受单－垂直力的多曲方丝弓有限元应力分析

目的：对受单一垂直力的多曲方丝弓进行有限元应力分析。方法：Pro/E软件建立IGES格式的牙列-托槽-弓丝三维几何实体模型,多曲方丝弓通过托槽粘接在下牙列上,弓丝和托槽采用四点四面体单元划分后,采用ANSYS对模型进行力学分析,在下牙列一侧3号和4号牙位之间的弓丝上加2.5牛的垂直向上的力。结果：建立了多曲方丝弓简单受力的有限元分析模型,多曲方丝弓在在某个局部（如3、4牙间）受力较大时,在其他牙位托槽处（1、2、5、6、7）的支反力并不大,力量轻柔,尤其在第一磨牙处更明显。结论：多曲方丝弓简单受力的有限元分析模型能为更好地研究其整体力学特性、揭示其技术矫治特点、探讨作用机理提供理论依据。     

正畸方丝弓与多曲方丝弓简单受力的有限元对比研究

目的:利用有限元力学分析方法比较口腔正畸方丝弓与多曲方丝弓在简单受力时对受力侧牙列的影响.方法:Pro/E软件建立IGES格式的牙列-托槽-弓丝三维几何实体模型,方丝弓和多曲方丝弓通过托槽粘接在下牙列上,弓丝和托槽采用四点四面体单元划分后,采用ANSYS对模型进行力学分析,在下牙列一侧3号和4号牙位之间的弓丝上加2.5 N的垂直向上的力.结果:多曲方丝弓在各托槽处的支反力几乎不到方丝弓的一半,在某个局部(如3、4牙间)受力较大时,在其他牙位托槽处(1、2、5、6、7)的支反力并不大,力量轻柔,尤其在第一磨牙处更明显.结论:跟方丝弓比较,对多曲方丝弓上的个别牙做垂直牵引或被动人槽时,牙列上的其它牙受力极轻,基本不会受到不利影响.     

受单一垂直力的多曲方丝弓有限元应力分析

目的:对受单一垂直力的多曲方丝弓进行有限元应力分析。方法:Pro/E软件建立IGES格式的牙列-托槽-弓丝三维几何实体模型,多曲方丝弓通过托槽粘接在下牙列上,弓丝和托槽采用四点四面体单元划分后,采用ANSYS对模型进行力学分析,在下牙列一侧3号和4号牙位之间的弓丝上加2.5牛的垂直向上的力。结果:建立了多曲方丝弓简单受力的有限元分析模型,多曲方丝弓在在某个局部(如3、4牙间)受力较大时,在其他牙位托槽处(1、2、5、6、7)的支反力并不大,力量轻柔,尤其在第一磨牙处更明显。结论:多曲方丝弓简单受力的有限元分析模型能为更好地研究其整体力学特性、揭示其技术矫治特点、探讨作用机理提供理论依据。     

方丝弓技术结合平面导板矫治成人深覆

目的为探讨打开成人前牙深覆（牙合）的有效方法.方法20例Ⅱ°、Ⅲ°前牙深覆（牙合）患者使用方丝弓矫治器和平面导板联合进行治疗研究.结果与单纯方丝弓矫治器相比,其打开咬合快且时间短,Ⅱ°深覆（牙合）平均4.5个月,Ⅲ°深覆牙合平均6.5个月.单纯方丝弓矫治打开咬合的时间为Ⅱ°深覆（牙合）平均6.8个月,Ⅲ°深覆牙合平均9.5个月.两者有显著差异(P＜0.05).结论方丝弓矫治结合平面导板联合矫治前牙深覆（牙合）是一种非常有效的方法.     

方丝弓技术结合平面导板矫治成人深覆(牙合)

目的:为探讨打开成人前牙深覆（牙合）的有效方法.方法:20例Ⅱ°、Ⅲ°前牙深覆（牙合）患者使用方丝弓矫治器和平面导板联合进行治疗研究.结果:与单纯方丝弓矫治器相比,其打开咬合快且时间短,Ⅱ°深覆（牙合）平均4.5个月,Ⅲ°深覆牙合平均6.5个月.单纯方丝弓矫治打开咬合的时间为:Ⅱ°深覆（牙合）平均6.8个月,Ⅲ°深覆牙合平均9.5个月.两者有显著差异(P＜0.05).结论:方丝弓矫治结合平面导板联合矫治前牙深覆（牙合）是一种非常有效的方法.     

方丝弓托槽片段弓技术治疗牙及牙槽外伤11例

目的 探讨使用方丝弓托槽片段弓技术固定牙外伤及牙槽外伤的临床效果.方法 利用方丝弓矫治原理和矫治方法 对外伤性牙松动、牙脱落及牙槽骨骨折共11例,22颗患牙进行固定结扎.结果 20颗患牙成功固定,恢复正常,仅2颗失败.结论 方丝弓托槽片段弓技术治疗牙外伤及牙槽外伤,牙齿复位精确,咬合关系恢复佳,有利于牙周健康,是外伤性牙及牙槽损伤可靠的治疗方法 .     

方丝弓矫治恒牙列反(牙合)35例的临床技巧及临床应用

目的采用方丝弓矫治技术解除反(牙合)的临床应用.方法35例恒牙反(牙合)患者应用方丝弓矫治器矫治10-18个月,观察扩弓矫治的效果.结果35例患者矫治后反(牙合)解除,牙齿排列整齐,覆合覆盖关系正常.结论方丝弓矫治器扩弓可以改善牙弓宽度,对反(牙合)有较好的矫治效果.     

26例前牙反（牙合）的直丝弓治疗

目的探讨直丝弓矫治器对前牙反（牙合）的矫治效果。方法选择26例前牙反患者,采用直丝弓矫治器配合下颌（牙合）垫对反覆（牙合）较深的前牙反（牙合）患者进行矫治。结果 26例反（牙合）患者均取得了满意的矫治效果。结论直丝弓矫治器加下颌（牙合）垫的联合使用是矫治前牙深反（牙合）的有效方法。它能提高矫治效果的关键在于打开了上下前牙的锁结关系,消除了下前牙对上前牙的阻力干扰,而且使上前牙能尽早粘托槽,使上下牙能同时进行矫治,不仅缩短了疗程而且疗效显著。     

26例前牙反(牙合)的直丝弓治疗

目的 探讨直丝弓矫治器对前牙反(牙合)的矫治效果.方法 选择26例前牙反(牙合)患者,采用直丝弓矫治器配合下颌牙合垫对反覆(牙合)较深的前牙反(牙合)患者进行矫治.结果 26例反(牙合)患者均取得了满意的矫治效果.结论 直丝弓矫治器加下颌牙合垫的联合使用是矫治前牙深反牙合的有效方法.它能提高矫治效果的关键在于打开了上下前牙的锁结关系,消除了下前牙对上前牙的阻力干扰,而且使上前牙能尽早粘托槽,使上下牙能同时进行矫治,不仅缩短了疗程而且疗效显著.     

生理性支抗控制矫治器技术结合压低辅弓打开咬合的三维有限元建模及数值分析北大核心

背景:生理性支抗控制矫治器是近几年来应用于正畸临床治疗的一种新型矫治器。其在支抗控制、力矩主导及摩擦力控制等方面均有其优越性。生理性支抗控制矫治器矫治技术在打开咬合方面也有其独特性。目的:通过建立包含压低辅弓的PASS矫治器三维有限元模型,分析压低辅弓在PASS矫治技术中对前牙的压低作用以及对磨牙增强支抗的作用。方法:将CT扫描数据输入Mimicsl7.0软件获得牙齿及颌骨的三维模型。利用Geomagic Studio、NX、ANSYSl5.0等一系列建模软件获得包含压低辅弓和生理性支抗控制矫治器的上颌牙列三维有限元模型。分析主辅弓结扎位点分别置于中切牙近中、侧切牙近中、侧切牙远中时牙列的整体受力情况及前牙的运动趋势。结果与结论:①结扎位点在中切牙间时,前牙压低效果明显;侧切牙近中结扎时前牙唇倾效果明显;侧切牙远中结扎时,前牙出现舌倾伴压低的趋势。3种工况下磨牙后倾的位移趋势均较大;②结果表明,结扎在中切牙近中时,切牙运动趋势最大,主要作用是压低切牙,3种工况对磨牙均产生较大后倾力。实验模拟了临床牙齿受力情况和位移趋势,有利于临床对该项技术的理解和应用。     

高角骨性Ⅲ类错牙合牙齿倾斜位置特征

目的　了解高角Ⅲ类错牙合 畸形患者全牙轴倾及转矩特征,以期为临床治疗提供指导。 方法　收集符合纳入标准的高角骨性I类（13名）及Ⅲ类（11名）错牙合 畸形共计24名患者头颅CBCT影像Dicom数据,利用invivo 5.1软件进行全牙轴倾度及转矩测量。 结果　（1）高角I类及Ⅲ类左右同名牙倾斜度一致性较好,P＞0.05,此后左右同名牙数据一并处理。（2）高角Ⅲ类与I类矢状向比较：①高角Ⅲ类,上前牙根舌向转矩增大趋势,但仅在上尖牙表现统计学差异,P＜0.05;②高角Ⅲ类,下前牙根舌向转矩减小,P<0.05,差异有统计学意义;③ 高角Ⅲ类,上后牙近中轴倾、下后牙远中轴倾趋势,但差异无统计学意义,P>0.05。（3）高角Ⅲ类与I类横向比较：①高角Ⅲ类,上前牙远中轴倾增加,差异有统计学意义;下前牙轴倾变化趋势不明,仅下中切牙表现远中轴倾（P<0.05）;② 高角Ⅲ类,上后牙根舌向转矩增大,有统计学差异;下后牙根舌向转矩减小趋势,但差异无统计学意义。（4） 高角I类及Ⅲ类与Andrews正常牙合 矢状向及冠状向各牙倾斜位置比较：① 矢状向：高角I类Ⅲ类上下前牙根舌向转矩增大,上下后牙明显近中倾斜;② 冠状向：高角I类Ⅲ类上下前牙远中倾斜增大,上下后牙根舌向转矩加大。 结论　（1）高角骨性Ⅲ类牙齿位置在垂直方向的代偿表现强于矢状方向;（2）高角骨性Ⅲ类上下前牙唇舌向倾斜移动风险较高,移动时更应注重牙齿的整体移动;（3）高角骨性Ⅲ类上颌后牙明显颊向倾斜,上牙列横向扩展范围减小,扩弓后稳定性可能降低。     

高角骨性Ⅲ类错牙合牙齿倾斜位置特征

目的　了解高角Ⅲ类错牙合 畸形患者全牙轴倾及转矩特征,以期为临床治疗提供指导。 方法　收集符合纳入标准的高角骨性I类（13名）及Ⅲ类（11名）错牙合 畸形共计24名患者头颅CBCT影像Dicom数据,利用invivo 5.1软件进行全牙轴倾度及转矩测量。 结果　（1）高角I类及Ⅲ类左右同名牙倾斜度一致性较好,P＞0.05,此后左右同名牙数据一并处理。（2）高角Ⅲ类与I类矢状向比较：①高角Ⅲ类,上前牙根舌向转矩增大趋势,但仅在上尖牙表现统计学差异,P＜0.05;②高角Ⅲ类,下前牙根舌向转矩减小,P<0.05,差异有统计学意义;③ 高角Ⅲ类,上后牙近中轴倾、下后牙远中轴倾趋势,但差异无统计学意义,P>0.05。（3）高角Ⅲ类与I类横向比较：①高角Ⅲ类,上前牙远中轴倾增加,差异有统计学意义;下前牙轴倾变化趋势不明,仅下中切牙表现远中轴倾（P<0.05）;② 高角Ⅲ类,上后牙根舌向转矩增大,有统计学差异;下后牙根舌向转矩减小趋势,但差异无统计学意义。（4） 高角I类及Ⅲ类与Andrews正常牙合 矢状向及冠状向各牙倾斜位置比较：① 矢状向：高角I类Ⅲ类上下前牙根舌向转矩增大,上下后牙明显近中倾斜;② 冠状向：高角I类Ⅲ类上下前牙远中倾斜增大,上下后牙根舌向转矩加大。 结论　（1）高角骨性Ⅲ类牙齿位置在垂直方向的代偿表现强于矢状方向;（2）高角骨性Ⅲ类上下前牙唇舌向倾斜移动风险较高,移动时更应注重牙齿的整体移动;（3）高角骨性Ⅲ类上颌后牙明显颊向倾斜,上牙列横向扩展范围减小,扩弓后稳定性可能降低。     

Forces applied by anterior and posterior teeth and roles of periodontal afferents during hold-and-split tasks in human subjects

Hold-and-split tasks were performed by 20 subjects (12 females and 8 males) using the right central incisors, canines, 2nd premolars, and 1st molars, respectively. Half a peanut was positioned on a transducer-equipped plate and the subject was instructed to hold the plate with the peanut between two antagonistic teeth, and not using more force than necessary. After ca. 3 s the subject was instructed to split the peanut in a natural manner. Each session consisted of a series of three in which the subject performed the hold-and-split task five times for each tooth. Thus, in total, data were obtained from 60 trials for each subject. The magnitude of the forces and the force rates used to split the peanut increased distally along the dental arch. However, the duration of the split phase was similar for the various teeth examined. During anesthesia of the periodontal ligament (four subjects), no significant changes were seen in the split phase. The forces used to hold the peanut between the teeth also increased distally along the dental arch: 0.60 N for the incisor, 0.77 N for the canine, 1.15 N for the 2nd premolar, and 1.74 N for the 1st molar. The difference in hold forces for the various teeth can be explained by the different sensitivity characteristics of the periodontal afferents innervating anterior and posterior teeth. During periodontal anesthesia, the magnitude and variability of the hold forces increased for all types of teeth, thus supporting the suggestion that periodontal afferent information is used in the regulation of the level of forces used to hold and manipulate morsels between the teeth.     

股骨颈骨折术中空心加压螺纹钉螺纹部分陷入盆腔成功取出1例报道并文献复习

目的：报道1例股骨颈骨折术中空心加压螺纹钉螺纹部分突入盆腔并成功取出的经验,结合文献复习,对空心加压螺纹钉治疗股骨颈骨折的手术原则、注意事项等内容进行归纳总结,为临床医师提供参考。方法：1例股骨颈骨折术中空心加压螺纹钉螺纹部分突入盆腔,将尖端拐弯呈钩状的不锈钢丝插入空心内六角改锥,然后进入空心加压螺纹钉,通过倒钩状尖端钩住螺纹钉并施加适当的牵引力,不锈钢丝钩状尖端抓住空心加压螺纹钉;再以适当的力量牵拉不锈钢丝,逆时针方向转动空心内六角改锥,将其顺利旋出。结果：通过带倒钩的不锈钢丝辅助牵引、内六角改锥反转退钉,成功取出螺纹部分突人盆腔的空心的加压螺纹钉,患者无并发症,骨折顺利愈合。结论：老年患者因骨质疏松,股骨近端外侧骨皮质较薄弱,拧人空心拉力螺纹钉时钉尾易陷入骨皮质;在拧人空心加压螺纹钉的过程中,应在x线透视监视下进行,在最上方的空心加压螺纹钉尾端应安装垫片。     

不锈钢麻花丝牙周夹板在牙周病松动牙治疗中的应用

目的探索不锈钢麻花牙周夹板在牙周病松动牙康复治疗中的应用。方法在牙周基础治疗的基础上,采用不锈钢麻花丝与光固化树脂联合制作牙周夹板治疗牙周病松动牙。结果 26例中、晚期牙周病患者松动牙固定,经6~18月复查,松动牙固定效果好,牙周病发展得到控制。结论利用不锈钢麻花丝与光固化树脂联合制作的牙周夹板强度好,美观适用。     

Distribution of 3H-proline within transseptal fibers of the rat following release of orthodontic forces

Maxillary right first molar teeth of rats were tipped mesially with an orthodontic appliance for 2 weeks (experimental group), ³H-proline was injected, and orthodontic forces were removed 6 hr later (time 0). The contralateral molar teeth of treated (internal control group) and age- and weight-matched untreated animals (external control group) were also studied. Diastemata were created between the molar teeth by the orthodontic appliance, and transseptal fibers between first and second (P<0.001) and second and third molars (P<0.005) were significantly lengthened as compared to external and internal controls at time 0. Diastemata between molar teeth were closed 5 days after removal of orthodontic force. Transseptal fibers adjacent to the source of the orthodontic force (mesial region) had the highest mean number of ³H-proline-labeled proteins at time 0 and at all times following removal of the force (P<0.001), and had the highest rate of labeled protein removal (P<0.001). Half-lives for removal of ³H-proline-labeled transseptal fiber proteins were significantly greater in mesial and distal regions and significantly less in middle regions of experimentals than in corresponding regions of external controls (P<0.001). These data suggest the following: (1) transseptal fibers adjust their length by rapid remodeling in regions experiencing a tensile force; (2) collagenous protein turnover within the middle third of the transseptal fibers is more rapid subsequent to release of orthodontic force than during normal physiologic drift, suggesting that this region adapts rapidly to changes in adjacent tooth position and that these fibers do not play a significant role in relapse of orthodontically relocated teeth; and (3) significant differences in turnover rates of ³H-proline-labeled transseptal ligament proteins of external and internal control quadrants suggest that tooth movement produces both local and systemic effects on collagenous protein metabolism.     

干髓术与根管治疗术在后牙V类洞充填中的抗折率比较

目的:探讨后牙V类洞干髓术的抗冠折疗效。方法:选择68例患牙随机分为干髓组及根管治疗组。6—12个月复查,观察干髓术与根管治疗术的患牙抗折率。结果:后牙V类洞干髓术的抗折率高于根管治疗组,两者间差异有显著性(p<0.05)。结论:后牙V类洞干髓术较根管治疗术抗折率高。     

三种固定方法在颅骨骨瓣回复固定模型中生物力学评价的实验研究

目的对三种骨瓣固定方法在颅骨骨瓣回复固定模型中的生物力学性能进行比较、评价。方法6个颅骨标本共制备24个骨瓣,分为三组,分别采用丝线、不锈钢丝和颅骨固定钉三种方法固定,就操作时间、初始移位、垂直受力试验及最大承受力等方面进行比较。结果颅骨固定钉组的操作时间最短(94±13)s,初始移位最小(0.20±0.12)mm,最大承受力最大(385.4±63.1)N均明显优于不锈钢丝组和丝线组。结论颅骨固定钉操作简便快速,具有良好的复位效果及较大的强度,是较理想的颅骨固定装置。     

Encoding of amplitude and rate of tooth loads by human periodontal afferents from premolar and molar teeth

Microneurographic recordings were obtained from 20 periodontal mechanoreceptive afferents in the inferior alveolar nerve while force profiles of different amplitudes and rates were applied to a premolar or the first molar in the most sensitive direction. The majority of afferents (17/20) showed a hyperbolic relationship between the steady-state discharge rate and the amplitude of the stimulating force, featuring a pronounced saturation tendency. These afferents were also characterized by a similar decline in dynamic sensitivity with increasing amplitude of background force. However, a few afferents (3/20) showed nearly linear stimulus-response relationships and a small decline in dynamic sensitivity with increasing tooth load. Quantitative models developed for all afferents successfully predicted the afferent discharge rates for novel force stimulations. Application of the transfer function to chewing forces predicted that the discharge rates of periodontal afferents rapidly increased at initial tooth contact and continued to discharge as long as the tooth was loaded. However, due to the marked saturation tendencies at higher forces, most periodontal afferents poorly encoded the magnitude of the strong chewing forces. In addition, the discharge rates of a minority of afferents continued to reflect the force profile during high chewing forces. The results revealed that periodontal afferents of posterior teeth were less sensitive at low tooth loads compared with afferents of anterior teeth. During each chewing cycle, periodontal afferents may provide information about the mechanical properties of food shortly after tooth contact that can be used to scale the muscle commands of the upcoming power phase.     

骨性Ⅲ类错牙合体分段长轴倾斜方向的一致性评价

目的通过分段测量骨性Ⅲ类错牙合畸形患者上下牙列牙弓内所有牙齿(除第三磨牙)的轴倾角和转矩角,评价牙冠、牙根及全牙位置指标间的关系。方法选取符合纳入标准的29例成人骨性Ⅲ类错牙合患者,拍摄CBCT并收集其Dicom数据,利用Invivo5.1软件对上、下颌各牙的牙冠、牙根、全牙的转矩角和轴倾角进行测量。结果 (1)骨性Ⅲ类错牙合,上、下牙列冠、根及全牙轴倾角一致性较好,两两比较,P0.05。(2)骨性III类错牙合,在全牙列的转矩角中,上牙列冠、根及全牙的一致性较好,两两比较,P0.05,而下牙列除磨牙外所有牙齿冠、根倾斜存在统计学差异,P0.05,牙根与牙体长轴方向及程度较一致,差异无统计学差异,P0.05。结论 (1)骨性Ⅲ类错牙合牙冠的倾斜角度与牙根或全牙的倾斜角度的一致性不高,可能存在牙体位置判别误差;(2)牙根倾斜程度与全牙倾斜程度较一致。