The influence of oral microflora on oral health among a sample of portuguese adolescents

INTRODUCTION: The oral cavity is inhabited by hundreds of bacterial strains that play vital roles in maintaining oral health or in shifting to a diseased state such as dental caries. The aim of this study was to determine the prevalence of salivary Streptococcus mutans , Lactobacillus and Actinobacillus actinomycetemcomitans and the relationship with the decayed, missing and filled teeth scores (DMFT scores) among Portuguese adolescents. METHODS: An observational cross-sectional study was designed including a final sample of 447 adolescents aged between 12 and 19 years old, attending a public school in Sa´ ta˜o, Portugal. A self-administered questionnaire with questions about socio-demographic variables and oral health behaviours was filled out by the adolescents. Clinical examination of oral health status was carried out in order to determine DMFT scores. Saliva collection was accomplished by the passive drool method and the identification of the bacterial strains was accomplished using the Polymerase Chain Reaction technique. RESULTS: The prevalence of Streptoccoccus mutans in the sample studied was 80.8%, of Lactobacillus was 99.5% and of Actinobacillus actinomycetemcomitans was 15.2%. The presence of Streptococcus mutans was associated with gender (male ¼ 76.1% vs female ¼ 83.6%, P ¼ 0.04) and history of dental pain at least once in their lives (77.3% vs 87.8%, P < 0.01). The presence of Actinobacillus actinomycetemcomitans was associated with age ( < 15yrs ¼ 12.3% vs 15yrs ¼ 20.3%, P ¼ 0.03) and residence area (rural ¼ 18.2% vs urban ¼ 11.0%, P ¼ 0.04). No significant statistical differences were found between the DMFT scores and the bacterial strains Streptoccoccus mutans (0 ¼ 78.9% vs 1–3 ¼ 80.9% vs 4 ¼ 84.1%, P > 0.05), Lactobacillus (0 ¼ 100.0% vs 1–3 ¼ 100.0% vs 4 ¼ 99.4%, P > 0.05) and Actinobacillus actinomycetemcomitans (0 ¼ 12.2% vs1-3 ¼ 12.5% vs 4 ¼ 18.2%, P > 0.05). CONCLUSIONS: We found no association between bacterial strains and dental caries. The presence of oral microflora is clearly one of the main etiological factors for dental caries development, but cannot be considered in an isolated manner. Oral diseases can appear in the presence of changes of the oral bacterial communities’ structure and that may be related with the shift from health to disease.