龈下菌斑对种植体周围边缘骨吸收有影响

为探讨龈下菌斑对种植体周围边缘骨吸收的影响,本研究选取2015年2月至2017年10月在我院治疗的80例后牙缺失患者,根据种植后3个月改良菌斑指数(modified plaque index, m PLI)分为A组54例(m PLI为0分)和B组26例(mPLI为1~3分),观察两组种植体周围骨吸收及龈沟出血指数(sulcular bleeding index,SBI),同时检测龈下菌斑微生物。结果表明:A组种植后SBI为(1.06±0.11)分,明显低于B组的(1.20±0.16)分(p0.05);A组近中和远中边缘骨吸收量分别为(1.20±0.16) mm和(1.23±0.18) mm,明显低于B组的(1.40±0.15) mm和(1.37±0.16) mm (p0.05);种植前,A组中间普氏菌、牙龈卟啉单胞菌、福赛拟杆菌和齿垢密螺旋体比例分别为33.33%、18.52%、14.81%和22.22%,明显低于B组的65.38%、61.54%、73.08%和84.62%(p0.05),而直肠弯曲菌和伴放线放线杆菌比例比较差异无统计学意义(p0.05)。本研究初步结论表明龈下菌斑对种植体周围边缘骨吸收有影响,与菌斑微生物可能有一定关系,故在种植体修复时,应注意牙周基础治疗。     

牙龈组织与钛骨内牙种植体的附着

牙龈与牙种植体颈部的附着是影响牙种植体长期功效的重要因素之一,钛是一种非常理想的牙种植生物材料,在临床上得到较广泛的应用。本文就牙龈组织与种植体钛面的附着、附着机理、种植体钛面的性质、结构对龈附着的影响等研究现状作一综述。     

骨诱导无机材料BAM 修复牙种植体周围骨缺损的实验研究

目的:评价骨诱导磷酸钙生物陶瓷(BAMOICPC)与可吸收胶原膜(BME-10X医用胶原膜)在牙种植体周围骨缺损中的修复能力。方法:在兔股骨上植入羟基磷灰石涂层BLB种植体,然后在其侧壁制造高4 mm、宽3 mm、深2 mm的骨缺损。对照组为单纯侧壁骨缺损,实验A组骨缺损区仅覆盖BME-10X膜,B组骨缺损区植入BAMOICPC,C组骨缺损区植入BAMOICPC并加盖BME-10X膜。于术后6个月取带种植体的骨段,通过HE染色和扫描电镜(SEM)分析。结果:对照组骨缺损区种植体表面见纤维包裹,实验A组骨缺损边界区少许骨质移行覆盖,实验B组下半部分缺损区新生骨覆盖。C组新生骨完全覆盖骨缺损区,且较B组硬度高,扫描电镜见与种植体结合更紧密。组织学观察B、C两实验组新生骨均可见比较成熟的哈弗氏管系统。结论:骨诱导磷酸钙生物陶瓷BAMOICPC是一种较理想的骨替代材料,联合运用胶原膜修复种植体周骨缺损效果佳。     

以牙种植体为中心的骨壁测厚方法及其评价

目的:研究一种以牙种植体为中心来测量其周围骨壁厚度的方法,并对由此方法制作完成的改良游标卡尺进行精确性评价.方法:使用Solid Edge软件设计制作一种以ITI种植体为中心来测量其周围骨壁厚度的改良游标卡尺;将种植体植入透明复合树脂块中;使用改良游标卡尺测量种植体周围树脂壁厚度,然后将树脂块连同种植体沿其长轴纵切开;拍照并用Digimizer软件对树脂块纵剖面实际壁厚进行测量;最后将两组数据通过SPSS软件进行配对t检验.结果:改良游标卡尺组测量结果为7.97-8.09mm,树脂块纵剖面组测量结果为7.98-8.12mm,标准差为0.03,t值为1.09,P值为0.28,两种测量方法差异无统计学意义.结论:以种植体为中心的改良游标卡尺满足了设计要求,精确度高且可重复性强,可用于评估种植体唇颊侧骨壁的骨吸收情况.     

股骨骨折术后1年随访骨愈合模型的有限元分析

目的：对股骨骨折髓内钉术后1年骨愈合模型快速建模,通过有限元分析研究对比术前术后模型,通过术前判定内固定取出后骨折断端是否断裂。方法：运用Mimics、Geomagic Studio、Abaqus等软件采用快速个体化建模方法对股骨骨折髓内钉术后1年内固定取出术前后的多层螺旋CT数据进行快速建立模型,术前模型模拟剥除钢板后进行有限元分析,施加人体单腿站立时的静力载荷和约束,并将分析结果与术后模型进行对比,观察米塞斯应力分布情况、最大值及其所处部位。结果：按照材料属性进行区别显示米赛斯应力的最大值及最小值,在不同应力载荷下,手术前后各类型材料的米赛斯应力最大值及最小值部位相同,各类型材料中,最大值均没有位于骨折断端,不同方法的最大应力值部位相近,均在股骨中远端1/4交界处,手术前后应力分布基本相同。结论：采用个体化建模方法可以对骨折内固定取出前的骨愈合模型进行运算分析,快速预判术后是否导致骨折断端断裂。     

股骨骨折术后1 年随访骨愈合模型的有限元分析

目的：对股骨骨折髓内钉术后1 年骨愈合模型快速建模,通过有限元分析研究对比术前术后模型,通过术前判定内固定取出后骨折断端是否断裂。方法：运用Mimics、Geomagic Studio、Abaqus等软件采用快速个体化建模方法对股骨骨折髓内钉术后1年内固定取出术前后的多层螺旋CT 数据进行快速建立模型,术前模型模拟剥除钢板后进行有限元分析,施加人体单腿站立时的静力载荷和约束,并将分析结果与术后模型进行对比,观察米塞斯应力分布情况、最大值及其所处部位。结果：按照材料属性进行区别显示米赛斯应力的最大值及最小值,在不同应力载荷下,手术前后各类型材料的米赛斯应力最大值及最小值部位相同,各类型材料中,最大值均没有位于骨折断端,不同方法的最大应力值部位相近,均在股骨中远端1/4 交界处,手术前后应力分布基本相同。结论：采用个体化建模方法可以对骨折内固定取出前的骨愈合模型进行运算分析,快速预判术后是否导致骨折断端断裂。     

llizarov骨搬运技术治疗胫骨骨缺损的疗效及术后延迟愈合或不愈合的影响因素分析

摘要 目的：探讨 llizarov骨搬运技术治疗胫骨骨缺损的疗效及术后延迟愈合或不愈合的影响因素分析。方法：选取 2016年 6月-2020年 10月本院收治的 90例胫骨骨缺损患者为研究对象,患者均给予 llizarov骨搬运技术治疗。对患者的手术效果指标、并发症发生率进行记录统计。并对患者进行门诊随访观察,统计患者延迟愈合或不愈合的发生情况,据此将患者分为愈合组和延迟愈合或不愈合组。采用单因素及多因素 Logistic回归分析患者术后延迟愈合或不愈合发生的影响因素。结果：患者住院时间为(12.11± 2.98)d、开始负重时间为(45.39± 7.78)d、完全负重时间(76.41± 11.23)d。患者术后并发症发生率为 8.89%(8/90)。经随访观察,共有 29例患者出现术后延迟愈合或不愈合,发生率为 32.22%（29/90）。而延迟愈合或不愈合组患者的伤口感染、合并软组织损伤、合并腓骨骨折、术后过早活动及有吸烟史的人数占比高于愈合组患者(P<0.05)。经多因素 Logistic回归分析显示：伤口感染、合并软组织损伤、合并腓骨骨折、术后过早活动、有吸烟史是患者术后延迟愈合或不愈合的危险因素(P<0.05)。结论：llizarov骨搬运技术治疗胫骨骨缺损的疗效较好,患者的手术时间短、术中失血量少、住院时间、开始负重时间均较短,并发症发生率低,治疗安全性较好,但患者易出现术后延迟愈合或不愈合现象,可能与伤口感染、合并软组织损伤、合并腓骨骨折、术后过早活动、吸烟史有关。     

骨水泥凝固前有无血液环境对骨水泥与骨界面稳定性的影响

目的:研究在有血和无血环境下粘合骨水泥和骨,比较两种粘合骨水泥的方式对骨与骨水泥界面稳定性影响的区别。方法:选取新鲜猪肱骨头20块,随机分成两组:实验组在有血的环境下用骨水泥将股骨头与金属粘合;对照组在无血的环境下用骨水泥将肱骨头和金属粘合,再将两组实验材料分别做拉伸试验,至骨与骨水泥界面断裂,最后再沿垂直于截骨面的方向做骨切片,在扫描电镜下观察并测量出每个实验对象中骨水泥的最大浸润深度。比较两组实验过程中拉力的最大载荷和断裂时的拉力以及骨水泥最大浸润深度。结果:实验组10个实验对象拉力最大载荷平均为738.50±262.15 N,断裂时的拉力平均为656.50±242.88N,骨水泥最大浸润深度平均为1.22±0.19 MM;对照组10个实验对象实验过程中拉力最大载平均为739.60±306.98 N,断裂时的拉力平均为658.80±264.56 N,骨水泥最大浸润深度平均为1.22±0.21 MM。20个实验对象在实验过程中均无意外断裂的情况发生,均在骨与骨水泥界面发生断裂。两组实验的拉力最大载荷与断裂拉力以及骨水泥最大浸润深度,均无统计学差异(P0.05)。结论:血液环境不能增加骨与骨水泥界面的不稳定因素。因此,与应用止血带相比,在TKA手术中不用止血带可能不会对骨与骨水泥界面稳定性和假体的寿命产生影响。     

肌注神经生长因子及血小板衍生生长因子对胫骨干闭合骨折大鼠早期骨愈合的影响及机制探究

摘要 目的：探讨肌肉注射神经生长因子（NGF）和血小板衍生生长因子（PDGF）对胫骨干闭合骨折大鼠早期骨愈合的效果及潜在机制。方法：采用随机数字表法将80只健康成年雄性SD大鼠分为模型组、NGF组、PDGF组和NGF+PDGF组,各20只。建立胫骨干闭合骨折模型后,给予NGF组大鼠肌注0.8 μg NGF;给予PDGF组大鼠肌注0.8 μg PDGF,给予NGF+PDGF组大鼠肌注0.8 μg NGF和0.8 μg PDGF;给予模型组大鼠肌注等体积生理盐水。分别在治疗第2周（T0）、第4周（T1）、第6周（T2）通过X线检查计算骨痂体积,采用酶联免疫吸附法检测血清中碱性磷酸酶（AKP）水平。颈椎脱臼法处死大鼠后采用苏木精-伊红（HE）染色观察胫骨骨折端病理学改变,采用实时荧光定量PCR法检测骨痂组织骨形态发生蛋白2（BMP2）、血管内皮生长因子（VEGF）和胰岛素样生长因子-1（IGF-1）mRNA相对表达水平。结果：NGF+PDGF组大鼠在T1时骨折断端愈合,骨痂体积大于其他三组;NGF组、PDGF组大鼠在T2时骨折断端愈合,骨痂体积大小均大于模型组（P<0.05）。模型组大鼠T2时骨折断端尚未完全愈合,骨痂体积显著大于其他三组（P<0.05）。NGF+PDGF组大鼠T0~T1时血清AKP水平均显著高于其他三组,NGF组和PDGF组大鼠血清AKP水平显著高于模型组（P<0.05）。T2时4组大鼠血清AKP水平比较无显著差异（P>0.05）。T1时,NGF组、PDGF组和NGF+PDGF组大鼠均可见骨小梁形态更加粗大、致密,呈栅栏状排列,骨小梁间的间隙变小,NGF+PDGF组大鼠骨断裂处被新生骨填满,NGF组、PDGF组骨断裂处仍有少量间隙。T1时NGF+PDGF组大鼠BMP2、VEGF和IGF-1相对表达水平均显著高于其他三组（P<0.05）,NGF组和PDGF组大鼠各指标mRNA相对表达水平比较无显著差异（P>0.05）,但均显著高于模型组（P<0.05）。T2时各组大鼠骨痂组织中BMP2、VEGF和IGF-1 mRNA相对表达水平比较无显著差异（P>0.05）。结论：NGF和PDGF对胫骨干闭合骨折大鼠早期骨愈合有协同促进作用,可能与促进BMP2、VEGF和IGF-1表达上调有关。     

替牙期乳牙牙根及牙槽骨吸收过程中RANKL/RANK通路及其调控的研究进展

乳恒牙替换是一系列复杂的生理过程.乳牙牙根及牙槽骨吸收是这个过程中的重要环节.以往RANK/RANKL通路研究较多的集中到其对破骨细胞的作用,认为RANK将细胞分化等信号传入破骨细胞前体细胞内,从而诱导破骨细胞的增殖、分化、激活和骨吸收等生物学活性.而RANK/RANKL通路在替牙期乳牙牙根及牙槽骨吸收过程中调控作用的研究特别是对破牙细胞的作用,是近年来研究的热点.本文就乳牙牙根以及牙槽骨吸收过程中RANKL/RANK通路及其调控的研究进展进行了综述;同时介绍了可能参与这一过程的众多细胞因子,它们对这一过程起着正向或负向的调节作用.     

A comparison of the peri-implant bone stress generated by the preload with screw tightening between ‘bonded’ and ‘contact’ model

A number of finite element analyses (FEAs) for the dental implant were performed without regard for preload and with all interfaces ‘fixed-bonded’. The purpose of this study was comparing the stress distributions between the conventional FEA model with all contacting interfaces ‘fixed-bonded’ (bonded model) and the model with the interfaces of the components in ‘contact’ with friction simulated as a preloaded implant (contact model). We further verified the accuracy of the result of the FEA using model experiment. In the contact model, the stress was more widely distributed than in the bonded model. From the model study, the preload induced by screw tightening generated strain at the peri-implant bone, even before the application of external force. As a result, the bonded model could not reproduce the mechanical phenomena, whereas the contact model is considered to be appropriate for analysing mechanical problems.     

Resonance frequency analysis of overdenture retainer implants with immediate loading

doi: 10.1111/j.1741‐2358.2011.00488.x
Resonance frequency analysis of overdenture retainer implants with immediate loading Objective: To evaluate 16 patients of both sexes with lower overdenture and upper complete dentures, by analysing the resonance frequency of the initial and late stability of implants used to retain the overdenture under immediate loading. Background: Oral rehabilitation treatment with complete dentures using implants has been increasingly more common among the specialists in the oral rehabilitation area. This is an alternative for obtaining retention and stability in treatments involving conventional complete dentures, where two implants are enough to retain the overdenture satisfactorily. Materials and methods: The Osstell? Mentor device was used for the analysis in the initial period (primary stability), 3 and 15 months after the installation of the lower overdenture (secondary stability). The statistical analysis was performed with the repeated measures model (p < 0.01). Results: The implant stability quotients were observed to increase after 15 months of the rehabilitating treatment. Conclusion: The use of overdentures over two lower implants should become the treatment of choice for individuals who have a fully edentulous mandible.     

Pyruvate Formate-lyase and Its Activation by Pyruvate Formate-lyase Activating Enzyme

The activation of pyruvate formate-lyase (PFL) by pyruvate formate-lyase activating enzyme (PFL-AE) involves formation of a specific glycyl radical on PFL by the PFL-AE in a reaction requiring S-adenosylmethionine (AdoMet). Surface plasmon resonance experiments were performed under anaerobic conditions on the oxygen-sensitive PFL-AE to determine the kinetics and equilibrium constant for its interaction with PFL. These experiments show that the interaction is very slow and rate-limited by large conformational changes. A novel AdoMet binding assay was used to accurately determine the equilibrium constants for AdoMet binding to PFL-AE alone and in complex with PFL. The PFL-AE bound AdoMet with the same affinity (∼6 μm) regardless of the presence or absence of PFL. Activation of PFL in the presence of its substrate pyruvate or the analog oxamate resulted in stoichiometric conversion of the [4Fe-4S]¹⁺ cluster to the glycyl radical on PFL; however, 3.7-fold less activation was achieved in the absence of these small molecules, demonstrating that pyruvate or oxamate are required for optimal activation. Finally, in vivo concentrations of the entire PFL system were calculated to estimate the amount of bound protein in the cell. PFL, PFL-AE, and AdoMet are essentially fully bound in vivo, whereas electron donor proteins are partially bound.     

Osteoblast-targeted disruption of glucocorticoid signalling does not delay intramembranous bone healing

Objective

Glucocorticoids at pharmacological doses have been shown to interfere with fracture repair. The role of endogenous glucocorticoids in fracture healing is not well understood. We examined whether endogenous glucocorticoids affect bone healing in an in vivo model of cortical defect repair.

Methods

Experiments were performed using a well characterised mouse model in which intracellular glucocorticoid signalling was disrupted in osteoblasts through transgenic overexpression of 11β-hydroxysteroid-dehydrogenase type 2 (11β-HSD2) under the control of a collagen type I promoter (Col2.3-11β-HSD2). Unicortical bone defects (∅0.8 mm) were created in the tibiae of 7-week-old male transgenic mice and their wild-type littermates. Repair was assessed via histomorphometry, immunohistochemistry and microcomputed tomography (micro-CT) analysis at 1-3 weeks after defect creation.

Results

At week 1, micro-CT images of the defect demonstrated formation of mineralized intramembranous bone which increased in volume and density by week 2. At week 3, healing of the defect was nearly complete in all animals. Analysis by histomorphometry and micro-CT revealed that repair of the bony defect was similar in Col2.3-11β-HSD2 transgenic animals and their wild-type littermates at all time-points.

Conclusion

Disrupting endogenous glucocorticoid signalling in mature osteoblasts did not affect intramembranous fracture healing in a tibia defect repair model. It remains to be shown whether glucocorticoid signalling has a role in endochondral fracture healing.     

Crystal Structure and Functional Characterization of the Complement Regulator Mannose-binding Lectin (MBL)/Ficolin-associated Protein-1 (MAP-1)

The human lectin complement pathway activation molecules comprise mannose-binding lectin (MBL) and ficolin-1, -2, and -3 in complex with associated serine proteases MASP-1, -2, and -3 and the non-enzymatic small MBL associated protein or sMAP. Recently, a novel plasma protein named MBL/ficolin-associated protein-1 (MAP-1) was identified in humans. This protein is the result of a differential splicing of the MASP1 gene and includes the major part of the heavy chain but lacks the serine protease domain. We investigated the direct interactions of MAP-1 and MASP-3 with ficolin-3 and MBL using surface plasmon resonance and found affinities around 5 nm and 2.5 nm, respectively. We studied structural aspects of MAP-1 and could show by multi-angle laser light scattering that MAP-1 forms a calcium-dependent homodimer in solution. We were able to determine the crystal structure of MAP-1, which also contains a head-to-tail dimer ∼146 Å long. This structure of MAP-1 also enables modeling and assembly of the MASP-1 molecule in its entirety. Finally we found that MAP-1 competes with all three MASPs for ligand binding and is able to mediate a strong dose-dependent inhibitory effect on the lectin pathway activation, as measured by levels of C3 and C9.     

泥河湾发现的板齿犀肢骨化石(英文)

板齿犀属(Elasmotherium)由Fischer(1808)根据在西伯利亚发现的材料建立,模式种为西伯利亚板齿犀(E.sibiricum)。板齿犀是一种很特别的犀牛,以其巨大的体型和强壮的额角为特征。目前板齿犀有两个有效种,即E.sibiricum和高加索板齿犀(E.caucasicum)。板齿犀的地理分布范围包括俄罗斯、阿塞拜疆、乌兹别克斯坦、蒙古和中国,时代为更新世。在中国,德日进等曾报道了在泥河湾发现的板齿犀的一块牙齿碎片和几件肢骨,但未进行详细的描述和深入的讨论(TeilharddeChardinandPiveteau,1930)。后来周明镇(1958)又根据山西的零星材料建立了板齿犀的两个新种。不过,中国的这些板齿犀材料最近都被Antoine(2002,2003)归入到E.caucasicum中。在俄罗斯的西伯利亚南部曾发现过相当丰富的E.sibiricum的化石材料,其中包括不少完整的头骨(Fischer,1808,1809)。另一方面,最早发现于亚速海南岸地区的E.caucasicum材料不多,主要是一些孤立的牙齿和齿列,肢骨特别少(Borissiak,1914)。在天津自然博物馆收藏的泥河湾化石标本中有一些桑志华采集的板齿犀的肢骨材料,以远端肢骨为主。此前在中国的板齿犀类方面只有对通古尔的西班牙犀(Hispanotherium)部分肢骨的研究发表(Cerdeo,1996)。本文描述和讨论了泥河湾的板齿犀肢骨材料,包括1件桡尺骨(THP20355)、3件腕舟骨(THP20325,20326,20336)、2件月骨(THP20328,20337)、1件三角骨(THP20338)、2件小多角骨(THP20330,20341)、4件钩骨(THP20333,20327,20329,20339)、3件第三掌骨(THP20342,20343,20332)、2件第四掌骨(THP20318,20319)、3件距骨(THP20303,20308,20310)、1件跟骨(THP20311)、2件跗舟骨(THP20305,20322)、2件骰骨(THP20304,20306)、2件第二骨(THP20316,20317)。早更新世早期的泥河湾动物群中已知包括云簇犀(Dicerorhinusyunchuensis)、泥河湾披毛犀(Coelodontanihowanensis)和E.caucasicum三种犀牛,但前两种犀牛的体型远小于板齿犀,所以仅从肢骨的尺寸上就可以很好地区别它们。泥河湾的这批材料增加了我们对E.caucasicum的了解,它与E.sibiricum在肢骨方面有很多相似性状,如桡骨上容纳腕伸肌的沟宽深,第三掌骨前视可见对头状骨关节面,第四掌骨的近端关节面呈三角形,第五掌骨退化,掌骨上附着腕伸肌的止端显著,距骨对腓骨的关节面倾斜、距骨颈低到中等、滑车与远端关节面的夹角轻度倾斜、对蜗突关节面具长大的舌状延伸、对载距突关节面与对跟骨的外下关节面分离,跟骨对胫骨关节面存在、跟结节粗大、附着腓长肌的止端平滑,肢骨细长,掌骨和骨的中央直嵴低平、骨干上附着骨间肌的止端长但无远端后侧结节。另一方面,这两种板齿犀也存在一些差别,如E.caucasicum的尺骨远端没有对桡骨的第二关节面,而E.sibiricum有;E.caucasicum的钩骨未显示有第五掌骨与其关节,而E.sibiricum钩骨上对第五掌骨的关节面还与对三角骨的关节面联合;E.caucasicum距骨上对腓骨的关节面凹陷,而E.sibiricum平坦。对比已知的少量E.caucasicum肢骨,泥河湾标本在性状和尺寸上与其完全一致,进一步证明将这些标本归入E.caucasicum是可信的。从泥河湾材料我们还了解到板齿犀属的一些未知性状,如骰骨近端呈三角形、跗舟骨顶视呈矩形、距骨的宽/高比达1.21、厚/高比达0.74、对骰骨关节面具后侧突起等。此前的支序分析表明Elasmotherium是板齿犀类中最进步的一个属,泥河湾标本所显示的大多数性状确实是进步的,但仍然有一些原始性状。在板齿犀的两个种中,E.caucasicum可能比E.sibiricum更进步,不过这两个种实际上相当接近。板齿犀类不是一个丰富的犀科类群,然而特别的是在中国有较多的发现,包括几个大型的属,如Elasmotherium、中华板齿犀(Sinotherium)、副板齿犀(Parelasmotherium)、宁夏犀(Ningxiatherium)和伊朗犀(Iranotherium),但都很少有肢骨化石发现。将泥河湾的材料与已知的少量Parelasmotherium和Iranotherium的肢骨相比,显示后两个属不比Elasmotherium进步,这与对它们系统关系的分析结果吻合。E.caucasicum细长的远端肢骨与其高冠和釉质褶皱丰富的颊齿相一致,指示它是干旷草原的硬草取食者。     

高效的骨诱导生长因子——成骨蛋白-1

成骨蛋白-1(OP-1)又称骨形态发生蛋白-7(BMP-7),属转化生长因子β(TGF-β)超家族成员.重组人OP-1(rhOP-1)在体内和体外都显示了高效的骨诱导活性,可使多种实验动物的骨缺损满意愈合,有良好的临床应用前景.