Effect of procedure on diametral tensile strength of composite resin

The sensitivity of the test for diametral tensile strength to variations in testing procedure was investigated. Composite resin specimens of four different surface roughnesses at both ends of the specimens were loaded at one of three crosshead speeds. The diametral tensile strength values varied between 43.9 and 65.7 MPa. Diametral tensile strength was found to decrease with increasing loading rate, with decreasing roughness of the specimens, and with increasing length of the cylindrical specimens. The significant influence of the surface roughness is suggested to be a result of the correlation between roughness and length of specimens, and not the expression of a true influence on diametral tensile strength of surface roughness of the specimens' ends.     

三种临床常用核树脂材料的抗压和径向抗拉性能研究

目的：测试三种常用核树脂材料的抗压和径向抗拉性能。方法：选取三种核树脂材料,按材料使用说明要求制备圆柱状标准试件60个。在万能力学试验机上测试抗压和径向抗拉强度。结果：抗压强度Z250〉Light-core〉LuxcaCore-Dual;抗拉强度Z250最高,Light-core和LuxcaCore-Dual无显著差异。结论：不同核材料的抗压和抗拉强度有较大差异,临床使用时应综合参考材料的力学性能和临床操作便利性选择合适材料。     

光照强度对光固化复合树脂抗压和抗拉强度的影响

目的 :探讨光照强度对光固化复合树脂抗压、抗拉强度的影响。方法 :用WDW 10 0型微机控制电子万能试验机 ,测试比较不同光照强度 [第 1组 ,3 0 0mW /cm2 × 40s ;第 2组 ,5 0 0mW /cm2 × 40s ;第 3组 ,80 0mW /cm2 × 40s ;第 4组 ,(3 0 0mW /cm2 × 10s) + (5 0 0mW /cm2 × 3 0s) ;第 5组 ,(3 0 0mW /cm2 × 10s) + (80 0mW /cm2 × 3 0s) ]对光固化复合树脂抗压强度、微拉伸强度的影响。结果 :采用弱光引导固化方法固化的光固化复合树脂的抗压强度、微拉伸强度明显优于采用传统方法固化的树脂。结论 :采用弱光引导固化对提高复合树脂抗压和抗拉强度有积极意义     

Hardness and compressive strength of indirect composite resins: effects of immersion in distilled water

The aim of this study was to evaluate the effect of ageing in distilled water on the hardness and compressive strength of a direct composite resin Z100, a feldspatic porcelain (Noritake) and three indirect composites (Artglass, Solidex and Targis). For the Vickers hardness tests, five disk-shaped specimens (2 x 4 mm) of each material were prepared according to the manufacturers' instructions. The hardness tests were conducted using a Vickers diamond indentor. Compressive strength measurements were recorded on cylindrical specimens with a diameter of 6 mm and a length of 12 mm. The compression tests were carried out with a constant cross-head speed of 0.5 mm min(-1) on a mechanical test machine. For each material, 10 specimens were tested after 7 days of dry storage at 37 +/- 1 degrees C and 10 specimens were tested after water storage at 37 +/- 1 degrees C for 180 days. Noritake porcelain specimens showed higher hardness values than the composites. Among the composite materials, Z100 promoted the highest VHN values, regardless of the ageing periods. The results showed that Solidex and Z100 had the highest compressive strength values. Ageing in water reduced the hardness for all composites, but had no long-term effect on the compressive strength.     

二期处理光固化复合树脂径向抗张强度和硬度

目的：探讨经过二期处理的光固化复合树脂其径向抗张强度和硬度与单纯光固化复合树脂的差异。方法：Ｓｔａｒｆｉｌ Ａ２０ 、后牙用复合树脂、Ｒｅｓｔｏｒａｔｉｖｅ Ｚ１００ 三种光固化复合树脂光固化４０ｓ 后,分别光照５ｍｉｎ,１４０℃加热处理７．５ｍｉｎ 和０ ．６ＭＰａ １２０℃加热加压处理７ｍｉｎ ,测量其径向抗张强度和硬度。结果：径向抗张强度测试：经过处理的光固化复合树脂除光照５ｍｉｎ 组外,其它两个处理组均高于对照组（ 仅光固化４０ｓ）,且有统计学差异（ Ｐ＜ ０．０５） 。硬度测试：除Ｓｔａｒｆｉｌ Ａ２０ 和后牙用复合树脂光照５ｍｉｎ 组外,其余各处理组均高于对照组,且有统计学差异（Ｐ＜ ０ ．０５） 。结论：与单纯光固化复合树脂相比,经过二期处理的光固化复合树脂,其径向抗张强度和硬度不同程度的提高。     

Effect of different curing times and distances on the microhardness of nanofilled resin-based composite restoration polymerized with high-intensity LED light curing units

PurposeThis study examined the effect of different distances and curing times on the microhardness (VHN) of nanofilled resin-based composite (RBC) restorations polymerized with high-intensity LED LCUs.Materials and methodsSeventy-five RBC specimens (2 mm thickness and 5 mm diameter) were fabricated from Tetric-N-Ceram (Ivoclar Vivadent). Each of the 25 specimens was polymerized by means of one of three types of high-intensity LED LCUs: (B) Blue-Phase-G2 (polywave LED, Ivoclar Vivadent), (E) Elipar S10 ^TM (single-peak, 3 M ESPE), and (P) Planmica Lumion (single-peak, Mectron) at three different distances (0 mm, 2 mm, and 4 mm) at 20 sec, 40 s, and 60 sec. A microhardness tester (NOVA, Innovatest, The Netherlands) was used to measure the VHN from the top and bottom surfaces. Data for VHN were analyzed using mixed ANOVA, followed by post hoc analyses with p-values < 0.05.ResultsA significant difference was found in VHN between all three LED LCUs, where (B) specimens had the highest means, followed by (E) and (P). Bottom surface VHN values were reduced significantly (p < 0.05) compared to top surface values in all LCU types. With increasing distances up to 2 mm and 4 mm, VHN values with (E) and (P) were significantly reduced on the top and bottom surfaces (p < 0.05). When the curing times were increased for 40 and 60 sec, the VHN values were significantly improved (p < 0.05). Meanwhile, increasing the distance with (B) did not significantly reduce the VHN. Moreover, increasing the curing times did not significantly improve the VHN of the bottom surfaces.ConclusionHigh-intensity LCUs have variable effects on the surface (top/bottom) hardness of Tetric-N-Ceram nanofilled RBC restoration. With increasing distance, VHN was reduced; therefore, compensation with more curing time (2 mm/40 sec and 4 mm/60 sec) is highly recommended with Elipar S10 and Planmica Lumion LCUs to improve the material surface hardness.     

复合树脂的不同固化方法对抗压强度影响

目的 探讨不同固化方法处理后对复合树脂抗压强度的影响。方法 采用光固化、光固化＋光固化、光固化＋热固化,3种不同固化方法处理3M和贺利氏复合树脂,在万能验试机上测试抗压强度。结果 2次处理的复合树脂抗压强度均比1次处理的复合树脂有较大提高,范围在51.8%-91.6%之间。不同的2次固化方法相比,统计学无显著差异。结论 复合树脂经2次固化方法处理,其抗压强度高于1次光固化方法的处理。     

牙科复合树脂材料与牙体硬组织剪切粘接强度的方向性

目的　考察复合树脂材料与牙体硬组织粘接强度的方向性。方法　采用 2种复合树脂材料及配套的粘接剂 ,分别与牛牙牙釉质和牙本质粘接。测试了剪切力分别沿根尖方向和切缘方向作用的静剪切和冲击剪切强度。结果　 2种复合树脂材料与牙釉质粘接的剪切粘接强度均表现为根尖方向的剪切强度大于切缘方向的剪切强度。在静剪切实验中 ,前者约为后者的 2～ 3倍 (P <0 0 5) ;在冲击剪切实验中 ,前者约为后者的 3～ 4倍 (P <0 0 0 1 )。 2种复合树脂材料与牙本质的粘接强度受作用力方向的影响较小 ,在静剪切实验和冲击剪切实验中 ,2个方向的数据之间差异均无显著性 (P >0 0 5 ,P >0 5)。结论　复合树脂与牛牙牙釉质之间的剪切粘接强度与剪切力作用的方向有关。     

Leaching behaviors of computer-aided design/computer-aided manufacturing composite resin component elements immersed in water

Purpose

Immersion tests in purified water were conducted to evaluate the leaching behaviors of filler elements contained in computer-aided design/computer-aided manufacturing (CAD/CAM) composite resin.

Effect of different surface treatments of human occlusal sclerotic dentin on micro-tensile bond strength to resin composite core material

The objectives of this study were to evaluate the micro-tensile bond strength (μTBS) of composite bonded to human occlusal sclerotic dentin following different surface treatments to determine the sclerotic dentin morphology. Human molars without (normal dentin; group 1) or with occlusal wear (sclerotic dentin; groups 2–5) were divided and subjected to different surface treatments, including the normal protocol for the Contax self-etch bonding system (group 1 and 2); doubled etch-prime time (group 3); pre-conditioning with 37% phosphoric acid before normal protocol (group 4); or pre-conditioning with 37% phosphoric acid before doubling the self-etching time (group 5). All teeth were restored with composite (Luxacore Z dual), sectioned into stick specimens and stored for 24 h in water before specimens were subjected to the μTBS test (n = 50 per group). The μTBS of normal dentin was not statistically significantly different from that of the sclerotic dentin groups, except for the doubled etch-prime time group which showed lower μTBS. Sclerotic dentin pre-treated with phosphoric acid resulted in less sclerotic casts and wider dentinal tubules, while doubled etch-prime time did not alter the morphology, as shown by scanning electron microscopy. In conclusion, the use of 37% phosphoric acid before applying self-etch bonding resulted in more tubule openings and a significantly higher μTBS when compared with the doubled etch-prime time group.     

固化灯及照射距离对纳米树脂显微硬度的影响

目的观察在不同照射距离下,不同固化模式对复合树脂表面显微硬度的影响。方法将复合树脂制备成直径4mm,厚2mm的圆片状实验模块,根据照射距离（2mm、5mm、10mm）与固化模式（430mw／cm^2卤素灯40秒与860mw／cm^2二极管固化灯20秒）分成6组,每组6个,共36个。固化后用硬度计测定每个树脂块顶面与底面的韦氏硬度值。统计分析各组间显微硬度值的差别。结果随照射距离增大,树脂块显微硬度显著降低（p〈0．01）;各组树脂块顶面显微硬度值均高于底面（p〈0．01）;在2mm与5mm照射距离下,不同固化方式对树脂块表面硬度无显著影响（p〉0．05）;在10mm照射距离下,二极管固化灯组底面的显微硬度显著高于卤素灯组（p〈0．01）。结论远距离照射下,要使深层复合树脂充分固化应选择高功率的固化模式。     

The Knoop hardness of a composite resin polymerized with different curing lights and different modes

AIM: The purpose of this study was to compare the surface hardness of a hybrid composite resin polymerized with different curing lights. METHODS AND MATERIALS: Two 3.0 mm thick composite resin discs were polymerized in a prepared natural tooth mold using: (1) a conventional quartz-tungsten halogen light (QTH- Spectrum 800); (2) a high-intensity halogen light, Elipar Trilight (TL)-standard/exponential mode; (3) a high-intensity halogen light, Elipar Highlight (HL)-standard/soft-start mode; (4) a light-emitting diode, Elipar Freelight (LED); and (5) a plasma-arc curing light, Virtuoso (PAC). Exposure times were 40 seconds for the halogen and LED lights, and three and five seconds for the PAC light. Following polymerization, the Knoop hardness was measured at the bottom and the top surfaces of the discs. RESULTS: Significant differences were found between top and bottom Knoop Hardness number (KHN) values for all lights. The hardness of the top and bottom surfaces of both specimens cured by the PAC light was significantly lower than the other lights. No significant hardness differences were observed between the remaining curing units at the top of the 2.0 mm specimens. Significant differences were found between the LED and two modes of HL on the bottom surfaces. For the 3.0 mm thick samples, while significant differences were noted between LED and TL standard mode and between the two TL curing modes on the top, significant differences were only observed between QTH and the standard modes of TL and HL at the bottom.     

Influence of thermal cycles in water on flexural strength of laboratory-processed composite resin

Recently a new generation of laboratory-processed composite resins containing submicron glass fillers was introduced, with claims of high strength. The purpose of this study was to evaluate the effect of thermal cycling in water on the flexural strength and hardness of several laboratory composite systems. The flexural strength of the new laboratory processed composite resins (Artglass [AG], Targis [TR] and Estenia [ES]) was significantly higher than that of conventional resins (Dentacolor [DC] and Cesead II [CS]). Thermocycling caused a reduction of the flexural strength but not a reduction of the hardness for most of materials tested. It was concluded that thermocycling affected the properties of the laboratory-processed hybrid type composite resin, ES, AG and TR. However, the changes of these properties were smaller than those of microfine type composite resin DC. Thus, ES, AG and TR may maintain better properties during service compared with DC.     

Clinical performance of a hybrid resin composite with and without an intermediate layer of flowable resin composite: A 7-year evaluation

Objective

The objective of this prospective clinical follow up was to evaluate the long term clinical performance of a hybrid resin composite in Class II restorations with and without intermediate layer of flowable resin composite.

Methods

Each participant received at least two, as similar as possible, Class II restorations of the hybrid resin composite. One resin composite restoration of each pair (59) was chosen at random to be restored with an intermediary layer with flowable resin composite. The other was restored without. The 118 restorations were evaluated using slightly modified USPHS criteria at baseline and then yearly during 7 years.

Results

Four drop outs were registered during the 7-year follow up (2 with and 2 without flowable) restorations. A prediction of the caries risk showed that 18 of the evaluated 46 patients were considered as high risk patients. Seventeen failures were observed, 8 in restorations with and 9 in restorations without an intermediate layer of flowable resin composite, resulting in a 14.9% failure rate after 7 years. The main reasons for failure were: fracture of resin composite (8), secondary caries (4) and cusp fracture (3). No statistical difference was seen between restorations restored with and without flowable layer.

Conclusion

The hybrid resin composite showed a good clinical performance during the 7-year evaluation. The use of flowable resin composite as an intermediate layer did not result in improved effectiveness of the Class II restorations.     

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目的评价不同黏结剂用于光固化复合树脂充填体表面托槽黏结的效果。方法2012年3月于中国医科大学口腔医学院正畸科制作10个自凝树脂长方体试件,在其4个表面制备窝洞并行光固化复合树脂充填。将40个树脂充填体随机分为A、B、C、D组（每组10个）,分别用京津釉质黏结剂、3M Unite化学固化黏结剂、3M Transbond光固化黏结剂和可乐丽菲露AP—X光固化复合树脂黏结金属托槽,进行抗剪切强度测试,并测评光固化树脂面黏结剂残留指数（ARI积分）。结果4种黏结剂的抗剪切强度分别为：A组（7．763±1．240）MPa;B组（8．231±0．338）MPa;C组（8．654±0．916）MPa;D组（8．349±0．820）MPa。4种黏结剂的抗剪切强度均达到临床要求,其中c组与A组的抗剪切强度差异有统计学意义（P〈0．05）,其余各组间的抗剪切强度差异无统计学意义（P〉0．05）。各组的ARI积分差异无统计学意义（P〉0．05）。结论在经过打磨粗糙表面处理后的光固化复合树脂表面黏结托槽时,4种黏结剂均能满足临床要求。其中3MTransbond“光固化黏结剂产生的抗剪切强度最大。     

Porcelain repair - Influence of different systems and surface treatments on resin bond strength

PURPOSE

The purpose of this study was to evaluate the bond strength of composite resin on the fracture surface of metal-ceramic depending on the repair systems and surface roughening methods.

MATERIALS AND METHODS

A total of 30 disk specimens were fabricated, 15 of each were made from feldspathic porcelain and nickel-chromium base metal alloy. Each substrate was divided into three groups according to the repair method: a) application of repair system I (Intraoral Repair Kit) with diamond bur roughening (Group DP and DM), b) application of repair system I with airborne-particle abrasion (Group SP and SM), and c) application of repair system II (CoJet Intraoral Repair System, Group CP and CM). All specimens were thermocycled, and the shear bond strength was measured. The data were analyzed using the Kruskal-Wallis analysis and the Mann-Whitney test with a significance level of 0.05.

RESULTS

For the porcelain specimens, group SP showed the highest shear bond strength (25.85 ± 3.51 MPa) and group DP and CP were not significantly different. In metal specimens, group CM showed superior values of bond strength (13.81 ± 3.45 MPa) compared to groups DM or SM.

CONCLUSION

Airborne-particle abrasion and application of repair system I can be recommended in the case of a fracture localized to the porcelain. If the fracture extends to metal surface, the repair system II is worthy of consideration.     

酸蚀和粘结对陈旧性树脂表面粘结强度的影响

目的：研究不同的表面处理方式对陈旧性树脂与新鲜树脂间粘结强度的影响。方法：制备Z350纳米树脂样本40例,浸泡于37℃蒸馏水2个月,表面经金刚砂车针研磨后随机分为4组：A组（对照组）表面未经处理;B组表面仅涂布粘结剂;12组表面仅37％磷酸酸蚀;D组表面37％磷酸酸蚀后涂粘结剂。上述表面处理后使用新鲜树脂完成样本制备。万能材料试验机上测定材料的微拉伸强度。结果：仅涂粘结剂组微拉伸强度最大,对照组次之,仅酸蚀组最小,酸蚀后涂粘结剂组与对照组间无显著性差异。结论：表面使用粘结剂可明显提高陈旧性树脂与新鲜树脂间的粘结强度。     

三种树脂粘接剂对可切削复合树脂与牙本质粘接强度的比较研究

目的 通过比较3种树脂粘接剂对聚甲基丙烯酸甲酯-纳米二氧化硅-二氧化锆(polymethylmecrylate/nano SiO2-ZrO2,PNSZ)可切削复合树脂与牙本质的粘接强度的差异,寻找适合PNSZ可切削复合树脂的树脂粘接剂,为临床应用提供参考.方法 使用树脂粘接剂A(RelyX ARC)、B(Panavia-F)和c(Variolink II)粘接PNSZ可切削复合树脂与牙本质,测试剪切粘接强度和微拉伸粘接强度(各分为A、B、C 3组,每组10个试件),并采用50倍立体显微镜观察断裂模式.结果 剪切测试中A、B、C组试件的粘接强度分别为(14.07±4.67)、(13.17±4.63)、(12.10±2.18)MPa,差异无统计学意义(P＞0.05);微拉伸测试中A、B、C组试件的粘接强度分别为(11.49±4.90)、(9.66±4.15)、(10.11±4.20)MPa,差异无统计学意义(P＞0.05).立体显微镜观察显示,3种粘接剂的断裂模式均以牙本质-粘接剂界面的断裂为主.结论 3种树脂粘接剂对PNSZ可切削复合树脂与牙本质的粘接效果相近.PNSZ可切削复合树脂一粘接剂界面的粘接优于牙本质-粘接剂界面.     

Effect of ascorbic acid,ethanol and acetone on adhesion between the treated fiber posts and composite resin cores

PURPOSE

The aim of the present study was to assess the effect of ascorbic acid, ethanol and acetone on microtensile bond strength between fiber posts pre-treated with hydrogen peroxide and composite resin cores.

MATERIALS AND METHODS

Twenty four fiber posts were pre-treated with 24% hydrogen peroxide and divided into 4 groups as follows: G1: no treatment, as control group; G2: treatment with 10% ascorbic acid solution for 5 minutes; G3: treatment with 70% ethanol solution for 5 minutes; and G4: treatment with 70% acetone solution for 5 minutes. Each fiber post was surrounded by a cylinder-shaped polyglass matrix which was subsequently filled with composite resin. Two sections from each sample were selected for microtensile test at a crosshead with speed of 0.5 mm/min. Statistical analyses were performed using one-way ANOVA and a post hoc Tukey HSD test. Fractured surfaces were observed under a stereomicroscope at ×20 magnification. The fractured surfaces of the specimens were observed and evaluated under a SEM.

RESULTS

Means of microtensile bond strength values (MPa) and standard deviations in the groups were as follows: G1: 9.70±0.81; G2: 12.62±1.80; G3: 16.60±1.93; and G4: 21.24±1.95. G4 and G1 had the highest and the lowest bond strength values, respectively. A greater bond strength value was seen in G3 compared to G2. There were significant differences between all the groups (P<.001). All the failures were of the adhesive mode.

CONCLUSION

Application of antioxidant agents may increase microtensile bond strength between fiber posts treated with hydrogen peroxide and composite cores. Acetone increased bond strength more than ascorbic acid and ethanol.