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The lactate dehydrogenase isoenzyme pattern of biopsies from Indian oral leukoplakia, submucous fibrosis and carcinoma of the oral mucosa as well as that of oral mucous membrane biopsies from clinically normal Indian persons has been studied. The LDHIV/LDHII isoenzyme ratios found for leukoplakias, carcinomas and control biopsies did not differ significantly. The mean isoenzyme ratio of Indian control biopsies was significantly above that reported for Danish control biopsies. Submucous fibrosis was accompanied by a significant depression of the isoenzyme ratio. No clear correlation between LDH isoenzyme pattern and epithelial thickness was found. Smoking and chewing habits, which may be correlated with prevalence and localization of oral leukoplakias and carcinomas, did not significantly influence the isoenzymatic structure. Although final conclusions cannot be drawn, the high isoenzyme ratio of the Indian control material may represent an early precancerous condition, unrelated to smoking and chewing, preceding the histopathological manifestations of precancerous lesions.

An international group of epidemiologists, clinicians and pathologists with a special interest in oral white lesions and their precancerous significance has reviewed earlier work on this topic and identified some of the problems associated with previous definitions, descriptions and classifications. Modifications to these definitions, descriptions and classifications have been proposed, accompanied by explanations of the reasons for identifying the need for changes to be made. Leukoplakia may be a provisional or definitive diagnosis dependent upon the circumstances of oral examination and the availability of other information. Guidelines are provided to assist in the application of the definitions of oral leukoplakia and illustrations depict the homogeneous and non-homogeneous clinical variants. Consideration is also given to the importance of a red component in a white lesion, or a lesion that is entirely red (erythroplakia). A new clinical staging procedure for oral leukoplakia is also proposed.

Oral mucosal lesion findings from a national multistage probability oral health survey of United States schoolchildren in kindergarten through grade 12 are reported. In the 1986-87 school year 39,206 children aged 5-17 yr were examined by 14 dentists trained in standardized clinical diagnostic criteria for dental caries, periodontal conditions and oral mucosal lesions. In addition all children were asked whether or not they ever had "cold sores," "fever blisters," or "canker sores", and adolescents (grades 6-12) were questioned about their history of tobacco use. About 4% of the children had one or more oral mucosal lesions present at the time of the examination, while 33 and 37% reported a history of recurrent herpes labialis and recurrent aphthous ulcers, respectively. The most prevalent lesions clinically observed were recurrent aphthous ulcers (1.23%), recurrent herpes labialis (0.78), smokeless tobacco lesions (0.71), and geographic tongue (0.60). Differences in prevalence were analyzed by age, sex, race, metropolitan area, and geographic region. Almost 10% of 12-17-yr-olds reported current use of some type of tobacco product. In adolescents the current use of tobacco products had a marked effect on the prevalence of oral lesions.

The melanin pigmentation in the palate of Indian reverse smokers was histologically studied in 80 biopsies, which were compared with corresponding tissue from 49 nontobacco users. The morphology of epithelium containing melanin in its basal part was normal in smokers and nonsmokers, in contrast to areas with a local melanin depigmentation of the epithelium found in some of the reverse smokers. Here an epithelial thinning, inflammation in the underlying connective tissue, and eventually a cancer was found. The histologic appearance was in accordance with the theory that as long as a smoker's melanosis or a genetic melanin pigmentation is present, melanin functions as a defence against toxic agents penetrating into the oral mucosa.

One hundred and twenty Danish homosexual men were enrolled to characterize risk factors for anal type-specific human papillomavirus (HPV) expression and to examine its association with anal epithelial atypia. Detection of HPV strongly correlated with immunosuppression measured by T-lymphocyte subset markers and rose nearly linearly from 7.3% among subjects with CD4/CD8 ratios above 1.0 to 35.3% among those with a ratio below 0.4 (p trend = 0.003). No association was found between presence of HPV and a wide range of lifestyle factors including number of sex partners/year, smoking, alcohol consumption and illegal drug intake. However, self-reported history of anal condyloma in the past year was correlated with HPV (p less than 0.001). Simultaneous testing for presence of HPV in the oral cavity showed evidence of HPV 16,18 and 31,33,35. Anal smears were abnormal in 19.5% of the men and correlated strongly with presence of HPV (OR = 6.1, p less than 0.001). Type-specific associations were found with HPV 31/33/35 (OR = 8.5) and HPV 16/18 (OR = 3.1) only. The association remained significant after adjusting for immune status. Overall, HPV was detected in 50% of the cases with abnormal smears. However, HPV was found in all subjects with abnormal smears and a CD4/CD8 ratio below 0.4, compared to only 3 of 14 subjects with abnormal smears and a ratio greater than or equal to 1.3. In conclusion, (1) HPV may be missed in a substantial number of infected subjects with a normal immune system. This may have an impact on studies trying to describe risk factors for HPV transmission and its correlation with cancer development. (2) The finding of HPV 16,18 and 31,33,35 in the oral cavity makes oral-genital sexual activity at least a hypothetical route of transmission for these HPV types. (3) HPV appears to play a central role in the development of anal epithelial abnormality.

A case-control study to elucidate the etiology of oral submucous fibrosis was conducted in Bhavnagar, Gujarat. Sixty consecutively arriving oral submucous fibrosis patients at a dental clinic were selected as cases. An equal number of controls matched for age, sex, religion and socioeconomic status were selected from individuals who did not exhibit any oral mucosal lesion or condition. Among cases, 98% chewed areca nut regularly in one form or the other whereas among controls 35% chewed areca nut, giving an overall relative risk of 109.6. Areca nut chewing was practiced most commonly in the form of mawa: a mixture containing mainly areca nut (over 90% by weight), some tobacco, and a few drops of lime. Mawa chewers and those who chewed mawa along with other chewing habits showed very high relative risks. The relative risks increased with increase in the frequency as well as the duration of chewing habits. In a bivariate analysis the effect of frequency and duration of chewing appeared to be multiplicative. The present findings confirm areca nut as the most important etiologic factor in oral submucous fibrosis.

Epstein-Barr virus and multivesicular structures appearing in lesions of hairy leukoplakia have been examined ultrastructurally in serial sections. It was found that both structures probably represent various levels of sectioning of transversely cut cell processes. The so-called viral nucleocapsid having a single membrane results when the plane of section is at right angles to one of the membranes but tangential to the other. While the so-called viral particle having two membranes would result if the plane of section is perpendicular to both the membranes of adjacent cells. The internal electron-dense core probably represents filaments enclosed within these processes and therefore does not represent DNA nucleotides. In addition, these nuclei contained bundles of filaments which probably represented tonofilaments. This was found to be due to tangential sectioning of the nuclear membrane surrounding deep cytoplasmic invaginations which led to the appearance of these filaments as if free within the nucleus.

Besides genetic factors, tobacco smoking is known to be the main cause of oral melanin pigmentation. The present study compares the frequency of oral melanin pigmentation in a large number of former smokers with that of non-smokers. It also describes in two patients the disappearance of smoker's melanosis in the buccal mucosa following a considerable reduction in smoking.

One hundred Danes with oral cancer who were collected consecutively from 1986 to 1991 were evaluated retrospectively. The study included subjective and objective observations in 56% men and in 44% women. M:F ratio was 1.2:1. Fifty percent of the patients were non-smokers. Nine percent were women who did not drink alcohol. Ten percent of the patients were between 40 and 49 years of age, 20% between 50 and 59 years, 35% were between 60 and 69 years and 20% between 70 and 79 years of age. This may reflect a tradition of early drinking and smoking. Doctor's delay was the cause of delayed referral in 14% of the cases while 72% of the patients were the cause themselves for the delayed referral.

A benign but locally invasive polymorphic neoplasm consisting of proliferating odontogenic epithelium, which usually has a follicular or plexiform pattern, lying in a fibrous stroma.

The classification applies only to carcinomas of the vermilion surfaces of the lips and of the oral cavity, including those of minor salivary glands. There should be histological confirmation of the disease.The following are the procedures for assessment of the T,N and M categories: T categories Physical examination and imaging N categories Physical examination and imaging M categories Physical examination and imaging

Histological Classification of Cancer and Precancer of the Oral Mucosa.- Definitions and Explanatory Notes.- Carcinomas.- Benign Lesions Capable of Microscopically Resembling Oral Squamous Cell Carcinoma and Oral Verrucous Carcinoma.- Precancerous Lesions (Clinical Classification).- Precancerous Lesions (Histological Classification).- Benign Lesions Capable of Resembling Oral Precancerous Lesions.- Precancerous Conditions.- TNM Classification of Lip and Oral Cavity Carcinomas.- Illustrations.

Oral submucous fibrosis (OSF) is a high risk precancerous condition, predominantly affecting Indians. Consumption of chilli was hypothesized as an etiologic factor on the basis of ecological observations and a solitary animal experimental study. Subsequent epidemiologic studies that included case-series reports, large cross-sectional surveys, case-control studies, cohort and intervention studies have identified areca nut as the major etiologic agent. Tissue-culture studies involving human fibroblasts, areca nut extracts and areca nut alkaloids supported this etiologic hypothesis by showing fibroblastic proliferation and increased collagen formation. Currently, the role of genetic susceptibility and that of autoimmunity are receiving attention. The influence of nutritional factors, if any, remains unclear.

A total of 84 HIV-infected homosexual men having either normal oral mucosa (NOM), erythematous candidiasis (EC) or pseudomembranous candidiasis (PsC) were included in the study. The patients were evaluated by median number of peripheral CD4+ cells, CD8+ cells and by lymphocyte function assessed by poke-weed mitogen test. There was a significant difference between CD4+ counts among patients with the two subtypes of candidiasis (95% CI of median difference: 10-240/mm3; P = 0.03), but not for pokeweed mitogen response. Survival analysis showed that after 2 y there was no significant difference in development of AIDS between patients with EC and PsC (P = 0.29). If patients with both types of oral candidiasis were pooled and compared with patients with NOM, a significant difference in development of AIDS was found (P = 0.04). It is concluded that HIV-infected patients with oral candidiasis of any subtype (EC or PsC) are significantly more immune suppressed and show a faster development of AIDS than HIV-infected patients with NOM. However, in this cohort, EC and PsC are of equal importance as predictors for immune suppression and AIDS development.

In 1967, the World Health Organization (WHO) established a WHO Collaborating Centre for Oral Precancerous Lesions in Copenhagen. In 1972, while work was being carried out at this center, a meeting arranged by WHO was held in Geneva with the aim of defining precancerous lesions in different organs of the body. As result of this meeting, the suggestion of distinguishing between precancerous lesions and precancerous conditions was made. A precancerous lesion is a morphologically altered tissue in which cancer is more likely to occur than in its apparently normal counterpart. A precancerous condition, on the other hand, is a generalized state associated with a significantly increased risk of cancer. Examples of precancerous conditions are syphilis, submucous fibrosis, and lichen planus.

Incidence of oral submucous fibrosis was calculated from a 10-yr prospective intervention study of 12,212 individuals with a strong component of health education on tobacco and area nut chewing. Based on 11 new cases among 6341 chewers, the annual incidence was 8.0 per 100,000 among men and 29.0 for women. An earlier 10-yr follow-up study, with no intervention component, served as control. Based on 11 new cases among 3,809 chewers, the annual incidence was 21.3 per 100,000 for men and 45.7 for women controls. Although the decrease in the incidence in the intervention cohort was not statistically significant due to small number of cases, the results underscored the causal role of areca nut chewing and indicated the potential for primary prevention of oral submucous fibrosis.

A group of 20,358 villagers in two districts of India has been followed for 7 years to study the incidence of oral leucoplakia. The follow-up rate of the population in two districts ranged from 61% to 71%. In one of the districts (Bhavnagar) no new cases of leucoplakia were found among females in the 7-year period. Among males 105 cases developed (4-0/1000/year). The incidence was highest among hookli (clay pipe) smokers. In the Ernakulam district the incidence among males was 3-3/1000/year whereas among females it was 1-9/1000/year. The mixed habits group had the highest incidence of oral leucoplakias (7-2 and 9-9/1000/year among males and females respectively).

The course of reticular, papular, bullous, plaque-type, atrophic and ulcerative lesions of oral lichen planus (OLP) was studied in 611 patients. Mean age of the patients was 53 years and two-thirds were women. The patients were followed for periods from 1 to 26 years (mean, 7.5 years). The various clinical types had somewhat different courses. Papular affections were seen mainly in the initial phase and had a transitory course. Ulcerative lesions, although more persistent, also generally showed a short-term course. The atrophic form was fluctuating with many remissions and new-established affections. The plaque-type was a more constant form, but also demonstrated many newly established affections. After a few years, many patients had persistent lesions that no longer included the affections most characteristic of OLP, i.e. the reticular and the papular form. Initial presence of papular affections was associated with ages below 50 and atrophic lesions with ages above 60. Plaque-type affections were seen with a significantly higher frequency among tobacco smokers at the onset of OLP. No other correlation was found between the initial presence, the remission and the development of the different clinical forms and various factors as age, sex, general diseases, medication and tobacco smoking. Treatment with topical steroid and/or antimycotics had no effect on the long-term course of the various clinical forms, and it had no persistent effect on symptoms related to OLP. Complete remission was seen in 17% of the patients, and it showed a reverse association with the initial presence of plaque-type affections. However, complete remission was associated with an initial presence of papular affections. No other predictive factor of total remission was found.

In the eastern part of Java and on the island of Bali betel chewing is a very common habit confined principally to females. The purpose of the present study was to examine the influence of betel chewing on the prevalence of dental caries. The study, which is based upon 982 villagers, indicates a strong inverse relationship between the prevalence of dental caries and the intensity of betel chewing. The possible mechanisms whereby betel chewing may have a caries-inhibiting effect are discussed.

A review of the world literature has revealed 113 cases of the calcifying epithelial odontogenic tumor. The clinical, radiographic, and histopathologic features are analyzed. Various treatments that have been carried out are related to the frequency of recurrence. The theories of histogenesis are discussed and an attempt is made to explain the nature and origin of the amyloid-like substance.

A study of 112 biopsy specimens from Danish oral leukoplakia patients and 145 biopsy specimens from Indian leukoplakia patients revealed a chevron-like keratinization of the epithelium in a number of cases. Clinically, this type of keratinization was often characterized by a pumice-like appearance. The clinical and histologic changes were only observed in tobacco users, and appeared to be associated particularly with use of pipes, snuff, and hooklis.

Verrucous hyperplasia of the oral mucosa is a relatively unrecognized entity that may resemble verrucous carcinoma clinically and histologically. This study describes the clinical and histological features of the condition, particularly in relation to verrucous carcinoma. Sixty-eight cases were selected by screening all lesions accessioned as verrucous or papillary lesions of various kinds, dysplasias and leukoplakias. More cases occurred in women (56%) than in men (44%). All but 3 patients were 50 yr. or older, and 35% were over 70. Gingiva or alveolar mucosa were involved most frequently (27%), followed by cheek (24%), tongue (17%), floor of mouth and lip (12% each), and palate (8%). Verrucous processes are either sharp and heavily keratinized or blunt with a thin parakeratin layer. In 36 patients (53%), there was associated leukoplakia; in 20 (29%), there was associated verrucous carcinoma; in 45 (66%), associated epithelial dysplasia; and in 7, (10%) there was associated squamous carcinoma. Verrucous carcinoma or squamous carcinoma. Verrucous hyperplasia is best distinguished from verrucous carcinoma in biopsies taken at the margins of the lesions. In the former, the verrucous processes and the greater part of the hyperplastic epithelium are superficial to adjacent normal epithelium. In the latter, the verrucous processes are superficial, but the broad rete processes extend considerably deeper than adjacent normal epithelium, often pulling a margin of normal epithelium down with them into the underlying connective tissue.

A house-to-house survey of 11 villages selected by random sampling was carried out in Bilugyun, Chaung-zone township, Mon State of South Eastern Burma to study the prevalence of oral precancerous lesions and smoking and chewing. A total of 6000 villagers who were above 15 years at the time of this study were examined. The prevalence of preleukoplakia was 0.3%, leukoplakia 1.7%, lichen planus 0.4%, leukokeratosis nicotina palati 2.3, erythroplakia 0.1%, submucous fibrosis 0.1 %, and cancer 0.03%. A correlation was done between habits and lesions.

– The occurrence in oral submucous fibrosis of small raised blue spots has not been reported. This feature was observed in nine (22%) of 40 submucous fibrosis cases diagnosed in the Ernakulam district, Kerala, India. None of the patients complained of bleeding from the spots or from elsewhere, nor was there any history of systemic disorders. Histologically, the lesions could be explained by juxtaepithelial, endorthelial-lined luminae containing erythrocytes and the presence of juxta- and intraepithclial petechial homorrhages.

During an epidemiologic study of oral cancer and precancerous lesions among Indian villagers, a lichen planus-like lesion was observed in Kerala. The lesion consisted of white, wavy, parallel, non-elevated lines that could not be scraped off. The lesion occurred exclusively among chewers and at the site of placement of quid. There were no subjective symptoms. The peak prevalence of the 35 diagnosed lesions was in the 35-44 years age-group for males and 45-54 for females. There was a marked female predominance. The histologic features were very similar to those seen in oral lichen planus.

A cohort of 12,212 tobacco users was followed up annually to assess malignant potential of oral precancerous lesions in the Ernakulam district in Kerala, India. A total of 19 new oral cancers were diagnosed over a period of 8 years, and 15 (79%) of these arose from some preexisting precancerous lesion or condition. Nodular leukoplakia showed highest rate of malignant transformation (16% per year) as six of 13 nodular leukoplakia underwent malignant transformation over a mean follow-up period of 2.8 years. The relative risk (3243.2) compared with individuals with tobacco habits but without any precancerous oral lesion was also the highest for nodular leukoplakia. In addition, nodular leukoplakia was associated with submucous fibrosis in two patients, which progressed to oral cancer and was the clinical diagnosis for four lesions that turned out to be malignant on histopathologic examination. Nodular appearance was noted in two other precursor lesions as well. Thus, 14 of 19 oral cancers (74%) were either preceded by nodular leukoplakia and with lesions showing a distinct nodular appearance, or had the clinical appearance of nodular leukoplakia.

The histopathologic criteria set down by Lever for skin lesions of discoid lupus erythematosus (DLE) and the criteria for oral DLE suggested by the World Health Organization (WHO) have been tested on 136 biopsy specimens from oral lesions comprising 42 cases of clinically typical DLE, 24 cases of atypical DLE, 25 cases of lichen planus (LP), 25 cases of leukoplakia, 13 cases of indefinite diagnosis termed DLE? LP? and seven electrogalvanically- induced white lesions. Following studies of inter- and intraexaminer variation, the final recording was done in random order without the investigators knowing the clinical diagnosis in each case. The results showed that Lever's criteria had a high specificity for oral DLE as compared to LP and leukoplakia, but the sensitivity for clinically atypical oral DLE was rather low. The criteria established by the WHO showed no specificity for oral DLE as compared to LP. Neither the criteria by Lever nor the criteria of the WHO were specific for oral DLE as compared to electrogalvanically induced white lesions. Both sets contained criteria showing rather high inter- and intraexaminer variation. Therefore, there is a need to establish a set of histopathologic criteria showing high sensitivity and specificity for both clinically typical and atypical DLE, based on criteria showing a low inter- and intraexaminer variation.

The occurrence of central papillary atrophy of the tongue among tobacco users, its clinical characteristics and the long term behavior in relation to changes in tobacco use was studied in 182 individuals in Ernakulam district, Kerala, India. Almost all (98%) lesions occurred among bidi smokers. Clinically, about 31% occurred in combination with bidi smoking associated lesions such as palatal erythema (14%), leukoplakia (8%) or both (3%). Histologic evaluation in 12 biopsies using single PAS stained sections showed candidal hyphae in 67%. A 10-yr follow-up (mean: 6.7 yr) of the 182 lesions showed that the regression was highest (87%) among those who stopped their smoking habit and persistence among those who did not reduce or stop their smoking habits. The findings from this study confirm a strong link between bidi smoking and central papillary atrophy of the tongue in rural Indian populations.

The malignant potential of oral lichen planus was assessed on the basis of observations in 722 patients found among 27,599 individuals examined in various epidemiologic studies in Kerala, Ernakulam district, India. Seven hundred and two patients with oral lichen planus were re-examined annually over a 10-year period with a mean observation period of 5.1 years. Most of the lesions (93%) were observed among tobacco users. Carcinoma developed in 3 (0.4%) patients with oral lichen planus. Clinically, all 3 had atrophic components in their lesions, and all were tobacco users. The relative risk of a lichen planus developing oral cancer compared to a tobacco user was estimated as 3.3. However, this relative risk was not significant. Histologically, 74% of the 94 biopsies from oral lichen planus showed epithelial atrophy. Two of the 3 in whom cancer developed also showed epithelial atrophy. It is felt that epithelial atrophy probably renders the mucosa more vulnerable to the carcinogenic action of tobacco. Although this study could not confirm the precancerous nature of this disease with a high degree of certainty, the disease did not appear to be innocuous either.

In an extensive epidemiologic house-to-house survey, undertaken to study oral cancer and precancerous conditions, 101,761 villagers were examined in the Poona district in the Maharashtra state in India. Besides detection of 12 oral cancers, prevalences were established for leukoplakia (0.67%), preleukoplakia (0.86%), and submucous fibrosis (0.03%). The sample was also studied for chewing and smoking habits, which were practised by 54.4% of the individuals. Among males the most common habit was chewing tobacco with lime, whereas the dominating habit among females was the use of mishri (burned tobacco). The strongest association found was between bidi smoking and mixed habits and leukoplakia. Only a few cases of leukoplakia were found among mishri users. Except for submucous fibrosis it was found that prevalence does not depend on sex if tobacco habits are taken into account. Une etude epidemiologique du cancer buccal et de l'etat precancŕeux chez 101 761 villageois du Maharashtra (Inde) Dans le cadre d'une vaste enquěte epidemiologique de porte en porte, entreprise dans le but d'etudier le cancer buccal et l'etat precancereux, 101 761 villageois on ete examines dans le district de Poona de l'Etat du Maharashtra (Inde). L'etude a permis de depister 12 cancers buccaux, mais aussi d'etablir des prevalences pour la leucoplasie (0.67%), la preleucoplasie (0.86%) et la fibrose sous-muqueuse (0.03%). On a egalement observe les habitudes de ces villageois en ce qui concerne l'usage du tabac et la mastication de certaines substances, qui sont pratiques par 54.4% d'entre eux. L'habitude la plus repandue chez les hommes consiste a mǎcher du tabac et de la chaux, alors que les femmes preferent le mishri (tabac brǔle). L'association que l'on a constatee le plus souvent est celle de l'usage du bidi ou d'habitudes combinees et de la leucoplasie. Quelques cas de leucoplasie ont ete observes chez les amateurs de mishri. La fibrose sous-muqueuse mise a part et compte tenu de l'usage du tabac, on constate que la prevalence ne depend pas du sexe.

The prevalence of leukoedema, preleukoplakia and leukoplakia has been studied among 1226 Papuans and New Guineans in two coastal areas and in one highland area. Leukoedema is found in 2.4-16.9%, preleukoplakia in 10.6- 13.4% and leukoplakia in 3.1-6.2%. Chewing and smoking habits seem to be associated with varying rates of the conditions recorded. In view of a previously supposed obvious association with the betel chewing habit, it is deeply interesting that the results of this study indicate that smoking may be more closely associated with the risk for these conditions. Epithelial atypia, carcinoma in situ or carcinoma were not noted among 26 biopsies taken from the lesions studied.

(1966). The Calcifying Epithelial Odontogenic Tumor. Review of Literature and Report of An Extra-Osseous Case. Acta Odontologica Scandinavica: Vol. 24, No. 4, pp. 419-430.

In a sample of 450 patients with oral leukoplakias, 32 used snuff, which was a Danish wet variety, Goteborg snus ® (Gothenburg Snuff). The group of snuff users consisted of males only, with a mean age of 58.4 years. The mean life exposure time lo snuff was 197,000 hours, the equivalent of 22 years of constant use. Patients with leukoplakia due lo the use of snuff experienced fewer symptoms than did patients with leukoplakia due to other unknown causes. The snuff users also tended to be older at first examination, and to have a higher alcohol intake. Histological changes characteristic of snuff-users' leukoplakias were: (1) vacuolated cells in the upper part of the spinous cell layers of the epithelium with intervening streaks of parakeratinized cells, (2) epithelial hyperplasia, and (3) hyalinized, eosinophilic deposits around salivary glands. However, statistically significant differences were not found between snuff-induced leukoplakias and other leukoplakias either as lo dysplasia observed histologically or as to malignant development.

Results of an epidemiologic house-to-house survey of oral cancer and leukoplakia among 50915 adult villagers in 4 states of India which were selected according to various types of chewing and smoking habits are presented. 26 oral cancer cases were found in the survey. There was a predominance of men. Leukoplakias were already observed in the 15-24 year old age group and a considerable number were in the 25-34-year age group. Intra-oral locations of the leukoplakias were found to vary within the 4 states depending on the chewing and smoking habits prevailing. The leukoplakias were analyzed with regard to intra-oral locations and correlation with habits. Special habits such as hookli smoking and reverse smoking were associated with leukoplakias on the labial mucosa and on the palate respectively. The histologic analysis of biopsies from 723 leukoplakias showed variations in the type of hyperkeratosis which may depend on habits. The prevalence of epithelial atypia ranged from 3-12.4% in the 4 states. Epithelial atypia was seen in 8.4% of homogeneous leukoplakias but in 59.1% of speckled leukoplakias.(BJB (AU. MOD.))