Study On Black-pigmented Bacteria In Infected Root Canal

OBJECTIVETo study the colonization of Black-pigmented bacteria(BPB)in infected root canals and discuss the correlation between Black-pigmented bacteria and clinical symptoms in chronic periodontitis.METHODS1.Study of the colonization of BPB in infected root canal:Five species of BPB in root canals suffered from pulpitis and apical periodontitis were detected by 16S rDNA PCR.The difference of relevance ratio of the five species was analyzed by binominal distribution. The relationship of the five species of BPB was investigated by monofactorial odds ratio.The difference of relevance ratio of BPB in 20 pulpitis and 30 chronic apical periodontitis was analyzed by Chi-square test.2.Study of the correlation between BPB and clinical symptoms in chronic apical periodontitis:The colonization of the five species of BPB in 30 infected root canals with chronic apical periodontitis was detected by 16S rDNA PCR.The association between BPB and clinical symptoms of chronic periodontitis was evaluated by monofactorial odds ratio.RESULTS1.The relevance ratio of BPB in infected root canals:By PCR 60% of the infected root canals harbored P.e(38%),P.n(32%),P.g(30%),P.m (18%)and P.i(14%).The relevance ratio of P.e and P.n was significantly higher than P.m and P.i,(P＜0.05).The statistic analyses showed positive correlation(OR＞2)among P.g/P.e,P.g/P.n,P.e/P.n.2.The relevance ratio of BPB in pulpitis and chronic apical periodontitis:The relevance of P.e in chronic apical periodontitis(50%) was significantly higher than P.e in pulpitis(36.67%).The relevance ratio of P.n,P.g,P.i and P.m in group chronic apical periodontitis(43.33%,36.67%,16.67%,16.67%)and in group pulpitis(20%,20%,10%,15%),did not show a significant statistic difference(P＞0.05).3.The correlation between BPB and clinical symptoms in chronic apical periodontitis:The relationship between P.g,P.e and pain,swelling in chronic apical periodontitis showed positive correlation(OR＞2).But there was no correlation with pain of percussion and sinus.The relationship between P.n and pain of percussion,swelling in chronic apical periodontitis showed positive correlation(OR＞2).But it had no correlation with pain and sinus.There was no correlation between P.i,P.m and pain,pain of percussion,sinus and swelling in chronic apical periodontitis.CONCLUSIONS1.BPB were more frequently present in the infected root canal.The relevance ratio of P.e and P.n was significantly higher than P.m and P.i. P.g/P.e,P.g/P.n,P.e/P.n had positive correlation(OR＞2).There were no significant difference in the colonization of the five species of BPB in infected root canal in pultitis and chronic apical periodontitis except P.e. The pultitis and chronic apical periodontitis have common pathogenic bacteria.2.BPB are one of the pathogenic bacteria in chronic apical periodontitis.P.g,P.e and P.n play an important role in pain and swelling in chronic periodontitis.There was no correlation between P.i,P.m and clinical symptoms in chronic periodontitis.