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Objective:To investigate the effects of bone morphogenetic protein 2(BMP-2)expression in the related periodontal tissue on bone remodeling under different distracting force during rapid tooth movement by resistance reduction and distraction. Methods:1 2 Beagle dogs were randomly divided into 4 groups as follows:5 d distraction,1 5 d distraction,1 5 d distraction and 1 0 d retaining and 1 5 d distraction and 90 d retaining.4 4 were distalized.6 teeth in each group were randomly assigned to re-sistance and distracting method,resistance and conventional method and conventional method,and there were 2 teeth in each group.Moving teeth models were prepared regularly.BMP-2 expression was examined by immunohistochemistry.Results:The BMP-2 positive expression of the 3 groups of different distraction schedule showed similar distribution area,and it reached peak at the end of 1 5-day distration,but the group of resistance and distracting method showed the maximum peak(P 0.05).Conclusion:Resistance reduction with sustained strong distracting force can significantly increased the positive expression of BMP-2 and effectively accelerate new bone formation in periodontal tissue.
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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 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.
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Objective To investigate the histological changes of rapid tooth movement in dogs treated by resistance reduction and distraction osteogenesis, aiming to establish an animal model and further to reveal the remodeling mechanism of rapid tooth movement. Methods A total of 8 local hybrid dogs were selected as subjects for this study. The second pre-molar was extracted on both sides. The experimental side underwent alvelor surgery for resistance reduction and a home-made tooth-borne intraoral distraction device was installed for rapid tooth movement, while for the other side (control side) only tooth-borne intraoral distraction device was used for rapid tooth movement. The longest active force-delivery span was 2 weeks, followed by 6-week retention. The distance between the moved tooth and anchor unit was recorded weekly, and radiography was performed for each side before and after distraction. The surrounding tissues including periodontal ligament and alveolar bone were sectioned for histological analysis. Results The average distance of tooth movement was 3.55mm on the experimental side and 1.11mm on the control side. The rate of tooth movement was notably higher (P<0.01) and no significant apical root resorption was detected by X-ray on the experimental side. The active alvelor bone remodeling was found on the tension and pressure sides. However, there was no significant difference between the experimental side and the control side after the retention period. Conclusion The rate of orthodontic tooth movement can be accelerated through resistance reduction and periodontal distraction without any unfavorable effects but at minimal anchorage loss.
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Objective: To investigate the histological changes of rapid tooth movement in dogs treated by resistance reduction and distraction osteogenesis, aiming to establish an animal model and further to reveal the remodeling mechanism of rapid tooth movement. Methods: A total of 8 local hybrid dogs were selected as subjects for this study. The second pre-molar was extracted on both sides. The experimental side underwent alvelor surgery for resistance reduction and a home-made tooth-borne intraoral distraction device was installed for rapid tooth movement, while for the other side (control side) only tooth-borne intraoral distraction device was used for rapid tooth movement. The longest active force-delivery span was 2 weeks, followed by 6-week retention. The distance between the moved tooth and anchor unit was recorded weekly, and radiography was performed for each side before and after distraction. The surrounding tissues including periodontal ligament and alveolar bone were sectioned for histological analysis. Results: The average distance of tooth movement was 3.55 mm on the experimental side and 1.11 mm on the control side. The rate of tooth movement was notably higher (P<0.01) and no significant apical root resorption was detected by X-ray on the experimental side. The active alvelor bone remodeling was found on the tension and pressure sides. However, there was no significant difference between the experimental side and the control side after the retention period. Conclusion: The rate of orthodontic tooth movement can be accelerated through resistance reduction and periodontal distraction without any unfavorable effects but at minimal anchorage loss.
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Self-ligating brackets have a permanently installed movable component to entrap the archwire which reduces much of the friction created by conventional ligation. Therefore, it allows for rapid tooth movement and shorter overall treatment time. Due to these advantages, interest in self-ligating brackets is increasing. In this report, several practical considerations for using self-ligating brackets are given to appreciate and maximize their benefits. It is thought that self-ligating brackets make shorter and more efficient treatment possible.
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Fricción , Ligadura , Técnicas de Movimiento DentalRESUMEN
The movement of tooth-bone segments by osteotomy can simultaneously shift tooth and surrounding alveolar bone in a relatively short period. The purpose of this study was to evaluate the tissue changes in pulp, periodontal ligament, and alveolar bone in rapid tooth-bone movement with osteotomy. The mandibular 3rd premolar of a dog was extracted and cortical bones of the buccal and lingual area were eliminated, and then cortical bones around the mesial and distal area of root, and below the root apex of the mandibular 4th premolar were osteotomized. After a one-week latency period, a tooth-borne distraction device was activated for 6 days. And pulp, periodontal ligament and alveolar bone were evaluated clinically, radiologically, histologically and immunohistochemically at 0, 1, 2, 4, 6, 8 weeks of the consolidation period and conclusions were reached as follows. 1. Latency period didn't affect total amount of tooth movement and healing process of tissue during consolidation period. 2. Bone formation continued through 8 weeks of consolidation in distracted side, with a high peak at 1-2 weeks, and the lowest at 6-8 weeks of consolidation. 3. At 1 week of consolidation, alveolar bone resorption, osteoclast appearance and inflammatory cell infiltration were the most active, and dentinoclasts characteristically appeared on the pulp and pressure side of the periodontal ligament 4. The expression of TGF-beta was area-specific, as it was strong-positive at bone matrix, osteoblast, osteoclast of alveolar bone, and dentinoclast inside pulp, but weak in pulp, cementoblast and acellular cementum. 5. The expression of TGF-beta was generally observed at the initial 1-2 weeks of consolidation at vessels, periodontal ligament cells, and osteoblast near alveolar bone on the distraction side of the periodontal ligament, and was significantly decreased after 6 weeks of consolidation.