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Objective To investigate the effects of intermaxillary factors and distraction frequency on rapid teeth movement through reducing resistance and distraction by establishing experimental animal models. Methods Twelve Beagle dogs were equally divided into two groups randomly. One group was randomly operated on with different treatments in the maxillary: distraction twice a day through reducing resistance, distraction six times a day through reducing resistance, and conventional distraction. Each treatment was carried out on 4 sides. The other group underwent the same operation in the mandible. Distance of teeth transportation, pulp vitality, tooth mobility and cone-beam computed tomography (CBCT) images were evaluated at two time points: 15 days after distraction and 30 days after distraction. Results After 15 days of distraction, the distance of teeth transportation had no significant difference for intermaxillary discrepancy with frequencies of 2q·d-1 and 6q·d-1 through reducing resistance and distraction (P>0.05), and the speed of movement was significantly higher than that of conventional distraction without obvious side effects (P<0.05). Conclusion Teeth can be moved rapidly through reducing resistance and distraction in the maxillary and the mandible, and distraction with high frequency is more beneficial to physiological reconstruction of teeth. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the role of transforming growth factor-β1 (TGF-β1) 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-β1 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-β1 of tension side of the distracted tooth, and accelerate periodontal tissue reconstruction.