Influence of fiber posts on the fracture resistance of endodontically treated premolars with different dental defects

This study aimed to evaluate the influence of quartz fiber post placement on the fracture resistance of endodontically treated premolars with different dental defects under dynamic loading.Fifty extracted single-rooted mandibular premolars were randomized into five groups.Each group was prepared according to numbers of residual walls ranged from 0 to 4.Then each group was divided into two subgroups with one restored with quartz fiber posts and the other without posts.In no-post groups,gutta percha point 2 mm below cemento-enamel junction was removed.Composite resin was adapted to the well and used to shape the core directly.Each tooth was restored with a complete metal crown.Dynamic loading was carried out in a masticatory simulator with a nominal load of 50 N at 2 Hz for 300 000 loading cycles.Then a quasi-statically load was applied in a universal testing machine 306 to the long axis with a crosshead speed of 1 mm？min21until fracture.Data were analyzed with one-way analysis of variance and pairwise comparison（P,0.05）.No specimens failed during dynamic loading.The fracture resistance enhanced with the increase of numbers of coronal walls and the differences were significant（P,0.05）.Placement of fiber posts had a significant effect when fewer than two walls remained（P,0.05）,but it had no significant influence in groups with two,three or four walls（P.0.05）.Fiber post did not change failure mode,and the fracture pattern was mainly favorable.More dentin walls need to be retained in clinic.When no less than two walls remained,a fiber post is not always necessary.

Compressive properties of glue-laminated timber circular post modified by basalt fiber reinforced polymer

Glued timber structure is one of the main forms of modern wood architecture,which has gradually developed towards mid-and high-rise buildings.Glue-laminated timber(GLT)is comprised of several laminates of parallel-to-grain dimension lumber that are bonded together with durable,moisture resistant structural adhesives.GLT can be used in horizontal applications as a beam and in vertical applications as a post.So,its compressive performance has a significant impact on structural safety.Fiber reinforced polymers(FRPs)were commonly used to improve the bearing capacity of GLT components,and the structural and process parameters largely determined the reinforcement effect.This study was aimed at investigating the influence of structural and process parameters on the axial compression performance of GLT components.Three wrapping methods(middle-part,end-part and full wrapping)and three lengths(0.6,0.8,and 1.0 m)of wood post specimens were designed in this work and the axial compression performance and ductility of GLT post specimens modified by basalt fiber reinforced polymer(BFRP)were studied.The results showed that the effect of different BFRP wrapping methods on the compressive strength and elastic modulus of laminated wood was not statistically significant(P>0.05).The compressive bearing capacity of unreinforced GLT posts decreased with the increase of aspect ratio.The GLT posts with middle-part and end-part wrapping still followed this pattern,while the compressive bearing capacity of GLT posts with full wrapping showed a pattern of first decreasing and then increasing.For GLT with low aspect ratios(4.0 or 5.3),there was no correlation between the wrapping method and the compressive bearing capacity,while the compressive bearing capacity of GLT with a high aspect ratio(6.7)for middle-part,end-part and full wrapping increased by 3.5%,7.5%and 9.7%,respectively.Compared to the unreinforced group,the ultimate axial compressive strength and modulus of elasticity(MOE)of the 6-E series specimens reinforced at both ends decreased by 2.58%and 6.70%,respectively.The ultimate axial compressive strength of the 8-E specimens reinforced at both ends increased by 8.62%and the MOE decreased by 1.91%.The compressive strength of the 10-E specimens reinforced at both ends increased by 7.51%and the MOE increased by 8.14%.The failure modes of GLT with different aspects were consistent under the same BFRP wrapping,while the failure modes of GLT with the same aspect ratio were different for different BFRP wrapping methods.The ductility performance of GLT with different aspects ratio was improved by the BFRP wrapping.

Comparison of the Clinical Effect of Prefabricated Fiber Post and Plastic Fiber Post in Oral Repair

Objective:To observe and analyze the clinical effect of prefabricated fiber posts and plastic fiber posts in oral repair.Methods:A total of 128 patients admitted to our hospital from January 2023 to June 2024 underwent oral prosthesis treatment,of which the control group(n=64)was treated with prefabricated fiber posts and the observation group(n=64)with plastic fiber posts.The efficacy,retention rate,and complication rate of the two groups were compared.Results:The total effective rate of the observation group was 96.88%,which was significantly higher than that of the control group(84.38%)(P<0.05).The restoration retention rate in the observation group was 95.31%,which was significantly higher than that in the control group(85.94%)(P<0.05).The incidence of postoperative complications in the observation group was 4.69%,which was significantly lower than that in the control group(15.63%)(P<0.05).Conclusion:For patients with oral prostheses,the use of plastic fiber posts for treatment shows better clinical effects,effectively improving the retention rate of the prosthesis and reducing the incidence of complications.Thus,it is worthy of popularization and application.

纤维桩联合不同冠部修复方式修复穿髓型非龋性颈部缺损牙体的力学分析

背景:使用纤维桩修复穿髓型非龋性颈部缺损可以改变牙齿的应力分布,显著降低患牙折裂风险,但关于纤维桩改善牙体抗折性的力学机制及穿髓型非龋性颈部缺损的最佳冠部修复方式尚有争论。目的:综述纤维桩修复穿髓型非龋性颈部缺损后的应力分布模式,在各种受力状态下的抗折能力与断裂模式,以及纤维桩联合不同冠部修复方式的最新研究进展。方法:应用计算机在PubMed和中国知网数据库中检索2008年9月至2023年9月发表的相关文献,英文检索词为“non-carious cervical lesions,endodontically treated teeth restoration,endodontically treated teeth stress distribution”,中文检索词为“非龋性颈部缺损,根管治疗后牙体修复,根管治疗后牙齿应力分布”,最终纳入56篇文献进行分析。结果与结论:穿髓型非龋性颈部缺损根管治疗后,应用纤维桩修复可部分改善牙齿颈部应力,同时不会增加牙根纵裂的风险;使应力分布更加均匀,提高牙齿的抗折性。使用纤维桩修复的非龋性颈部缺损牙齿若折断,其断裂模式显示出有利的、可恢复的或可修复的断裂模式。纤维桩联合瓷贴面或贴面式嵌体可能会成为修复穿髓型非龋性颈部缺损的一种较理想微创修复方法。

Fracture Resistance and Failure Patterns of Open Apex Root Teeth with Different Posts after Endodontic Treatment

The aim of this study is to investigate the influence of different posts on the fracture mechanics of endodontically-treated teeth with open apex. Forty-eight human maxillary anterior teeth were collected, and the root was transversely sectioned 12 mm under the cementoenamal junction （CEJ）. These samples were then randomly divided into two groups, i.e., minor diameter open apex root （group A） and major diameter open apex root （group B）, with mineral trioxide aggregate （MTA） placed into the apical 4 mm in the root canals. Subsequently, both groups were respectively further divided into three subgroups as follows： fiber-post （subgroup 1）, metal post （subgroup 2） and non-post （subgroup 3） group. Teeth were restored with a composite resin crown and tested by using a universal testing machine at the rate of 1 mm/min cross-head. Values of the maximum fracture resistance and failure patterns were recorded and compared among all subgroups. In addition, the changes of MTA properties were carefully examined via X-ray photography. Our results indicate that （1） In group A, the mean value of fracture resistance for teeth restored with fiber posts were statistically higher than that with either metal post or non-post; （2） In group B, there was no statistically significant difference in the mean value of fracture resistance among three subgroups; （3） No statistical significance in the mean value of fracture resistance was found between group A and group B; （4） The failure modes of most samples （58%） were irreparable; （5） MTA in two teeth developed cracks after loading tests. In conclusion, endodontically-treated teeth restored with fiber posts are more resistant to fracture than those restored with either metal posts or non-post, and most of the fracture modes are catastrophic in nature.

Remote structural health monitoring with serially multiplexed fiber optic acoustic emission sensors

Development and testing of a serially multiplexed fiber optic sensor system is described.The sensor differs from conventional fiber optic acoustic systems,as it is capable of sensing AE emissions at several points along the length of a single fiber.Multiplexing provides for single channel detection of cracks and their locations in large structural systems. An algorithm was developed for signal recognition and tagging of the AE waveforms for detection of' crack locations,Labora- tory experiments on plain concrete beams and post-tensioned FRP tendons were pcrlormed to evaluate the crack detection capability of the sensor system.The acoustic emission sensor was able to detect initiation,growth and location of the cracks in concrete as well as in the FRP tendons.The AE system is potentially suitable lot applications involving health monitoring of structures following an earthquake.

Effect of fiber angle on LYP steel shear walls behavior

Steel shear wall(SSW) was properly determined using numerical and experimental approaches.The properties of SSW and LYP(low yield point) steel shear wall(LSSW) were measured.It is revealed that LSSW exhibits higher properties compared to SSW in both elastic and inelastic zones.It is also concluded that the addition of CFRP(carbon fiber reinforced polymers) enhances the seismic parameters of LSSW(stiffness,energy absorption,shear capacity,over strength values).Also,stress values applied to boundary frames are lower due to post buckling forces.The effect of fiber angle was also studied and presented as a mathematical equation.

Using Brillouin fiber-optic ring laser to provide base station with uplink optical carrier in a 10 GHz radio over fiber system

In this paper, a 10 GHz radio over fiber system is analyzed. The Brillouin fiber-optic ring laser is used in the center station （CS） to suppress the optical carrier for the modulation depth enhancement. Simultaneously, the Stockes wave induced by the Brillouin amplification injects and locks the Fabry-Perot （FP） laser to output a signal-mode optical source, which works as the uplink optical carrier.

AN EXPERIMENTAL STUDY ON POST-BUCKLING BEHAVIOR OF SLENDER COLUMN WITH FIBER REINFORCED COMPOSITE MATERIAL

Equilibrium paths of post-buckling are measured for large slenderness column specimens made of the fiber reinforced composite material. The influence of the initial curvature is investigated experimentally and compared with the result of the initial post-buckling theory. Both the theoretical and experimental results reveal that the column with the initial curvature has stable post-buckling behaviors and is not sensitive to the imperfection in the form of initial curvature. The experimental results show that when the lateral buckling displacement is less than 20 percent of the column length, the experimental results agree with the results from the theory of initial post-buckling quite well, while they agree with the results from the large deflection theory in a quite large range.

Enhanced gas separation performance of mixed matrix hollow fiber membranes containing post-functionalized S-MIL-53

Mixed matrix hollow fiber membranes（MMHFMs）filled with metal-organic frameworks（MOFs）have great potential for energy-efficient gas separation processes,but the major hurdle is polymer/MOFs interfacial defects and membrane plasticization.Herein,lab-synthesized MIL-53 was post-functionalized by aminosilane grafting and subsequently incorporated into Ultem-1000 polymer matrix to fabricate high performance MMHFMs.SEM,DLS,XRD and TGA were performed to characterize silane-modified MIL-53（S-MIL-53）and prepared MMHFMs.Moreover,the effect of MOFs loading was systematically investigated first;then gas separation performance of MMHFMs for pure and mixed gas was evaluated under different pressures.MMHFMs containing post-functionalized S-MIL-53 achieved remarkable gas permeation properties which was better than model predictions.Compared to pure HFMs,CO2permeance of MMHFM loaded with 15%S-MIL-53 increased by 157%accompanying with 40%increase for CO2/N2selectivity,which outperformed the MMHFM filled with naked MIL-53.The pure and mixed gas permeation measurements with elevated feed pressure indicated that incorporation of S-MIL-53 also increased the resistance against CO2plasticization.This work reveals that post-modified MOFs embedded in MMHFMs facilitate the improvement of gas separation performance and suppression of membrane plasticization.

Experimental Study of Concrete Column Shape Modification Using Fiber Reinforced Polymer Composite Shells and Expansive Cement Concrete

Fiber Reinforced Polymer （FRP） composites are an effective material for strengthening circular concrete columns. The effectiveness of FRP confinement for square and rectangular columns is greatly reduced due to stress concentrations at the sharp comers and loss of the membrane effect at the fiat sides of the cross-section. Shape modification can eliminate the effects of column comers and flat sides, and thereby restore the membrane effect and improve the compressive behavior of FRP-confined square and rectangular concrete columns. Shape modification using chemical post-tensioning, achieved by using expansive cement concrete, is described and several mix designs for obtaining the optimal level of expansion are presented. In addition, parametric studies regarding the optimal geometry of the shape-modified cross-section are presented utilizing the analytical model.

Comparison of Fracture Resistance Strength of Six Non-metal Dental Posts under the Oblique Load in Vitro

目的:测试6种非金属桩钉的抗折性能,以了解不同桩钉的强度,从而指导临床合理选择桩钉。材料:将36件桩钉按种类分为6个实验组(n=6):A组:Parapost fiber(Whaledent Coltene);B组:Aesthetic Plus(Bisco);C组:Cosmopost(Ivoclar Vivadent);D组:Exper-fiber A(NWPU);E组:Exper-fiber B(NWPU);F组:Exper-fiber C(NWPU)。将待测的桩钉固定于特别加工的夹具中,用通用电子力学试验机测试桩钉在135°单端受力时的破坏载荷,对结果进行方差分析和SNK检验。结果:不同种类桩钉的抗折力不同,Exper-fiber A posts和Exper fiber Bposts的抗折力无显著差异,分别是(87.21±3.12)N和(89.26±1.72)N。与其他组相比Exper-fiber C posts的抗折力最高为(99.93±1.97)N。Parapost-fiber组的抗折力最低为(47.07±1.36)N。结论:不同种类非金属桩钉的抗折力不同,临床使用中应根据实际受力情况合理选择。

基于自动纤维定量技术研究卒中后抑郁的纤维束改变

目的通过自动纤维定量(automated fiber quantification,AFQ)技术研究卒中后抑郁(post-stroke depression,PSD)神经纤维束的结构改变,并探索与抑郁程度相关的纤维节段。方法纳入单部位前循环脑梗死患者,分为PSD组和卒中后非抑郁(non-PSD)组,收集发病1个月时的汉密尔顿抑郁量表(Hamilton depression scale,HAMD)和MRI数据,采用AFQ提取神经纤维束节段的部分各项异性(fractional anisotropy,FA),评估纤维束节段FA组间差异,以及差异纤维束节段FA与HAMD的相关性。结果共收集8例PSD和18例non-PSD患者。与non-PSD组相比,PSD组胼胝体、左侧下纵束和钩状束的节段FA降低(P<0.05)。所有患者胼胝体小钳(r=-0.418,P=0.047)和左侧钩状束(r=-0.467,P=0.029)部分节段FA与其HAMD呈负相关。结论AFQ精确地揭示了PSD患者的神经纤维束存在节段性的微结构损害,且胼胝体小钳和钩状束节段性微结构损害与抑郁严重程度有关。

牙体缺损类型与纤维桩位置对桩核冠修复上颌前磨牙抗折性能的影响

纳入120颗离体上颌前磨牙分成5组(每组24颗),制备360°牙本质肩领(A组)、颊侧180°牙本质肩领(B组)、腭侧180°牙本质肩领(C组)、远中180°牙本质肩领(D组)、近中180°牙本质肩领(E组),分别用树脂核+全冠修复、颊侧根管纤维桩+树脂核+全冠修复、腭侧根管纤维桩+树脂核+全冠修复、颊、腭侧根管纤维桩+树脂核+全冠修复。结果显示:A组样本牙的抗折破坏载荷值高于B、C、D、E组(P<0.05),颊侧根管置入纤维桩抗折强度高于腭侧(P<0.05)。提示360°完整牙本质肩领能提供最佳的抗折强度,牙本质肩领不完整时,推荐置入颊侧根管纤维桩修复。

三种不同树脂粘结系统对纤维桩粘结效果的影响

目的评价全酸蚀粘结系统、自酸蚀粘结系统及自粘结树脂对纤维桩粘结效果的影响。方法选取2021年10月至2022年3月于泰州职业技术学院口腔门诊部行前牙纤维桩修复的82例患者(共122颗前牙)作为研究对象,按照不同树脂粘结系统将其分为全酸蚀组(28例,40颗)、自酸蚀组(26例,40颗)及自粘结组(28例,42颗)。全酸蚀组使用Tetric-N Bond全酸蚀树脂粘结剂对纤维桩进行粘结,自酸蚀组使用All-Bond Universal自酸蚀树脂粘结剂对纤维桩进行粘结,自粘结组使用Relyx Unicem自粘结树脂对纤维桩进行粘结,完成纤维桩粘结后行全瓷冠修复。比较三组纤维桩核的稳固率及全瓷冠修复体的红色美学指数(PES)、白色美学指数(WES)评分。结果粘结6、12、18个月后,三组纤维桩核的稳固率组间及组内比较,差异无统计学意义(P>0.05)。粘结18个月后,三组全瓷冠修复体的PES、WES评分比较,差异无统计学意义(P>0.05)。结论三种树脂粘结系统对纤维桩的粘结效果在短期内相当,远期效果还需进一步的观察。

纤维桩、纳米复合树脂结合氧化锆烤瓷冠修复牙楔状缺损的效果及对龈沟液炎性介质水平、美学评分的影响

目的探究纤维桩、纳米复合树脂结合氧化锆烤瓷冠修复牙楔状缺损的效果及对龈沟液(GCF)炎性介质水平、美学评分的影响。方法选择2018年4月至2021年6月收治的96例牙楔状缺损患者为研究对象,以随机数字表法将其分为对照组和观察组,每组48例。对照组接受金属桩核结合金属烤瓷冠修复,观察组实施纤维桩、纳米复合树脂结合氧化锆烤瓷冠修复。比较两组的修复效果。结果观察组的口腔致病菌检出率低于对照组,修复成功率高于对照组(P<0.05)。修复后,观察组GCF中的神经激肽A(NKA)、组织基质金属蛋白酶抑制剂-1(TIMP-1)、基质金属蛋白酶-9(MMP-9)及白细胞介素-8(IL-8)水平均低于对照组(P<0.05)。修复后,观察组的红色美学指数(PES)、白色美学指数(WES)评分均高于对照组(P<0.05)。修复后,观察组的GCF量及碱性磷酸酶(ALP)、天冬氨酸转氨酶(AST)水平均低于对照组(P<0.05)。结论纤维桩、纳米复合树脂结合氧化锆烤瓷冠修复牙楔状缺损可改善GCF量及GCF中炎性介质、ALP、AST表达,提高修复成功率及美学评分。

基于FP腔实现光纤与边缘耦合器高效对准

【目的】通过集成在片上的硅基边缘光耦合器(以下简称边缘耦合器),硅光子芯片可以与光纤实现低损耗耦合。在商用硅光子芯片的封装流程中,大规模的光纤与硅光子芯片对准需求对光纤与边缘耦合器的对准效率提出了更高的要求。文章的研究目的是基于光纤端面与边缘耦合器端面之间形成的法布里-珀罗(FP)腔对光纤与边缘耦合器的对准流程进行优化。在光纤轴向(文章中表示为x轴方向)这一自由度上对光纤与边缘耦合器之间的距离进行测量后,将光纤沿该方向进行单次调节即可完成与边缘耦合器的高精度对准。【方法】文章研究了光纤端面与边缘耦合器端面之间形成的FP腔结构,建立了FP腔的反射/透射光谱与端面间距之间的物理模型。搭建光纤对准平台完成了基于FP腔测量端面之间距离的实验,然后基于FP腔测距结果,将光纤沿光纤轴向进行单次位置调整来实现与边缘耦合器的对准。【结果】实验中得到的FP腔长值与仿真得到的理想FP腔模型腔长值的偏差小于1μm,测得的光纤位移距离在实际位移的误差范围(±1μm)内。基于测距结果调整光纤位置后,在输出端口光纤与边缘耦合器之间的光耦合损耗为3.52 dB,与参考值(3.30 dB)的误差仅为0.22 dB。【结论】文章验证了基于FP腔实现光纤与边缘耦合器高效对准的可行性。通过FP腔实现了对光纤与边缘耦合器间距以及光纤位移的测量,测量精度为亚微米级。文章还通过实验验证了基于FP腔的测距结果,仅需对光纤进行单次位置调整即可实现与边缘耦合器的高精度对准。

用于高压测量的MEMS硅-玻光纤FP压力传感器

研究了一种基于微机电系统(MEMS)技术用于高压测量的硅-玻光纤法布里-珀罗(FP)压力传感器。该传感器以硅材料作为敏感元件,将电感耦合等离子体(ICP)干法刻蚀后的单晶硅膜片和高硼硅玻璃阳极键合构成FP腔。传感头使用MEMS技术批量制造,结构稳定、抗过载能力强、在高压环境下不容易失效。实验结果表明,该传感器能够实现30 MPa的高压压力测量,灵敏度为46.94 nm/MPa,线性拟合度为0.99897,测量结果具有较好的一致性和可靠性,所设计的压力传感器在高压检测方面有很强的应用前景。

3D打印多孔钛合金桩的粘接强度及粘接破坏模式和表面、粘接界面特征

目的 观察3D打印多孔钛合金桩的粘接强度及粘接破坏模式和表面、粘接界面特征,以期利用多孔结构的机械嵌合来提高金属桩核的粘接强度。方法 实验设计4组,A组选取10根预成纤维桩,扫描并获取三维数据,B、C、D组均使用A组获得的数据分别进行3D打印实心钛合金桩、3D打印多孔钛合金桩、氧化锆桩的设计与制作,将各组桩包埋、切片,使用万能力学实验机将桩从桩核树脂中推出,记录各组桩的粘接强度和粘接破坏模式,并用扫描电镜观察桩的表面、粘接界面特征。结果 A、B、C、D组粘接强度分别为(229.11±80.15)、(389.29±58.39)、(572.35±128.08)、(137.54±26.81)MPa,组间两两比较,P均<0.05。A、B、C、D组粘接界面破坏的例数分别为7、2、1、8例,粘接内部破坏的例数分别为0、1、3、0例,混合粘接破坏的例数分别为3、7、6、2例,组间两两比较,P均<0.05。A组扫描电镜下可见纤维桩表面大量排列紧密的纤维束,纤维桩与桩核树脂结合紧密;B组可见3D打印实心钛合金桩的表面有大量点状颗粒,点状颗粒间可见树脂嵌入,钛合金实心桩与桩核树脂结合紧密;C组可见3D打印多孔钛合金桩表面大量不规则空隙,桩的表面也存在大量点状颗粒,在颗粒间以及空隙间可见大量树脂嵌入,极大的增加了桩与桩核树脂的机械嵌合作用;D组可见氧化锆桩和表面相对平整,桩与桩核树脂结合紧密,机械嵌合明显少于前面三组。结论 与预成纤维桩、氧化锆桩和3D打印实心钛合金桩相比,使用3D打印技术制作的多孔钛合金桩,粘接强度有明显的提升,粘接破坏模式主要为混合粘接破坏,桩表面有大量不规则空隙及点状颗粒,在颗粒间及空隙间可见大量树脂嵌入,极大增加了桩与桩核树脂的机械嵌合作用。

聚醚醚酮及其复合材料修复桩核冠:问题与临床应用价值

背景:聚醚醚酮是具有良好机械性能、生物相容性、化学稳定性的特种塑料聚合物,可加入不同的填料形成新型复合材料,在桩核修复中有潜在的临床应用价值。目的:综述聚醚醚酮及其复合材料的性能、在桩核修复中的临床应用进展。方法:以“聚醚醚酮,桩核修复,金属桩,纤维桩,氧化锆桩”为中文检索词检索中国知网数据库,以“PEEK,polyetheretherketone post,post core repair,dental Dowels”为英文检索词检索PubMed数据库,检索时间范围重点为2019年1月至2023年10月。通过阅读文献题目、摘要及全文筛选,根据纳入与排除标准进行筛选,最后纳入71篇文献进行综述。结果与结论:聚醚醚酮是高性能热塑性聚合物,实验研究证明聚醚醚酮及其复合材料在机械性能、生物相容性、抗老化性、化学稳定性、粘接性能等方面具有优越性,在桩核修复领域应用前景喜人。聚醚醚酮及其复合材料作为桩核修复临床应用局限于前牙和前磨牙,但都获得了满意的修复效果。聚醚醚酮及其复合材料在桩核修复中属于新型材料,目前还有诸多问题尚待解决,如:3D打印设备和打印过程是否会影响材料的机械性能;临床修复效果观察时间短,缺乏长期的研究验证;缺乏聚醚醚酮及其复合材料作为桩核材料修复磨牙的病例报道等,后续还需不断完善相关研究。