Microhardness of resin cements after light activation through various translucencies of monolithic zirconia

PURPOSEThis study aimed to investigate the Vickers Hardness Number (VHN) of light- and dual cured resin cements cured through monolithic zirconia specimens (VITA YZ) of various translucencies: translucent (T); high translucent (HT); super translucent (ST); and extra translucent (XT) at 0, 24, and 48 h after curing.MATERIALS AND METHODSFour zirconia specimens from each translucency were prepared. Two light-cured resin cements (Variolink N LC; VL and RelyX Veneer; RL) and two dual-cured resin cements (Variolink N DC; VD and RelyX U200; RD) were used. The cement was mixed and loaded in a mold and cured for 20 s through the zirconia specimen. The upper surface of cements was tested for VHN using a microhardness tester at 0, 24, and 48 h after curing. The VHN were analyzed using two-way repeated, Brown-Forsythe ANOVA with Games Howell post-hoc analysis and independent t-tests (P < .05).RESULTSAll cements showed significantly higher VHN from 0 h to 24 h (P < .001). At 48 h, the VHN of light-cured cements were significantly lower when cured under the T groups than under XT groups (P = .001 in VL, P = .014 in RL). At each post curing time of each translucency, VD showed higher VHN than VL (P < .05), and RD also showed higher VHN than RL (P < .05).CONCLUSIONThe translucency of zirconia has an effect on the VHN for light-cured resin cements, but has no effect on dual-cured resin cements. Dual-cured resin cement exhibited higher VHN than the light-cured resin cement from the same manufacturer. All resin cements showed significantly higher VHN from 0 h to 24 h.     

光照射强度和水储存条件对双重固化树脂机械性能的影响

目的:探讨水储存条件对不同光强度照射条件下的双重固化树脂粘接剂机械性能的影响.方法:按照ISO 4049标准,将3种双重固化树脂粘接剂(Linkmax HV, Nexus 2和VariolinkII HV)制作成2 mm×2 mm×25 mm长方形试件,接受800, 310 和80 mW/cm2光强度照射后,干燥储存1 d或水储存90 d.储存后的试件接受三点弯曲试验测量其挠曲强度和弹性模量.使用SPSS 11.5统计软件对每种粘接剂的试验数据进行双因素方差分析.结果:光强度的减弱显著降低了3 种树脂粘接剂的挠曲强度和弹性模量;而90 d的水储存只显著降低了Linkmax HV和VariolinkII HV的弹性模量和挠曲强度,其中只有VariolinkII HV的弹性模量在光照射条件与水储存条件间出现在统计学上有显著性差异的交互作用,随着光强度的减弱其弹性模量呈现出加速降低的趋势.结论:双重固化树脂粘接剂仍然需要足够的光照射强度才能获得良好的机械性能和性能的稳定.     

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.     

Effects of curing protocol and storage time on the micro-hardness of resin cements used to lute fiber-reinforced resin posts

Objectives

To determine the micro-hardness profile of two dual cure resin cements (RelyX - U100^®, 3M-ESPE and Panavia F 2.0^®, Kuraray) used for cementing fiber-reinforced resin posts (Fibrekor^® - Jeneric Pentron) under three different curing protocols and two water storage times.

Material and methods

Sixty 16mm long bovine incisor roots were endodontically treated and prepared for cementation of the Fibrekor posts. The cements were mixed as instructed, dispensed in the canal, the posts were seated and the curing performed as follows: a) no light activation; b) light-activation immediately after seating the post, and; c) light-activation delayed 5 minutes after seating the post. The teeth were stored in water and retrieved for analysis after 7 days and 3 months. The roots were longitudinally sectioned and the microhardness was determined at the cervical, middle and apical regions along the cement line. The data was analyzed by the three-way ANOVA test (curing mode, storage time and thirds) for each cement. The Tukey test was used for the post-hoc analysis.

Results

Light-activation resulted in a significant increase in the microhardness. This was more evident for the cervical region and for the Panavia cement. Storage in water for 3 months caused a reduction of the micro-hardness for both cements. The U100 cement showed less variation in the micro-hardness regardless of the curing protocol and storage time.

Conclusions

The micro-hardness of the cements was affected by the curing and storage variables and were material-dependent.     

Mechanical properties of luting cements after water storage

This study determined the effect of water storage on flexural strength (FS) and compressive strength (CS) of 12 luting cements from different material classes. In addition, the influence of the curing method on the mechanical properties was investigated. The materials examined were two zinc phosphate cements (Harvard cement and Fleck's zinc cement), two glass ionomer cements (Fuji I and Ketac-Cem), three resin-modified glass ionomer cements (Fuji Plus, Fuji Cem and RelyX Luting), four resin cements (RelyX ARC, Panavia F, Variolink II and Compolute) and one self-adhesive universal resin cement (RelyX Unicem). The samples were prepared and tested according to ISO specifications. Specimens for FS and CS were loaded to fracture at a constant crosshead speed of 1 mm/minute. The mechanical properties were measured after the materials were stored in distilled water at a temperature of 37.0 +/- 1.0 degrees C for 24 hours and 150 days after mixing. In a one-way ANOVA, multiple mean value comparisons using Duncan's multiple comparison tests were performed. Resin cements had the highest flexural and compressive strengths, followed by self-adhesive universal resin cement. These materials were statistically stronger than resin-modified glass ionomer cements, glass ionomer cements and zinc phosphate cements.     

Influence of curing method and storage condition on microhardness of dual-cure resin cements

This study evaluated the influence of curing method and storage condition on the microhardness of dual-cure resin cements: Panavia F 2.0 (PF) and Nexus 2 (NX). The specimens were either light-cured (LC) or chemically cured in darkness (CC). After 24 hours of storage in dry chamber (Dry) or distilled water (DW), the specimens were sectioned and polished. The microhardness of resin cement matrix was measured using a nanoindentation tester (ENT-1100). The data (n = 6) were statistically analyzed with t-test, two-way ANOVA (p < 0.05), and Tukey HSD test (alpha = .05). It was found that the factors of curing method and storage condition had significant effect on microhardness. For both PF and NX, LC presented higher microhardness than CC, while DW showed higher microhardness than Dry. In conclusion, dual-cure resin cements could achieve high degree of cure when light-cured. In addition, the microhardness of the resin cements evaluated did not decrease when kept in water.     

Comparison of the effect of storage media on shear punch strength of resin luting cements

Objectives

To measure the shear punch strength of eight resin-containing luting cements before and after immersion in acidic solution and ethanol at different temperatures (37° C and 60 °C). Method: Specimens were prepared from six resin luting cements; Set (SDI), Panavia F (Kuraray), RelyX Veneer (3M/ESPE), VarioloinkII (Ivoclar), Maxcem (Kerr), Nexus2 (Kerr) and two Resin-modified glass-ionomer luting cements (RM-GICs); GC Fuji Plus (GC Corporation), RelyX Luting 2 (3 M/ESPE). For each material a total of 114 disc-shaped specimens were prepared. Six specimens were immersed in distilled water for 24 h at 37 °C, polished and subjected to baseline measurement for shear punch strength. The remaining 108 specimens were randomly divided into 18 groups of six, and immersed in three solutions; distilled water, 0.01 mol/L lactic acid, and 50% ethanol at 37 °C or 60 °C, for 1 week, 1 month or 3 months. Specimens were washed, dried and tested for final shear punch strength.

Results

Values were material and solution dependent. Values of Nexus 2 and Rely X Veneer are the highest, and Rely X Luting 2 the lowest. Ethanol and lactic acid specimens showed significantly lower values compared with the distilled water specimens. Conclusion: The shear punch strengths of the resin-containing luting cements were affected by time and storage solution. While some of the resin luting cements had significantly higher values compared to that of the RM-GICs, there were no significant differences between the RM-GICs and resin cements such as Panavia F and Set.     

三种纤维桩树脂粘接材料的吸水性和溶解性比较

目的 比较3种纤维桩树脂粘接材料的吸水性和溶解性,为临床应用提供实验依据.方法 选取Paracore Automix、DMG Luxacore和可乐丽菲露DC core 3种双重固化树脂粘接剂,每种材料各制备5个试件,浸泡于蒸馏水中28d,通过测量浸泡前后的重量变化,计算材料的吸水值与溶解值.结果 ParaCore、Luxacore和DC core 3种粘接材料的吸水值分别为（20.13±0.97）μg/mm3、（17.67±1.46）μ g/mm3和（18.29±2.77）μ g/mm3,溶解值分别为（4.81±3.13）μ g/mm3、（3.32±0.74）μg/mm3和（2.57±1.08）μg/mm3,ParaCore的吸水值和溶解值最大,与其他两种材料的吸水值与溶解值之间的差异均有统计学意义（P＜0.05）,DC core的吸水值和溶解值相对较低.结论 三种纤维桩树脂粘接材料中DC core具有较好的稳定性;ParaCore的吸水值和溶解值最大,其远期力学性能较差,使用寿命缩短.     

Microhardness of acid-treated and resin infiltrated human dentine

OBJECTIVE: The aim is to determine if superficial or deep dentine microhardness (MH) is affected by different chemical dentine pre-treatments performed for resin bonding. METHODS: Dentine discs of superficial (SD) and deep dentine (DD) were obtained by transversally sectioning the crowns of human third molars. Knoop MH was measured after different treatments: (1) polished up to 4000 grit, (2) polished and etched (37% ortophosphoric acid for 15 s), (3) resin (Single Bond -SB-) infiltrated dentine after acid etching, (4) polished, etched and treated with 5% NaOCl for 2 min, (5) resin infiltrated (SB) after etching and NaOCl treatment. For resin infiltrated surfaces care was taken in order to remove the excess adhesive layer, and obtain infiltrated dentine, by measuring thickness of the sample before resin infiltration and polishing after resin infiltration until obtaining the initial thickness of the sample. Indentations (n=20) were performed on moist surfaces with a standard Knoop MH tester (20 g, 5 s). Data were expressed in Knoop Hardness Numbers (KHN) and analysed by ANOVA and multiple comparisons (P<0.05). RESULTS: Dentine KHN decreased on both SD and DD after acid etching. NaOCl treatment after acid etching did not affect MH on SD, but KHN of DD was lowered. Resin infiltration increased KHN but did not recover the initial MH values in both SD and DD. CONCLUSIONS: Treating dentine with either H3PO4 or NaOCl caused marked reduction of its surface hardness and subsequent resin infiltration was not capable to restore it.     

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。     

Enhancement of adhesion between resin coating materials and resin cements

Resin coating technique is a unique method that improves the dentin bond strength of resin cements in indirect restorations. However, the weak link of a specimen bonded using the resin coating technique was reported to be the bonded interface between the resin coating material and resin cement. The purpose of this study, therefore, was to enhance the bonding performance between a resin coating material and a resin cement. Two light-cured flowable composites, Protect Liner F and Clearfil Flow FX, were used as coating materials, and two dual-cure composite materials, Panavia F 2.0 and Clearfil DC Core Automix, were used as resin cements. The ultimate tensile strength of each material and the microtensile bond strengths of the bonded specimens of resin coating material and resin cement were measured using a crosshead speed of 1.0 mm/min. Three-way ANOVA (p=0.05) revealed that the highest microtensile bond strength was obtained using a combination of Clearfil Flow FX and Clearfil DC Core Automix, and when the surface of the coating material was treated with ED Primer II. It was strongly suggested that materials with a higher ultimate tensile strength, when used in both resin coating and cementation, could enhance the bond strength between the two.     

自粘接树脂水门汀与两种粗化处理的二硅酸锂陶瓷的粘接性能评价

摘要］目的：评价自粘接树脂水门汀与喷砂和氢氟酸酸蚀两种方式粗化处理的二硅酸锂陶瓷的粘接强度及耐久性。材料和方法：制作二硅酸锂瓷片183个,烧结后随机分为2组分别进行氢氟酸酸蚀和喷砂,随后根据粘接策略的不同分为RU（RelyX Unicem）、RU200(RelyXTM U200)以及RV(silane+RelyX Veneer) 3个亚组分别制作粘接试件。各组试件一半于37℃下水储24h,另一半进行20000次冷热循环,随后测试剪切粘接强度。氢氟酸酸蚀、喷砂及未进行粗化处理的陶瓷试件采用扫描电镜观察表面形貌。结果：氢氟酸组产生显著高于喷砂组的粘接强度（p<0.05）;单纯应用自粘接树脂水门汀组的粘接效果与传统树脂水门汀结合硅烷预处理组无统计学差别（p=0.057）;所有组的粘接强度在老化后均显著降低（p<0.05）。结论：氢氟酸酸蚀可以获得较氧化铝喷砂处理更佳的粘接效果;自粘接树脂水门汀在无需硅烷预处理的条件下用于二硅酸锂陶瓷的粘接可获得较好的粘接效果。     

Effects of barriers on chemical and biological properties of two dual resin cements

The aim of this study was to investigate the degree of conversion, monomer release, and cytotoxicity of two dual‐cure resin cements (Cement‐One and SmartCem2), light‐cured across two indirect restorative materials in an attempt to simulate in vitro the clinical conditions. The results obtained show that the degree of conversion was influenced by both barriers, but the effect of the composite material was greater than that of the ceramic one. The amount of monomers released from the polymerized materials in the absence of barriers was significantly lower than that released in the presence of either the ceramic or the composite barrier. However, a higher amount of monomers was released in the presence of the ceramic barrier. All materials, in all the experimental conditions employed, induced slight cytotoxicity (5–10%) on human pulp cells. Our examinations showed that the two resin cements had similar chemical and biological properties. The decreased degree of conversion of the dual‐curing self‐adhesive composite showed that the light‐curing component of these materials has an important role in the polymerization process. In clinical practice, it is therefore important to pay attention to the thickness of the material used for the reconstruction.     

瓷块厚度及透光性对树脂水门汀固化硬度的影响

目的 研究瓷块的厚度和透光性对不同类型树脂水门汀固化硬度的影响,为临床的全瓷粘接提供参考。方法 选择三种树脂水门汀Choice2,Duolink,RelyX Ultimate Clicker,分别通过不同厚度(0.5 mm、1.0 mm、1.5 mm、2.0 mm)的高透(HT)和低透(LT)的IPS e.max Presss瓷块,用800 mw/cm²高强度LED灯进行光照固化。三种树脂水门汀透过盖玻片照射的试件作为对照组。在固化后30 min和24 h通过显微硬度仪测量固化后树脂的表面努氏硬度值。评价瓷块厚度和透光性对树脂水门汀固化硬度的影响。结果 Choice 2固化后的努氏硬度值在各个厚度及透光度下与对照组相比均显著降低。Duolink和RelyX Ultimate固化后的努氏硬度值在HT瓷块厚度达到2.0mm时,实验组与对照组相比显著降低。在LT瓷块中,当厚度达到1.5 mm时,实验组硬度值即显著降低。结论 当IPS e.max Presss低透瓷块达到1.5 mm厚度,高透瓷块达到2.0 mm厚度时,树脂水门汀的固化硬度会显著降低,从...     

不同表面处理对钛-树脂粘接强度的影响

目的 探讨不同表面处理方式对钛-树脂粘接强度的影响.方法 使用CAD/CAM技术切削出56个底面直径10 mm,厚3 mm的商业Ⅱ级纯钛片,并随机分为7组(n=8).试件表面分别进行喷砂(B组)、涂布硅烷偶联剂(C组)、涂布金属处理剂(D组)、喷砂+硅烷偶联剂(E组)、喷砂+金属处理剂(F组)及喷砂+偶联剂+金属处理剂(G组)处理,而对照组(A组)则不作任何处理.粘接试件使用万能实验机测试剪切粘接强度,结果进行单因素方差分析,并使用Tukey检验进行组间比较(α=0.05).观察断裂模式.结果 与对照组相比,各实验组均表现出较高的粘接强度(P<0.05),其中F组的粘接强度最高,为(20.9±4.3)MPa,与G组之间无统计学差异;F、G组与其他组之间,B、D组与A、C组之间存在统计学差异(P<0.05).断裂模式分析显示,各实验组以界面断裂和混合断裂为主.结论 对纯钛表面进行适当的表面处理,尤其是喷砂与金属处理剂联合处理有利于提升树脂粘接强度.