Quantitative detection of Porphyromonas gingivalis by real-time PCR of orthodontic patients after removal of orthodontic appliances

Objective To detect Porphyromonas gingivalis and clinical index in subgingival specimens after removal of orthodontic appliances and to evaluate clinical index and P.gingivalis factors associated with orthodontic appliances during an episode of gingival inflammation and the impact of appliance removal on periodontal health.Methods Choose 20 patients prepare to removal of orthodontic appliances.Plaque index(PLI),sulcus bleeding index(SBI) and probing depth(PD) of observed teeth were examined and subgingival plaques were collected at prior to appliance removal(baseline) and 1,3 and 6 months after appliance removal.The numbers of P.gingivalis,total bacteria,the proportion of P.gingivalis and the prevalence of P.gingivalis in the samples were detected with the TaqMan real-time PCR.Results The prevalence of P.gingivalis decreased from baseline to the 6th month after fixed appliance removal in two groups,and significant change was found in 6th month(P ＜ 0.05); The numbers of P.gingivalis significantly reduced from baseline to the 6th month(P ＜ 0.05); The proportion of P.gingivalis in subgingival plaque decreased from baseline to the 6th month(P ＜0.05).PLI,SBI and PD significantly decreased from baseline to the 6th month after fixed appliance removal.Conclusion After fixed appliance removal,most of patients can recover periodontal tissue health in good oral hygiene.The percentage of P.gingivalis are closely associated with periodontal status.TaqMan real-time polymerase chain reaction has a high sensitivity and specificity.It was demonstrated the broad potential of application on detection of oral microbes. Key words: Fixed orthodontic treatment; Periodontal clinical index; Porphyromonas gingivalis; Real-time PCR; TaqMan system