Microtensile bond strength of composite resin to human enamel prepared using erbium: Yttrium aluminum garnet laser

The Erbium: Yttrium Aluminum Garnet (YAG) laser used for preparation of cavity can alter the substrate and it could influence the bond strength of enamel. The aim of this in vitro study was to evaluate the influence of Er:YAG laser's energy using microtensile bond test. Three groups were obtained (cavity preparation) and each group was divided into two subgroups (adhesive system). After that the adhesive protocol was performed, sections with a cross-sectional area of 0.8 mm2 (+/-0.2 mm2) were obtained. The specimens were mounted in a universal testing machine (0.5 mm/min). Statistical analysis showed a decrease in bond strength for lased groups (p < 0.01) and when the total-etching adhesive system was used the laser 300 mJ subgroup showed higher bond strength compared to the laser 250 mJ (p < 0.01). It was concluded that the cavities prepared using laser appear less receptive to adhesive procedures than conventional bur-cut cavities.     

The effects of three different desensitizing agents on the shear bond strength of composite resin bonding agents

The aim of this study was to evaluate the effects of three desensitizing agents on the shear bond strengths of four different bonding agents used to bond composite resin to dentin.A total of 160 extracted human molars were sectioned parallel to the occlusal plane under water cooling, polished and randomly divided into 4 groups of 40. Each group was treated with a different desensitizing agent (Tooth Mousse, Ultra-EZ, Cervitec Plus), except for an untreated control group. Each group was then randomly subdivided into 4 groups of 10, and a different dentin bonding agent (XP Bond, AdheSE, Adper Prompt L-pop, GBond) was applied to each group in order to bond the specimens to a resin composite (Gradia Direct) built up using a plastic apparatus. A Universal Testing Machine was used to measure the shear bond strength of each specimen. Statistical analysis was performed using one-way ANOVA and Tukey’s tests.With the exception of the Control/AdheSE and Ultra-EZ/XP Bond groups, no statistically significant differences were found in the shear bond strength values of the groups tested. These findings suggest that the use of different desensitizing agents does not affect the shear bond strength of various adhesive systems used to bond resin composite to dentin.     

Effect of surface treatment on the shear bond strength of three resin cements to a machinable feldspatic ceramic

The aim of this study was to evaluate the shear bond strength of three resin cements to Vita Mark II ceramics under different pretreatments of the ceramic surface and to examine whether simplified pretreatment procedures would result in satisfying results compared to the state of the art. RelyX Unicem (RXU), Calibra (CAL), and Variolink II (VAR) were used as resin cements and bonded to machine milled feldspatic disks, pretreated in five different ways. (1) no pretreatment of the ceramic surface; (2) surface etched with hydrofluoric acid (HF); (3) ceramic surface silanized; (4) ceramic surface etched (HF) and silanized, (5) ceramic surface etched (HF), silanized, and covered with Heliobond. The shear bond strengths were measured initially, after 5000 and 10,000 thermocycles (TC). After 10,000 TC for CAL only procedure 5 resulted in a reliable adhesion median value of 10.7 MPa. VAR showed median values of 24.6, 17.2, and 18.1 MPa for pretreatments 5, 3, and 4, respectively. RXU performed 25.9, 22.0, and 11.0 MPa for procedures 5, 4, and 3, respectively. For procedure 2, RXU revealed the significantly highest value with 15.4 MPa (U-test, p = 0.05). Only RXU-luted specimens of procedure 1 survived the 10,000 thermocycles. The results revealed that a simplification of the ceramic pretreatment for VAR and RXU might be possible.     

Influence of femtosecond laser treatment on shear bond strength of composite resin bonding to human dentin under simulated pulpal pressure

This in vitro study evaluated the influence of femtosecond laser (fs-laser)-generated patterns on shear bond strength (SBS) of composite resin bonded to human dentin under simulated pulpal pressure. Laser treatment was used to produce two different patterns on dentin surfaces. Three test groups and a control group without laser treatment under pulpal pressure were investigated. Dentin discs of 800 nm thickness were cut from 60 extracted caries-free human molars. Using a perfusion machine, the discs were exposed to Ringer solution on their basal surfaces. Clearfil SE Bond/Herculite XRV system was used. The samples were stored in distilled water and thermocycled. Bonding failures caused by a test set-up to challenge SBS were analyzed by scanning electron microscope (SEM). An 80 μm-sized cube-shaped pattern caused more cohesive failures in dentin or resin compared with the 160 μm-sized cube-shaped pattern. Weibull statistics demonstrated a significant difference between the two laser patterns, but only the test group with small-sized laser pattern was significantly different from the control group. The Weibull moduli ranged from 4.3 to 9.6 (control group). The 160 μm-sized pattern enhanced the bonding quality and avoided dentin weakening. It was concluded that fs-laser treatment in a 160 μm-sized cube-shaped pattern enabled a simplified bonding procedure by dispensing the primer without affecting SBS, compared with the control group.     

An investigation of the shear bond strength of compomer restorative material to enamel and dentine

The aim of this study was to investigate the effect of one step adhesives on the shear bond strength of a compomer restorative material to both enamel and dentine. Human extracted teeth were used for the study. Ten samples were prepared for both enamel and dentine specimens for each of the five groups: Tooth, no etch, Prime and Bond NT (P+B NT); tooth, Non-Rinse Conditioner (NRC), P+B NT; tooth, NRC, Prime and Bond 2.1 (P+B 2.1); tooth, etch, P+B NT; tooth, etch, P+B 2.1. The specimens were subjected to bond testing. The shear bond strength was measured using an Inston 1193 testing machine using a cross head speed of 1 mm/minute. The specimens were tested to destruction. The results show that for the enamel specimens the highest bond strength was recorded for those specimens subjected to Etch, P+B 2.1 (22.1 MPa) and Etch P+B NT (20.0 MPa). The groups of specimens which did not undergo etching had very low bond strengths ranging from 11.4 MPa for NRC, P+B 2.1, 8.5 MPa for NRC P+B NT to 6.9 MPa for P+B NT. For the dentine specimens, for all of the groups, the shear bond strengths were low. Those groups subjected to etching produced the highest values of 7.9 MPa for NRC P+B 2.1 with the lowest value of 6.1 MPa for NRC P+B NT. These bond strengths were significantly lower than those achieved for bonding to enamel. Prime and Bond NT and Prime and Bond 2.1, used in conjunction with acid etching, produce satisfactory bond strengths of compomer restorative material to enamel. Bond strengths to dentine were low.     

不同复合树脂材料硬度及黏结强度的比较

背景：与传统复合树脂材料相比,大块充填复合树脂材料具有增加光固化深度、降低聚合收缩率、简化临床操作程序等特点,但不同类型大块充填复合树脂材料的性能各异。 目的：分析4种复合树脂材料的硬度及黏结强度。 方法：取大块填充复合树脂Tetric EvoCeram BulkFill、SDR,以及传统复合树脂P60、Z350,检测4种复合树脂材料分别在2,3,4,5 mm光固化深度下的维氏显微硬度,以及4种复合树脂材料与牙本质间的剪切黏结强度。 结果与结论：不同光固化深度下的硬度顺序为：P60复合树脂>Z350复合树脂>Tetric EvoCeram BulkFill复合树脂> SDR复合树脂,4组间比较差异有显著性意义(P < 0.05);Tetric EvoCeram BulkFilll和SDR复合树脂光固化后的硬度未随着固化深度的增加而明显减小。Tetric EvoCream BulkFil和SDR复合树脂的剪切黏结强度显著高于P60和Z350复合树脂(P < 0.05)。表明大块充填树脂材料Tetric EvoCeram BulkFill和SDR的综合机械性能较高,并且具有较高的剪切黏结强度。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

The bond strength of light-curing composite resin to finally polymerized and aged glass fiber-reinforced composite substrate

OBJECTIVE: This study examines the shear bond strength of visible light-curing composite resin (VCR) to aged glass fiber-reinforced composite (FRC) substrate with multi-phase polymer matrix. METHODS: Linear polymethyl methacrylate and dimethacrylate monomer preimpregnated unidirectional glass fiber reinforcement was used as an adhesion substrate for low-viscosity diacrylate veneering composite resin and restorative composite resin. A total of 60 test specimens were divided into three groups according to the brand and the use of an intermediate monomer resin (IMR). The used IMRs were either BisGMA-HEMA-resin, BisGMA-TEGDMA resin or the controls were left without the IMR treatment. Dry- and water-stored FRC-substrates were used for adhering the VCR with or without the IMR. The shear bond strength of the VCR to the substrate was measured for dry and thermocycled specimens and the results were analyzed with multi-variate ANOVA. RESULTS: The highest mean shear bond strength (23.9 +/- 4.8 MPa) was achieved with FRC/BisGMA-HEMA/VCR combination when the FRC substrate was water stored and the test specimen was thermocycled. FRC/BisGMA-TEGDMA/VCR combination resulted in 15.7 +/- 6.0 MPa with the water-stored FRC substrate and after thermocycling of the test specimens. The lowest shear bond strength (1.0 +/- 0.5 MPa) was obtained with FRC/VCR combination with water-stored substrate and after thermocycling of the test specimens. Significant differences were found between the mean values of three groups according to the use of IMR (p<0.001). The storage conditions of the FRC substrate were related to brand of the IMR or the composite (p<0.001). High mean values of the shear bond strength after thermocycling fatigue were related to the type of IMR (p<0.001). SIGNIFICANCE: The results suggest that the IMRs used in this study greatly influence the mean shear bond strength values when the test specimens are thermocycled.     

Effect of light-cure time of adhesive resin on the thickness of the oxygen-inhibited layer and the microtensile bond strength to dentin

A thick oxygen-inhibited layer (OIL) on a cured adhesive layer (AL) is believed to result in both good adaptation of composite resin (CR) and high bond strength. A high degree of conversion (DC) of the AL is also needed for durable bonding. This study evaluated the hypothesis that increasing the DC by prolonging the light-curing time of adhesive bonding resin might decrease the bond strength of the adhesive to dentin because of the subsequent thinning of the OIL thickness. The OIL thickness and the DC of solvent-removed One Step and D/E bonding resin of All Bond 2 (Bisco, USA) were measured simultaneously with FT-NIR spectroscopy according to increasing light-cure times (10, 20, 30, and 60 s) so as to evaluate their effect on the microtensile bond strength. The bonded interfaces were evaluated using scanning electron microscopy. Excessive irradiation of light-curing adhesives increased the DC, but decreased the OIL thickness. When the OIL was significantly thin by curing the adhesives for 30 or 60 s, defects were observed at the interface between the AL and the CR, as well as at the interface between the AL and the hybrid layer. When the OIL was thick, free radicals from the overlying CR may have diffused into the unreacted monomer mixtures of the OIL, chemically connecting the cured AL and the newly curing composite. It was found that to obtain maximum dentin bond strength, light-curing adhesives should be cured for the irradiation time recommended by the manufacturer.     

Effect of LED curing on the microleakage, shear bond strength and surface hardness of a resin-based composite restoration

To determine the effect of Light emitting diode (LED) curing on dental resins, microleakage, shear bond strength and surface hardness of a dental composite cured with different LEDs were determined and compared with conventional halogen curing. For microleakage, Class V cavities were restored with Esthet-X, divided into groups, and exposed to one of the curing protocols (Elipar Freelight in soft start and standard modes; Ultra-Lume 2; Spectrum 800). Standard dye penetration tests were performed and the data summarised in a 2-way contingency table of observed frequencies. The Chi-square test was used (p<0.05) to test for significant differences between the lights. For surface hardness, samples of Esthet-X were exposed to the light-curing units (LCUs). Vickers hardness was determined on the upper and the bottom surfaces. Data was subjected to statistical analysis using ANOVA (p<0.05). Shear bond strength was determined using a push out method. Comparisons (ANOVA, p<0.05) were made between the different curing protocols. No significant difference in microleakage could be demonstrated between the different LCUs at the enamel side (p=0.60). At the dentin side only the Elipar Freelight (soft start), could significantly reduce microleakage (p<0.01). The hardness score for the halogen light was significantly lower than for the LED lights (p<0.01). The Spectrum 800 and the Elipar Freelight (soft start) have significantly higher shear bond strengths than the others (p<0.01). It was concluded that the LED source is more efficient for a comparable overall power output.     

Effect of molar mass of an experimental primer on shear bond strength to dentin

A novel oligomer was synthesized in different molecular masses and used as a primer in dentin bonding. The hypothesis was that an intermediate molecular mass would optimize the conflicting needs for diffusion into etched dentin (low M(w)) and high mechanical properties (high M(w)). The initial oligomer synthesized was tert butylmethacrylate-co-maleic anhydride, which was further reacted to add hyrdoxyethyl methacrylate (HEMA) across the anhydride. The oligomer was synthesized in a series of molecular masses from approximately 800-6000 amu. The oligomer with an average M(w) of approximately 1000 amu provided the highest bond strength (16 MPa), with both lower and higher molar mass oligomers producing lower bond strengths. A polynomial model was fitted to the data with an R(2) = 0.606, while a linear model only had an R(2) = 0.534. This implies that the graph of molar mass to bond strength has a maximum in the range of molar masses examined, and that an optimum molar mass can be found between 800 and 6000 amu.     

不同表面处理对Ceramage聚合瓷黏结强度的影响

背景：长期以来修复材料与基牙的黏接技术一直是口腔修复学的研究热点,其中尤为引人关注的是黏结工件的表面处理工艺。 目的：对比观察8种表面处理方法对Ceramage聚合瓷黏结强度的影响,筛选适合Ceramage聚合瓷的表面处理方法。 方法：将Ceramage聚合瓷制成试件80个,随机分成8组,分别采用喷砂,酸蚀,偶联剂,喷砂+酸蚀,喷砂+偶联剂,酸蚀+偶联剂,喷砂+酸蚀+偶联剂处理聚合瓷表面并与树脂黏结剂黏结,对照组不进行任何处理。在37 ℃水浴24 h后测试样本剪切强度,并用扫描电镜观察处理后的聚合瓷表面形貌。 结果与结论：各组的剪切强度值由高到低分别为：喷砂+酸蚀+偶联剂处理组(31.12±2.81) MPa,喷砂+酸蚀组(27.62±1.70) MPa,酸蚀+偶联剂组(27.31±2.18) MPa,喷砂+偶联剂组(26.91±1.97) MPa,喷砂组(24.23±2.03) MPa,偶联剂组(23.50± 2.19) MPa,酸蚀组(17.61±2.14) MPa,对照组(8.13±0.63) MPa,除喷砂组、偶联剂组之间,喷砂+酸蚀组、喷砂+偶联剂组、酸蚀+偶联剂组之间比较差异无显著性意义外(P > 0.05),其余组间比较差异均有显著性意义(P  < 0.05)。结果显示7种表面处理方法都提高了黏结强度,喷砂、酸蚀联合硅烷偶联剂处理的聚合瓷黏结强度最高,是适合Ceramage聚合瓷黏结的表面处理方法。     

饰瓷温度烧结对氧化锆陶瓷与树脂黏结剂剪切强度的影响

背景：研究已证实硅烷偶联剂和喷砂等表面处理方式,以及增加氧化锆陶瓷表面的微裂纹可提高氧化锆陶瓷与树脂黏结剂间的黏结强度,但有关多次反复烧结是否会对氧化锆陶瓷黏结剪切强度产生影响尚缺少相关研究。 目的：测试饰瓷温度烧结对牙科氧化锆陶瓷与树脂黏结剂黏结剪切强度的影响。 方法：从40片氧化锆瓷片随机选择20片,分成 5组,按照常规烧结程序分别烧结0(对照组),2,4,6,8次,热处理起始温度为500 ℃,最终温度1 000 ℃,升温速率55 ℃/min,抽真空时间7 min。每次烧结最终温度恒定不变。将各组分别用树脂黏结剂与剩余未烧结的陶瓷片对位黏结,用万能材料试验机测黏结界面的剪切强度;使用扫描电镜观察剪切后的试件断面形貌。 结果与结论：烧结4,6,8次组试件剪切强度高于对照组(P < 0.05);烧结2次组试件剪切强度稍高于对照组,但差异无显著性意义(P > 0.05);烧结8次组试件剪切强度高于烧结4,6次组(P < 0.05)。未烧结氧化锆陶瓷表面未见裂纹;经过2次烧结后表面可见细微裂纹;经过4次烧结后表面可见裂纹增多;经过6次烧结后表面已经开始有明显变化,裂纹增多并伴有细微空隙产生,少量黏结剂残留;经过8次烧结后表面可见裂纹与空隙明显增多并有黏结剂残留。表明经过4,6,8次烧结后的氧化锆陶瓷对树脂黏结剂有较好的黏结剪切强度,烧结8次后的黏结剪切强度最强。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

Effect of oxygen inhibition on composite repair strength over time

The study was aimed at examining whether an oxygen inhibition layer is required for bonding a repairing to a pre-existing composite, and to determine the time required for free radicals within a composite substrate to decay to the extent that the composite repair strength drops significantly. Ten slabs of Gradia Direct Anterior (GC Corp.) were divided into (1) control group: an interfacial oxygen inhibition layer was created by applying and light-curing two layers of bonding resin (D/E Resin, Bisco) to the slabs surface in atmospheric air; (2) experimental group: the absence of an interfacial oxygen inhibition layer was obtained by light-curing the second bonding resin layer in a nitrogen atmosphere. After 1 and 2 h, 1, 14, and 30 days of air storage, a composite repair was layered over the bonding resin. Microtensile bond strengths were measured and statistically analyzed. The curing atmosphere was not a significant factor for bond strength (p = 0.82), and time and curing atmosphere-time interaction were significant (p < 0.001). The 30 day-strengths were the lowest (p < 0.05). An oxygen-inhibited layer is not initially required for bonding to resin composite, and it takes more than 14 days before the bond strength between a pre-existing and a fresh composite drops.     

Shear bond strength between titanium alloys and composite resin: sandblasting versus fluoride-gel treatment

The aim of this study was to investigate the effect of fluoride gel treatment on the bond strength between titanium alloys and composite resin, and the effect of NaF solution on the bond strength of titanium alloys. Five titanium alloys and one Co-Cr-Mo alloy were tested. Surface of the alloys were treated with three different methods; SiC polishing paper (No. 2000), sandblasting (50-microm Al2O3), and commercially available acidulated phosphate fluoride gel (F-=1.23%, pH 3.0). After treatment, surfaces of alloy were analyzed by SEM/EDXA. A cylindrical gelatin capsule was filled with a light-curable composite resin. The composite resin capsule was placed on the alloy surface after the application of bonding agent, and the composite resin was light cured for 30 s in four different directions. Shear bond strength was measured with the use of an Instron. Fluoride gel did not affect the surface properties of Co-Cr-Mo alloy and Ni-Ti alloy, but other titanium alloys were strongly affected. Alloys treated with the fluoride gel showed similar bond strengths to the alloys treated with sandblasting. Shear bond strength did not show a significant difference (p<0.05) regardless of treatment time (5, 10, and 20 min) of fluoride gel. After the ultrasonic cleaning subsequent to the fluoride-gel treatment, residues of fluoride ion or any other titanium-fluoride complexes were not detected. NaF solution did not reduce the shear bond strength of titanium alloys. To enhance the bond strength of composite resin to titanium alloys, fluoride-gel treatment may be used as an alternative technique to the sandblasting treatment.     

不同瓷表面处理对长石质可切削陶瓷黏结强度的影响

背景：长石质可切削陶瓷作为全瓷材料中不可分割的一种,应用于牙科椅旁CAD/CAM系统,具有精确、快速、高效并且一次就诊等优点,其黏结效果与各种瓷表面处理方法息息相关。 目的：比较不同瓷表面处理对长石质可切削陶瓷的黏结强度的影响。 方法：将切割好的32个Vita MarkⅡ瓷片分为4组：空白组瓷表面无处理;酸蚀组Porcelain Etchant酸蚀40 s,流水冲洗1min后吹干;硅烷偶联剂组使用RelyX Ceramic Primer处理,1 min后吹干;酸蚀和硅烷偶联剂联合组按上述方法酸蚀后涂布硅烷偶联剂,1 min后吹干。每组依次与RelyX Unicem进行黏结。万能材料试验机测其剪切强度,扫描电镜观察黏结界面。 结果与结论：酸蚀和硅烷偶联剂联合组的黏结强度最高,显著高于其余3组(P < 0.05),硅烷偶联剂组黏结强度显著高于酸蚀组与空白组(P < 0.05)。酸蚀和硅烷偶联剂联合组黏结界面最紧密。说明酸蚀和硅烷偶联剂联合应用可提高长石质可切削陶瓷的黏结强度。     

Improvement of the bond strength of 4-META/MMA-TBB resin to collagen-depleted dentin

It has been reported that the tensile bond strength between the 4-META/MMA-TBB resin and dentin pretreated with 10% citric/3% ferric chloride solution decreased after immersion in water for 2 years. The current study investigated the effect of an experimental dentin conditioner on the bonding of 4-META/MMA-TBB resin to dentin after thermocycling. The experimental conditioner was an aqueous solution of 10% ascorbic acid and 5% ferric chloride (Exp). Human teeth were prepared to expose flat dentin surfaces. These were treated sequentially with 40% phosphoric acid, 10% sodium hypochlorite, and the experimental conditioner. A commercially available dentin conditioner, an aqueous solution of 10% citric/3% ferric chloride (10-3) was used for a control group. Stainless steel rods were bonded to the pretreated dentin surfaces with the use of the 4-META/MMA-TBB resin. Tensile bond strengths were determined after 0, 5,000, 10,000, 20,000 themocycles. All data were analyzed by ANOVA, and differences among groups were analyzed by Duncan's new multiple range test (n = 10, p < 0.05). The experimental group showed no significant decrease in bond strength through 20,000 thermocycles, while the control group exhibited significant decrease after 10,000 thermocycles. Mean bond strength of the experimental groups were significantly higher than those of the control group at both 10,000 and 20,000 thermocycles. A hybrid layer could not be identified in SEM micrographs of the experimental groups. 10-3-conditioned specimen SEMs displayed crack formation between the adhesive resin and a hybrid layer. The experimental dentin pretreatment improved the bond strength of a 4-META/MMA-TBB resin to human dentin compared to 10-3 treatment after thermocycling.     

Anticipation of future events improves the ability to estimate elapsed time

It is widely recognized that neuronal network activity can be modulated via activation of nicotinic and muscarinic acetylcholine receptors located pre- and postsynaptically. It was established in our earlier study that the activation of presynaptic nicotinic receptors greatly facilitates the retinotectal glutamatergic transmission. In the present study, we have determined a transmitter of tectal recurrent excitation and explored the effects of muscarinic acetylcholine receptor activation on the recurrent excitation and the activity of frog tectum column in vivo. Discharge of a single retinal ganglion cell was elicited by a minimal electrical stimulation of the retina. Evoked activity of the tectum column was recorded using the carbon-fiber microelectrode inserted into the tectum layer F. We found the following: 1. The recurrent excitation in the tectum column was not affected by d-tubocurarine (10 μM) and was greatly depressed by the kynurenic acid (500 μM), demonstrating glutamatergic nature of the recurrent excitation. 2. The glutamatergic recurrent excitation was largely reduced by carbamylcholine (100 μM) and oxotremorine-M (10 μM), demonstrating that the activation of muscarinic receptors, located, presumably, on the presynaptic terminals of recurrent pear-shaped neurons, inhibits the recurrent excitation in the tectum column. 3. The muscarinic inhibition of glutamatergic recurrent transmission had critical influence on the activity of the tectum column, preventing the generation of an output signal through suppression of the NMDA receptor activation and establishing necessary conditions for returning of the network to its resting state.     

Effect of resin hydrophilicity and water storage on resin strength

This study evaluated the change in the ultimate tensile strength (UTS) of five polymerised resin blends of increasing hydrophilicity, after ageing in distilled water or silicon oil. Resin blocks were prepared from each resin blend by dispensing the uncured resin into a flexible, embedding mould, containing multiple cavities. The resins were polymerised in the moulds under nitrogen at 551.6 kPa and light-activated at 125 degrees C for 10 min. After dry ageing for 24 h at 37 degrees C, the middle third of each resin specimen was trimmed into an 'I' shape. Fifteen control specimens were randomly selected from each resin blend for baseline UTS evaluation. The UTS of the experimental specimens were determined after 1, 3, 6 and 12 months of ageing in water or oil. The UTS of each group of resins at different storage periods in water or oil were analysed using the Friedman multiple ANOVA on ranks and Dunn's multiple comparison tests at 95% confidence level. Significant reduction (p < 0.01) in UTS was observed in Groups II-V resins after 12-month storage in water, while the most hydrophobic Group I resin showed no significant change (p > 0.05) in the same period. The percentage reduction in UTS increased with the hydrophilicity of the resin blends. Long-term water storage of hydrophilic resin blends such as those employed in dentine adhesives, resulted in a marked reduction in their mechanical strength that may compromise the durability of resin-dentine bonds.     

Post silanization improves bond strength of translucent posts to flowable composite resins

The aim of the study is to evaluate the effect of post silanization on the microtensile bond strength (MTBS) of translucent fiber posts to seven flowable composite resins used as core material. Seventy fiber posts were employed. In half of the posts, silanization was performed with Monobond-S. A cylindrical plastic matrix was placed around the post and filled with different resins: UniFil Flow Experimental, UniFil Low Flow Plus Experimental, Venus Flow, Revolution Formula 2, Point 4 Flowable, X-Flow, and Wave mv. Five posts were bonded per group. After polymerization, two longitudinal cuts were made on two opposite sides of the post at its outermost periphery. Then, each specimen was serially sectioned, obtaining 30-35 beams with 1-mm(2) cross-sectional area. Each beam was tested in tension in an Instron machine at 0.5 mm/min. ANOVA and Student Newman Keuls tests were performed. The different resin composite materials and the post silanization procedure had a significant effect on MTBS. The application of a silane coupling agent increased MTBS of flowable composite resins to translucent posts. X-flow and Point 4 attained the highest MTBS regardless of the silane treatment.     

两种不同处理方法对牙釉质结构及正畸托槽粘接强度的影响

背景：当前临床托槽黏结前处理牙釉质的方法有酸蚀与喷砂两种,但将喷砂技术直接用于未处理牙釉质面的研究较少。目的：观察酸蚀、喷砂处理方法对牙釉质表面的损伤程度,并比较两种不同牙釉质表面处理方法下金属托槽粘接强度的差异。方法：将9颗人正畸拔除前磨牙随机均分为3组,分别进行喷砂、酸蚀与抛光清洁处理,扫描电镜下观察牙体表面粗化效果。将40颗人正畸拔除前磨牙随机均分为2组,分别进行喷砂、酸蚀处理,粘接托槽24 h后,利用材料力学实验机测定剪切强度,并统计粘接剂残留指数。结果与结论：扫描电镜观察发现,抛光清洁处理组牙釉质表面光滑,无破坏;喷砂组与酸蚀组牙釉质遭到破坏,表面粗糙,并且喷砂组牙釉质的破坏程度更大。喷砂组粘接强度显著高于酸蚀组(P < 0.05),喷砂组与酸蚀组的粘接剂残留指数比较差异无显著性意义(P > 0.05)。表明相对于酸蚀处理,喷砂处理可提高牙釉质与托槽的粘接强度,但对牙釉质的破坏程度更大。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程