Effects Of Orthodontic Treatment On Periodontal Micro-ecological Environments

Malocclusion is a common oral disease, and adolescents are the major patients. 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. 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 microflora. Microbiological and clinical examinations for periodontal tissue were taken in this study to interpret the basic characters of periodontal tissue of adolescence malocclusion patients. The dynamic variation of periodontal microflora and clinical indexes were also observed following the placement of the fixed orthodontic appliances.53 malocclusion patients aged 11-21 were selected. Right maxillary first molar 16 and right mandibular central incisor 41 were the observed teeth. The periodontal status of observed teeth was examined before orthodontic treatment. Plaque index(PI), gingival index(GI), bleeding on probing(BOP) and probing depth(PD) were registered, and gingival marginal plaques were collected at medial-buccal axial ridge of observed teeth. The total counts ofcultivable flora, the detective counts (CFU/g) and detective ratio (%) of each flora were assayed by cultivation and biochemical identification. The results revealed that the detective counts and the detective ratio of Streptococcus.spp, Veillonella.spp, Actinomyces. spp, Peptostreptococcus.spp,Fusobacterium.spp, non-black-pigmented Prevotella (NBPP) and Bacteroides.spp, Eubacterium.spp, Propionibacterium.spp, and Capnocytophaga.spp were relatively high, while Campylobacter.spp and black-pigmented gram negative anaerobic rod{BPAR) were relatively low among the periodontal flora of adolescent malocclusion patients aged 11-21. In clinical examination, PD was no less than 3 mm and belonged to the normal range. P1I and GI scores and positive rate of BOP were relatively low. To assess the effects of fixed orthodontic treatment on periodontal micro-ecological environments, clinical and microbiological examinations were taken from 30 patients at the two observed teeth at different time intervals: prior to the placement of fixed appliances, 1st months, 3rd months, and 6th months after the placement. The aim was to assess the variation of the total cultivable flora, the detective counts and detective ratio of each flora, and periodontal clinical indexes at different time intervals before and after the appliances were carried on. With the placement of fixed appliances, the detective ratio of Veillonella at 16 and Actinomyces at 41 decreased gradually, while the ratio of Campylobacter and BPAR increased at both two observed teeth(P<0.05). The detective ratio of Eubacterium and Fusobacterium at 41 increased too (P<0.05). Compared with baseline, the detective counts of Veillonella at 16 decreased, while the counts of Campylobacter, BPAR and NBPP-Bacteroides increased at both two observed teeth. The total counts offlora, Eubacterium and Fusobacterium at 41 and Peptostreptococcus at 16 also increased compared with baseline. P1I (lingual side) of 16 and 41 decreased, while GI (buccal side) and PD (buccal and lingual sides) of 16 increased (PO.05).In conclusion, the periodontal status of adolescent malocclusion patients was relatively healthy. The major flora was the dominant bacteria of the normal periodontal tissues, and the ratio of suspected periodontal pathogens was relatively low. The ecosystem of oral flora changed after the placement of fixed orthodontic appliances. The counts and constitutions of periodontal flora were varied, and the detective counts and ratio of suspected periodontal pathogens increased.