Aim: It is confirmed the important role that some bacterial species play on the onset and progression of the periodontal disease. The goal of this research is to study whether some of these bacterial species prefer to colonize specific periodontal sites rather than others. Material and Methods: 30 consecutive patients with moderate to severe chronic periodontal disease were enrolled for the study. Subjects with a recent history (3 months) of antibiotic consumption were excluded. Presence and bacterial count (CFU/ml) of 6 periodontal pathogens [Aggregatibacter actinomicetencomitans (Aa), Phorphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td), Fusobacterium nucleatum (Fn), Prevotella intermedia (Pi)] were determined by using a DNA-polymerase PCR test. By mean of sterile paper cones subgingival plaque samples were collected from periodontal pockets deeper than 4 mm. Four sites by patient were examined for a total of 120 plaque samples. Two-step cluster analysis was used to divide cases into uniform groups on the basis of either categorical (bacterial species and site) or quantitative (bacterial count) data. The first step of the procedure is the formation of preclusters that are clusters of the original cases based on the distances between all possible pairs of cases; when preclustering is complete, all cases in the same precluster are treated as a single entity. In the second step, a standard hierarchical clustering algorithm is used on the preclusters. The choice of a similarity measure and the determination of the number of clusters were based on the Log-likelihood distance and Schwarz’s Bayesian Criterion (BIC), respectively. -level was set at 0.05. Results: No statistically significant association was observed between bacterial species and tooth type or dental arch. Cluster analysis identifies 3 clusters based on BIC= 795.17 and the highest measure of distance of the Log-likelihood (ratio=1.807): the first cluster groups 38.3% of the cases, the second 49.2% of the cases and the third 12.5% of the cases. Identifying the clusters on the basis of the prevailing sites, the first cluster is defined by the mesio-vestibular one while the second cluster groups all the other sites (p=0-0001). As for the bacterial species Pg, Tf and Fn are present in all the sites except for the mesio-vestibular one (p<0.05); Aa and Td are present in both clusters; Pi isn’t linked either to the first or to the second cluster. Considering the cell counts no link appears with the sites. Discussion Chemical and physical factors potentially connected to an easier access for the oral hygiene might be responsible of the difference observed for the mesio-vestibular site. As previously reported, the similar colonization of Pg, Tf and Fn may be caused by: 1) the synergic action between Pg and Tf that can facilitate the formation of a biofilm; 2) the capacity of co-aggregation between Pg and Fn. Finally, the colonization of Pg and Tf is improved by the co-aggregation with Fn in the biofilm. Conclusion The anatomical site seems to influences the distribution of Pg, Tf and Fn; on the contrary either the tooth type or the dental arch don’t result to have a role on the distribution of the examined species.
M. Montevecchi, V. Checchi, M.R. Gatto, L. Checchi (2010). ANATOMICAL DISTRIBUTION OF 6 PERIODONTAL PATHOGENS. AN OBSERVATIONAL STUDY ON CHRONIC PERIODONTAL PATIENTS.
ANATOMICAL DISTRIBUTION OF 6 PERIODONTAL PATHOGENS. AN OBSERVATIONAL STUDY ON CHRONIC PERIODONTAL PATIENTS
MONTEVECCHI, MARCO;CHECCHI, VITTORIO;GATTO, MARIA ROSARIA;CHECCHI, LUIGI
2010
Abstract
Aim: It is confirmed the important role that some bacterial species play on the onset and progression of the periodontal disease. The goal of this research is to study whether some of these bacterial species prefer to colonize specific periodontal sites rather than others. Material and Methods: 30 consecutive patients with moderate to severe chronic periodontal disease were enrolled for the study. Subjects with a recent history (3 months) of antibiotic consumption were excluded. Presence and bacterial count (CFU/ml) of 6 periodontal pathogens [Aggregatibacter actinomicetencomitans (Aa), Phorphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td), Fusobacterium nucleatum (Fn), Prevotella intermedia (Pi)] were determined by using a DNA-polymerase PCR test. By mean of sterile paper cones subgingival plaque samples were collected from periodontal pockets deeper than 4 mm. Four sites by patient were examined for a total of 120 plaque samples. Two-step cluster analysis was used to divide cases into uniform groups on the basis of either categorical (bacterial species and site) or quantitative (bacterial count) data. The first step of the procedure is the formation of preclusters that are clusters of the original cases based on the distances between all possible pairs of cases; when preclustering is complete, all cases in the same precluster are treated as a single entity. In the second step, a standard hierarchical clustering algorithm is used on the preclusters. The choice of a similarity measure and the determination of the number of clusters were based on the Log-likelihood distance and Schwarz’s Bayesian Criterion (BIC), respectively. -level was set at 0.05. Results: No statistically significant association was observed between bacterial species and tooth type or dental arch. Cluster analysis identifies 3 clusters based on BIC= 795.17 and the highest measure of distance of the Log-likelihood (ratio=1.807): the first cluster groups 38.3% of the cases, the second 49.2% of the cases and the third 12.5% of the cases. Identifying the clusters on the basis of the prevailing sites, the first cluster is defined by the mesio-vestibular one while the second cluster groups all the other sites (p=0-0001). As for the bacterial species Pg, Tf and Fn are present in all the sites except for the mesio-vestibular one (p<0.05); Aa and Td are present in both clusters; Pi isn’t linked either to the first or to the second cluster. Considering the cell counts no link appears with the sites. Discussion Chemical and physical factors potentially connected to an easier access for the oral hygiene might be responsible of the difference observed for the mesio-vestibular site. As previously reported, the similar colonization of Pg, Tf and Fn may be caused by: 1) the synergic action between Pg and Tf that can facilitate the formation of a biofilm; 2) the capacity of co-aggregation between Pg and Fn. Finally, the colonization of Pg and Tf is improved by the co-aggregation with Fn in the biofilm. Conclusion The anatomical site seems to influences the distribution of Pg, Tf and Fn; on the contrary either the tooth type or the dental arch don’t result to have a role on the distribution of the examined species.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
