表面接枝技术对纤维加强树脂基桩力学性能的影响

目的探讨石英纤维表面接枝技术对纤维增强光固化树脂复合材料(FRC)桩力学性能的影响。方法将石英纤维随机分成5组分别进行以下表面处理:A组,10%H_2O_2浸泡20 min;B组,10%H_2O_2浸泡20 min+γ-MPS处理;C组,10%H_2O_2浸泡20 min+γ-MPS处理+Bis-GMA接枝1 h;D组,10%H_2O_2浸泡20 min+γ-MPS处理+Bis-GMA接枝3 h;E组,10%H_2O_2浸泡20min+γ-MPS处理+Bis-GMA接枝7 h。将处理好的石英纤维按相同体积比浸入光固化树脂基质中制成纤维增强树脂桩。测试试样的弯曲模量、弯曲强度、弯曲载荷,SEM观察断面的显微结构。结果不同接枝时间的石英纤维对FRC桩的力学性能有影响,其中E组力学性能明显提高,弯曲模量(24.65±2.20)GPa,弯曲强度(696.24±12.85)MPa,弯曲载荷(185.67±3.43)N,与其余组有显著差异(P<0.05)。结论纤维表面接枝技术能提高树脂基纤维桩材料的力学性能。     

不同硅烷化处理对纤维桩剪切粘结强度的影响

目的比较研究纤维桩表面不同硅烷化处理对纤维桩剪切粘结强度的影响。方法40根纤维桩,根据表面处理不同分为4组:表面无处理组、椅旁硅烷化处理组、预先硅烷化处理组、预先硅烷化处理+椅旁硅烷化处理组。每组再平均分成两个小组,其中一组水保存24h,不进行冷热循环,另一组进行水保存150d和冷热循环15000次。用树脂核材料置于纤维桩周围制成直径4mm,高12mm的圆柱形标准试件,包埋,切成1mm薄片,在Instron万能试验机上进行微推出实验,记录数值并进行统计学分析。结果无冷热循环的剪切粘结强度依次为:(12.38±1.80)、(18.31±0.90)、(24.47±1.43)、(24.92±1.36)MPa;进行冷热循环的剪切粘结强度依次为:(6.76±0.72)、(13.64±1.20)、(21.67±1.45)、(21.04±1.08)MPa。表面硅烷化处理组均高于对照组;预先硅烷化处理组优于椅旁硅烷化处理组;预先硅烷化处理+椅旁处理组与单纯预先处理组之间无差异;冷热循环和水保存后各组剪切粘结强度均降低。结论纤维桩表面预先硅烷化处理有效提高了纤维桩剪切粘结强度,但其粘结耐久性值得进一步研究。     

核壳纳米纤维增强牙科树脂基体的力学性能与界面研究

目的研究PAN—PMMA核壳纳米纤维对牙科光固化树脂基体力学性能的增强效果。方法通过静电纺丝法制备PAN—PMMA核壳纳米纤维,同时将纳米纤维分别按1wt％、2wt％、3wt％和5wt％的质量比直接纺入Bis—GMA／TEGDMA光固化树脂单体制成纳米纤维树脂复合物。空白组是Bis—GMA／TEGDMA纯光固化树脂。在万能力学测试机上用三点弯曲法测试各组的弯曲强度、模量及断裂功,用SPSS软件进行统计学分析。SEM观察各组样条断面纤维与树脂界面及纤维分散状态。结果2wt％纳米纤维增强组弯曲强度和模量及断裂功较空白组分别增加了25％、74％、47％,统计学分析有显著性差异（P〈0．05）;SEM结果显示断面拔出的纤维表面粗糙,纤维分散均匀,有较好的界面形成。结论2wt％质量比的PAN—PMMA核壳纳米纤维可以提高光固化树脂基质的力学性能。     

不同表面处理对纤维桩粘结强度的影响及电镜观察

目的 比较研究不同表面处理对纤维桩剪切粘结强度的影响及各自的粘结面超微结构。方法 20根纤维桩分为4组（n=5）：表面无处理组（A）、椅旁硅烷化处理组（B）、厂家预处理组（C）、厂家预处理+椅旁硅烷化处理组（D）。分别用树脂核材料置于纤维桩周围制成圆柱形标准试件,包埋,切割成1 mm薄片。每根纤维桩可获得10个薄片。每组5个薄片用于电镜观察纤维桩与树脂核材料粘结界面的超微结构;45个薄片在万能实验机上进行微推出实验,记录数值并进行统计学分析。结果 各组的剪切粘结强度依次为（13.46±1.78）、（18.39±1.60）、（24.54±1.34）、（24.39±1.65） MPa。表面处理组均高于A组,C组高于B组,D组与C组之间无差异。电镜观察各组纤维桩与树脂核材料粘结界面结合良好。C组和D组的纤维桩粘结界面可见微机械固位结构。结论 纤维桩表面由厂家预处理有效提高了纤维桩剪切粘结强度,表面预处理形成的微机械固位和化学粘结固位是增强纤维桩粘结强度的重要因素。     

石英纤维根管桩复合材料的力学性能研究

目的:对自行研制的用于预成根管桩的石英纤维增强环氧树脂复合材料的力学性能进行研究。方法:利用石英纤维和环氧树脂,制备出不同的复合材料棒材,测量不同组分复合材料的纤维含量、弯曲强度和剪切强度,并计算不同组分的弹性模量,电镜观察截面和断裂面形貌。采用单因素方差分析和Student-Newman-Keuls检验对各实验组的弯曲强度和剪切强度进行统计学处理。结果:本研究制备得到的复合材料的弯曲强度和剪切强度随着纤维含量的增加而增加,弯曲强度范围在741～1165MPa之间,剪切强度范围在36.7～50.4MPa之间,相应的纤维质量含量范围在53.3～78.6Wt%之间,弹性模量范围在30.6～51.9GPa之间。电镜观察显示:纤维在树脂中分布均匀;纤维与树脂结合良好。统计学分析显示:各试验组弯曲强度和剪切强度与对照组均有显著性差异(P<0.01),各试验组之间的弯曲强度和剪切强度均有显著性差异(P<0.01)。结论:制备得到的石英纤维/环氧树脂复合材料具备良好的机械性能,能够满足根管桩材料的要求。     

不同纳米粒子对纤维增强光固化树脂基桩力学性能的影响

目的研究2种纳米颗粒对自行研制的高强玻璃纤维增强光固化树脂复合材料(FRC)桩的力学性能的影响。方法自行配置光固化树脂基质,将纳米ZrO2和纳米Al2O3分别按1%、3%、4%、5%的比例加入树脂基质,用拉挤法制成纤维增强树脂基牙科桩,用万能力学试验机测试FRC桩的弯曲模量、弯曲强度、弯曲载荷。结果不同含量的纳米粒子对FRC桩的力学性能有影响,含4%纳米ZrO2、Al2O3的光固化树脂制成的FRC桩综合性能最佳,弯曲模量(20.42±0.88)、(19.96±0.69)GPa,弯曲强度(464.89±18.84)、(481.17±24.68)MPa,弯曲载荷(146.05±5.92)、(151.23±7.79)N,与未添加纳米粒子的FRC桩有显著差异(P<0.05)。结论少量纳米粒子对FRC桩有增韧效果。     

钛表面ALD构建氧化锌纳米薄膜及其性能研究

目的 比较研究原子层沉积法(atomic layer deposition, ALD)不同沉积周期制备氧化锌(ZnO)纳米薄膜的理化特点及其抗菌效应。方法 根据不同的沉积周期，将实验分为4组(光滑钛组、300循环组、600循环组、1 200循环组)。以二乙基锌、水为前驱体，在纯钛试件表面利用ALD技术制备氧化锌纳米薄膜。采用扫描电子显微镜(SEM)观察薄膜表面形貌，能谱仪(EDS)和X射线衍射仪(XRD)检测薄膜的元素组成和晶型，水接触角检测仪检测薄膜的亲水性，椭偏仪检测镀膜厚度。通过CCK-8实验、光密度法评估薄膜的细胞毒性及其对金黄色葡萄球菌的体外抗菌效果。结果 SEM结果显示ALD在纯钛表面制备的薄膜均匀致密，晶粒尺寸随着沉积周期增加而增大，EDS、XRD结果显示镀膜主要由Zn、O元素构成，成分为氧化锌晶体。水接触角结果显示薄膜为疏水。椭偏仪结果显示各实验组薄膜厚度为纳米级，与沉积周期之间呈线性关系。各实验组均未表现出细胞毒性，具有体外抗金黄色葡萄球菌效果，1 200循环组在24、48 h表现出最高抗菌率，分别为65.9%和52.3%,效果最佳。结论 ALD法在纯钛表面制备的不同...     

不同粘结界面处理方法对纤维桩钉固位力的影响

目的研究纤维桩钉在不同粘结条件下的固位力,为临床选择合适的操作方法提供依据。方法根管壁牙本质和纤维桩表面分别经酸蚀、硅烷化处理后使用4种粘固材料(PermaCem双固化树脂水门汀;LuxaCore双固化树脂;Dulink双固化树脂水门汀;Rely-X Unicem双固化树脂水门汀)将桩钉粘固于离体人牙根管内,万能电子力学试验机测试其固位力,电子探针分析界面情况。结果根管壁牙本质经酸蚀后桩钉固位力平均值均大于未酸蚀组,处理前后数值有显著性差异(P<0.05);纤维桩表面硅烷化处理后固位力平均值均大于未硅烷化组,PermaCem组和LuxaCore组处理前后数值有显著性差异(P<0.05),但Dulink组和Rely-X Unicem组处理前后数值无统计学差异(P>0.05);两种表面处理方法粘结界面均显示了良好的粘结完整性。结论根管壁牙本质和纤维桩表面分别经酸蚀、硅烷化处理后,纤维桩固位力增大。     

不同表面处理的纤维桩微拉伸粘接强度研究

目的:通过微拉伸粘接强度测试法测试在纤维桩表面经过6种不同的处理后与核树脂的粘接强度,探索何种表面处理方法能显著提高纤维桩与核树脂的粘接强度,为临床应用提供参考。方法:将30根石英纤维桩随机分成6组,每组5根。A组纤维桩表面涂布粘接剂,B组涂布硅烷处理剂,吹干后涂粘接剂,C组5%氢氟酸酸蚀30sec,流水冲洗吹干后处理同A组,D组5%氢氟酸酸蚀30sec,流水冲洗吹干后处理同B组,E组24%双氧水处理,后操作同A组,F组24%双氧水处理后操作同B组。在桩周分层固化核树脂,用低速锯沿纤维桩外周平行片切,再垂直粘接面片切成横截面约0.9mm×0.9mm的长方柱状试件,每组15个,用微拉伸粘接强度测试法测试纤维桩与核树脂的微拉伸粘接强度,体视显微镜观察断裂类型。结果:A组微拉伸粘接强度8.78±2.20MPa,B组9.35±1.92MPa,C组15.50±2.87MPa,D组22.98±3.24MPa,E组16.64±2.70MPa,F组24.88±3.9 0MPa。用氢氟酸酸蚀的C组和D组和用双氧水处理的E组和F组的微拉伸粘接强度明显高于A组B组(P<0.05)。用氢氟酸酸蚀后再硅烷化处理的D组比C组、用双氧水处...     

两种石英纤维桩机械性能与结构特征的实验研究

目的:对比研究两种石英纤维桩的机械性能和结构特征.方法:选择锥形石英纤维桩D.T.Light post(DT)和表面带固位凹槽的锥形石英纤维桩Macro-Lock post(ML)各15根用作实验研究对象.万能测试机测试其机械性能,扫描电镜观察纤维桩结构,Image J软件分析纤维直径及含量.结果:DT和ML纤维桩的断...     

Effect of silane activation on shear bond strength of fiber-reinforced composite post to resin cement

PURPOSE

Among the surface treatment methods suggested to enhance the adhesion of resin cement to fiber-reinforced composite posts, conflicting results have been obtained with silanization. In this study, the effects of silanization, heat activation after silanization, on the bond strength between fiber-reinforced composite post and resin cement were determined.

MATERIALS AND METHODS

Six groups (n=7) were established to evaluate two types of fiber post (FRC Postec Plus, D.T. Light Post) and three surface treatments (no treatment; air drying; drying at 38℃). Every specimen were bonded with dual-curing resin cement (Variolink N) and stored in distilled water for 24 hours at 37℃. Shear-bond strength (MPa) between the fiber post and the resin cement were measured using universal testing device. The data were analyzed with 1-way ANOVA and by multiple comparisons according to Tukey''s HSD (α=0.05). The effect of surface treatment, fiber post type, and the interactions between these two factors were analyzed using 2-way ANOVA and independent sample T-tests.

RESULTS

Silanization of the FRC Postec Plus significantly increased bond strength compared with the respective non-treated control, whereas no effect was determined for the D.T. Light Post. Heat drying the silane coupling agent on to the fiber-reinforced post did not significantly improve bond strength compared to air-syringe drying.

CONCLUSION

The bond strength between the fiber-reinforced post and the resin cement was significantly increased with silanization in regards to the FRC Postec Plus post. Bond strength was not significantly improved by heat activation of the silane coupling agent.     

A simple etching technique for improving the retention of fiber posts to resin composites

Coupling of fiber posts to composites is hampered by absence of chemical union between epoxy resins and methacrylate-based resins. This study examined a clinically feasible protocol for creating micromechanical retention on the surface of fiber posts, using hydrogen peroxide etching to remove the surface layer of epoxy resin. This was followed by silanization of the exposed quartz fibers to enhance their chemical bonding to composites. Etching with 24% H2O2 for 10 min or 10% H2O2 for 20 min produced a 50 microm thick surface zone that is depleted of epoxy resin, leaving intact, undamaged quartz fibers for silanization. Low viscosity flowable composites were employed to infiltrate this zone, to simulate the creation of hybrid layers in acid-etched dentin by dentin adhesives. Interfacial strengths were enhanced with the adjunctive use of H2O2 etching and silanization, and were probably dependent on the ability of the flowable composites to completely infiltrate this interdiffusion zone.     

Composite resin reinforced with pre-tensioned fibers: a three-dimensional finite element study on stress distribution

Pre-tensioned construction material is utilized in engineering applications of high strength demands. The purpose of this study was to evaluate the effect of the pre-tensioning fibers of fiber-reinforced composite (FRC) using three-dimensional finite element (FE) analysis. The 3D FE models of particulate composite resin (CR), FRC and composite resin reinforced with pre-tensioned fibers (PRE-T-FRC) were constructed. The uniaxial three-point bending test was simulated using FE analysis to calculate the principal stress distribution. In the FRC and PRE-T-FRC, stresses were higher than CR, and they were located in the fiber. However, the maximum principal stress value at the composite of PRE-T-FRC was lower than the FRC and CR. Composite resin reinforced with pre-tensioned fibers was advantageous for stress distribution and lowering the stress at the composite itself. Experimental studies on physical properties of pre-tensioned FRC are encouraged to be conducted.     

The relationship between fibre post geometry and flexural properties: an assessment through a modified three-point bending test

The aim of this study was to investigate the flexural properties of five types of fiber-reinforced dowels using a modified three-point bending test. Fiber-reinforced resin dowels were tested by a modified three-point bending test associated with models for cylindrical and conical simple-supported beams. The fracture load ranged from 86 to 246 N and the flexural strength from 423 to 1192 MPa. FRC Postec had significantly higher flexural strength and fracture loads values. Thus, the present study demonstrated higher flexural strength values for the FRC Postec fibre posts, suggesting that this system would present a better response to the forces of mastication.     

4种纤维桩的弯曲强度和显微结构的研究

目的 测试不同纤维桩的弯曲强度,并研究纤维桩弯曲强度与结构特征之间的联系。方法 选择4种品牌的纤维桩进行研究,D.T.Light-Post(BISCO),Pare PostTaper Lux(Coltene/Whaledent),LuxaPost(DMG),国产纤维桩(实德隆)各6根,随机选取5根进行三点弯曲测试,剩余1根及每种品牌中弯曲测试结果最高和最低者用于扫描电镜分析。结果 4种纤维桩的断裂载荷在127.80～157.40N,弯曲强度在820.03～937.95MPa,纤维/基质比值范围为54.56%～78.68%。各项分析结果显示纤维/基质比值与弯曲强度有相关性(P=0.024,r=0.976)。结论 纤维桩弯曲强度与其结构特征相关,纤维/基质比值越高,弯曲强度越大。     

Adhesion between fiber posts and resin luting agents: a microtensile bond strength test and an SEM investigation following different treatments of the post surface

PURPOSE: (1) To evaluate the interfacial strength between FRC Postec posts and three luting agents (Multilink, Variolink II, and MultiCore Flow) following different surface treatments, and (2) to observe the effect of sandblasting (Rocatec Pre) on the surface morphology of methacrylate-based fiber posts. MATERIALS AND METHODS: The posts received one of the following surface treatments: (1) sandblasting, (2) sandblasting + silanization, (3) silanization or (4) no treatment. The three luting agents were bonded to the post and the post-cement bond strength was evaluated with the microtensile test. SEM observation of sandblasted and nontreated posts was performed. Post-cement interfaces were also evaluated. Data were statistically analyzed with two-Way ANOVA with post treatment and luting agent as factors. Tukey's test was applied for post-hoc comparisons. RESULTS: Post treatment and the interaction between type of luting agent and type of post treatment were significant factors for bond strength (p < 0.001). The type of luting agent did not significantly influence bond strength (p = 0.07). Sandblasting + silanization performed better than sandblasting or no treatment (p < 0.001). Silanization resulted in significantly higher bond strengths than no treatment (p = 0.045). No differences were detected between sandblasting + silanization and silanization. SEM observation revealed an increased surface roughness and exposure of fibers in sandblasted posts. CONCLUSION: Silanization was confirmed to be a reliable method for improving the bond strength of resin luting agents to fiber posts. Bond strength of resin luting agents to fiber posts was not influenced by the type of luting agent. The sandblasting procedure modified the methacrylate-based post surface texture.     

Influence of airborne-particle abrasion on mechanical properties and bond strength of carbon/epoxy and glass/bis-GMA fiber-reinforced resin posts

STATEMENT OF PROBLEM: Controversy exists concerning the use of fiber-reinforced posts to improve bond strength to resin cement because some precementation treatments can compromise the mechanical properties of the posts. PURPOSE: The purpose of this study was to analyze the influence of airborne-particle abrasion on the mechanical properties and microtensile bond strength (MTBS) of carbon/epoxy and glass/bis-GMA fiber-reinforced resin posts. MATERIAL AND METHODS: Flexural strength (delta(f)), flexural modulus (E(f)), and stiffness (S) were assessed using a 3-point bending test for glass fiber-reinforced and carbon fiber-reinforced resin posts submitted to airborne-particle abrasion (AB) with 50-microm Al(2)O(3), and for posts without any surface treatment (controls) (n=10). Forty glass fiber (GF) and 40 carbon fiber (CF) posts were submitted to 1 of 4 surface treatments (n=10) prior to MTBS testing: silane (S); silane and adhesive (SA); airborne-particle abrasion with 50-microm Al(2)O(3) and silane (ABS); airborne-particle abrasion, silane, and adhesive (ABSA). Two composite resin restorations (Filtek Z250) with rounded depressions in the lateral face were bilaterally fixed to the post with resin cement (RelyX ARC). Next, the specimen was sectioned with a precision saw running perpendicular to the bonded surface to obtain 10 bonded beam specimens with a cross-sectional area of 1 mm(2). Each beam specimen was tested in a mechanical testing machine (EMIC 2,000 DL), under stress, at a crosshead speed of 0.5 mm/min until failure. Data were analyzed by 2-way ANOVA followed by Tukey HSD test (alpha=.05). Failure patterns of tested specimens were analyzed using scanning electron microscopy (SEM). RESULTS: The 3-point bending test demonstrated significant differences among groups only for the post type factor for flexural strength, flexural modulus, and stiffness. The carbon fiber posts exhibited significantly higher mean flexural strength (P=.001), flexural modulus (P=.003), and stiffness (P=.001) values when compared with glass fiber posts, irrespective of surface treatment. An alteration in the superficial structure of the posts could be observed by SEM after airborne-particle abrasion. MTBS testing showed no significant effect for the surface treatment type; however, significant effects for post system factor and for interaction between the 2 factors were observed. For the carbon fiber post, the ABSA surface treatment resulted in values significantly lower than the S surface treatment. SEM analysis of MTBS-tested specimens demonstrated adhesive and cohesive failures. CONCLUSIONS: Airborne-particle abrasion did not influence the mechanical properties of the post; however, it produced undesirable surface changes, which could reduce the bond strength to resin cement. For the surface treatments studied, if silane is applied, the adhesive system and airborne-particle abrasion are not necessary.     

Evaluation of the flexural strength of carbon fiber-, quartz fiber-, and glass fiber-based posts

This study investigated the flexural strength of eight fiber posts (one carbon fiber, one carbon/quartz fiber, one opaque quartz fiber, two translucent quartz fiber, and three glass fiber posts). Eighty fiber posts were used and divided into eight groups (n = 10): G1: C-POST (Bisco); G2: AESTHETI-POST (Bisco); G3: AESTHETI-PLUS (Bisco); G4: LIGHT-POST (Bisco); G5: D.T. LIGHT-POST (Bisco); G6: PARAPOST WHITE (Coltene); G7: FIBERKOR (Pentron); G8: REFORPOST (Angelus). All of the samples were tested using the three-point bending test. The averages obtained were submitted to the ANOVA and to Tukey's test (p < 0.05). The mean values (MPa) of the groups AESTHETI-POST-carbon/quartz fiber post (Bisco) and AESTHETI-PLUS-quartz fiber post (Bisco) were statistically similar and higher than the mean values of the other groups. The mean values of the groups C-POST-carbon fiber post (Bisco), LIGHT-POST-translucent quartz fiber post (Bisco), D.T. LIGHT-POST-double tapered translucent quartz fiber post (Bisco), PARAPOST WHITE-glass fiber post (Coltene) and FIBREKOR--glass fiber post (Pentron) were similar and higher than the group REFORPOST-glass fiber post (Angelus).     

Strength and mode of failure of unidirectional and bidirectional glass fiber-reinforced composite materials

PURPOSE: The flexural strength of two commercially available dental fiber-reinforced composites (FRC) (glass fiber-reinforced composite material), one unidirectional and the other bidirectional, were investigated. MATERIALS AND METHODS: Ten uniform beams of core materials and ten beams of laminated core materials were fabricated for FibreKor and Vectris Frame. The specimens were subjected to a three-point bending test. Flexural strength for both FRC materials was determined with and without their composite laminations. The strength data were analyzed using the Weibull method. Modes of failure for both systems were determined using SEM. RESULTS: The strength of FibreKor was significantly greater than that of Vectris Frame when comparing the core materials with and without their respective composite laminations. Mode of failure of FibreKor was predominantly debonding with fiber fracture. Vectris Frame did not exhibit debonding failure. Mode of failure for Vectris Frame was fiber fracture with delamination and matrix microfracture. CONCLUSION: FibreKor, a unidirectional FRC, demonstrated higher flexural strength than Vectris Frame, a bidirectional FRC. Debonding of fibers from the matrix possibly contributed to toughening mechanisms such as crack deflection, fiber pullout, and fiber bridging in FibreKor.