Bond strength and interfacial micromorphology of etch-and-rinse and self-adhesive resin cements to dentin

Purpose: To evaluate the microtensile bond strength and interfacial micromorphology of indirect composite restorations to dentin using three commercial resin cements after 24 hours and 30 days of water storage. Materials and Methods: The medium dentin of third human molars was exposed (N = 30, n = 10 per group). Three commercial resin cements were used to cement indirect resin composite restorations to dentin: the auto‐cured C&B Cement/All Bond 2, the dual‐cured RelyX ARC/Adper Single Bond 2, and the self‐adhesive dual‐cured RelyX Unicem. Teeth were sectioned after water storage at 37°C (24 hours and 30 days) to obtain beams with a bonded area of 0.8 mm². The specimens were tested in a universal testing machine at a 0.5 mm/min crosshead speed. Scanning electron microscopic fractographic and interfacial micromorphology analyses were performed. Data were analyzed using two‐way ANOVA and Tukey′s test (α= 0.05). Results: Mean bond strength (MPa) after 24 hours: C&B Cement 19.5 ± 3.8, RelyX ARC 40.8 ± 9.4, RelyX Unicem 31.3 ± 7.4; after 30 days: C&B Cement 24.5 ± 5.1, RelyX ARC 44.2 ± 8.5, RelyX Unicem 28.3 ± 7.1. The mean bond strengths of both dual‐cure cements were significantly higher than that obtained with C&B Cement after 24 hours. A significant increase in the bond strength of C&B Cement was verified after 30 days, reaching values statistically equivalent to those produced by RelyX Unicem and RelyX ARC. The self‐adhesive cement preserved the same level of bond strength after 30 days. Fractographic analysis revealed a prevalence of cohesive fractures in the hybrid layer for C&B Cement, mixed (cohesive in the cement, hybrid layer, and adhesive) for RelyX ARC, and cohesive in the cement for RelyX Unicem. No distinguishable hybrid layer or resin tags were observed in the interaction of RelyX Unicem with dentin. Conclusions: The particular interaction of each cement with dentin results in specific bond strength and failure patterns that varied among groups in both evaluation times. Even though the self‐adhesive cement tested exhibited no authentic hybrid layer, it was able to promote reliable adhesion with the underlying dentin.     

Flexural Strength, Elastic Modulus, and pH Profile of Self-etch Resin Luting Cements

Purpose: To determine the flexural strength, modulus of elasticity, and 24‐hour pH profile of three self‐etching resin luting cements and to obtain comparative data for representative conventional resin and resin‐modified glass ionomer luting cements. Materials and Methods: Three self‐etching resin luting cements [RelyX Unicem (3M ESPE), Maxcem (Kerr), Embrace Wetbond (Pulpdent)] were tested and compared with two conventional resin cements [RelyX ARC (3M ESPE), Linkmax (GC)] plus two resin‐modified glass ionomer luting cements [Fuji Plus (GC), RelyX Luting Plus (3M ESPE)]. Flexural strength and modulus of elasticity were determined using bar‐shaped specimens (2 × 2 × 25 mm³) at 24 hours, using an Instron universal testing machine. Setting pH was measured using a flat‐surface pH electrode at 0, 2, 5, 15, and 30 minutes and 1, 2, 4, 6, and 24 hours after mixing. Testing was performed under both dual‐cured and self‐cured conditions for all dual‐cure cements. Data analysis included ANOVA and Tukey's test (p < 0.05). Results: The self‐etching cements showed similar flexural strength to the conventional resin cements, except for Embrace Wetbond self‐cured, which was considerably lower. Modulus of elasticity results were both higher and lower than for conventional resin cements. All photopolymerized conventional and self‐etch dual‐cure cements showed markedly higher flexural strength and modulus than when solely self‐cured. The resin‐modified glass ionomer cements were characterized by lower flexural strength and elastic modulus. Self‐etching resin cements showed lower initial pH (2.0 to 2.4) than conventional resin cements (4.8 to 5.2) and a wide range of final pH values (3.9 to 7.3) at 24 hours. One self‐etching cement (Unicem) revealed a unique pH profile characterized by a more rapid rise in pH to neutrality both when dual‐cured (15 minutes) and when auto‐cured (1 hour). Conclusions: The self‐etching resin cements evaluated in this study displayed disparate properties and cannot be considered a homogeneous group. Flexural strength properties were most uniform and were similar to those of the conventional resin cements, whereas moduli of elasticity showed greater variation. Setting pH profiles differed, depending on the brand and mode of cure, even within the same category of luting cement. All cements with dual‐cure capability, both conventional and self‐etch, showed significantly superior properties when photopolymerized.     

Bacterial colonization of resin composite cements: influence of material composition and surface roughness

So‐called secondary caries may develop in the cement gap between the tooth and the bonded restoration. Cement materials with a low susceptibility to biofilm formation are therefore desirable. In the present study, the adhesion of Strepococcus mutans onto three adhesive (Multilink Automix, RelyX Ultimate, and Panavia V5) and three self‐adhesive (Multilink Speed Cem, RelyX Unicem 2 Automix, and Panavia SA plus) resin composite cements was evaluated. Previous studies have failed to evaluate concomitantly the effect of both the composition of the cements and their surface roughness on biofilm formation. The presence of S. mutans on cement surfaces with differing degrees of roughness was therefore recorded using fluorescence microscopy and crystal violet staining, and the composition of the cements was analyzed using energy‐dispersive X‐ray spectroscopy mapping. Biofilm formation on resin composite cements was found to be higher on rougher surfaces, implying that adequate polishing of the cement gap is essential. The use of copper‐containing cements (Multilink Automix, Panavia V5, and Panavia SA plus) significantly reduced biofilm formation.     

Influence of power density and primer application on polymerization of dual‐cured resin cements monitored by ultrasonic measurement

Takubo C, Yasuda G, Murayama R, Ogura Y, Tonegawa M, Kurokawa H, Miyazaki M. Influence of power density and primer application on polymerization of dual‐cured resin cements monitored by ultrasonic measurement. Eur J Oral Sci 2010; 118: 417–422. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci We used ultrasonic measurements to monitor the influence of power density and primer application on the polymerization reaction of dual‐cured resin cements. The ultrasonic equipment comprised a pulser–receiver, transducers, and an oscilloscope. Resin cements were mixed and inserted into a transparent mould, and specimens were placed on the sample stage, onto which the primer, if used, was also applied. Power densities of 0 (no irradiation), 200, or 600 mW cm^?2 were used for curing. The transit time through the cement disk was divided by the specimen thickness to obtain the longitudinal sound velocity. When resin cements were light‐irradiated, each curve displayed an initial plateau of ～1,500 m s^?1, which rapidly increased to a second plateau of 2,300–2,900 m s^?1. The rate of sound velocity increase was retarded when the cements were light‐irradiated at lower power densities, and increased when the primer was applied. The polymerization behaviour of dual‐cured resin cements was therefore shown to be affected by the power density of the curing unit and the application of self‐etching primer.     

Comparison of the Flexural Strength of Five Adhesive Resin Cements

Statement of Problem : The increased use of adhesive resin cements in bonded prosthetic restorations has led to restorations debonding under function. Purpose : This investigation evaluated the differences in the flexural strength of new adhesive resin cements as a function of specimen age and storage condition. Materials and Methods : Four new dual‐cure cements were compared to C/B Metabond. Twenty specimens of each of the five cements were prepared in a rectangular glass mold (25 × 2 × 2 mm). The new cements were light‐activated with a 550 mW/cm² lamp for 80 seconds on both the top and bottom surfaces. The auto‐cured cement was allowed to set according to manufacturer's directions. Half the specimens were tested immediately after curing while the other half were stored in distilled water at 37°C for 30 days. A three‐point bending test was performed using an Instron at a crosshead speed of 1 mm/min. The results were analyzed by analysis of variance and Scheffé tests ( p < 0.05) to examine the effect of specimen age and storage condition. Results : RelyX ARC exhibited a significantly higher flexural strength compared with Calibra and Panavia F when tested immediately. The standard cement, C/B Metabond, deformed and did not fracture at the immediate test time. After storage, the flexural strength had significantly improved from the immediate test time for Calibra, Cement‐It, Panavia F, and C/B Metabond. However, there were no significant differences in the flexural strength among the cements when tested after 30 days in water at 37°C. Conclusion : Immediately after curing, these new adhesive resin cements are not equivalent, as evidenced by the significant variability in the measured flexural strength. The distinctions among the cements diminish after aging in water, which may be due to residual polymerization or a plasticizing effect from water absorption. Clinical Significance : When light‐cured, all the new adhesive resin cements have greater early strengths than the auto‐cured cement; however, the wide variation in immediate bending strength suggests that some cements may be more appropriate for use in high‐stress clinical situations such as resin‐bonded fixed partial dentures.     

Microleakage of Porcelain and Composite Machined Crowns Cemented with Self‐Adhesive or Conventional Resin Cement

Purpose: Resistance of machined crowns to microleakage when cemented with new self‐adhesive cements has not been fully investigated. This study evaluated microleakage of machined crowns milled from porcelain and composite blocks and bonded to teeth with self‐adhesive and conventional resin cement. Materials and Methods: Thirty‐two freshly extracted premolars of similar shape and size were sterilized and mounted in resin blocks. Teeth received standard crown preparations with 1‐mm circumferential shoulder finish line, flat occlusal surface reduced by 2 mm, and ideal angle of convergence. Prepared teeth were divided into two equal groups and assigned to either porcelain (Vita Mark II, Vident) or composite (Paradigm MZ100, 3M ESPE) blocks for crown fabrication. Optical impressions were captured for each tooth with the intraoral camera of a CEREC 3D machine. Crowns were designed and milled from both materials. Each group was then subdivided into two subgroups (n = 8) according to cement used (self‐adhesive resin cement, RelyX Unicem, 3M ESPE or resin cement with self‐etching adhesive, Panavia F 2.0, Kuraray). Following seating, a 5‐kg weight was applied on the occlusal surface of the crown for 5 minutes. Specimens were then stored in water at 37°C for 24 hours. Specimens were thermocycled for 3000 cycles between 5°C and 55°C, then coated with nail varnish and immersed in a 2.0% basic red fuchsine dye solution for 24 hours. Teeth were then rinsed and sectioned mesiodistally and assessed under magnification for microleakage. A five‐point scale was used to score degree of microleakage. Data were statistically analyzed with 2‐way ANOVA and Kruskal‐Wallis nonparametric test. Results: Crown material had no significant effect on microleakage (p= 0.67); however, cement type had a significant effect (p < 0.0001), with Panavia F 2.0 resulting in lower microleakage scores than RelyX Unicem. Conclusions: Compared to the self‐adhesive cement, the resin cement with separate primer/bonding agent resulted in significantly lower microleakage scores, irrespective of crown material.     

Ultrasonic monitoring of the setting of glass-ionomer luting cements

This study used ultrasonic measurements to monitor the setting behaviour, and changes in the elastic modulus, of glass–ionomer cements. The ultrasonic equipment comprised a pulser–receiver, transducers, and an oscilloscope. The two-way transit time through the mixing cement disk was divided by two, in order to account for the down-and-back travel path, and then multiplied by the sonic velocity within the material. The sonic velocities of the longitudinal and shear waves were used to determine the elastic modulus. In the earliest stages of the setting process, most of the ultrasound energy was absorbed by the cements and the second echoes were relatively weak. As the cements hardened, the sound velocities increased until they reached a plateau. The changes in sound velocities differed among the glass–ionomer cements tested. The mean elastic moduli of the specimens ranged from 2.6 to 6.2 GPa after 15 min, from 13.4 to 20.4 GPa after 24 h, and from 11.4 to 22.4 GPa after 1 month. The ultrasonic method used in this study has considerable potential for determining the setting processes of luting cements.     

Bonding of dual-curing resin cements to dentin

PURPOSE: The purpose of the study was three-fold: 1) to determine the strength of the bond between a number of dual-curing resin cements and dentin treated with corresponding adhesive systems, 2) to determine the effect on bond strength of not light curing the cements, and 3) to investigate whether application of a solution of sodium sulfinate or ascorbic acid would increase the bond strength in the cases where the manufacturer's version of an adhesive system resulted in low bond strength with chemically cured cement, ie, cement cured without light. MATERIALS AND METHODS: The adhesive systems comprised 5 simplified systems (Adper Scotchbond 1 XT, ED Primer II, Excite DSC, OptiBond Solo Plus, and Prime and Bond NT), and as controls, two three-step etch and rinse systems (Adper Scotchbond Multi-Purpose Plus and Gluma Solid Bond). The corresponding dual-curing resin cements were RelyX ARC, Panavia F 2.0, Variolink II, Nexus 2, Calibra, RelyX ARC, and 2Bond2. The cements were either light and chemically cured or only chemically cured. The adhesive systems were used as recommended by the manufacturers, which for some systems involved inclusion of a so-called activator or catalyst when used with chemically cured cement. Sodium sulfinate and ascorbic acid were applied as a 1% ethanol solution. The bond strengths were measured in shear after storing specimens for 24 h in 37 degree C water. RESULTS: When the dual-curing resin cements had been both light and chemically cured, the bond strengths increased in this order: Gluma Solid Bond < ED Primer II < Prime and Bond NT < Adper Scotchbond Multi-Purpose Plus < Excite DSC < Adper Scotchbond 1 XT < OptiBond Solo Plus. Omission of light curing of the cements decreased the bond strengths with OptiBond Solo Plus and Prime and Bond NT. The use of activator in conjunction with OptiBond Solo Plus and Prime and Bond NT increased the bond strength to chemically cured cement, but not to the level obtained when the cement was both light and chemically cured. The use of the catalyst of Adper Scotchbond Multi-Purpose Plus did not increase the bond strength with chemically cured cement. Pretreatment with a solution of sodium sulfinate or ascorbic acid increased the bond strength with chemically cured cement in the case of OptiBond Solo Plus, whereas only the solution of sodium sulfinate was effective with Prime and Bond NT. CONCLUSION: Clinicians should be aware that in situations where a dual-curing resin cement cannot be light cured, some adhesive systems suffer a loss of efficacy, even when respective activators are used. Pretreatment with a 1% ethanol solution of sodium sulfinate may restore much of the lost bond strength.     

Adhesive bonding of resin cements to cast titanium with adhesive primers

The purpose of this study was to evaluate the effects of adhesive primer applications on the bond strength of resin cements to cast titanium. Four adhesive primers - Metaltite, Metal Primer II, Alloy Primer and Ceramic Primer - and their respective resin cements - Bistite II DC, Link Max, Panavia F 2.0, RelyX Unicem and RelyX ARC - were tested. Cast plates were prepared from titanium ingots (n=6 specimens/cement) and had their surfaces airborne-particle abraded with Al2O3 (50 μ m). Three resin cement cylinders were built on each bonded titanium surface, using a cylindrical translucent tubing mold and were subjected to micro-shear testing. Data were analyzed statistically by two-way ANOVA and Tukey's post-hoc test (α=0.05). The application of Metal Primer II and Ceramic Primer resulted in significant higher bond strength for Link Max and RelyX Unicem resin cements, respectively, than nonuse of adhesive primers. Panavia F 2.0 and RelyX ARC yielded high bond strength means with or without adhesive primers. The use of adhesive primers might increase the bond strength to cast titanium depending on the resin cement used.     

紫外线照射老化树脂黏固剂对色度值及相对透明率的影响

目的探讨紫外线照射老化对4种树脂黏固剂颜色及相对透明率参数的影响。方法分别采用Biscem（双固化型）、Choice（光固化型）、PermaCem（化学固化型）和RelyX Aplicap（化学固化型）树脂黏固剂制取树脂试件,每种黏固剂制取5个试件,分别设为A、B、C、D组,按厂家推荐的方法光照或自然固化。在黑暗环境保持24 h后用色度计测量色度值CIE L*、a*、b*,并计算其相对透明率。然后将各组试件分别经紫外线照射老化8、16、24 h后再次测量,分析色度值和相对透明率的变化。结果4组树脂黏固剂试件在紫外线照射后均发生了颜色变化,照射时间越长色差值越大。照射时间相同时,4组试件的色差值不同,B组与D组的色差值较小,C组最大。A、B与D组的相对透明率受紫外线老化的影响较小,C组在紫外线照射后相对透明率发生改变。结论紫外线照射老化能够引起树脂黏固剂发生颜色改变,但是多数产品的相对透明率能够保持相对稳定。     

Effect of Dentin Surface Modification on the Microtensile Bond Strength of Self‐Adhesive Resin Cements

Purpose: To explore the potential to modify human dentin surface as a means of improving the microtensile bond strength (μTBS) of resin cement to dentin. Materials and Methods: Sound human molars were collected, and their occlusal surfaces were ground flat to expose polished dentin. Indirect composite resin cylinders were cemented to the teeth with RelyX Unicem or G‐Cem self‐adhesive cements following dentin surface treatments: 6.5% grape‐seed extract, 5% glutaraldehyde, or 25% polyacrylic acid and control (no pretreatment). After 24 hours, the teeth were sectioned into beams to produce a cross‐sectional area of 1.0 mm². Specimens of each group (n = 25) were individually mounted on a jig and placed on a tensile testing machine. A tensile force was applied to failure at a 1 mm/min crosshead speed. Results: The use of polyacrylic acid on dentin prior to cementation with RelyX Unicem resulted in a statistically significant increase in μTBS compared to the control group (p= 0.0282). Polyacrylic acid (p= 0.0016) or glutaraldehyde (p= 0.0043) resulted in a statistically significant increase in μTBS of G‐Cem to dentin when compared to the control group. Treatment with grape‐seed extract did not result in a statistically significant increase in μTBS for either cement (p > 0.05). Conclusions: Priming dentin surfaces prior to the use of self‐adhesive resin cements may be a promising means of improving μTBS. In addition, it was concluded that the results of this study are material dependent as well as being dependent of the type of dentin primer.     

2种不同粘接水门汀对树脂类冠修复材料和全瓷托槽剪切粘接力的影响

目的 评价两种不同粘接水门汀对树脂类冠修复材料和全瓷托槽剪切粘接力的影响。方法 选用2种水门汀Transbond XT和RelyX Ultimate,将上颌前磨牙全瓷托槽Inspire Ice与4种树脂类冠修复材料粘接。试件冷热循环5 000次后测量断裂载荷（N）,并观察破坏形态。结果 单因素方差分析结果F=4.52（P＜0.001）,显示粘接条件对陶瓷托槽和树脂类冠修复材料的剪切粘接力影响具有统计学意义。其中Lava Ultimate+Transbond XT组和Lava Ultimate+ RelyX Ultimate+托槽喷砂组分别为（325.10±135.54）N和（304.71±35.71）N,较其他组高,Lava Ultimate+ Transbond XT+托槽喷砂组最低,为（118.12±57.58）N。结论 树脂基陶瓷材料Lava Ultimate和全瓷托槽的剪切粘接力较暂时冠修复材料高。全瓷托槽未喷砂时,正畸全瓷托槽粘接水门汀Transbond XT和修复用水门汀RelyX Ultimate的粘接力未见明显区别,喷砂后全瓷托槽失去固位小球,RelyX Ultimate有更高的粘接力。     

Push-out bond strength and failure mode of single adjustable and customized glass fiber posts

PurposeTo evaluate the push-out bond strength (PBS) and failure mode of single adjustable (SAP) and customized (CP) posts cemented to root canal dentin using conventional (RelyX Ultimate) or self-adhesive (RelyX U200) dual-cure resin cements.MethodsHerein, 40 bovine mandibular incisors were divided into four groups (n = 10): SAP cemented with RelyX Ultimate (SAP-UT), SAP cemented with RelyX U200 (SAP-U2), CP cemented with RelyX Ultimate (CP-UT), and CP cemented with RelyX U200 (CP-U2). PBS and failure modes were analyzed. Three-way repeated measures ANOVA test followed by Tukey’s test and Fisher–Freeman–Halton exact test were used for data analysis (α = 5%).ResultsThe PBS values for SAP (p < .05) were higher than those for CP and were not influenced by the root third and resin cement (p > .05). When conventional resin cement was used, the SAP showed significant differences compared to CP (p < .05). When cemented with RelyX Ultimate, a higher prevalence of mixed and adhesive failures for SAP and CP, respectively, was observed (p < .05). For the self-adhesive resin cement, the failures were mostly adhesive (p < .05).ConclusionSAP showed better performance than CP. The root third and resin cements did not influence the PBS. The most prevalent failures were adhesive and mixed.     

Nd: YAG激光对3种树脂水门汀与牙本质粘接强度的影响

目的观察Nd: YAG激光照射前后树脂水门汀-牙本质粘接界面的微观形貌特征,评价Nd: YAG激光对3种树脂水门汀与牙本质间粘接强度的影响。方法选择人离体前磨牙30颗,分为颊、舌两部分,将试件随机分为激光组和对照组。激光组以0.8 W、10 Hz脉冲Nd: YAG激光作用于牙本质表面25 s,联合3种树脂水门汀RelyX ARC、Panavia F和RelyX Unicem充填;对照组直接使用树脂水门汀充填。然后测试剪切强度,在根管显微镜下观察断裂模式并分类。另选人离体前磨牙6颗,按照标准的牙本质粘接面预备后,使用Nd: YAG激光照射3颗牙牙本质表面,并联合充填不同的树脂水门汀,用扫描电镜观察Nd: YAG激光照射前后树脂水门汀-牙本质界面的微观形貌变化。结果
激光照射可以提高自酸蚀树脂水门汀Panavia F和自粘接树脂水门汀RelyX Unicem与牙本质之间的剪切强度（P＜0.05）。激光会降低全酸蚀树脂水门汀RelyX ARC与牙本质间的剪切强度（P＜0.05）。根管显微镜下观察可见：试件断裂大部分发生在树脂水门汀-牙本质界面。扫描电镜观察可见：Nd: YAG激光照射后,全酸蚀亚组和自酸蚀亚组的混合层变薄、树脂突变短且少;自粘接亚组变化不明显,未见树脂突。结论Nd: YAG激光照射后,可提高Panavia F和RelyX Unicem与牙本质的剪切强度,建议临床联合应用。     

In vitro wear simulation measurements of composite versus resin-modified glass ionomer luting cements for all-ceramic restorations

Background: Although composite cements are generally indicated for cementation of all‐ceramic restorations, some manufacturers of dental cements propose that resin‐modified glass ionomers (RMGIs) may be used for cementation of high‐strength ceramic restorations. Purpose: This study was undertaken to compare the in vitro abrasion and attrition wear of two dual‐cure cements (in dual‐cure and self‐cure modes) and two RMGI cements when placed between ceramic and enamel to simulate the margin of a restoration. Methods: Rectangular fragments of pressed ceramic (Empress 2) were cemented between the halves of bovine incisors sectioned mesiodistally, using one of the following materials: RelyX ARC, Variolink II, RelyX Luting, or ProTec CEM. The two resin cements were tested in dual‐cure and self‐cure modes. A three‐body wear test was performed in the new Oregon Health Sciences University (OHSU) oral wear simulator (100,000 cycles; abrasion load: 20 N; attrition load: 90 N). Degree of conversion of resin cements was determined by Fourier transform infrared spectroscopy. Results were analyzed by analysis of variance and Tukey's test (p = .05). Epoxy replicas of wear specimens were observed in the scanning electron microscope. Results: No significant differences in abrasion wear (RelyX ARC dual‐cure: 11± 4.4 urn; RelyX ARC self‐cure: 17 ± 7.0 urn; Variolink dual‐cure: 14 ± 8.6 urn; Variolink self‐cure: 23 ± 10.7 um) or attrition wear (RelyX ARC dual‐cure: 18 ± 6.4 um; RelyX ARC self‐cure: 31 ± 4.5 um; Variolink dual‐cure: 32 ± 6.8 um; Variolink self‐cure: 39 ± 15.9 pm) were found between activation modes of the resin cements. ProTec CEM (32 ± 8.7 um) showed abrasion similar to that of Variolink II and RelyX ARC self‐cure. Resin‐modified glass ionomers showed more attrition wear than the resin cements (ProTec CEM: 62 ± 13.0 um; RelyX Luting: 69 ± 7.1 um). RelyX ARC showed a similar degree of conversion for both activation modes (dual‐cure: 70 ± 4.3%; self‐cure: 68 ± 1.2%), but Variolink II had a higher degree of conversion in dual‐cure mode (67 ± 0.5% vs 60 ± 1.0%). Cement wear was accompanied by marginal breakdown and increased surface roughness of enamel and ceramic. Conclusions: The activation mode of resin cements did not influence their wear resistance. The RMGIs underwent higher attrition wear than the resin cements. CLINICAL SIGNIFICANCE Increased submargination associated with marginal breakdown and increased roughness of the surrounding structures may be expected when ceramic inlays are cemented with resin‐modified glass ionomers.     

Evaluation of ISO 4049: water sorption and water solubility of resin cements

The aim of this study was to evaluate the water sorption and solubility test design of ISO 4049 for resin cements. Sorption and solubility of six dual‐curing resin cements [RelyX Unicem 2 Automix (RUN), Multilink Speed CEM (MLS), Panavia SA Plus (PSA), RelyX Ultimate (RUL), Multilink Automix (MLA), and Panavia V5 (PV5)] were analyzed by storage in distilled water after dual‐curing. In addition, sorption and solubility during thermal cycling were assessed with self‐cured and dual‐cured specimens. After water storage, all cements revealed sorption in the range of 30 μg mm^?3 except for PV5, for which sorption was markedly lower (mean ± SD = 20.8 ± 0.4 μg mm^?3). Solubility values were negative for RUN and RUL (?2.1 ± 0.08 μg mm^?3 and ?1.9 ± 0.13 μg mm^?3, respectively). All other cements attained positive values in the range of 0.4–0.8 μg mm^?3. Thermal cycling effects were more pronounced. The assessment of water sorption according to ISO 4049 provides reliable results. Solubility results must be interpreted with care because absorbed water may distort the values.     

Shear bond strength of composite resin cements to lithium disilicate ceramics

The aim of this study was to evaluate the shear bond strength of different commercial composite resin cement systems to lithium disilicate all-ceramic substrate. Five adhesive resin cement systems Panavia 21 and Panavia F (Kuraray), Variolink 2 (Ivoclar-Vivadent), RelyX Unicem Applicap and RelyX ARC (3M ESPE) were used on all-ceramic (IPS Empress 2; Ivoclar-Vivadent) substrate. Shear bond strength of adhesive resin cement to substrate was tested after thermocycling, or without thermocycling (n = 10). Substrate surfaces of the specimen after loading were SEM microscopically examined. The highest bond strengths in water stored conditions were obtained with RelyX ARC (28.7 +/-3.9 MPa), while in thermocycled conditions the highest bonding values were obtained with Variolink 2 (23.2 +/- 7.5 MPa). The lowest values in both water stored (5.8 +/- 4.0 MPa) and thermocycled (2.4 +/- 2.9 MPa) conditions were obtained with Panavia 21. Shear bond strengths appeared to be affected significantly by thermocycling (anova, P < 0.05). It was concluded that there were significant differences between the bond strengths of adhesive resin cements to lithium disilicate substrate.     

Film thickness of resin cements used with adhesive systems

The final film thickness of a resin adhesive and a resin cement could be affected by previous polymerization of the adhesive systems on dentin surfaces. The aim of this work was to evaluate changes in the film thickness of dual resin based cements with their adhesives as a function of polymerization of the latter on dentin surfaces. The materials used were: RelyX ARC (R) + Single Bond (SB) and Variolink base (VB) and high (HV) or low (LV) viscosity catalyst + Syntac Classic (S) or Excite DSC (E); 56 human dentin discs and 56 composite resin discs (Z250). Dentin disc surfaces were treated with 35% phosphoric acid (except for S) and the adhesive system was either polymerized or not polymerized. A 0.05 ml increment of cement mixture was placed on the dentin disc and covered with the resin disc. A 25 N load was applied for ten minutes and then, the combined thickness was measured with a digital micrometer. Sample size (n) was 4 for each cement or condition. A two-way analysis of variance was performed with a level of significance of p < 0.05. The mean film thickness (and standard deviations) in microm, with and without previous polymerization of the adhesive layer, were: R+SB: 16.50 (2.64) and 17.00 (1.41); VB+S: 21.75 (5.37) and 62.25 (0.95); VB LV+S: 24.50 (3.87) and 72.75 (1.89); VB HV+S: 28.75 (8.46) and 93.00 (53.63); VB+E: 31.75 (8.38) and 42.75 (4.34); VB LV+E: 47.75 (2.50) and 45.75 (3.20); VB HV+E: 49.25 (25.50) and 45.75 (2.75). Significant differences (p < 0.01) were found for the cements and polymerization condition as well as for the interaction between them. Instructions regarding polymerization of the adhesive layer must be followed when adhesive systems are used in combination with dual polymerized resin based cements. Otherwise, final film thickness of the adhesive and the resin cement could be affected.     

Evaluation of the adhesion of fiber posts cemented using different adhesive approaches

The aim of this study was to investigate the adhesion of fiber posts cemented with luting agents that utilize three currently available adhesive approaches: etch‐and‐rinse, self‐etch, and self‐adhesive. Forty‐two intact single‐rooted human premolars were used in the study. Teeth were divided into six groups. In each group, a different resin cement with its adhesive system (if needed) and a fiber post were used. The groups were classified, according to the adhesive approach, into the following three categories. (i) Etch‐and‐rinse groups: Calibra resin cement/XPBond adhesive + self‐curing activator (SCA)/RadiX Fiber Post (Dentsply Caulk), FluoroCore 2 core build‐up material/XPBond + SCA/RadiX Fiber Post (Dentsply Caulk), and MultiCore Flow luting and core build‐up material/Excite DSC adhesive/FRC Postec Plus fiber post (Ivoclar Vivadent). (ii) Self‐etch group: Panavia F 2.0/ED primer (Kuraray)/RadiX Fiber Post (Dentsply Caulk). (iii) Self‐adhesive groups: experimental self‐adhesive cement/RadiX Fiber Post (Dentsply Caulk), and RelyX Unicem/RelyX Fiber Post (3M ESPE). The adhesion between the post and the root canal walls was assessed using the ‘thin‐slice’ push‐out test. In the test arrangement used, the self‐etching approach may offer less favourable adhesion to root canal dentin in comparison with etch‐and‐rinse and self‐adhesive approaches.     

Morphological and bond strength evaluation of different resin cements to root dentin

This study correlated the morphological characteristics with the bond strengths of various resin cements used for bonding fiber posts to root canal dentin. Fifty glass-fiber posts (FRC Postec Plus) were luted into the root canals of extracted human anterior teeth using five resin cements ( n  = 10): Panavia F 2.0, PermaFlo DC, Variolink II, RelyX Unicem, and Clearfil Core. Before insertion of the post, the adhesive systems were labeled with fluorescein and the resin cement was labeled with rhodamine isothiocyanate. The roots were sectioned into three slices (of 2 mm thickness), and each slice was analyzed using confocal laser scanning microscopy in dual fluorescence mode to determine hybrid layer thickness, the number of resin tags, and the number of broken tags. Bond strengths were measured using a micro push-out test. Bond strengths to root canal dentin, as well as the morphological characteristics, were significantly affected by the materials. However, these factors did not correlate. The self-adhesive resin cement, which showed the formation of a hybrid layer and resin tags only sporadically, had the highest bond strengths. These results indicate that chemical interactions between the adhesive cement and hydroxyapatite may be more crucial for root dentin bonding than the ability of the same material to hybridize dentin.