cells can act as a molecular fingerprint for malignancies.

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Background: Saliva is a unique fluid, which is important for normal functioning of the oral cavity. Diabetes mellitus (DM) is a disease of absolute or relative insulin deficiency characterized by insufficient secretion of insulin by pancreatic beta-cells. The diagnosis of diabetes through blood is difficult in children, older adults, debilitated and chronically ill patients, so diagnosis by analysis of saliva can be potentially valuable as collection of saliva is noninvasive, easier and technically insensitive, unlike blood. The aim of the study was to correlate blood glucose level (BGL) and salivary glucose level (SGL) in DM patients. Methodology: A cross-sectional study was conducted in 120 patients, who were categorized as 40 controlled diabetics, 40 uncontrolled diabetics and 40 healthy, age- and sex-matched individuals constituted the controls. The blood and unstimulated saliva samples were collected from the patients at the different intervals for fasting, random and postprandial levels. These samples were then subjected for analysis of glucose in blood and saliva using glucose oxidase/peroxidase reagent in HITACHI 902^(R) Automatic analyzer, and the results were recorded. Results: The mean SGLs were higher in uncontrolled and controlled diabetic groups than in nondiabetic group. A highly statistically significant correlation was found between fasting saliva glucose and fasting blood glucose in all the groups. Conclusion: With increase in BGL, increase in SGL was observed in patients with diabetes suggesting that SGL can be used for monitoring glycemic level in DM.

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Background: Diabetes mellitus is a metabolic disease leading to abnormal fat, carbohydrate and protein metabolism. Reduced salivary flow rate caused by hyperglycemia is characteristic mainly for periods of poor metabolic control of diabetes, thereby facilitating the growth of aciduric bacteria and caries-lesion development. The objective of our study was to evaluate the effects of diabetes mellitus on dental caries micro-organisms responsible for caries. Materials and Methods: This study was carried out on 60 subjects consisting of 2 groups. The Group A (study group) consisted of 30 subjects with diabetes mellitus and dental caries, and the Group B (control group) consisted of 30 subjects with dental caries but no systemic disease. DFS/dfs index in all subjects was evaluated and compared. Unstimulated salivary flow was collected and levels of Streptococcus mutans were analyzed. Results: It was found that the fasting blood sugar in Group A subjects because of which there was increased streptococcus mutans count and hence high caries index as compared to that of Group B. Conclusion: From our study, we could conclude that with increased age, blood sugar levels, DMFT values, dental caries increases in diabetics than in normal (control) subjects and therefore relationship does exist between diabetis mellitus, oral microbiota and dental caries.

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Background: Histological grading is an important diagnostic tool to predict the clinical and biological behaviour of cancer. Cervical lymph node metastasis indicate poor prognosis of oral cancer. Considering economical status of a third world country, Anneroth's grading system is less expensive, more informative than TNM staging and Broder's grading system. Anneroth's grading system also shows co-relationship with lymph node metastasis. So we are trying to evaluate the Anneroth's grading as a standard one among these three system. Objective: To study the grading of histological malignancy according to Anneroth's classification of biopsy specimens in relation to metastasis in the cervical lymph nodes and comparing the Anneroth's with the other two recognized classifications. Materials and Methods: Fifty(50) patients with oral squamous cell carcinoma was included in the study. Specimen of 35 non-metastatic tumors were compared with 15 metastatic cases. All of the patients were graded to TNM, Broder's and Anneroth's system. TNM is clinical assessment and Broder's is based on only differentiation of cells. On the other hand, six parameters of Anneroth's gives a detail about the morphology of the tumor, invasion criteria in the host tissue and show its correlation with lymph node metastasis. Scoring system of Annearoth's grading indicates demarcation points of worseness of tumor and signifies the possibility of lymph node metastasis. Results: Both Anneroth's(P=0.002) and Broder's grading(P=0.012) have been significant but Anneroth's one is more significant then Broder's. Conclusion: Anneroth's classification can be taken as a standerd diagnostic factor and predictive factor of lymph node metastasis.

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The majority of opportunistic oral mucosal fungal infections are due to Candida albicans and Aspergillus fumigatus species. Mucor and Cryptococcus also have a major role in causing oral infections, whereas Geotrichum, Fusarium, Rhodotorula, Saccharomyces and Penicillium marneffei are uncommon pathogens in the oral cavity. The broad spectrum of clinical presentation includes pseudo-membranes, abscesses, ulcers, pustules and extensive tissue necrosis involving bone. This review discusses various uncommon opportunistic fungal infections affecting the oral cavity including their morphology, clinical features and diagnostic methods.

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Context: Microbial contamination, which occurs during dental procedures, has been a potential threat to dental professionals and individuals. There has been a growing concern over the role of bioaerosols in spread of various airborne infections and also to reduce the risk of bioaerosol contamination. Aims: This study was to analyze the number of colony forming units (CFUs) in bioaerosols generated during ultrasonic scaling procedure as well as to evaluate the efficacy of chlorhexidine 0.12% (CHX) preprocedural mouth rinse and high volume evacuator (HVE) in minimizing the bioaerosol contamination. Methods: About 45 individuals were divided into three Groups A, B and C. These groups underwent ultrasonic scaling before and after the use of CHX (0.12%), HVE and combination of CHX (0.12%) and HVE. Bioaerosols were collected on blood agar plates which were incubated at 37°C for 48 h, and the CFUs were counted with manual colony counting device. A comparison was also done between A versus B, B versus C and A versus C groups. Statistical Analysis Used: Student's t-test. Results: We found a significant reduction in the CFUs when CHX (0.12%) preprocedural rinse (P < 0), or HVE (P < 0.001) or combination of both CHX (0.12%) and HVE were employed (P < 0.001). Maximum reduction in CFUs was observed when CHX (0.12%) and HVE were used in combination as compared to their individual use. A moderate significance was seen between A versus C groups but not with B versus C groups and A versus B groups. Conclusion: From our study, we conclude that individual methods such as CHX (0.12%) and HVE were useful to reduce the dental bioaerosols; however, combination of both CHX (0.12%) and HVE is more efficient to reduce dental bioaerosols than individual method.

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Background: Immunohistochemistry (IHC) is a molecular technique that has grown tremendously over the years. However, the assessment is only qualitative which is subjective and causes errors. Due to this limitation, several excellent markers have not gained importance and reached clinical trials. Hence, we aimed to quantify IHC by ImageJ analysis with a novel IHC profiler plugin. ImageJ has not been tried in oral precancerous tissues with minimal attempt for matrix markers. Aim: This study aimed to validate the quantification of immunoexpression of tenascin-C (TN-C) in oral precancerous tissues and oral squamous cell carcinoma (OSCC) using ImageJ software with IHC profiler plugin. Materials and Methods: After IHC staining for TN-C and image acquisition, ImageJ analysis was performed as per the standard recommended algorithm. Assessment was done by two observers by blinding the histopathological diagnosis. The immunoscore was assessed for interobserver variability using Kohen's kappa statistics. Results: All our cases were in agreement and found to be statistically significant with P < 0.005. Moderate agreement was for mild dysplasia, moderate dysplasia and oral lichen planus. Substantial agreement was for oral submucous fibrosis and OSCC and almost perfect agreement noted for cases of severe dysplasia. Conclusion: IHC can now be quantified using freely downloadable software ImageJ analysis in oral precancerous tissues and OSCC. This software with good threshold control can quantify matrix marker such as TN-C. Hence, herewith, we propose that IHC markers should be quantified using ImageJ by our entire oral pathology fraternity so as to have a standard immunoscore for all markers.

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Glucose, a major source of energy for all cells, is transported into cells with the help of glucose transporters (GLUTs). These transporters are of two types, namely sodium-dependent GLUTs and facilitative GLUTs. These transporters are present in a tissue-specific pattern and have substrate specificity. Among these transporters, GLUT1 (facilitative GLUT) is present ubiquitously on all tissues of the body and helps in the basal uptake of glucose. GLUT1 is known to have many physiological functions in the body from the time of implantation of an embryo and is also seen associated with pathologies, including cancers. This review mainly focuses on GLUT1 in physiological and pathological conditions and the recent advances related to its role in cancer development and applications in cancer therapeutics.

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Cleft lip and palate (CLP) are birth defects that affect the upper lip and the roof of the mouth. CLP has a multifactorial etiology, comprising both genetic and environmental factors. In this review we discuss the recent data on the etiology of cleft lip and palate. We conducted a search of the MEDLINE database (Entrez PubMed) from January 1986 to December 2010 using the key words: 'cleft lip,' 'cleft palate,' 'etiology,' and 'genetics.' The etiology of CLP seems complex, with genetics playing a major role. Several genes causing syndromic CLP have been discovered. Three of them-T-box transcription factor-22 (TBX22), poliovirus receptor-like-1 (PVRL1), and interferon regulatory factor-6 (IRF6)-are responsible for causing X-linked cleft palate, cleft lip/palate-ectodermal dysplasia syndrome, and Van der Woude and popliteal pterygium syndromes, respectively; they are also implicated in nonsyndromic CLP. The nature and functions of these genes vary widely, illustrating the high vulnerability within the craniofacial developmental pathways. The etiological complexity of nonsyndromic cleft lip and palate is also exemplified by the large number of candidate genes and loci. To conclude, although the etiology of nonsyndromic CLP is still largely unknown, mutations in candidate genes have been identified in a small proportion of cases. Determining the relative risk of CLP on the basis of genetic background and environmental influence (including smoking, alcohol use, and dietary factors) will be useful for genetic counseling and the development of future preventive measures.

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Context: Most of the adult population is colonized by Candida in their oral cavity. The process of colonization depends on several factors, including the interaction between Candida and salivary proteins. Therefore, salivary gland hypofunction may alter the oral microbiota and increase the risk for opportunistic infections, such as candidiasis. Hence, it is necessary to evaluate the relationship between salivary flow rates (SFRs) and Candida colony counts in the saliva of patients with xerostomia. Aims: This study aims to determine and evaluate the relationship between SFRs and Candida colony forming units (CFUs) in patients with xerostomia. Settings and Design: This study was a descriptive study. Subjects and Methods: The study participants were taken from the patients attending outpatient department in a private dental college. Fifty patients, who reported xerostomia in a questionnaire of the symptoms of xerostomia, were selected. Chewing stimulated whole saliva samples were collected from them and their SFRs were assessed. Saliva samples were inoculated in the Sabouraud dextrose agar culture media for 24–48 h, and Candida CFUs were counted. Statistical Analysis Used: Chi-squared test was used to analyze the data. Results: There was a significant inverse relationship between salivary flow and candida CFUs count when patients with high colony counts were analyzed (cutoff point of 400 or greater CFU/mL). Females had less SFR than males. Most of the patients who had hyposalivation were taking medication for the underlying systemic diseases. Candida albicans was the most frequent species. Conclusions: There was a significantly negative correlation between SFRs and Candida CFUs in the patients with xerostomia.

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Cancer stem cells (CSCs) have the ability to self-renew and are present in most tissues including breast, brain, lung, head and neck, prostates, testis, ovary, esophagus, colon and liver. Their origin is yet to be discovered though a series of hypotheses have been proposed in this regard. CSCs play a role in not only the creation of cancer but also its evolution, metastasis and recurrence. CSCs have an important role in cancer therapy and the resistance toward chemotherapeutic agents. This article reviews the characteristics of CSCs in terms of origin, methods of isolation and cancer therapy.

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