Soluble urokinase-type plasminogen activator receptor is associated with signs of periodontitis in adolescents.

Owing to its molecular stability in body fluids, soluble urokinase-type plasminogen activator receptor (suPAR) is used as a biomarker for the level of systemic inflammation. This study compares the suPAR levels in serum with those in the saliva of adolescents and evaluates their association with the periodontal conditions. Adolescents identified as screen positive (n = 87) or screen negative (n = 73) for periodontitis had saliva and serum samples taken, along with subgingival plaque samples. The concentrations of suPAR were determined in saliva and serum, and 18 microbial species and the immunoglobulin response to them was evaluated. Factor analyses were used to reduce the number of variables within each of the domains of clinical, microbiological, and immunological findings. The median salivary suPAR concentration was 13.18 [(interquartile range (IQR): 6.20-23.36] µg l-1 and was not associated with the serum suPAR levels (median 2.05; IQR: 1.62-2.46 µg l-1 ). Linear regression analysis showed that the log10 (salivary suPAR concentration) was statistically significantly positively associated with the clinical phenotype 'Periodontitis Extent' (ß = 0.28; 95% CI: 0.16-0.39) along with 'Putative periodontopathogens' (ß = 0.65; 95% CI: 0.51-0.79). The study represents the first determination of salivary suPAR concentration in a larger well-defined adolescent population. Our results suggest the potential for clinical use of suPAR in saliva as an inflammatory risk indicator/biomarker of periodontitis.

Methodological issues in assessing the association between periodontitis and caries among adolescents.

OBJECTIVES: We aimed to investigate the association between dental caries and periodontitis among adolescents participating in a case-control study of periodontitis. In addition, we compared 2 analytical approaches to estimate the association: conventional regression and structural equation modelling (SEM). METHODS: Along with periodontal recordings, data were obtained on caries, just as subgingival plaque samples were collected. Sociodemographic information was collected with a questionnaire. We used factor analyses to express the many correlated clinical periodontal dimensions in a smaller number of factors. The association between caries (counts of enamel and dentin lesions, or dentin lesions only) and periodontitis was tested using negative binomial regression with robust variance (conventional regression) and weighted least squares (SEM) estimation. RESULTS: Factor analysis revealed 2 different latent periodontal variables: "extent" and "severity" of periodontitis. Using conventional regression, the "extent" of periodontitis was positively associated with higher counts of dentin caries lesions, even after adjustments for maternal education and subgingival microbial composition (rate ratio 1.34; 95% CI 1.07-1.68). The "severity" of periodontitis was associated with lower counts of enamel and dentin caries lesions (rate ratio 0.85 95% CI 0.77-0.92). The SEM revealed a positive association between periodontitis "extent" and number of dentin caries lesions (coefficient 0.29; P < .0001). The "severity" of periodontitis was negatively associated with enamel and dentin caries (coefficient -0.44; P < .0001). CONCLUSIONS: We found an association between caries and periodontitis among adolescents. The "severity" of periodontitis was negatively associated with enamel/dentin caries, whereas the "extent" of periodontitis was positively associated with dentin caries irrespective of the analytical approach employed.

Clustering of subgingival microbial species in adolescents with periodontitis.

It has become increasingly recognized that groups of microorganisms interact within the subgingival plaque of adult subjects with periodontitis. It is much less clear, however, whether the consortia of microorganisms associated with periodontitis are different in early and more advanced cases of periodontitis. To investigate this point further, subgingival plaque was collected from six sites in 87 adolescents with periodontitis and 73 controls and the samples were analyzed for the detection of 18 microbial species using the DNA-DNA hybridization technique. Actinomyces oris accounted for the highest proportion of the flora and was more predominant among controls. Prevotella nigrescens, Prevotella intermedia, Porphyromonas gingivalis, and Tannerella forsythia were present at higher levels among the subjects with periodontitis. Factor analyses identified one factor characterized by highly positive loadings for T. forsythia, Campylobacter rectus, P. gingivalis, P. intermedia, P. nigrescens, Parvimonas micra, and Treponema denticola, and another factor characterized by highly positive loadings of A. oris, Capnocytophaga ochracea, Eikenella corrodens, Streptococcus intermedius, Selenomonas noxia, Streptococcus oralis, Streptococcus sanguinis, and Veillonella parvula. Aggregatibacter actinomycetemcomitans and Streptococcus mutans did not load on any of the two factors, while Fusobacterium nucleatum loaded on both. These findings confirm the occurrence of clustering of subgingival bacteria according to case status also among young individuals.