MicroRNA expression profile of human periodontal ligament cells under the influence of Porphyromonas gingivalis LPS.

Periodontitis is a chronic inflammatory disease which is caused by bacterial infection and leads to the destruction of periodontal tissues and resorption of alveolar bone. Thus, special attention should be paid to the mechanism under lipopolysaccharide (LPS)-induced periodontitis because LPS is the major cause of periodontitis. However, to date, miRNA expression in the LPS-induced periodontitis has not been well characterized. In this study, we investigated miRNA expression patterns in LPS-treated periodontal ligament cells (PDLCs). Through miRNA array and differential analysis, 22 up-regulated miRNAs and 28 down-regulated miRNAs in LPS-treated PDLCs were identified. Seven randomly selected up-regulated (miR-21-5p, 498, 548a-5p) and down-regulated (miR-495-3p, 539-5p, 34c-3p and 7a-2-3p) miRNAs were examined by qRT-PCR, and the results proved the accuracy of the miRNA array. Moreover, targets of these deregulated miRNAs were analysed using the miRWalk database. Database for Annotation, Visualization and Integration Discovery software were performed to analyse the Gene Ontology and Kyoto Encyclopaedia of Genes and Genomes pathway of differential expression miRNAs, and the results shown that Toll-like receptor signalling pathway, cAMP signalling pathway, transforming growth factor-beta signalling pathway, mitogen-activated protein kinase (MAPK) signalling pathway and other pathways were involved in the molecular mechanisms underlying LPS-induced periodontitis. In conclusion, this study provides clues for enhancing our understanding of the mechanisms and roles of miRNAs as key regulators of LPS-induced periodontitis.

[Effect of TGF-ß1 expression on periodontal tissue reconstruction for rapid teeth movement through reducing resistance and distraction].

PURPOSE: To investigate the role of transforming growth factor-ß1 (TGF-ß1) in periodontal tissue reconstruction during rapid teeth movement through reducing resistance and distraction. METHODS: Twenty Beagle dogs were randomly divided into five groups according to time points: distraction for 5 days, 10 days, 15 days, retaining 10 days after distraction for 15 days, and retaining 90 days after distraction for 15 days. The mandibular first premolar was moved by using reducing resistance and distraction (experimental group) or conventional distraction (control group) randomly. For each group, tooth movement distance was measured and first premolar periodontal tissue pieces were obtained in scheduled time. Hematoxylin-eosin stain, Picric acid-Sirius red, and immunohistochemistry were performed. The data was analyzed by using SPSS 18.0 software package. RESULTS: The speed of tooth movement and periodontal reconstruction of the experimental group were significantly faster than the control group. TGF-ß1 positive expression in two groups had similar distribution area, and reached peak at most active stage of osteogenesis in both groups. But in different stages of distraction, the positive expression in the experimental group was significantly higher than the control group(P<0.05). CONCLUSIONS: Compared with conventional orthodontic method, reducing resistance and distraction can obviously increase the expression of TGF-ß1 of tension side of the distracted tooth, and accelerate periodontal tissue reconstruction.

[Evaluation of rapid teeth movement through reducing resistance and distraction in Beagle dogs with cone-beam computed tomography].

OBJECTIVE: To evaluate the effect of rapid teeth movement through reducing resistance and distraction using cone-beam computed tomography (CBCT). METHODS: The left or right side of the mandible of 10 beagles (5 males and 5 females) was randomly selected as the control side (for the conventional distraction with a force of about 85 g) and the other side as the experimental side (subjected to reducing resistance and distraction). CBCT images were taken at 5, 10, and 15 days and also after retaining for 10 and 90 days after distraction for 15 days. The distance of teeth transportation, degree of inclination, alveolar bone density of the compressive area and root resorption were evaluated based on the CBCT images and Ez3D2009 visualization software. RESULTS: No significant difference was found between CBCT-based measurement and direct measurement of teeth transportation distance within the mouths (P>0.05). Teeth inclination on the experimental side was slightly greater than that on the control side (P<0.05). The root resorption on the experimental side was minimal, and the bone density increased gradually along with the teeth migration. The experimental side showed a comparable newly formed alveolar bone density and similar X-ray features of the compressive area with the control side. CONCLUSIONS: CBCT three-dimensional imaging can resolve the problems of overlapping and deformation of the two-dimensional images and is especially useful for measurement of teeth inclination and alveolar bone density in the process of reducing resistance and distraction.

[Related factors and effectiveness of rapid teeth movement through reducing resistance and distraction].

OBJECTIVE: To investigate the role of reducing resistance and distraction in rapid teeth movement and its reliability by establishing the Beagle dogs' experimental model. METHODS: The left or right sides in mandibles of 20 beagles were randomly operated with different treatments: distraction twice a day through reducing resistance; distraction 6 times a day through reducing resistance; conventional distraction through reducing resistance; and conventional distraction (the control group). Each treatment was carried out in 10 sides. The pulp vitality, tooth mobility and distance of teeth transportation were evaluated at different time points: before the distraction, distraction after 15 days, retaining 30 days after 15 days of distraction. The degree of inclination, root resorption and alveolar bone density of the compressive areas were evaluated by cone-beam computed tomography images. RESULTS: The distance of teeth transportation was similar in groups distraction twice daily and 6 times a day through reducing resistance (P>0.05), but their speed of transportation was significantly higher than that of conventional distraction through reducing resistance. The conventional distraction group had the lowest speed of transportation. The pulp vitality of distracted teeth was normal, and no root comprehensive resorption and periodontal defect were found. Distracted teeth in the reduced resistance and distraction groups (13.9°±3.5°) tipped more that in the conventional distraction group (6.6°±1.3°) (P<0.05). CONCLUSION: Reducing resistance and distraction are inseparable factors to realize fast teeth moving. The rate of orthodontic tooth movement can be accelerated through resistance reduction and periodontal distraction without obvious unfavorable effects but at minimal acceptable teeth inclination.