Epidemiologic study of excessive oral melanin pigmentation with special reference to the influence of tobacco habits

Abstract – The prevalence of oral melanin pigmentation was studied in a population of 30 118 adult individuals in Sweden. Among these, 9.9% showed melanin pigmentation in the oral mucosa. The anterior labial gingiva in the mandible was the most frequently pigmented location. The presence of melanin pigmentation was positively correlated to tobacco smoking. Among tobacco smokers 21.5% were pigmented as compared to 3.0% among individuals not using tobacco. The smoking-rdated oral pigmentation, smokers' melanosis, could thus be calculated at a prevalence of 18.5% among smokers and the total frequency of smokers' melanosis was calculated at 6.8%. The prevalence of pigmentation was found to increase promninendy during the first year of smoking but aiso to decrease to the level found among non-tobacco users about 3 years after cessation of smoking. Snuff dipping did not significandy elevate the prevalence of oral melanin pigmentation.     

Disappearance of smoker's melanosis after reducing smoking

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.     

The ultrastructure of the gingival epithelium in smokers''melanosis

The ultrastructural morphology of melanocytes and keratinocytes was studied in clinically pigmented and non-pigmented gingival tissue from smokers and non-smokers. No differences were found between clinically pigmented lesions in smokers and non-smokers. In contrast, clinically non-pigmented tissue of smokers contained significantly more melanin-loaded keratinocytes as compared to that of non-pigmented non-smokers. In tissue of smokers and pigmented non-smokers melanocytes contained well melanized melanosomes (stages III and IV) as compared to non-pigmented tissue of non-smokers where stage II melanosomes dominated.
It was concluded that tobacco smoking may be a causative factor in melanin pigmentation of the oral mucosa and that smoking activates the epithelial melanin unit in a non-specific way. The hypothesis was put forward that in the oral mucosa melanin plays a role as a binder of toxic products such as free radicals and polycyclic compounds. In this way the epithelial melanin unit serves a protective function and prevents tissue damage.     

Oral melanin pigmentation related to smoking in a Turkish population

OBJECTIVE: Besides genetic factors, tobacco smoking has been found to be the major cause of oral melanin pigmentation. The purpose of the present study was to evaluate the frequency of oral melanin pigmentation in a Turkish population and to present its correlation with clinical parameters relevant to periodontal status in current smokers, non-smokers, former smokers. METHOD: A sample of 496 patients was randomly selected. The subjects were interviewed regarding their smoking habits. They were clinically examined by a single examiner for the presence of oral melanin pigmentation in different oral mucosal regions. The same examiner recorded the clinical parameters including GI (gingival index), PI (plaque index), BOP (bleeding on probing), PD (probing depth) and GR (gingival recession). Examiner 2 completed a questionnaire concerning skin color and smoking habits. RESULTS: In the study group, 41% were current smokers, 46% nonsmokers and 13% former smokers. The frequencies of pigmented areas were significantly higher in current smokers than in those without any smoking habits. The clinical parameters revealed similar findings for all groups. Low GI and BOP values were observed for current smokers when compared with non-smokers and former smokers, respectively. GI values were significantly associated with the pigmentations in gingiva. CONCLUSIONS: The results of our study show that smokers in a Turkish population had significantly more pigmented oral surfaces than nonsmokers.     

The relationship between habitual clove cigarette smoking and a specific pattern of dental decay in male bus drivers in Jakarta, Indonesia

This study has been conducted to establish the relationship between habitual smoking of clove cigarettes and a specific type of dental decay. A retrospective cohort study of 1,160 bus drivers in Jakarta who smoked clove cigarettes and non-smokers showed that a specific type of decay occurs in terms of form, location and pathology. The prevalence was 55.8%. The type of decay is affected by the number of years of smoking and the number of cigarettes smoked each day. Thirty-two percent of the lesions were on the buccal surfaces of the upper teeth, 39.3% on the buccal surfaces of the lower teeth, and 18% of palatal surfaces were affected. The prevalence of clove cigarette caries was related to years of smoking and numbers of cigarettes smoked per day. Of the men who smoked 10 years or less, 27% had caries. The prevalence increased to 79.6% for those smoking for 11-15 years. For those smoking for more than 15 years the prevalence was 89.3%. The relative risk of those smoking 7-12 cigarettes a day was 2.66 (p<0.0001) compared to those smoking 0-6 cigarettes a day. The relative risk increased to 3.19 in those smoking 13-18 cigarettes and 2.96 (p<0.0001) in men smoking more than 18 cigarettes per day.     

Cigar, pipe, and cigarette smoking as risk factors for periodontal disease and tooth loss

BACKGROUND: Our purpose was to test the hypotheses that cigar and pipe smoking have significant associations with periodontal disease and cigar, pipe, and cigarette smoking is associated with tooth loss. We also investigated whether a history of smoking habits cessation may affect the risk of periodontal disease and tooth loss. METHODS: A group of 705 individuals (21 to 92 years-old) who were among volunteer participants in the ongoing Baltimore Longitudinal Study of Aging were examined clinically to assess their periodontal status and tooth loss. A structured interview was used to assess the participants' smoking behaviors with regard to cigarettes, cigar, and pipe smoking status. For a given tobacco product, current smokers were defined as individuals who at the time of examination continued to smoke daily. Former heavy smokers were defined as individuals who have smoked daily for 10 or more years and who had quit smoking. Non-smokers included individuals with a previous history of smoking for less than 10 years or no history of smoking. RESULTS: Cigarette and cigar/pipe smokers had a higher prevalence of moderate and severe periodontitis and higher prevalence and extent of attachment loss and gingival recession than non-smokers, suggesting poorer periodontal health in smokers. In addition, smokers had less gingival bleeding and higher number of missing teeth than non-smokers. Current cigarette smokers had the highest prevalence of moderate and severe periodontitis (25.7%) compared to former cigarette smokers (20.2%), and non-smokers (13.1%). The estimated prevalence of moderate and severe periodontitis in current or former cigar/pipe smokers was 17.6%. A similar pattern was seen for other periodontal measurements including the percentages of teeth with > or = 5 mm attachment loss and probing depth, > or = 3 mm gingival recession, and dental calculus. Current, former, and non- cigarette smokers had 5.1, 3.9, and 2.8 missing teeth, respectively. Cigar/pipe smokers had on average 4 missing teeth. Multiple regression analysis also showed that current tobacco smokers may have increased risks of having moderate and severe periodontitis than former smokers. However, smoking behaviors explained only small percentages (<5%) of the variances in the multivariate models. CONCLUSION: The results suggest that cigar and pipe smoking may have similar adverse effects on periodontal health and tooth loss as cigarette smoking. Smoking cessation efforts should be considered as a means of improving periodontal health and reducing tooth loss in heavy smokers of cigarettes, cigars, and pipes with periodontal disease.     

The prevalence of pathogenic periodontal microflora in healthy young adult smokers

BACKGROUND: Smoking is a major risk factor in periodontitis, although the mechanisms of its effects are not well understood. The overall goal of this clinical study was to determine if smoking enhances the colonization of the oral cavity by pathogenic bacteria in a periodontitis-free population. The prevalence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Campylobacter rectus, Eikenella corrodens, Bacteroides forsythus, and Treponema denticola was investigated in 25 smokers and 25 non-smokers by using DNA probes. METHODS: The subjects were 21 to 35 years of age with a healthy periodontium or slight gingivitis and were systemically healthy. The test group included subjects who had a minimum of a 1.5 pack-year history of smoking, while the control subjects never smoked. Subgingival plaque samples were taken by paper point following the assessment of multiple clinical parameters. RESULTS: This investigation showed: 1) no statistically significant differences were noted in any clinical parameter measured between the groups; 2) of the 8 subjects who were infected by at least 1 tested pathogen, seven were smokers (P= 0.02); 3) infected smokers had a 15.7+/-3.5 pack-year history and smoked a mean of 27+/-5 cigarettes/day versus 4.4+/-0.8 pack years and 15+/-1 cigarettes/day for the non-infected smokers (P = 0.0001 and P = 0.004); and 4) smokers were 18 times more likely to exhibit the presence of pathogens than non-smokers. CONCLUSIONS: These data indicate that the prevalence of colonization of the sulcus by pathogenic bacterial species in periodontitis-free individuals is related to the quantity and duration of cigarette smoking.     

The Effect of Tobacco Smoking on Salivation

Aim

The purpose of this study was to examine the detrimental effect of smoking on the function of the salivary glands.

Material and Methods

The study was conducted on 60 patients who were divided into two groups: a test group which included smokers and control group represented by non-smokers. Each group included 30 patients. General information was collected from all the respondents via a questionnaire as well as the data on the duration of smoking and number of cigarettes smoked per day. Saliva was collected by spitting method in a graduated tube and the amount of unstimulated and stimulated saliva was measured and recorded in ml per minute. Stimulated saliva was collected immediately after rinsing the mouth with a 2% aqueous solution of citric acid which is carried salivary stimulation. The presence of pigmentation on the teeth and coated tongue were recorded during clinical examination. The degree of oral hygiene was determined by plaque index. All the obtained data were statistically analyzed with significance level p <0.05.

Results

The results showed no significant differences in the amount of saliva between smokers and non-smokers, however, the amount of saliva decreases significantly with the duration of smoking and increasing age of smokers. Also proven was the difference in the quality of saliva: smokers have thick saliva and nonsmokers predominantly serous. In addition, smokers have poorer oral hygiene status than non-smokers, and demonstrated a positive correlation between the level of oral hygiene and length of smoking tobacco.

Conclusion

This study has proven that smoking adversely affects salivation: long-term smoking reduces the secretion of saliva and changes its quality.Key words: Smoking, Tobacco Use Disorder, Saliva, Salivation, Xerostomia     

Architectural organization of human oral epithelium as visualized by keratin staining pattern in tobacco-associated leukoplakias

The keratin staining pattern in clinical normal buccal mucosa in smokers and non-smokers and in tobacco-associated leukoplakias histologically characterized by the chevron type of keratinization were studied. No differences in keratin staining pattern were found in normal buccal mucosa in smokers and non-smokers. In the tobacco-associated leukoplakias we found distinct differences in staining pattern between areas overlying connective tissue papillae and epithelial ridge areas indicating a lateral organization of oral epithelium related to the ridge system. It seems possible to explain this pattern in terms of current hypotheses of the proliferative conditions in squamous epithelia as previously studied in detail in the epidermis and tongue filiform papillae. We conclude, that our results confirm the presence of subpopulations of suprabasal and basal cells and support the presence of proliferative units in oral epithelium. Furthermore, smoking does not seem to influence the keratin staining pattern in clinically normal buccal mucosa.     

Effect of cigarette smoking on periodontal status of healthy young adults

BACKGROUND: It has been shown that tobacco is a significant risk factor for periodontal disease; however, there have been few studies on young populations where problems of general health can be discounted. The purpose of this study was to examine the influence of tobacco consumption on the periodontal condition of a young, healthy population. METHODS: The study population consisted of 304 young Caucasian males (average age 19.38 +/- 0.72 years) entering the Armed Forces. All the subjects completed a self-administered questionnaire on age, oral hygiene habits, previous dental examinations, and quantity and length of tobacco use. The periodontal examination consisted of the plaque index (PI); periodontal bleeding index (PBI); probing depth (PD); and clinical attachment level (CAL). One- and 2-way ANOVA was used to compare data recorded between smokers and non-smokers. RESULTS: Forty-six percent of subjects reported that they brushed their teeth at least once a day, but only 13% visited a dentist at least once a year. Over half (53%) were habitual smokers, 43% smoking between 5 and 20 cigarettes per day; 39% of the smokers had been smoking for less than 5 years. Mean PI was 31.24 +/- 14.88 (27.19 +/- 15.93 for smokers and 35.78 +/- 12.17 for non-smokers), with significant differences between non-smokers and those who smoked 5 to 20 cigarettes per day (26.85 +/- 16.11, P<0.0001). Mean PBI was 42.29 +/- 8.43 (non-smokers 44.67 +/- 6.53 and smokers 40.17 +/- 9.46). Significant differences were found between the PBI of the non-smokers and of those who smoked 5 to 20 cigarettes per day (39.90 +/- 9.64, P <0.0001). There were also differences in the PBI between those who brushed their teeth once (40.53 +/- 9.61) and twice (44.86 +/- 5.9) a day (P<0.0001). Mean PD was 1.62 +/- 0.43 mm (non-smokers 1.56 +/- 0.36 and smokers 1.68 +/- 0.49). Deeper probing depths were recorded among smokers than among non-smokers, with statistically significant differences (P<0.049); statistically significant differences were also found between those who attended (1.49 +/- 0.50) and those who did not attend (1.65 +/- 0.42) regular dental check-ups (P<0.031). Mean CAL 1.75 +/- 0.41 (non-smokers 1.64 +/- 0.32 and smokers 1.82 +/- 0.44). CONCLUSIONS: It may be concluded that, even at such an early age, tobacco consumption affects the periodontal health. It is necessary to inform young smokers of the risk of tobacco use regarding periodontal health.     

Oral melanin pigmentation in 467 Thai and Malaysian people with special emphasis on smoker''s melanosis

At the faculties of dentistry in Chiang Mai, Thailand (CM), and Kuala Lumpur, Malaysia (KL), 234 and 233 consecutive out-patients were interviewed concerning tobacco and chewing habits and examined for the presence of oral melanin pigmentation. Tobacco was regularly used by 32% and 28% of the studied populations in CM and KL. Cigarette smoking was the predominant habit, but the chewing of betel and tea leaves (miang) and the smoking of banana leaf cigars (khi yo) was also registered. The genetically acquired pigmentation dominated. Although nearly all non-tobacco users in the Malay and Indian populations had oral melanin pigmentation, it was found that tobacco smokers had significantly more oral surfaces pigmented than non-tobacco users. Among Thais, the percentage of pigmented individuals was significantly higher among tobacco smokers. It was concluded that tobacco smoking stimulates oral melanocytes to a higher melanin production also in dark-skinned ethnic groups.     

Effects of smoking on the prevalence and intraoral distribution of Candida albicans

To find out whether smoking affects the prevalence and intraoral distribution of Candida albicans, swabs and saliva samples from 100 healthy persons, smokers and non-smokers were cultured for the presence of this fungus. The prevalence was the same (35%) in both smokers and non-smokers. Among carriers, the mean concentration of C. albicans colony-forming units in saliva of smokers was twice that of the non-smokers, and the isolation frequency of C. albicans at each of 5 mucosal sites was also higher in smokers than in non-smokers. However, a wide variation was found, and these differences were not significant at the 0.05 level. Men were carriers more often than women (p less than 0.025), and the mucosal site from which C. albicans was recovered most often was the posterior dorsum of the tongue. Although it has previously been claimed that cigarette smoking influences the carrier state of C. albicans, the present study suggests that the effect is only slight.     

Oral mucosal lesions in 65–74-year-old Hong Kong Chinese

Abstract There have been no reported surveys of oral mucosal lesions among the elderly in Asian countries. Therefore, the purpose of this study was to determine the prevalence of oral mucosal lesions among 65–74-yr-old, community-dwelling elderly Chinese in Hong Kong and to determine the prevalence of lesions in denture wearers, tobacco smokers, and alcohol drinkers. A total of 537 noninstitutionalized 65–74-yr-olds were interviewed and clinically examined in an oral health survey conducted in 1991. In the survey, the elderly underwent a systematic examination of their oral mucosa by one of the three examiners with the aid of an overhead light. The examiners were trained and calibrated before and during the survey, and a specially prepared colour atlas of oral mucosal lesions was used for lesion recognition. No mucosal lesions were detected in 64% of the elderly. In the 193 elderly subjects with lesions, 80% exhibited only one lesion. There was no difference in prevalence between men and women. The more common lesions, each being found in 5–7% of the elderly, were lingual varicosities, frictional keratosis on the buccal mucosa, denture stomatitis on the palatal mucosa, and denture-induced hyperplasia in the maxillary and mandibular buccal sulcus. Denture wearers had a higher prevalence of lesions (40%) than nonwearers (32%). There was no difference in the prevalence or number of oral mucosal lesions between those defined as users of tobacco and alcohol and those defined as nonusers in this study. No confirmed oral malignancies were found.     

Gingival recession in smokers and non-smokers with minimal periodontal disease

BACKGROUND/AIMS: Smoking is a major risk factor for destructive periodontal disease. There is limited information with regard to effects of smoking in subjects with minimal periodontal destruction. The aim of the present investigation was to assess the development of gingival recession in young adult smokers and non-smokers. METHODS: 61 systemically healthy young adults, 19 to 30 years of age completed the final examination. 30 volunteers smoked at least 20 cigarettes per day, whereas 31 subjects were non-smokers. Clinical periodontal conditions were assessed 4x within a time period of 6 months. Site-specific analyses considering the correlated structure of data were performed. RESULTS: At the outset, 50% of subjects presented with gingival recession at 1 or more sites. There was no significant difference in the prevalence of gingival recession between non-smokers and smokers. Severe recession in excess of 2 mm affected about 23% non-smokers but only 7% smokers. Some further gingival recession developed during the 6-month observation period. In a multivariate logistic regression analysis, the risk for recession development appeared not to be influenced by smoking status after adjusting for periodontal probing depth, recession at baseline, tooth brushing frequency, gender, jaw, tooth type and site. CONCLUSIONS: Present data did not support the hypothesis that smokers are at an increased risk for the development of gingival recession.     

Effect of cigarette smoking on periodontal healing following GTR in infrabony defects

Abstract This retrospective study examined the effect of cigarette smoking on the healing response following guided tissue regeneration (GTR) in deep infrabony defects. 71 defects in 51 patients underwent GTR with teflon membranes. 20 patients (32 defects) smoked more than 10 cigarettes per day, while 31 patients (39 defects) did not smoke. Clinical measurements were available at baseline, at membrane removal and at the 1-year follow-up. The oral hygiene of both groups was good, but smokers had significantly higher full mouth plaque scores. No significant differences were observed between smokers and non-smokers in terms of % of tissue gained at membrane removal. At the 1-year follow up, however, smokers gained significantly less probing attachment level than non-smokers (2.1 ± 1.2 mm compared with 5.2 ± 1.9 mm). A multivariate model, correcting for the oral hygiene level of the patients and the depth of the infrabony component, indicated that smoking was in itself a significant factor in determining the clinical outcome. A risk-assessment analysis indicated that smokers had a significantly greater risk than non-smokers to display a reduced probing attachment level gain following GTR. It is concluded that cigarette smoking is associated with a reduced healing response after GTR treatment, and may be responsible, at least in part, for the observed results.     

Biomonitoring of oral epithelial cells in smokers and non-smokers submitted to panoramic X-ray: comparison between buccal mucosa and lateral border of the tongue

The aim of the present study was to comparatively evaluate DNA damage (micronucleus) and cellular death (pyknosis, karyolysis, and karyorrhexis) in exfoliated oral mucosa cells from smokers and non-smokers submitted to dental X-ray using two anatomic sites: buccal mucosa and lateral border of the tongue. A total of 15 heavy smokers and 17 non-smokers were submitted to panoramic dental radiography for orthodontic reasons. Individuals had epithelial cells from cheek and lateral border of the tongue mechanically exfoliated, placed in fixative, and dropped in clean slides which were checked for the above nuclear phenotypes. The results pointed out no significant statistically differences (p > 0.05) of micronucleated oral mucosa cells before versus after X-ray exposure for both oral sites evaluated either to smokers or to non-smokers. X-ray exposure was able to increase other nuclear alterations closely related to cytotoxicity such as karrhyorexis, pyknosis, and karyolysis for two groups evaluated. Nevertheless, the most pronunciated effects were found to lateral border of the tongue of smokers. In summary, these data indicate that panoramic X-ray is able to induce cellular death in oral mucosa cells. It seems that lateral border of the tongue is more sensitive site to cytotoxic insult induced by ionizing radiation combined with continuous cigarette smoke exposure.     

The association between smoking cessation and periodontal status and salivary proteinase levels

BACKGROUND: Little information is available about the effects of the cessation of cigarette smoking on oral health, although cigarette smoking has been shown to be associated with a variety of oral diseases. The aim of this study was to compare periodontal status, salivary proteolytic activity, especially collagenase-2 (MMP-8) levels, and oral mucosal status in individuals who had quit smoking for at least 6 months (mean 3.5, SD 1.3 years) and in regular smokers. METHODS: The subjects were 409 white male smokers aged 55 to 74 years with 15 or more remaining teeth. They had participated in a major cancer prevention study (ATBC Study). Eighty-two of the men had given up smoking and 327 were smokers. The subjects were examined clinically to determine the prevalence of periodontal pockets, gingival bleeding (BOP) and suppuration, and prevalence of keratotic oral mucosal lesions. The loss of alveolar bone was determined radiographically. Candida albicans was cultivated, and lesions showing leukoplakia were examined histopathologically. General proteolytic activity and collagenase-2 or matrix metalloproteinase-8 (MMP-8) levels in saliva, salivary pH, and buffering capacity were measured. Linear regression, logistic regression, or Fisher's exact test were used in statistical analysis. RESULTS: Salivary general proteolytic activity and MMP-8 levels were lower in current smokers than in ex-smokers (P <0.05 and P <0.05, respectively). The prevalence of > or = 4 mm deep pockets, gingival suppuration, and loss of crestal bone were statistically significantly lower (P = 0.003, P<0.001, and P<0.05, respectively) and salivary buffering capacity higher (P <0.05) in those who had quit smoking compared to current smokers; there was no difference in BOP. The prevalence of oral leukoplakia did not differ significantly between smokers and quitters, but was higher in those who smoked >15 cigarettes per day compared to quitters (odds ratio 3.5, 95% CI, 0.8 to 15.3). CONCLUSIONS: These data suggest that periodontal status and oral mucosal health are better in those who have quit cigarette smoking compared to current smokers. However, the data further suggest that smoking may significantly lower both general proteolytic enzyme activity and MMP-8 levels in saliva. Thus, care should be taken in interpreting results revealing salivary/mouthrinse proteinases as diagnostic markers for oral/periodontal disease activity.     

Analysis of color changes of oral mucosa by smoking

Smoking has various influences on oral mucosa, including color change. We quantitatively analyzed color changes of oral mucosa by smoking. To examine the influence of smoking over a wider age range, we measured the color of oral mucosa of 62 nonsmokers and 56 smokers (age 30-83 years). We measured color with a colorimeter by a perpendicular course, illuminating the measuring sites from a distance of 1 meter by artificial sunlight. Before measuring, we used standard white for calibration. We used the CIE L * a * b * colorimetric system for the color specification. The measured sites were the lips, gingiva, tongue and buccal mucosa. Before colorimetry, we examined the precision and repeatability of colorimeter, but the change was small. Moreover, we similarly examined the sex difference and age difference, but there was no significant difference. This study was approved by the Tokyo Medical and Dental University ethics screening committee. Among nonsmokers and smokers, a statistical difference was recognized in lips L *, a *, gingiva L *, a *, and buccal mucosa L *, b *. Smoking decreased the luminosity of the lips, gingiva, buccal mucosa and caused a blue coloration of gingiva and buccal mucosa.     

Smoking behaviour and knowledge in high school students in Riyadh and Belfast.

Smoking is one of the risk factor associated with onset, severity and progression of periodontal disease. AIM: The aim of the study was to examine the smoking behaviour and dental health knowledge of high school students in Riyadh and Belfast. MATERIALS AND METHODS: Eight schools from Riyadh and 6 from Belfast were randomly selected by cluster distribution sampling method. Two hundred and ninety students from Riyadh and 144 from Belfast were included giving an overall response rate of 85%. The age range was between 16-17 years. A questionnaire was used to assess demography, smoking habits, dental health knowledge and oral hygiene practices. RESULTS: The results showed that 18% of students were smokers; 24% in Belfast and 15% in Riyadh (x2 (1) = 4.29: P = 0.04). 24% of students in Belfast and 56% in Riyadh smoked at least 1 cigarette per day. 61% of students had bleeding gums although 85% stated that they brushed their teeth at least daily. Bleeding on brushing was common with 53% of Belfast students compared with 65% from Riyadh. Students in Belfast (2.51 +/- 1.15) had significantly higher mean scores for their knowledge about gum health compared with Riyadh students (2.21 +/- 1.44) (t = 2.29: P = 0.02). There was no differences in knowledge about oral health and smoking between the students. However, non-smokers from Belfast and Riyadh (3.32 +/- 1.60) had greater knowledge about oral health and smoking than those who smoked (2.81 +/- 1.45) (t = 2.73: P = 0.007). There was no difference in knowledge about gum health between smokers and non-smokers. CONCLUSIONS/RECOMMENDATIONS: Smoking is more prevalent in Belfast but more cigarettes are smoked in Riyadh. As non-smokers had greater knowledge of the ill-effects of smoking upon their oral health, there is a need to develop location specific interventions to control smoking habits in late adolescence.