this was a comparative cross - sectional study carried out over 2 years ( from october 2013 to september 2015 ) . it was part of a project approved by the local ethical committee of farhat hached university hospital and conducted in accordance with the declaration of helsinki . the project aimed at evaluating the effect of the use of narghile on oral health on the basis of clinical , radiological and biological data . the clinical part of the study was conducted in the department of oral medicine at the basic health group , and radiological exams were performed in a private radiological center in sousse , tunisia . in unpublished data , the adjusted prevalence rates of smoking among males aged 20 years and more living in sousse were 12.7% for narghile and 40.1% for cigarettes . in tunisia , participants were individually informed about the purpose of the study and all of them signed an informed written consent form prior to the study . subjects diagnosed with any oral pathology were given treatment or were scheduled for the right specialist . subjects were recruited by convenience sampling from acquaintances of people involved in the study and via flyers distributed in cafes in the city . the non - inclusion criteria were as follows : number of remaining teeth < 20 , tobacco use < 5 pack - years for ecs or < 5 narghile - years for ens , jurak and/or tombac tobacco use , known systemic medical condition such as diabetes mellitus , previous head or neck radiation therapy , and consumption of drugs known to affect the periodontium such as antidepressants , anticonvulsants , cyclosporine a , or calcium antagonists . the number of analyzed teeth < 20 , because of the bad quality of the radiological exam , was applied as an exclusion criteria . the sample size was estimated using the following formula ( 32 ) : n=[(z 
 /2)p(1 p)d]/e 
 ; p was the proportion of the main event of interest ( i.e. bone loss ) , e was the margin of error , z 
 /2 was the normal deviation for two - tailed alternative hypothesis at a level of significance , d was the design ( = 1 for simple random sampling ) . previous literature gives an estimate of bone loss of 17% ( p=0.17 ) in the surveyed population ( 17 ) , and assuming 90% confidence interval ( ci ) ( z 
 /2=1.64 ) and 5% margin of error ( e ) , the total sample size was 151 smokers . data were collected on sociodemographic variables , smoking habits ( i.e. lifetime cigarette or narghile smoking , narghile smoking mixture ) , and oral hygiene ( i.e. daily tooth brushing frequency ) and yearly number of visits to the dentist . two schooling levels were arbitrarily defined : low ( illiterate , primary education ) and high ( secondary and university education ) . two socioeconomic levels were defined according to professional status : low ( e.g. unskilled workers , jobless ) and high ( e.g. skilled workers , farmers , managers ) . the level of tobacco consumption was expressed in terms of narghile - years (  narghile session per daynumber of years of consumption ) or pack - years (  packs of cigarettes smoked per daynumber of years of consumption ) ( 8) . according to their tobacco consumption levels , smokers were divided into two subgroups : 510 or 1015 narghile - years or pack - years . applying  one daily tooth brushing frequency as a cutoff , smokers were classified arbitrarily into two subgroups : irregular ( = 0 ) and regular ( 1 ) daily tooth brushing . the examination was performed by an experienced dentist ( mk in the authors list ) . the silness  le plaque index ( 33 ) was used to assess oral hygiene . it is a dental index that assesses the thickness of plaque at the cervical margin of the tooth ( closest to the gum ) . four scores are possible ( 0 : no plaque ; 1 : a film of plaque adhering to the free gingival margin , adjacent to the tooth ; 2 : moderate accumulation of soft deposits within the gingival pocket or between the tooth and gingival margin ; 3 : abundance of soft matter within the gingival pocket and/or on the tooth and gingival margin ) . a plaque indicator was used to evaluate the plaque index . the presence of visible dental plaque was recorded on four sites ( vestibular , lingual , mesial , and distal ) of all existing teeth , except the third molars . as previously done by one author ( 20 ) , three plaque index classes ( 01 , 12 , and 23 ) were arbitrarily defined . extraoral digital panoramic radiographs ( rayscan  , ray , hwaseong , south korea ) were performed to visualize and measure the marginal pbh . to represent the mean pbh per individual , the mesial and distal bone heights were determined as a proportion of the root length from all measurable teeth ( 34 ) . all images were analyzed by the same dentist ( mk in the authors list ) using an imaging software program ( rayscan 's smartdent ) . the root length was measured from the cementoenamel junction to the root apex ( 17 ) . the pbh was measured from the apex to a point where the lamina dura became continuous with the compact bone of the inter - dental septum ( 17 ) . a bone height level 0.70 was used as a cutoff reference value signifying bone loss ( 17 ) . distribution of variables was normal and results were expressed as meanstandard deviation ( sd ) ( 95% ci ) . student 's t - test and chi test were used to compare , respectively , the two groups quantitative and qualitative data . all mathematical computations and statistical procedures were performed using statistica software ( statistica kernel version 6 ; stat software . this was a comparative cross - sectional study carried out over 2 years ( from october 2013 to september 2015 ) . it was part of a project approved by the local ethical committee of farhat hached university hospital and conducted in accordance with the declaration of helsinki . the project aimed at evaluating the effect of the use of narghile on oral health on the basis of clinical , radiological and biological data . the clinical part of the study was conducted in the department of oral medicine at the basic health group , and radiological exams were performed in a private radiological center in sousse , tunisia . in unpublished data , the adjusted prevalence rates of smoking among males aged 20 years and more living in sousse were 12.7% for narghile and 40.1% for cigarettes . in tunisia , participants were individually informed about the purpose of the study and all of them signed an informed written consent form prior to the study . subjects diagnosed with any oral pathology were given treatment or were scheduled for the right specialist . subjects were recruited by convenience sampling from acquaintances of people involved in the study and via flyers distributed in cafes in the city . the non - inclusion criteria were as follows : number of remaining teeth < 20 , tobacco use < 5 pack - years for ecs or < 5 narghile - years for ens , jurak and/or tombac tobacco use , known systemic medical condition such as diabetes mellitus , previous head or neck radiation therapy , and consumption of drugs known to affect the periodontium such as antidepressants , anticonvulsants , cyclosporine a , or calcium antagonists . the number of analyzed teeth < 20 , because of the bad quality of the radiological exam , was applied as an exclusion criteria . the sample size was estimated using the following formula ( 32 ) : n=[(z 
 /2)p(1 p)d]/e 
 ; p was the proportion of the main event of interest ( i.e. bone loss ) , e was the margin of error , z 
 /2 was the normal deviation for two - tailed alternative hypothesis at a level of significance , d was the design ( = 1 for simple random sampling ) . previous literature gives an estimate of bone loss of 17% ( p=0.17 ) in the surveyed population ( 17 ) , and assuming 90% confidence interval ( ci ) ( z 
 /2=1.64 ) and 5% margin of error ( e ) , the total sample size was 151 smokers . data were collected on sociodemographic variables , smoking habits ( i.e. lifetime cigarette or narghile smoking , narghile smoking mixture ) , and oral hygiene ( i.e. daily tooth brushing frequency ) and yearly number of visits to the dentist . two schooling levels were arbitrarily defined : low ( illiterate , primary education ) and high ( secondary and university education ) . two socioeconomic levels were defined according to professional status : low ( e.g. unskilled workers , jobless ) and high ( e.g. skilled workers , farmers , managers ) . the level of tobacco consumption was expressed in terms of narghile - years (  narghile session per daynumber of years of consumption ) or pack - years (  packs of cigarettes smoked per daynumber of years of consumption ) ( 8) . according to their tobacco consumption levels , smokers were divided into two subgroups : 510 or 1015 narghile - years or pack - years . applying  one daily tooth brushing frequency as a cutoff , smokers were classified arbitrarily into two subgroups : irregular ( = 0 ) and regular ( 1 ) daily tooth brushing . the examination was performed by an experienced dentist ( mk in the authors list ) . it is a dental index that assesses the thickness of plaque at the cervical margin of the tooth ( closest to the gum ) . four scores are possible ( 0 : no plaque ; 1 : a film of plaque adhering to the free gingival margin , adjacent to the tooth ; 2 : moderate accumulation of soft deposits within the gingival pocket or between the tooth and gingival margin ; 3 : abundance of soft matter within the gingival pocket and/or on the tooth and gingival margin ) . a plaque indicator was used to evaluate the plaque index . the presence of visible dental plaque was recorded on four sites ( vestibular , lingual , mesial , and distal ) of all existing teeth , except the third molars . as previously done by one author ( 20 ) , three plaque index classes ( 01 , 12 , and 23 ) extraoral digital panoramic radiographs ( rayscan  , ray , hwaseong , south korea ) were performed to visualize and measure the marginal pbh . to represent the mean pbh per individual , the mesial and distal bone heights were determined as a proportion of the root length from all measurable teeth ( 34 ) . all images were analyzed by the same dentist ( mk in the authors list ) using an imaging software program ( rayscan 's smartdent ) . the root length was measured from the cementoenamel junction to the root apex ( 17 ) . the pbh was measured from the apex to a point where the lamina dura became continuous with the compact bone of the inter - dental septum ( 17 ) . a bone height level 0.70 was used as a cutoff reference value signifying bone loss ( 17 ) . distribution of variables was normal and results were expressed as meanstandard deviation ( sd ) ( 95% ci ) . student 's t - test and chi test were used to compare , respectively , the two groups quantitative and qualitative data . all mathematical computations and statistical procedures were performed using statistica software ( statistica kernel version 6 ; stat software . among the 150 subjects , only 120 were retained ( 60 ens and 60 ecs ) . thirty smokers were excluded mainly because the number of teeth measured after the radiological analysis was < 20 . there were no significant differences between the two groups regarding age , quantities of consumed tobacco , and daily tooth brushing frequency . compared with the ecs group , the ens group had a significantly lower mean number of visits to the dentist and included significantly higher percentages of smokers having a low schooling level or having a high socioeconomic level . general characteristics of the study groups : exclusive narghile smokers ( ens , n=60 ) and exclusive cigarette smokers ( ecs , n=60 ) ny : narghile - years ; py : pack - years . figure 1 and table 2 display , respectively , the clinical and radiological data and the plaque index intervals and bone loss of the two groups . their main results were as follows : the ens group meanssd [ 95% ci ] of remaining teeth ( fig . 1b ) were significantly higher than those of the ecs group ( respectively , 27.870.50 [ 27.74 to 28.00 ] vs. 26.971.48 [ 26.58 to 27.35 ] and 1.840.73 [ 1.65 to 2.03 ] vs. 1.540.70 [ 1.36 to 1.72]).no significant difference was found between the two groups meanssd [ 95% ci ] pbh ( 0.860.04 [ 0.84 to 0.87 ] vs. 0.850.03 [ 0.84 to 0.86 ] , respectively ) ( fig . 1c ) . 
  the ens group meanssd [ 95% ci ] of remaining teeth ( fig . 1b ) were significantly higher than those of the ecs group ( respectively , 27.870.50 [ 27.74 to 28.00 ] vs. 26.971.48 [ 26.58 to 27.35 ] and 1.840.73 [ 1.65 to 2.03 ] vs. 1.540.70 [ 1.36 to 1.72 ] ) . no significant difference was found between the two groups meanssd [ 95% ci ] pbh ( 0.860.04 [ 0.84 to 0.87 ] vs. 0.850.03 [ 0.84 to 0.86 ] , respectively ) ( fig . remaining teeth , plaque index , and periodontal bone height of the study groups : exclusive narghile smokers ( ens , n=60 ) and exclusive cigarettes smokers ( ecs , n=60 ) . small rectangle : mean ; large rectangle : 95% ci ; error bars : standard deviation . clinical and radiological data of the study groups : exclusive narghile smokers ( ens , n=60 ) and exclusive cigarette smokers ( ecs , n=60 ) qualitative data : number ( percentage ) . the two groups included similar percentages of smokers having bone loss or divided according to the plaque index classes ( table 2 ) . the main result of the present study was that the two groups made up of 60 ens and 60 ecs have similar means of pbh and percentages of bone loss . studies analyzing the effects of narghile use on oral health ( 1529 ) , especially the periodontium ( 1518 , 20 , 29 ) , are scarce . this was recently criticized in two letters to the editor ( 14 , 30 ) . to the best of the authors knowledge , only two comparative cross - sectional studies ( 17 , 29 ) , largely described in table 3 , investigated the effect of narghile use on pbh and/or bone loss . study designs , characteristics , and results of studies aiming to evaluate the effects of narghile use on periodontal bone height bl : bone loss . significant differences since pbh decreases with age ( 17 , 31 ) and is positively related to sex ( 17 ) , only males aged between 20 and 35 years were included . inclusion of older smokers and/or of both males and females in the same group , as done by natto et al . ( 29 ) , some important non - inclusion criteria were applied ( e.g. diabetes mellitus , head and/or neck radiation therapy , and use of some medications ) , which are known to affect periodontal health and are therefore considered as confounding factors ( 35 , 36 ) . this important information ( 14 ) , not mentioned in previous similar studies ( 17 , 29 ) , makes between - studies comparison complicated . in the case of the use of other types of narghile tobacco ( such as tombak or jurak , frequently used in saudi arabia ) , and in comparison to tabamel as done previously ( 17 , 29 ) , the present study applied a non - validated medical questionnaire . this could be considered as a methodological limitation , and it is imperative that a standardized epidemiological questionnaire be developed that could be applied in studies addressing the effects of narghile use on health ( 38 ) . in the present study , radiological exams evaluating pbh play a complementary role in assessing the periodontium in conjunction with periodontal probing ( 39 ) . they have high sensitivity and reproducibility which yield fewer false - negative results compared with clinical records ( 39 ) . however , it was preferable to collect clinical data such as gingival index , probing depth and tooth mobility . these data will be further investigated . in the present study , the radiographic method used to evaluate bone loss was similar to that applied by natto et al . the latter study evaluated marginal bone loss defined as the vertical distance from 2 mm below the cementoenamel junction to the most crestal part of the marginal bone ( 29 ) . other researchers ( 15 ) aiming at detecting the vertical defect in the periodontal bone have performed a full set of intraoral radiographs including 16 periapical and 4 bitewing projections for smokers and non - smokers . however , it does not provide information on the height of the vestibular or lingual periodontal bone . panoramic radiography is also a rapid method ( 34 ) that is not very expensive ( 30 tunisian dinars , the equivalent of 13 euros ) . it has a lower radiation dose compared with a full mouth set of radiographs ( 40 ) . as done by natto et al . ( 17 ) , the ratio of the pbh to the root length was preferred to the measurement in millimeters ( as done by javed et al . this method minimizes the effect of shortening or elongating the radiographic image ( 41 ) . for more precision , one examiner measured the bone height measurements in all the radiographs . although calculations may be influenced by a within - variability , measurement error is 
 marginal and can be ignored when the radiographs are assessed by a single examiner ( 17 , 29 ) . in addition to the methodological limitation concerning medical questionnaire described above , four other limitations ( concerning blinding , convenience sampling , panoramic radiograph use especially for the anterior teeth , and the socioeconomic levels of smokers ) were noted . ( 17 ) , during the radiological data analysis , and by javed et al . ( 29 ) , during the questionnaire and clinical examination , is an important methodological feature that can minimize bias and maximize the validity of the results ( 42 ) . in future studies with similar aims as the present , researchers should strive to set up blinding not only for data analysts but also for radiological specialists and any other individuals involved in the study ( 42 ) . in spite of the advantages of convenience sampling , such as the availability of data and the rapidity of data gathering , it has several disadvantages such as the risk of the sample not being representative of the population as a whole and volunteer bias . although the panoramic radiographs used in the present study seem to be a more practical approach for a high number of participants and have less radiation , it would have been preferable to make a full mouth set of radiographs ( 40 ) . the socioeconomic level has an impact on periodontal health ( 43 ) . in the present study , 100% of ens had a high socioeconomic level ( table 1 ) , which could influence results . however , this higher percentage reflects the reality of narghile smokers in tunisia , since a previous local study ( 44 ) showed that 67% of ens had a high socioeconomic level . the main result in this study was that ens and ecs have similar means of pbh and percentages of bone loss . therefore , it appears that narghile use affects the pbh in the same way as cigarette smoking . compared with the ens and ecs pbh values and bone - loss percentages reported by natto et al . ( 17 ) , the present ones seem to be , respectively , higher and lower ( table 3 ) . these differences may be explained by the inclusion in the present study , compared with the one by natto et al . on the one hand , the pbh decreases with age ( 17 ) . on the other hand , in a subgroup of their total sample ( ecs , ens , mixed smokers ) aged 1730 years , natto et al . ( 17 ) found pbh values similar to the present study ( mean , 95% ci : 83.1% , 82.884.7% ) . the biological mechanisms responsible for the effect of narghile use on pbh are still elusive ( 17 ) . two hypotheses could be speculated.due to the inhalation of hazardous and toxic compounds in narghile smoke ( 12 ) , such as nicotine ( 17 ) , compared with non - smokers , ens have increased levels of nicotine and its principal saliva metabolite , that is , cotinine ( 45 ) . however , compared with cigarette smoking , narghile use is associated with similar plasma nicotine levels ( 46 ) . wu et al . ( 47 ) suggested that nicotine upregulated interleukin-1 secretion , which may promote alveolar bone loss . these could explain the similarity of bone loss in ens and ecs.implication of the matrix metalloproteinases in the degradation of periodontal tissues such as the alveolar bone ( 48 ) . 
  due to the inhalation of hazardous and toxic compounds in narghile smoke ( 12 ) , such as nicotine ( 17 ) , compared with non - smokers , ens have increased levels of nicotine and its principal saliva metabolite , that is , cotinine ( 45 ) . however , compared with cigarette smoking , narghile use is associated with similar plasma nicotine levels ( 46 ) . wu et al . ( 47 ) suggested that nicotine upregulated interleukin-1 secretion , which may promote alveolar bone loss . implication of the matrix metalloproteinases in the degradation of periodontal tissues such as the alveolar bone ( 48 ) . to conclude , the present study suggests that narghile use is detrimental to periodontal health . in their daily practice , dentists are urged to encourage their patients to quit smoking both narghile and cigarettes . besides , future research and gathering of clinical data , such as gingival index , periodontal probing depth , and tooth mobility , are encouraged . the american university of beirut , lebanon , supported a part of the present study ( grant no .
objectiveto compare the periodontal bone height ( pbh ) of exclusive narghile smokers ( ens ) with that of exclusive cigarette smokers ( ecs).methodstunisian males aged 2035 years who have been ens for more than five narghile - years or ecs for more than five pack - years were recruited to participate in this comparative cross - sectional study . 
 information about oral health habits and tobacco consumption were gathered using a predetermined questionnaire . 
 plaque levels were recorded in four sites using the plaque index of loe and silness . 
 the pbh was measured mesially and distally from digital panoramic radiographs of each tooth and expressed as a percentage of the root length . 
 a pbh level 0.70 was applied as a cutoff reference value signifying bone loss . 
 student t - test and chi2 test were used to compare quantitative and qualitative data of both groups.resultsthere were no significant differences between the ens ( n=60 ) and ecs ( n=60 ) groups regarding age and the consumed quantities of tobacco ( 284 vs. 275 years , 73 narghile - years vs. 83 pack - years , respectively ) . 
 compared with the ecs group , the ens group had a significantly higher plaque index ( meansd values were 1.540.70 vs. 1.840.73 , respectively ) . 
 however , the two groups had similar means of pbh ( 0.850.03 vs. 0.860.04 ) and tooth brushing frequencies ( 1.10.8 vs. 0.90.6 a day , respectively ) and had similar bone loss frequencies ( 15% vs. 12% , respectively).conclusionsboth ens and ecs exhibited the same pbh reduction , which means that both types of tobacco smoking are associated with periodontal bone loss .