title: Smoking behaviour and knowledge in high school students in Riyadh and Belfast.
abstract: Smoking is one of the risk factor associated with onset, severity and progression of periodontal disease.
  
  
  OBJECTIVE
  The aim of the study was to examine the smoking behaviour and dental health knowledge of high school students in Riyadh and Belfast.
  
  
  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
  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.
authors.affiliation: Preventive Dental Sciences, King Saud University, College of Dentistry, P.O. Box 60196, Riyadh, 11545 Kingdom of Saudi Arabia.
authors.forename: K
authors.initials: K
authors.lastname: Almas
authors.forename: F
authors.initials: F
authors.lastname: Maroof
authors.forename: C
authors.initials: C
authors.lastname: McAllister
authors.forename: R
authors.initials: R
authors.lastname: Freeman
mesh_terms: D000293:Adolescent; D001294:Attitude to Health; D016009:Chi-Square Distribution; D005260:Female; D005891:Gingivitis / Q000453:epidemiology; D015438:Health Behavior; D006266:Health Education / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D009660:Northern Ireland / Q000453:epidemiology; D009910:Oral Hygiene / Q000706:statistics & numerical data; D015995:Prevalence; D012529:Saudi Arabia / Q000453:epidemiology; D012907:Smoking / Q000453:epidemiology*; D013223:Statistics as Topic; D014099:Toothbrushing / Q000706:statistics & numerical data