Risk factors of periodontal disease in Vietnamese patients

Transcription

1 Received: 19 December 2016 Accepted: 7 March 2017 DOI: /jicd ORIGINAL ARTICLE Periodontics Risk factors of periodontal disease in Vietnamese patients Thuy A. V. Pham 1 Thoai Q. Kieu 1 Lan T. Q. Ngo 2 1 Department of Periodontology, Faculty of Odonto-Stomatology, University of Medicine and Pharmacy, Ho Chi Minh City, Vietnam 2 Department of Dental Basic Science, Faculty of Odonto-Stomatology, University of Medicine and Pharmacy, Ho Chi Minh City, Vietnam Correspondence Dr Thuy A. V. Pham, Department of Periodontology, Faculty of Odonto- Stomatology, University of Medicine and Pharmacy, Ho Chi Minh City, Vietnam. pavthuy@ump.edu.vn Abstract Aim: The aim of the present study was to assess the association of periodontitis with dental and smoking behaviors, self- perception of oral status, dental knowledge, and obesity in Vietnamese patients. Methods: A cross- sectional study was conducted on 367 adults who first visited the Faculty of Odonto- Stomatology, University of Medicine and Pharmacy, Ho Chi Minh City, Vietnam. Information on demographic characteristics, dental and smoking behaviors, self- perception of oral status, dental knowledge, and nutritional status was investigated by a self- administered questionnaire. Periodontal status, including plaque index, probing depth, and bleeding on probing, was examined. Multiple logistic regression analysis was performed to explore risk factors that were associated with periodontitis after adjusting for confounding factors. Results: Dental and smoking behaviors, dental knowledge, and nutritional status were all significantly related to periodontitis. The multiple logistic regression analysis showed that patients who had risk factors significantly associated with periodontitis were those who had dental scaling during the past year (odds ratio [OR]: 2.2), current smokers (OR: 2.47), who received instructions on oral hygiene (OR=1.73), and those who were overweight/obese (OR: 4.78). Conclusion: Periodontitis was correlated with dental and smoking behaviors, dental knowledge, and nutritional status in Vietnamese dental patients. Promoting a healthy lifestyle, reducing tobacco consumption, motivating oral self- care behaviors, together with normal weight maintenance, are necessary to reduce periodontal disease burdens. KEYWORDS dental behavior, dental knowledge, obesity, periodontitis, Vietnam 1 INTRODUCTION Periodontal disease is a significant global oral disease burden that challenges health systems around the world. 1 Periodontal disease ranges from the mildest stage, known as gingivitis, to severe stage, known as periodontitis, which is characterized by the destruction of connective tissue and dental bone support. 2,3 Five- to- 10% of the world s population is affected by severe periodontitis, which has been found to be the sixth most common disease. 4 In Vietnam, the last national survey in 2001 showed that 97.5% of the population suffered from periodontal disease; 91.8% of Vietnamese people in the 45- year and older age group had gingivitis and periodontal disease, and 35.7% of those had shallow periodontal pockets. 5 These results, observed at a population level with a high proportion of gingivitis and periodontal disease, suggest that more studies should be conducted with the aim to determine the relationship between periodontal disease and various risk factors so as to plan oral health care and prevention for the Vietnamese population. J Invest Clin Dent. 2018;9:e wileyonlinelibrary.com/journal/jicd 2017 John Wiley & Sons Australia, Ltd 1 of 7

2 2 of 7 PHAM et al. Despite the fact that specific bacteria are the essential cause, periodontal disease has multirisk factors, including unhealthy diet, excessive alcohol consumption, tobacco use, stress, and genetic factors. 4,6 Periodontal disease and some systemic diseases share a wide range of risk factors that are of concern, and receive global attention from healthcare professionals. Recently, numerous studies have implied the twoway relationship between periodontal disease and systemic diseases, such as diabetes, cardiovascular disease, and respiratory disease. 7 9 A recent study in a Vietnamese population also demonstrated the association between periodontal status and different related factors, including dental visit behaviors, smoking status, and toothbrushing frequency. 10 Oral health knowledge and dental behaviors have an important role in the treatment and prevention of periodontal disease. 11 However, available studies on the level of dental knowledge and oral self- care behaviors of Vietnamese dental patients and their association with periodontal disease are still lacking. Although the problem of identifying potential risk factors and predictors of periodontal disease has received considerable attention in the scientific literature, little is known about periodontitis and its correlated risk factors in Vietnamese dental patients who particularly have high dental needs and often have greater overall periodontal health problems. This could be due to the fact that periodontal disease often goes unnoticed by patients until it reaches a severe stage. The purpose of the present study was to investigate the relationship of periodontal disease with dental behaviors, perception of oral status, dental knowledge, and body mass index among patients who first visited the Faculty of Odonto- Stomatology, University of Medicine and Pharmacy, Ho Chi Minh City, Vietnam. 2 MATERIALS AND METHODS 2.1 Patients A cross- sectional study was conducted on a convenience sample of 367 adult patients (mean age: 34.9±13.5 years) who first visited the third outpatient section, Faculty of Odonto- Stomatology, University of Medicine and Pharmacy in Patients with systemic diseases, such as diabetes, cancer, and chronic kidney diseases, were excluded. All participants were informed both verbally and in writing about the purposes and procedures of the study before they signed a consent form. The protocol of this study was approved by the ethical committee of the University of Medicine and Pharmacy. 2.2 Questionnaire The questionnaire was administered prior to the oral examination. All items of this questionnaire were explained clearly to the participants. The questionnaire items covered demographic information, dental and smoking behaviors, self- perception of oral status, dental knowledge, and anthropometric data: (a) demographic information, including age and sex; (b) dental behaviors, including frequency of dental visits, dental scaling during the previous year, self-check-up gum/teeth behavior, toothbrushing frequency, and tongue brushing behavior; (c) smoking behavior (ie current or former smoker, or non-smoker); (d) dental knowledge. Questions were proposed to assess the level of dental knowledge of the patient about receiving oral hygiene instruction in the previous year, including knowledge of regular dental check-ups being essential for periodontal disease prevention, knowledge of periodontitis being caused by bacteria, and knowledge of the relationship of periodontitis with smoking and diabetes; (e) self-perception of oral status, including bleeding gums, cleanness of mouth/teeth, and the presence of calculus; (f) anthropometric indices, including height and weight of the patients. Body mass index (BMI) was calculated from weight in kilograms divided by square height in meters. Recommended BMI cut-off values for the Asian population by the World Health Organization (WHO, 2000) was used for defining overweight, obesity, normal weight, and underweight in the present study Oral examination All patients underwent a standard oral examination. Periodontal status, including plaque index, probing depth, and bleeding on probing, was examined for all teeth (wisdom teeth were excluded) by the same examiner. Plaque index was recorded according to Löe and Sillness (1964). The deepest pocket value was recorded for the tooth by using 1 mm- scaled William s periodontal probe at six sites on each tooth. Gingival bleeding was assessed within 30 seconds following the pocket depth measurement. The periodontal status of any tooth that had one or more 5 mm or deeper pockets, was also evaluated with radiographs to assess the level of bone loss. In the present study, patients were divided into two groups based on the combined presence of deep pockets ( 5 mm) and bone loss (more than one- third of the root length), as confirmed on the radiographs. Patients with at least one deep pocket plus evidence of bone loss were assigned to the periodontitis group. Patients without these findings were assigned to the non- periodontitis group. 10, Statistical analysis The χ 2 - test was used to verify the association between periodontitis and each independent variable, including demographic characteristics, dental behaviors, self- perception of oral status, dental knowledge, and BMI. P<.05 was accepted as being statistically significant. Multiple logistic regression analysis was performed using periodontitis (0=non- periodontitis, 1=periodontitis) as a dependent variable, and the demographic characteristics, dental behaviors, selfperception of oral status, and dental knowledge that showed statistically significant associations with periodontitis in the χ 2 -tests were used as independent variables. Adjusted odds ratios (ORs) and their 95% confidence intervals were calculated for each independent variable. Statistical analyses were carried out using SPSS 22.0 software (SPSS, IBM, Tokyo, Japan).

3 PHAM et al. 3 of 7 3 RESULTS 3.1 Demographic characteristics, dental and smoking behaviors, self- perception of oral status, and dental knowledge A total of 367 patients (mean age: 34.9±15 years) provided complete information; 59.7% of the study population was female. There were 207 patients (36.4%) patients who were aged over 18 years, but under 35 years. Approximately 52% of the patients answered that they made a dental visit during that past year. Over one- quarter (26%) of the patients reported that they visited the dentist for dental scaling within the past year. The majority of the study population (73.3%) did not check their teeth/gums regularly. All study patients reported that they brushed their teeth at least once daily. Toothbrushing three times or more per day was reported by one- third of the study population. Approximately half of the patients (49%) responded that they frequently brushed their tongue. Almost 85% were non- smokers, while only 55 of 367 patients were current or former smokers. Among the study population, 199 patients (54.2%) confirmed that they had received instructions on oral hygiene by dentists, 56.7% noticed their gums bled when brushing, and the present dental calculus was confirmed in 91.8% of the responders. A total of 324 patients reported that regular dental check- ups are essential for oral disease prevention. Approximately 65% (64.6%) of the study population answered they knew that several bacterial species participated in periodontal disease, and 247 (67.3%) reported that they knew that smoking correlated to periodontitis. The positive relationship between diabetes and periodontitis was noticed by 175 patients (47.7%). 3.2 Periodontal status All of the patients were dentate (7-28 teeth), and the mean number of teeth present was 25.9 (standard deviation [SD]: 4.1). The prevalence of periodontitis in the sample was 46.9%. The mean number of healthy teeth was 21.7 (SD: 5.8). The mean number of teeth with bleeding on probing was 7.0 (SD: 5.8), and the mean pocket depth was 1.6 (SD: 0.5). 3.3 Relationship of periodontitis with demographic characteristics and dental and smoking behaviors The association between demographic characteristics, dental and smoking behaviors, and periodontitis is shown in Table 1. There was TABLE 1 Relationship of periodontitis with demographic characteristics and dental and smoking behaviors Variable Non- periodontitis n (%) Periodontitis n (%) Total n (%) P-value Age (y) (54.6) 94 (45.4) 207 (100).529 >35 82 (51.2) 78 (48.8) 160 (100) Sex Male 76 (51.4) 72 (48.6) 148 (100).595 Female 119 (54.3) 100 (45.7) 219 (100) Dental check- up within the past year Yes 110 (57.9) 80 (42.1) 190 (100).061 No 85 (48.0) 92 (52.0) 177 (100) Dental scaling within the past year Yes 71 (74.7) 24 (25.3) 95 (100) <.001 No 124 (45.6) 148 (54.4) 272 (100) Frequency of self- checking teeth/gums Frequently/weekly 66 (67.3) 32 (32.7) 98 (100).001 Never/occasionally 129 (48.0) 140 (52.0) 269 (100) Frequency of tongue brushing Frequently/weekly 90 (50.0) 90 (50.0) 180 (100).195 Never/occasionally 105 (56.1) 82 (43.9) 187(100) Toothbrushing frequency 1-2 times/d 142 (51.4) 134 (48.6) 276 (100) times/d 53 (58.2) 38 (41.8) 91 (100) Smoking behavior Non- smoker/former smoker 81 (57.5) 134 (42.5) 315 (100) <.001 Current smoker 14 (26.9) 38 (73.1) 52 (100) P- value was calculated using χ 2 - test. Significant difference at P<.05.

4 4 of 7 PHAM et al. no statistically- significant relationship between age, sex, tongue brushing habit, toothbrushing frequency, and periodontitis. The prevalence of periodontitis was statistically significantly lower among those who had visited a dentist for scaling within the past 12 months or who frequently checked their teeth/gums in a mirror than their counterparts (P.001). There was a higher percentage of current smokers in the periodontitis group compared to the non- periodontitis group (P<.001). 3.4 Relationship of periodontitis with selfperception of oral status and dental knowledge The association between self- perception of oral status, dental knowledge, and periodontitis is shown in Table 2. Patients perception of present dental calculus, gum bleeding, and clean tooth/ mouth were not correlated to the presence of periodontitis. Dental knowledge of the relationship between smoking, diabetes, and periodontal disease; experience of oral hygiene instruction within the past year; and knowledge that periodontitis was caused by bacteria were all found to be significantly correlated to periodontitis in the bivariate analyses (P<.01). However, there was no significant association between knowledge of regular dental check- up is essential for oral disease prevention and the prevalence of periodontitis. 3.5 Relationship between nutritional status and periodontitis The relationship between nutritional status and periodontitis is shown in Figure 1. There was a statistically- significant difference in the prevalence of periodontitis according to nutritional status. The percentage of periodontitis increased from 38.1% of the underweight group to 38.6% of the normal weight group, and reached a peak of 76.5% among the obesity/overweight group (P<.001). 3.6 Multiple logistic regression analysis of periodontitis with different factors The results of the multiple logistic regression analysis are shown in Table 3. After adjusting factors of demographic characteristics, dental behaviors, self- perception of oral status and dental knowledge; the variables such as the frequency of scaling, dental calculus, smoking, the experience of oral hygiene instruction, and obesity were significantly associated with periodontitis. Current smokers were more likely than non- smokers and former smokers to have periodontitis (OR: 2.47, P=.012). Patients who did not have dental scaling within the past year (OR: 2.2, P=.008) or did not receive instruction on oral hygiene within the past year (OR: 1.73, P=.031) were more likely to have periodontitis than their counterparts. The overweight/obesity group was more likely to have periodontitis (OR: 4.78, P<.001) compared to their normal weight and underweight counterparts. TABLE 2 Relationship of periodontitis with self- perception of oral status and dental knowledge Variable Nonperiodontitis n (%) Self-perception of oral status Bleeding gum 4 DISCUSSION Periodontitis n (%) Total n (%) P-value Yes 116 (56.3) 90 (43.7) 208 (100).204 No 78 (49.4) 80 (50.6) 158 (100) Cleanness of teeth/mouth Yes 104 (49.8) 105 (50.2) 209 (100).141 No 91 (57.6) 67 (42.4) 158 (100) Presence of dental calculus Yes 177 (52.8) 158 (47.2) 335 (100).568 No 17 (58.6) 12 (41.4) 29 (100) Dental knowledge Received instructions on oral hygiene within the past year Yes 124 (62.3) 75 (37.7) 199 (100) <.001 No 71 (42.3) 97 (57.7) 168 (10) Regularly dental check up is essential for oral disease prevention Yes 175 (54.0) 149 (46.0) 324 (100).417 No 20 (46.5) 23 (53.5) 43 (100) Bacteria are responsible for periodontitis Yes 138 (58.2) 99 (41.8) 237 (100).009 No 57 (43.8) 73 (56.2) 130 (100) Smoking related to periodontitis Yes 146 (59.1) 101 (40.9) 247 (100).001 No/do not know 49 (40.8) 71 (59.2) 120 (100) Diabetes related to periodontitis Yes 108 (67.1) 67 (38.3) 175 (100).002 No/do not know 87 (45.3) 105 (54.7) 192 (100) P- value was calculated using χ 2 - test. Significant difference at P<.05. In the present study, we confirmed the strong relationship between regular professional plaque control with periodontal disease. The results from our multivariate analysis showed that patients who had not visited the dental clinic for dental scaling within the past year were more likely to have periodontitis compared with their counterparts. A number of studies have demonstrated that plaque and supragingival calculus accumulation is associated with periodontal disease Supragingival plaque can be a natural storage for periodontopathic bacteria, which will migrate subgingivally to form a subgingival biofilm when the host defense is overwhelmed. 17 Results from various studies have indicated the essential role of effective plaque control in the

5 PHAM et al. 5 of 7 FIGURE 1 Prevalence of periodontitis by nutritional status. P<.001 treatment of inflammatory periodontal disease, including longitudinal studies that have shown that excellent individual plaque control can result in cessation of periodontal disease progression. 18,19 As a consequence, frequent, professional scaling of dental calculus, including supragingival and subgingival cleaning, seems to have a beneficial effect on the control of subgingival microbiota, which is necessary for the initiation and progression of periodontal disease. The combination of professional plaque control with selfadministered plaque control has a beneficial effect on the periodontal health outcome. 20,21 Effective plaque control of individuals can be achieved via the delivery of professional oral hygiene advice. The results from the present study indicated that patients who checked their teeth/gums frequently and received instructions on oral health hygiene within the past year had significantly greater periodontal health status. Despite the fact that maintenance of effective plaque control and regular personal oral hygiene are required to prevent and control periodontal disease, many factors influence self- care behaviors, including lifestyle, knowledge, and attitude. 22 Motivating patients to clean better can be difficult, especially when dealing with adults who are unwilling to establish new cleaning habits. Dentists play a major role in motivating their patients to follow appropriate dental hygiene instructions and advice. Gaglut et al. indicated that patients perception of their degree of control over what happens to them affects the success of dental hygiene advice. 23 Therefore, providing accurate dental information, emphasizing the nature and etiology of the periodontal disease process, and introducing appropriate hygiene techniques and methods seem to be effective measures to instill better personal hygiene behaviors. An important task of oral health professionals is to provide patients with relevant dental information to raise their awareness of how to prevent oral diseases and instill correct dental behaviors. 24 The results of the present study indicated that there was a significant relationship between patients dental knowledge and periodontitis. Patients who received adequate dental information were more likely to improve their dental self- care practice to maintain their oral health. This finding, in agreement with previous studies, suggests that dental knowledge statistically significantly relates to oral health status and can influence oral health attitudes and behaviors. 25,26 This suggests that more community- based oral health- education programs should be conducted to improve oral health knowledge of the population. It also emphasizes the need for further dental health education, and indicates the important role of the dentist in providing proper dental information to their patients. The concept that periodontal health could be affected by smoking is not new. 27 A number of investigations of the correlation between smoking and periodontal disease have resulted in many publications. Recent studies have suggested a positive relationship between the intensity of smoking habit and the severity of periodontal disease. 10,28,29 A large OR of the factors is more likely to be an actual risk for the development of the disease. Our research indicated that smokers were 2.47 times more likely to have periodontal disease TABLE 3 Multivariate analysis of periodontitis with different factors Variables n (%) Odds ratio 95% confidence interval P- value Dental scaling within the past year Yes 95 (25.9) No 272 (74.1) Smoking behavior Non- smokers/former smoker 315 (85.8) Current smoker 52 (14.2) Receiving instructions on oral hygiene within the past year Yes 199 (54.2) No 168 (45.8) Body mass index Underweight/normal weight 286 (77.9) 1 <.001 Overweight/obese 81 (22.1) Adjusted by factors of demographic characteristics, dental behaviors, self- perception of oral status, and dental knowledge. Significant difference at P<.05.

6 6 of 7 PHAM et al. compared with non- smokers. This finding is in agreement with several studies, which reported the effect of smoking on periodontal health to have an odds ratio between 2 and 6, depending on the frequency of smoking Vietnam has one of the highest rates of smoking in the world, with a prevalence of 56.1% of men and 1.8% of women aged 15 years and older. 33 Therefore, antismoking and smoking- cessation strategies are urgently needed, and should be delivered via mass media nationwide. It is clear that it should be made illegal to smoke in public places, such as schools, hospitals, and stations, to protect nonsmokers from exposure to second- hand smoke. Smoking cessation is a difficult process for many people and is based on the level of nicotine dependence, education level, social support, and self- confidence in the ability to stop smoking. However, dentists play an essential role in providing smoking- cessation advice to their patients through the dissemination of information about the harm of smoking and the benefits of smoking cessation on general and oral health. Since 1998, when the relationship between obesity and periodontal disease in humans was reported for the first time, 34 a number of studies have been conducted to clarify this relationship. A meaningful finding is that obesity is associated with a chronic inflammatory response. Adipose tissue produces and secretes a variety of adipokines, cytokines, as well as chemokines, and activates some pro- inflammatory signaling pathways, which are related factors in the inflammatory response. 35,36 Genco et al. analyzed National Health and Nutrition Examination Survey III data and demonstrated that BMI was positively correlated with the severity of periodontal attachment loss. 37 Our study showed that the overweight and obesity group were more likely to have periodontal disease compare with their underweight and normal weight counterparts. Similarly, a recent study conducted in Vietnamese patients also found a significant association between periodontitis and obesity. Because obesity is difficult to treat, the prevention of overweight/obesity should be emphasized to reduce the prevalence and severity of periodontitis. Many of the strategies that produce successful weight loss and maintenance will help prevent obesity, and include diet, physical activity, pharmacological treatment, and surgical intervention. 38 Improving eating habits and increasing physical activity play a vital role in preventing obesity. Dentists should provide their obese patients with information about the risk of periodontal disease, and emphasize the importance of maintaining good oral health. The present study has certain limitations. We collected data from a convenience sample of patients in the dental hospital that was not representative of the general population in Vietnam. We suggest that future studies be conducted with a randomly- drawn sample at a population level. Furthermore, this was a cross- sectional analysis, in which only the relationship between periodontal disease and various presumptive risk factors were assessed. Future investigations using longitudinal studies will be required to clarify the true risk factors in this study group. However, despite these limitations, the present study provided valuable information on several modifiable risk factors of periodontitis in Vietnamese dental patients group that had not been previously investigated. REFERENCES 1. Petersen PE, Ogawa H. The global burden of periodontal disease: towards integration with chronic disease prevention and control. Periodontol ;60: Nora S, Loreto A, Denisse B, et al. Host response mechanisms in periodontal diseases. J Appl Oral Sci. 2015;23: Wayne DB, Trajtenberg CP, Hyman DJ. Tooth and periodontal disease: a review for the primary- care physician. South Med J. 2001;94: FDI. Oral Health Atlas 2nd edition: The Challenge Of Oral Disease A Call For Global Action; Tran VT, Trinh DH, Lam NA. National Oral Health Survey of Vietnam Hanoi, Vietnam: Medical Publishing House; 2002: AlJehani A. Risk factors of periodontal disease: review of the literature. Int J Dent. 2014;2014: Jemin K, Salomon A. Periodontal disease and systemic conditions: a bidirectional relationship. Odontology. 2006;94: Chavarry NGM, Vettore MV, Sansone C, Sheiham A. The relationship between diabetes mellitus and destructive periodontal disease: a meta-analysis. Oral Health Prev Dent. 2009;7: Preshaw PM, Alba AL, Herrera D, et al. Periodontitis and diabetes: a two-way relationship. Diabetologia. 2012;55: Pham TA, Ueno M, Shinada K, Yanagisawa T, Wright FA, Kawaguchi Y. Periodontal disease and related factors in Vietnamese dental patients. Oral Health Prev Dent. 2011;9: Al-Ansari JM, Honkala S. Gender differences in oral health knowledge and behaviour of health science college students in Kuwait. J Allied Health. 2007;34: World Health Organization. The Asia Pacific Perspective: Redefining Obesity. Sydney, NSW: WHO; 2000: Pham TAV. Relationship of a turbidity of an oral rinse with oral health and malodor in Vietnamese patients. J Investig Clin Dent. 2013;4: Christersson LA, Grossi SG, Drunford RG, Machtei EE, Genco RJ. Dental plaque and calculus: risk indicators for their formation. J Dent Res. 1992;71: Löe H, Anerud A, Boysen H. The natural history of periodontal disease man: prevalence, severity, and extent of gingival recession. J Periodontol. 1992;63: Grossi SG, Genco R, Machtei EE. Assessment of risk for periodontal disease. II. Risk indicators for alveolar bone loss. J Periodontol. 1995;66: Sakellari D, Belibasakis G, Chadjipadelis T, Arapostathis K, Konstantinidis A. Supragingival and subgingival microbiota of adult patients with Down s syndrome. Changes after periodontal treatment. Oral Microbiol Immunol. 2001;16: Axelsson P, Odont D. Concept and practice of plaque- control. Pediatr Dent. 1981;3: Lindhe J, Nyman S. The effect of plaque control and surgical pocket elimination on the establishment and maintenance of periodontal health. A longitudinal study of periodontal therapy in cases of advanced disease. J Clin Periodontol. 1975;9: Axelsson P, Lindhe J. The significant of maintenance care in the treatment of periodontal disease. J Clin Periodontol. 1981;8: Garret JS. Effects of nonsurgical periodontal therapy on periodontitis in humans. A reveiw. J Clin Periodontol. 1981;8: Ower P. The role of self- administered plaque control in the management of periodontal disease: 2. Motivation, technique and assessment. Dent Update. 2003;30: Galgut PN, Waite IM, Todd-Pokropek A, Barnby G. The relationship between the multidimensional health locus of control and the performance of subjects on a preventive periodontal programme. J Clin Periodontol. 1987;14:

7 PHAM et al. 7 of Vangipuram S, Rekha R, Radha G, Pallavi SK. Assessment of oral health attitudes and behavior among undergraduate dental students using Hiroshima University Dental Behavioral Inventory HU- DBI. J Indian Assoc Public Health Dent. 2015;13: Baseer MA, Alenazy MS, Alasqah M, Algabbani M, Mehkari A. Oral health knowledge, attitude and practices among health professionals in King Fahad Medical City, Riyadh. Dent Res J (Isfahan). 2012;9: Lin HC, Wong MC, Wang ZJ, Lo EC. Oral health knowledge, attitudes, and practices of Chinese adults. J Dent Res. 2001;80: Hilgers K, Kinane D. Smoking, periodontal disease and the role of the dental profession. Int J Dent Hyg. 2004;2: Bergstrom J, Eliasson S, Dock J. A 10- year prospective study of tobacco smoking and periodontal health. J Periodontol. 2000;71: Haffajee AD, Socransky SS. Relationship of cigarette smoking to the subgingival microbiota. J Clin Periodontol. 2001;28: Tomar SL, Asma S. Smoking- attributable periodontitis in the United States: findings from NHANES III. National Health and Nutrition Examination Survey. J Periodontol. 2000;71: Neto C, Batista J, Rosa EF, Pannuti CM, Romito GA. Smoking and periodontal tissues: a review. Braz Oral Res. 2012;26: Norderyd O, Hugoson A, Grusovin G. Risk of severe periodontal disease in a Swedish adult population. A longitudinal study. J Clin Periodontol. 1999;26: Ministry of Health of Vietnam, Hanoi Medical University, General Statistics Office; and Centers for Disease Control and Prevention. Global Adult Tobacco Survey (GATS). Vietnam, Hanoi: WHO; Saito T, Sakamoto M. Obesity and periodontitis. N Engl J Med. 1998;339: Fantizzi G. Adipose tissue, adipokines, and inflammation. J Allery Clin Immunol. 2005;115: Bastard JP, Maachi M, Lagathu C, et al. Recent advances in the relationship between obesity and insulin resistance. Eur Cytokine Netw. 2006;17: Genco RJ, Grossi SG, Ho A, Nishimura F, Murayama Y. A proposed model linking inflammation to obesity, diabetes, and periodontal infections. J Periodontol. 2005;76: McTigue KM, Harris R, Hemphill B, et al. Screening and intervention for obesity in adults: summary of the evidence for the U.S Preventive Services Task Force. Ann Intern Med. 2003;139: How to cite this article: Pham TAV, Kieu TQ, Ngo LTQ. Risk factors of periodontal disease in Vietnamese patients. J Invest Clin Dent. 2018;9:e jicd.12272