Kannan Ranganathan

Chemical and physical basics of routine formaldehyde fixation

Formaldehyde is the widely employed fixative that has been studied for decades. The chemistry of fixation has been studied widely since the early 20th 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.

Oral lichen planus: An update on pathogenesis and treatment

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.

Prevalence of oral lesions in relation to habits : Cross-sectional study in South India.

BACKGROUND Smoking, drinking and chewing tobacco product, common habits in India have been positively associated with oral lesions. No study has been conducted in this part of Tamilnadu regarding the prevalence of oral lesions in relation to habits. METHODS A hospital based cross-sectional study was carried out at Ragas Dental College, Chennai. Already existing data of two thousand and seventeen consecutive patients from sub-urban areas of Chennai, who attended the outpatient department, at Ragas Dental College, for dental complaints during a period of three months in 2004, who underwent oral examination and interviewer based questionnaire was used. RESULTS Oral soft tissue lesions were found in 4.1% of the study subjects. The prevalence of leukoplakia, OSF and oral lichen planus was 0.59%, 0.55%, and 0.15% respectively. The prevalence of smoking, drinking alcoholic beverages and chewing was 15.02%, 8.78% and 6.99% respectively. Smoking and chewing were significant predictors of leukoplakia in this population. DISCUSSION The prevalence of leukoplakia, OSF and oral lichen planus in our study population is similar to those found in other populations. The prevalence of consumption of alcoholic beverages in our study population was higher when compared to the Indian National Sample Survey study. However the prevalence of smoking and chewing was found to be lower. Smokers were more likely to develop smokers melanosis compared to other lesions. Among those who consumed alcoholic beverages alone, the prevalence of leukoplakia was higher compared to other lesions. OSF was the most prevalent lesion among those who chewed panmasala or gutkha or betel quid with or without tobacco.

Oral submucous fibrosis: a clinico-histopathological study in Chennai.

BACKGROUND Oral submucous fibrosis (OSF) is a precancerous condition associated with the use of areca nut in various forms. There are very few reports to correlate the clinical stage to histopathological grading in OSF. MATERIALS AND METHODS A hospital-based study was conducted on 75 OSF cases who visited our hospital in Chennai from 2000-2003. A detailed history of each patient was recorded along with a clinical examination. Biopsy was performed for histopathological correlation. Clinical stage of the disease in terms of the ability to open ones mouth was correlated with histopathological grading. RESULTS The male to female ratio of OSF cases was 6:1. All forms of areca nut products were associated with OSF. Chewing of paanmasala was associated with early presentation of OSF as compared to chewing of the betel nut. Out of 57 cases, which were in clinical stage II, 91.2% had histological grading of I and II in equal proportions and 8.8% had histological grade III. Out of 13 cases that showed a clinical stage of III, 52% showed a histological grade of II, 40% grade III and 8% grade I. CONCLUSION In the present study, there was no direct correlation between clinical stages and histopathological grading. The possibility of difference in the severity and extent of fibrosis in different regions of the oral mucosa and involved muscles were considered as contributory factors for this variation.

MicroRNAs - Biology and clinical applications

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.

Greater severity and extent of periodontal breakdown in 136 south Indian human immunodeficiency virus seropositive patients than in normal controls: A comparative study using community periodontal index of treatment needs

Apart from the more or less distinctive forms of periodontal disease associated with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome there remains considerable uncertainty as to whether or not conventional destructive periodontitis is exacerbated in HIV positive individuals. This is especially so in developing countries, from which few studies have been reported. The present study compared the severity and extent of periodontal break down in 136 HIV positive individuals from Chennai, South India, with 136 age-matched controls from the same low socio-economic and ethnic group. All surfaces of all teeth were scored for the community periodontal index of treatment needs (CPITN). Statistical analysis was performed using SPSS package. The results of the present study show that CPITN is a simple, useful technique to assess periodontal status in immunosuppressed patients and that periodontitis is associated with immunosuppression and oral candidiasis. The assessment of periodontal statuscould thus be a useful tool in minimally invasive screening of populations for HIV disease, especially in those parts of the world, like India and Africa, with high prevalence and rising incidence.

The prevalence of oral mucosal lesions in alcohol misusers in Chennai, south India

AIMS AND OBJECTIVES This study was conducted to assess the prevalence of various oral mucosal lesions (OML) among alcohol misusers attending a rehabilitation center in Chennai, south India. MATERIALS AND METHODS Qualified dental surgeons examined 500 consecutive alcohol misusers at Ragas Dental College and Hospital and TTK Hospital, India. Thorough history and oral findings were recorded in a pre-determined format. Data entry and statistical analysis were done using SPSS 10.0.5beta. The variables for this study were OML, Oral Hygiene Index (OHI), age, smoking, and alcohol misuse (type and units consumed and duration of misuse). RESULTS Of the 500 patients, 77% were in the 25-44 years old age group and 84% were married. The mean age of initiation of alcohol misuse was 34 years. In addition to alcohol, 72% smoked tobacco and 96% used other psychoactive substances. The mean alcohol use duration was 12.6 years. A total of 25% of the study group had at least one OML. The common oral lesions were smokers melanosis (10.2%), oral submucous fibrosis (8%), and leukoplakia (7.4%). Those who misused spirits had a higher incidence of OML than those who misused beer or both. Patients with fair oral hygiene had an odds ratio (OR) of 2.96 for OML compared with an OR of 2.08 for those who had OML with good oral hygiene. CONCLUSION This study indicates that subjects who misuse alcohol have poor oral hygiene and are at risk for the development of periodontal disease and OML. This survey indicates that oral examination and treatment should be a part of the standard care for alcohol misusers at rehabilitation centers.

A light microscopic study of fibrosis involving muscle in oral submucous fibrosis

Oral submucous fibrosis (OSF) is a common pre-malignant condition of the mouth in arecanut chewers in Indian subcontinent. It is characterized by restriction in opening of the mouth, tongue protrusion, and cheek flexibility. Reports of muscle changes in OSF, using light microscopy are few. Incisional biopsy sections of thirty OSF patients were stained with Massons Trichrome stain, to study the fibrosis involving the muscle. Wide spectrum of changes were observed where fibrosis was being evident sub-epithelially, not extending in to the muscle to cases where only a few remnants of muscle fibers were seen and the missing muscle bundle area being replaced by fibrous tissue. The probable mechanism by which these changes occur is discussed.

Orofacial and systemic manifestations in 212 paediatric HIV patients from Chennai, South India

BACKGROUND Lesions in the mouth and in other tissues and organs (oral and systemic lesions) in paediatric HIV infection are diverse and show differences in clinical presentation and severity from that of adults. Very little data exist for oral lesions in paediatric population in India. AIM To document and study oral and more widespread lesions in paediatric HIV seropositive patients. DESIGN A cross-sectional study. SETTING Paediatric HIV seropositive patients at tertiary centers: Ragas Dental College and Hospital and YRG CARE, Chennai, India. PATIENTS AND METHODS Two hundred and twelve paediatric HIV patients aged 0-14 years seen over a period of 1 year were included in the study. Clinical history, oral and systemic examinations were recorded by qualified dental surgeons and physicians. RESULTS One hundred and thirty-two patients had oral lesions ranging in number from one to three. Oral lesions included oral candidiasis (OC) (56.1%), gingivitis (10.8%), oral pigmentation (6.1%), depapillation of the tongue (5.7%), ulcers (4.2%), and oral hairy leukoplakia (1.4%). The most common systemic lesion observed was nonspecific lymphadenopathy (74.1%) followed by pruritic eruptions (53.8%), measles (51.4%), and tuberculosis (TB) (49.1%). Thirty-three (26%) patients were not immunosuppressed, 74 (58%) were moderately immunosuppressed, and 20 (15%) were severely immunosuppressed. Oral lesions exhibited positive correlation with lesions in other parts of the body. CONCLUSION Oral lesions are a common feature in paediatric HIV infection. Their management is vital to improve the quality of life of the infected children.

Tooth decay in alcohol and tobacco abusers.

Background: Alcohol and tobacco abuse are detrimental to general and oral health. Though the effects of these harmful habits on oral mucosa had been demonstrated, their independent and combined effect on the dental caries experience is unknown and worthy of investigation. Materials and Methods: We compared 268 alcohol-only abusers with 2426 alcohol and tobacco abusers in chewing and smoking forms to test the hypothesis that various components of their dental caries experience are significantly different due to plausible sociobiological explanations. Clinical examination, Decay, Missing, Filled Teeth (DMFT) Index and Oral Hygiene Index - Simplified were measured in a predetermined format. Descriptive statistics, Chi-square test and one-way ANOVA analysis were done using SPSS Version 16.0. Result: The mean DMFT were 3.31, 3.24, 4.09, 2.89 for alcohol-only abusers, alcohol and chewing tobacco abusers, smoking tobacco and alcohol abusers, and those who abused tobacco in smoke and smokeless forms respectively. There was no significant difference between the oral hygiene care measures between the study groups. Presence of attrition among chewers and those with extrinsic stains experienced less caries than others. Discussion and conclusion: The entire study population exhibited a higher incidence of caries experience. Use of tobacco in any form appears to substantially increase the risk for dental caries. Attrition with use of chewing tobacco and presence of extrinsic stains with tobacco use appear to provide a protective effect from caries. The changes in oral micro-flora owing to tobacco use and alcohol may play a critical role in the initiation and progression of dental caries.