Influence of local risk indicators upon relative site-specific bacterial charges in chronic periodontitis patients: Multilevel and Cluster analysis on 6 periodontal pathogens identified by mean of quantitative Real-Time PCR microbiological test.

Aim: The aim of the present study was to analyze the correlation among the site-specific relative bacterial charges and the local risk indicators. Methods: The data have been collected from the clinical and radiographic records of 40 consecutive chronic periodontitis patients. The examined indicators analyzed were presence or absence of: furcations, open contacts, enamel pearls, malpositon, root proximity, root fracture, endodontic problem, over hanging restauration and resorption. Furcation involvement and open contacts were previously identified by a pilot study as guidance indicators. The sample was divided into two groups: 20 subjects with at least one guidance indicator and 20 subjects with out. The studied bacteria were: Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td), Fusobacterium nucleatum (Fn) e Campylobacter rectus (Cr). The relative charges of the above mentioned bacteria were analyzed by mean of a site-specific quantitative Real-Time PCR microbiological test. With the Cluster analysis ecological niches presence was searched and the Multilevel analysis was used to quantify local risk indicators influence upon bacterial relative charges. Results: The Cluster analysis shows that all sites with the presence of at least one guidance indicator fall in the cluster where the relative bacterial charges are the highest. The Multilevel analysis indicates that the relative charges of Tannerella forsythia (Tf) and Porphyromonas gingivalis (Pg) are significantly more elevated in sites with presence of furcation and open contacts compared to the ones without (p= 0,004; p= 0,021). Conclusion: The results show the prognostic importance of the individuated guidance local risk indicators and their influence on the examined site-specific relative bacterial charges. From this study emerges that such local risk indicators can be considered as real ecological niches. In a comprehensive periodontal treatment a special effort should be made to eradicate these ecological niches.