title: Methods and background characteristics of the TOHNN study: a population-based study of oral health conditions in northern Norway.
abstract: OBJECTIVE
  The aim of the Tromstannen-Oral Health in Northern Norway (TOHNN) study was to investigate oral health and dental-related diseases in an adult population. This article provides an overview of the background of the study and a description of the sample characteristics and methods employed in data collection.
  
  
  METHODS
  Cross-sectional population-based study including a questionnaire and clinical dental examination.
  
  
  METHODS
  A randomly selected sample of 2,909 individuals (20-79 years old) drawn from the population register was invited to participate in the study. The data were collected between October 2013 and November 2014 in Troms County in northern Norway. The questionnaire focused on oral health-related behaviours and attitudes, oral health-related quality of life, sense of coherence, dental anxiety and symptoms from the temporomandibular joint. The dental examinations, including radiographs, were conducted by 11 dental teams in 5 dental offices. The examination comprised of registration of dental caries, full mouth periodontal status, temporomandibular disorders, mucosal lesions and height and weight. The participants were grouped by age (20-34, 35-49, 50-64 and 65-79) and ethnicity (Norwegian, Sámi, other European and other world).
  
  
  RESULTS
  From the original sample of 2,909 individuals, 1,986 (68.3%) people participated, of whom 1,019 (51.3%) were women. The highest attendance rate was among women 20-34 years old (80.3%) and the lowest in the oldest age group of women (55.4%). There was no difference in response rate between rural and urban areas. There was a positive correlation between population size and household gross income (p < 0.001) and education level (p < 0.001). The majority of Sámi resided in smaller municipalities. In larger cities, most participants used private dental health care services, whereas, in rural areas, most participants used the public dental health care service.
  
  
  CONCLUSIONS
  The TOHNN study has the potential to generate new knowledge on a wide range of oral health conditions beneficial to the population in Troms County. Due to the high participation rate, generalization both nationally and to the circumpolar area ought to be possible.
authors.affiliation: The Public Dental Health Service Competence Centre of Northern Norway, Tromsø, Norway.|Department of Clinical Dentistry, Faculty of Health Sciences, UiT the Arctic University of Norway, Tromsø, Norway; gro.eirin.holde@tromsfylke.no.
authors.forename: Gro Eirin
authors.initials: GE
authors.lastname: Holde
authors.affiliation: The Public Dental Health Service Competence Centre of Northern Norway, Tromsø, Norway.
authors.forename: Nils
authors.initials: N
authors.lastname: Oscarson
authors.affiliation: The Public Dental Health Service Competence Centre of Northern Norway, Tromsø, Norway.|Department of Clinical Dentistry, Faculty of Health Sciences, UiT the Arctic University of Norway, Tromsø, Norway.
authors.forename: Anders
authors.initials: A
authors.lastname: Tillberg
authors.affiliation: Public Dental Health Care Service, Tromsø County Council, Tromsø, Norway.
authors.forename: Peter
authors.initials: P
authors.lastname: Marstrander
authors.affiliation: The Public Dental Health Service Competence Centre of Northern Norway, Tromsø, Norway.|School of Education, Health and Social Studies, Dalarna University, Falun, Sweden.
authors.forename: Birgitta
authors.initials: B
authors.lastname: Jönsson
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D003430:Cross-Sectional Studies; D003729:Dental Care / Q000592:standards / Q000639:trends; D003731:Dental Caries / Q000453:epidemiology*; D003753:Dental Health Surveys / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D009909:Oral Health / Q000592:standards* / Q000639:trends; D012307:Risk Factors; D012424:Rural Population; D012737:Sex Factors; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: adults; dental health; epidemiology; prevalence; survey