Quantitative Study Of Porphyromonas Gingivalis By Real-time PCR Of Orthodontic Patients With Fixed Orthodontic Appliances

Objective: Malocclusion is a common disease of oral and maxillofacial region. The morbidity of malocclusion can range from 28% to 90%. Currently, fixed orthodontic treatment is one of the most widely used orthodontic methods, but its implications, such as gingival swelling, bleeding and hyperplasia, are often observed during therapy. And the other phenomenon is that adults and adolescents have different symptoms. Stagnant zones around fixed orthodontic appliances are considered to be the major cause, which in favor of the accumulation of bacterial plaque and colonization and reproduction of P.gingivalis. The dynamic variation of P.gingivalis and clinical examinations for periodontal tissue were taken in this study to interpret the basic characters of periodontal tissue of malocclusion patients and the difference between adults and adolescents.Methods: 28 malocclusion patients were selected randomly, including 11 adults and 17 adolescents. All the patients were treated by straight wire appliance. Both side of mandibular central incisor were the observed teeth. Plaque index(PLI), gingival index(GI), sulcus bleeding index(SBI) , probing depth(PD) and attachment loss(AL) of observed teeth were examined and subgingival plaques were collected at medial and distal buccal axial ridge of observed teeth before orthodontic treatment, one month after treatment and three months after treatment. We used real-time quantitative PCR to detecting and quantitating the total counts of bacteria and the counts of P.gingivalis in each sample.Results:1. Microbiological indexes: The positive rate of P.gingivalis increased from baseline to the third month, but no significant difference was found. The percentage of P.gingivalis ascended significantly from baseline to the third month of the whole samples. In addition, the adults'percentages of P.gingivalis were significantly higher than the adolescents at baseline and the first month, but they showed no marked difference at the third month.2. Periodontal indexes: PLI and SBI increased from baseline to the first and the third month both in adult and adolescent groups. PD which was more than 2mm and AL were not found in any patients in this study.Conclusions:Fixed orthodontic appliances caused the colonization of P.gingivalis in adolescents and the increasing of P.gingivalis in both adults and adolescents. The appliances also promoted the accumulation of plaque caused mild gingivitis. Some microbiological indexes had the synchronous trend with the clinical indexes. In addition, the effect of fixed orthodontic appliances was more significant in adolescents than in adults. The periodontal and microbiological statuses of malocclusion patients were influenced by the fixed orthodontic appliances, but they were relatively healthy in this study. The effect of fixed orthodontic appliances in the long run still needed further research. And using real-time PCR to test P.gingivalis percentage in the total bacteria in subgingival plaque was sensitive and rapid.