This study evaluated,over a 4-month study period,the amount of apical root resorption occurring in maxillary central incisors following their retraction when employing either micro-implant or J-hook headgear anchorage...This study evaluated,over a 4-month study period,the amount of apical root resorption occurring in maxillary central incisors following their retraction when employing either micro-implant or J-hook headgear anchorage.The prospective randomised clinical trial was conducted in Orthodontic Clinic,College of Stomatology,China from 2008-2009.Subjects are patients requiring fixed appliances on waiting list (n=20).In female Han Chinese patients aged from 16-26 years,standardized periapical radiographs from 10 randomly assigned patients with maxillary protrusions comprising the micro-implant group,and from 10 similar patients comprising the J-hook headgear group,were assessed for maxillary central incisor apical root resorption.Measurements before and after orthodontic therapy were also obtained from lateral cephalometric radiographs to calculate incisor horizontal retraction and vertical intrusion distances.Estimated retraction force vectors were calculated in horizontal and vertical directions for both treatment groups.Data analysis employed t-tests and the Pearson correlation test,with α=0.05 for statistical significance.The results showed that when compared with the J-hook group,significantly more apical root resorption shortening of the maxillary central incisors was observed in the micro-implant group (1.27 mm difference,95% CI=0.70-1.84,P<0.001),which was associated with a significantly larger retraction distance (P=0.004) and a smaller vertical force component (P<0.0001).We are led to conclude that continuous activation of the nickel-titanium coil springs used in the micro-implant group resulted in significantly more apical root resorption shortening and maxillary central incisor retraction than when intermittent J-hook retraction was employed.The employment of continuous duration orthodontic forces presents a risk for increased apical root resorption that requires careful radiographic monitoring.展开更多
In our previous studies, a novel cortex-like Ti O2 coating was prepared on Ti surface through micro-arc oxidation（MAO） by using sodium tetraborate as electrolyte, and the effects of the coating on cell attachment we...In our previous studies, a novel cortex-like Ti O2 coating was prepared on Ti surface through micro-arc oxidation（MAO） by using sodium tetraborate as electrolyte, and the effects of the coating on cell attachment were testified. This study aimed to investigate the effects of this cortex-like MAO coating on osseointegration. A sand-blasting and acid-etching（SLA） coating that has been widely used in clinical practice served as control. Topographical and chemical characterizations were conducted by scanning electron microscopy, energy dispersive X-ray spectrometer, X-ray diffraction, contact angle meter, and step profiler. Results showed that the cortex-like coating had microslots and nanopores and it was superhydrophilic, whereas the SLA surface was hydrophobic. The roughness of MAO was similar to that of SLA. The MAO and SLA implants were implanted into the femoral condyles of New Zealand rabbits to evaluate their in-vivo performance through micro-CT, histological analysis, and fluorescent labeling at the bone-implant interface four weeks after surgery. The micro-CT showed that the bone volume ratio and mean trabecular thickness were similar between MAO and SLA groups four weeks after implantation. Histological analysis and fluorescent labeling showed no significant differences in the bone-implant contact between the MAO and SLA surfaces. It was suggested that with micro/nanostructure and superhydrophilicity, the cortex-like MAO coating causes excellent osseointegration, holding a promise of an application to implant modification.展开更多
We put forward a protocolcombining laser treatment and acid etching to obtain multiscale micro/nano-texture surfaces of titanium alloy implant.Firstly,the operationalparameters of the laser were optimized to obtain an...We put forward a protocolcombining laser treatment and acid etching to obtain multiscale micro/nano-texture surfaces of titanium alloy implant.Firstly,the operationalparameters of the laser were optimized to obtain an optimum current.Secondly,the laser with the optimum operationalparameters was used to fabricate micro pits.Thirdly,multiple acid etching was used to clean the clinkers of micro pits and generate submicron and nanoscale structures.Finally,the bioactivity of the samples was measured in a simulated body fluid.The results showed that the micropits with a diameter of 150 μm and depth of 50 μm were built successfully with the optimized working current of 13 A.In addition,submicron and nanoscale structures,with 0.5-2 μm microgrooves and 10-20 nm nanopits,were superimposed on micro pits surface by multiple acid etching.There was thick and dense HA coating only observed on the multiscale micro/nano-textured surface compared with polished and micro-textured surface.This indicated that the multiscale micro/nano-texture surface showed better ability toward HA formation,which increased the bioactivity of implants.展开更多
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘This study evaluated,over a 4-month study period,the amount of apical root resorption occurring in maxillary central incisors following their retraction when employing either micro-implant or J-hook headgear anchorage.The prospective randomised clinical trial was conducted in Orthodontic Clinic,College of Stomatology,China from 2008-2009.Subjects are patients requiring fixed appliances on waiting list (n=20).In female Han Chinese patients aged from 16-26 years,standardized periapical radiographs from 10 randomly assigned patients with maxillary protrusions comprising the micro-implant group,and from 10 similar patients comprising the J-hook headgear group,were assessed for maxillary central incisor apical root resorption.Measurements before and after orthodontic therapy were also obtained from lateral cephalometric radiographs to calculate incisor horizontal retraction and vertical intrusion distances.Estimated retraction force vectors were calculated in horizontal and vertical directions for both treatment groups.Data analysis employed t-tests and the Pearson correlation test,with α=0.05 for statistical significance.The results showed that when compared with the J-hook group,significantly more apical root resorption shortening of the maxillary central incisors was observed in the micro-implant group (1.27 mm difference,95% CI=0.70-1.84,P<0.001),which was associated with a significantly larger retraction distance (P=0.004) and a smaller vertical force component (P<0.0001).We are led to conclude that continuous activation of the nickel-titanium coil springs used in the micro-implant group resulted in significantly more apical root resorption shortening and maxillary central incisor retraction than when intermittent J-hook retraction was employed.The employment of continuous duration orthodontic forces presents a risk for increased apical root resorption that requires careful radiographic monitoring.
基金financially supported by the Research and Development Fund for Applied Technology of Dalian(No.2014E14SF164)National Natural Science Foundation of China(No.51371042 and No.81171008)the Research Fund for the Doctoral Program of Higher Education of China(No.20130041110005)
文摘In our previous studies, a novel cortex-like Ti O2 coating was prepared on Ti surface through micro-arc oxidation（MAO） by using sodium tetraborate as electrolyte, and the effects of the coating on cell attachment were testified. This study aimed to investigate the effects of this cortex-like MAO coating on osseointegration. A sand-blasting and acid-etching（SLA） coating that has been widely used in clinical practice served as control. Topographical and chemical characterizations were conducted by scanning electron microscopy, energy dispersive X-ray spectrometer, X-ray diffraction, contact angle meter, and step profiler. Results showed that the cortex-like coating had microslots and nanopores and it was superhydrophilic, whereas the SLA surface was hydrophobic. The roughness of MAO was similar to that of SLA. The MAO and SLA implants were implanted into the femoral condyles of New Zealand rabbits to evaluate their in-vivo performance through micro-CT, histological analysis, and fluorescent labeling at the bone-implant interface four weeks after surgery. The micro-CT showed that the bone volume ratio and mean trabecular thickness were similar between MAO and SLA groups four weeks after implantation. Histological analysis and fluorescent labeling showed no significant differences in the bone-implant contact between the MAO and SLA surfaces. It was suggested that with micro/nanostructure and superhydrophilicity, the cortex-like MAO coating causes excellent osseointegration, holding a promise of an application to implant modification.
基金Funded by the National Natural Science Foundation of China(51175306 and 51575320)the Tai Shan Scholar Foundation(TS20130922)the Fundamental Research Funds for the Central Universities(2014JC020)
文摘We put forward a protocolcombining laser treatment and acid etching to obtain multiscale micro/nano-texture surfaces of titanium alloy implant.Firstly,the operationalparameters of the laser were optimized to obtain an optimum current.Secondly,the laser with the optimum operationalparameters was used to fabricate micro pits.Thirdly,multiple acid etching was used to clean the clinkers of micro pits and generate submicron and nanoscale structures.Finally,the bioactivity of the samples was measured in a simulated body fluid.The results showed that the micropits with a diameter of 150 μm and depth of 50 μm were built successfully with the optimized working current of 13 A.In addition,submicron and nanoscale structures,with 0.5-2 μm microgrooves and 10-20 nm nanopits,were superimposed on micro pits surface by multiple acid etching.There was thick and dense HA coating only observed on the multiscale micro/nano-textured surface compared with polished and micro-textured surface.This indicated that the multiscale micro/nano-texture surface showed better ability toward HA formation,which increased the bioactivity of implants.
