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
BACKGROUND Bimaxillary protrusion is a clinically common dentofacial deformity,particularly among Chinese patients.This kind of malformation can severely affect facial esthetics and,even in mild cases,is difficult to ...BACKGROUND Bimaxillary protrusion is a clinically common dentofacial deformity,particularly among Chinese patients.This kind of malformation can severely affect facial esthetics and,even in mild cases,is difficult to correct without surgery.Unfortunately,many patients abandon treatment because of fear of surgery.Here,we describe a case of severe skeletal bimaxillary protrusion treated with nonsurgical orthodontic treatments,highlighting an alternative treatment option.CASE SUMMARY A 31-year-old woman wished to address a severe protrusion profile(approximately 8 mm overbite)and gummy smile.Cephalometric analysis and superimposition showed a severe skeletal class II pattern with a mandibular retrusion,and proclined and protrusive mandibular incisors.Panoramic radiograph showed a missing mandibular right third molar.A diagnosis of severe bimaxillary dentoalveolar protrusion was made.Taking into account the patient’s fear of orthognathic surgery,she accepted the proposed alternative treatment using micro-implants and a self-made four-curvature torquing auxiliary.The treatment allowed for maximal en masse anterior tooth retraction,proper relocation of incisors,and alleviation of the skeletal class II pattern.Esthetically,the patient’s lip protrusion was significantly decreased as was the overjet(from 10.5 mm to 1.8 mm),and the results remained stable throughout the 2-year followup.CONCLUSION Nonsurgical treatment using micro-implants and a four-curvature torquing auxiliary may benefit severe cases of skeletal bimaxillary protrusion in adults.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National Natural Science Foundation of China,No.81970906and Sichuan Science and Technology Program,No.2019YJ0689.
文摘BACKGROUND Bimaxillary protrusion is a clinically common dentofacial deformity,particularly among Chinese patients.This kind of malformation can severely affect facial esthetics and,even in mild cases,is difficult to correct without surgery.Unfortunately,many patients abandon treatment because of fear of surgery.Here,we describe a case of severe skeletal bimaxillary protrusion treated with nonsurgical orthodontic treatments,highlighting an alternative treatment option.CASE SUMMARY A 31-year-old woman wished to address a severe protrusion profile(approximately 8 mm overbite)and gummy smile.Cephalometric analysis and superimposition showed a severe skeletal class II pattern with a mandibular retrusion,and proclined and protrusive mandibular incisors.Panoramic radiograph showed a missing mandibular right third molar.A diagnosis of severe bimaxillary dentoalveolar protrusion was made.Taking into account the patient’s fear of orthognathic surgery,she accepted the proposed alternative treatment using micro-implants and a self-made four-curvature torquing auxiliary.The treatment allowed for maximal en masse anterior tooth retraction,proper relocation of incisors,and alleviation of the skeletal class II pattern.Esthetically,the patient’s lip protrusion was significantly decreased as was the overjet(from 10.5 mm to 1.8 mm),and the results remained stable throughout the 2-year followup.CONCLUSION Nonsurgical treatment using micro-implants and a four-curvature torquing auxiliary may benefit severe cases of skeletal bimaxillary protrusion in adults.
