Prevalence of fimA genotypes of Porphyromonas gingivalis in adolescent orthodontic patients.

BACKGROUND: The placement of fixed orthodontic appliances may alter the composition of oral microbiota and has the potential risk of periodontal complication. Porphyromonas gingivalis fimbriae play a critical role in colonization of P. gingivalis in subgingival regions. In this study, we investigated the association between the prevalence of P. gingivalis-specific fimA genotypes and periodontal health status in adolescent orthodontic patients, to identify the pathogencity of P. gingivalis during orthodontic therapy. METHODS: Sixty-one adolescent orthodontic patients were enrolled in the case group, while the control group consisted of 56 periodontally healthy adolescents. At baseline (T0), clinical parameter (gingival index) was tested, and subgingival plaque samples were obtained from the lower incisors. The incidences of P. gingivalis and fimA genotypes were detected by polymerase chain reaction. All parameters were reassessed after 1 month (T1), 2 months (T2), 3 months (T3), and 6 months (T4) in the case group and then compared with those of the controls. RESULTS: Both microbiological and clinical parameters from orthodontic patients started to increase after placement of fixed appliances. Maximum values were reached at 3 months after placement and followed by their decreases at six months. However, the microbiological and clinical parameters in the case group were significantly higher than those of the control group. The GI of fimA II, IV-positive samples was significantly higher than that of negative samples. CONCLUSION: P. gingivalis carrying fimA II or IV was closely related to orthodontic gingivitis. In addition, proper oral hygiene control could lead to little increase in dental plaque accumulation, and exert a beneficial effect to periodontal tissues.

Profiling of subgingival plaque biofilm microbiota in adolescents after completion of orthodontic therapy.

BACKGROUND: Fixed orthodontic treatment is the most common method for malocclusion but has the potential risk of periodontal complication with unclear outcomes of whether microbiologic and clinical changes could be reversible in adolescents after orthodontic therapy. METHODS: Twenty adolescents with orthodontic treatment were enrolled in the study as the case group at end of the therapy, while 19 periodontally healthy adolescents were involved in the control group. At baseline (T0), clinical parameters including gingival index, probing depth and sulcus bleeding index were tested, and subgingival plaque samples were collected from the lower incisors. The counts of A. actinomycetemcomitans, P. gingivalis, P. intermedia, T. forsythia and total bacteria were determined by real-time PCR. All parameters were reassessed after 1 month (T1) and 3 months (T2) in the case group and compared with that of the controls. RESULTS: At baseline (T0), clinical parameters (including GI, PD, SBI) of the test sites in the case group were significantly higher than that of the control group (P<0.05 or P<0.01). At 3 months (T2), no differences were noticed in GI and SBI between two groups. The prevalence and counts of periodontopathogens tend to be normal (P>0.05), while PD and the amount of P.intermedia were still significantly higher compared with that of the control group (P<0.05 or P<0.01). CONCLUSION: After removal of appliances, the periodontal changes induced by orthodontic therapy are only partially reversible at 3 months after removal.

Study of recombinant human osteogenic protein-1 expressed in prokaryocyte on the repair of extracted socket in rabbits.

The study investigated the effect of recombinant human osteogenic protein-1 (rhOP-1) expressed in prokaryocyte, to promote the healing of alveolar socket. A model of rabbit extracted socket into which the composites of rhOP-1 and gelatin sponge was immediately implanted was created and the osteoinduction of rhOP-1 was assessed by histological method, quantitative measurement of calcium content and alkaline phosphatase (ALP) activity. The result of histology showed that bone healing in rhOP-1 side is 4-6 weeks earlier than that of the control side. ALP activity and calcium content in rhOP-1 side were significantly high compared with that of the control side. rhOP-1 has a satisfactory osteoinduction ability to promote the healing of extracted socket.

[Detection of gingipain K in the gingival crevicular fluid of orthodontic patients].

PURPOSE: To explore the correlation between gingipain K (Kgp) and inflammatory reaction of gum in the process of orthodontic treatment, and analyse the role of Kgp in the development of gingivitis during orthodontic treatment. METHODS: Totally 45 orthodontic healthy teenagers were randomly chosen for the study. The subgingival plaques were collected simultaneously before orthodontic treatment and 3 months after treatment. 16S rDNA PCR technique was used to detect Porphyromonas gingivalis (P.g) and Kgp. SPSS17.0 software package was used for statistical analysis. RESULTS: The detection rate of Kgp was 35.71% before orthodontic treatment and 67.86% after treatment. Positive correlation (P<0.05) was observed between Kgp and gingival inflammation. CONCLUSIONS: Fixed orthodontic appliances cause plaque accumulation, accordingly slight gingiva inflammation and the increament of P.gingivalis in the early stage.

Detection of fusobacterium nucleatum and fadA adhesin gene in patients with orthodontic gingivitis and non-orthodontic periodontal inflammation.

Fusobacterium nucleatum is one of the most abundant gram-negative bacilli colonizing the subgingival plaque and closely associated with periodontal disease. However it is unclear whether F. nucleatum is involved in gingival inflammation under orthodontic appliance. A novel adhesin, FadA, which is unique to oral Fusobacteria, is required for F. nucleatum binding and invasion to epithelial cells and thus may play an important role in colonization of Fusobacterium in the host. In this study, we evaluated the prevalence of F. nucleatum and its virulence factor FadA adhesion gene (fadA) in 169 subgingival biofilm samples from 55 cases of gingivitis patients with orthodontic appliances, 49 cases of gingivitis patients without orthodontic treatment, 35 cases of periodontitis patients and 30 cases of periodontally healthy people via PCR. The correlations between the F. nucleatum/fadA and gingivitis index(GI)was also analyzed. The detection rate of F. nucleatum/fadA in periodontitis group and non-orthodontic gingivitis group was higher than the other two groups (p<0.01) while it was higher in orthodontic gingivitis group than in health people (p<0.05). An obviously positive correlation was observed between the prevalence of F. nucleatum/fadA and GI. F. nucleatum carrying fadA may be more closely related to the development of gingivitis and periodontal disease compared with orthodontic gingivitis.

Prevalence of Porphyromonas gingivalis four rag locus genotypes in patients of orthodontic gingivitis and periodontitis.

Porphyromonas gingivalis is considered as a major etiological agent in periodontal diseases and implied to result in gingival inflammation under orthodontic appliance. rag locus is a pathogenicity island found in Porphyromonas gingivalis. Four rag locus variants are different in pathogenicity of Porphyromonas gingivalis. Moreover, there are different racial and geographic differences in distribution of rag locus genotypes. In this study, we assessed the prevalence of Porphyromonas gingivalis and rag locus genotypes in 102 gingival crevicular fluid samples from 57 cases of gingivitis patients with orthodontic appliances, 25 cases of periodontitis patients and 20 cases of periodontally healthy people through a 16S rRNA-based PCR and a multiplex PCR. The correlations between Porphyromona.gingivalis/rag locus and clinical indices were analyzed. The prevalence of Porphyromonas gingivalis and rag locus genes in periodontitis group was the highest among three groups and higher in orthodontic gingivitis than healthy people (p<0.01). An obviously positive correlation was observed between the prevalence of Porphyromonas gingivalis/rag locus and gingival index. rag-3 and rag-4 were the predominant genotypes in the patients of orthodontic gingivitis and mild-to-moderate periodontitis in Shandong. Porphyromonas.gingivalis carrying rag-1 has the strong virulence and could be associated with severe periodontitis.

[Effect of recombinant human bone morphogenetic protein-7 expressed in prokaryocyte to augment bone formation of alveolar ridge].

OBJECTIVE: To investigate new bone formation of alveolar augmentation with recombinant human bone morphogenetic protein-7 (rhBMP-7) expressed in prokaryocyte. METHODS: To create the model of rabbit extraction socket into which the composites of rhBMP-7 and the gelatin sponge was immediately implanted, then the samples were investigated 2, 4, 8 and 12 weeks postoperatively by gross observation, scanning electron microscope (SEM), quantitative measurement of calcium content and alkaline phosphatase (ALP) activity. RESULTS: There was significant difference in height of alveolar ridge absorpted between the experimental groups and the carrier control groups through gross observation. The result of SEM showed that bone healing in rhBMP-7 groups was 4-6 weeks earlier than that of control groups. ALP activity in rhBMP-7 groups were obviously high compared with that of control groups. CONCLUSION: The BMP-7 has a satisfactory osteoinduction ability to promote new bone formation and prevent alveolar bone absorption.