title: Cariogenic bacteria and dental health status in adolescents: the role of oral health behaviours.
abstract: OBJECTIVE
  To evaluate the association between dental health status and levels of cariogenic bacteria in teenagers and the influence of behaviours and socio-demographic background on levels of bacteria.
  
  
  METHODS
  Study design: A cross-sectional population-based sample of 13-year-old adolescents (112 females and 78 males, total 190) was examined. The number of decayed, missing and filled surfaces (DMFS), plaque and hygiene index were recorded according to the WHO criteria. The saliva samples were collected in a sterile container and then analysed by culture on Mitis Salivarius Bacitracin (MSB) agar for mutans Streptococci and on Man Rogosa Sharp (MRS) agar for Lactobacilli. The levels of bacteria were expressed as the number of colonies forming units per millilitre of saliva (CFU/ml). Associations between levels of mutans Streptococci and Lactobacilli and dental health were estimated by odds ratio (OR) and 95% confidence interval (95% CI) using unconditional logistic regression.
  
  
  RESULTS
  No mutans Streptococci were detected in 53.2% of the adolescents but 22.6% presented ≥ 10³ CFU/ml. For Lactobacilli, these values were, respectively 43.7% and 34.7%. After adjustment for gender and social class, the OR (95% CI) for DMFS >5 was 8.66 (3.57-21.02) if mutans Streptococci ≥ 10³ CFU and 2.11 (0.96-4.64) if Lactobacilli ≥ 10³ CFU.
  
  
  CONCLUSIONS
  This data allow us to conclude that hygiene habits and dental visits are not associated with high levels of cariogenic bacteria, but high scores of DMFS were found in adolescents with high levels of mutans Streptococci and lower parents' education.
authors.affiliation: Department of Clinical Epidemiology, Predictive Medicine and Public Health, University of Porto Medical School, Porto, Portugal - Department of Science, Oral Microbiology Laboratory, Instituto Superior de Ciências da Saúde-Norte, Gandra, Portugal.
authors.forename: M
authors.initials: M
authors.lastname: Relvas
authors.affiliation: Department of Science, Oral Microbiology Laboratory, Instituto Politécnico de Ciências da Saúde-Norte, Gandra, Portugal.
authors.forename: C
authors.initials: C
authors.lastname: Coelho
authors.affiliation: Department of Science, Oral Microbiology Laboratory, Instituto Superior de Ciências da Saúde-Norte, Gandra, Portugal.
authors.forename: C
authors.initials: C
authors.lastname: Velazco Henriques
authors.affiliation: Department of Clinical Epidemiology, Predictive Medicine and Public Health, University of Porto Medical School, Porto, Portugal - Institute of Public Health, University of Porto, Portugal.
authors.forename: E
authors.initials: E
authors.lastname: Ramos
mesh_terms: D000293:Adolescent; D058491:Bacterial Load; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004245:DMF Index; D003729:Dental Care / Q000706:statistics & numerical data; D003731:Dental Caries / Q000382:microbiology*; D003774:Dental Plaque Index; D004522:Educational Status; D005260:Female; D015438:Health Behavior; D006304:Health Status; D006801:Humans; D007778:Lactobacillus / Q000302:isolation & purification*; D008297:Male; D009909:Oral Health; D009911:Oral Hygiene Index; D010290:Parents / Q000193:education; D011159:Population Surveillance; D011174:Portugal; D012463:Saliva / Q000382:microbiology; D012737:Sex Factors; D012923:Social Class; D013295:Streptococcus mutans / Q000302:isolation & purification*; D014099:Toothbrushing / Q000706:statistics & numerical data