Effect of Thermocycling on the Bond Strength of Self-Adhesive Resin Cements Used for Luting CAD/CAM Ceramics to Human Dentin

The aim of the study was to evaluate the influence of thermocycling on the shear bond strength of self-adhesive, self-etching resin cements luted to human dentin and computer-aided design/computer-aided manufacturing (CAD/CAM) ceramics. Three modern self-adhesive dental cements (Maxcem Elite, RelyX U200, Panavia SA) were used to lute three CAD/CAM ceramics (IPS Empress CAD, IPS e.max CAD, IPS e.max ZirCAD) onto the dentin. One conventional cement (Panavia V5) served as a control. After preparation, the samples were subjected to thermocycling as a method of artificial aging of dental materials applied to simulate long-term use in oral conditions. Shear bond strength was evaluated according to PN-EN ISO 29022:2013-10 and failure modes were observed under a light microscope. Statistical analysis was performed. The study demonstrated that a combination of ceramics and cements directly impacts the bond strength. The highest bond strength was observed in Panavia V5, lower in Panavia SA and Maxcem Elite and the lowest–in RelyX U200. Adhesive failure between human dentin and cements was the most common failure mode. Moreover, thermocycling highly decreased bond strength of self-adhesive, self-etching cements.     

Bond Strength and Monomer Conversion of Bonding Agents Mixed with Restorative Composites Prior to Light Exposure

This study examined the effect of adhesive systems (either placed as directed or when mixed with composites prior to photocuring) on bond strength and monomer conversion. Occlusal surfaces of extracted human molars were ground flat and Scotchbond Multipurpose®, Single Bond®, or Clearfil SE Bond® adhesive systems were applied according to manufacturer's directions, mixed in situ with flowable or hybrid composites prior to photocuring. Specimens were prepared for microtensile bond-strength testing, and maximal bond strength at failure was recorded. Adhesives and composites were also placed on a diamond attenuated-total-reflectance unit, and infrared spectra were obtained kinetically. Addition of flowable Scotchbond prior to light-curing increased bond strength; however, no effect on Single Bond and Clearfil SE Bond was observed. The mixture of adhesives with composites resulted in lower monomer conversion for Scotchbond and Clearfil SE Bond.     

Bond strength and chemical interaction of self-adhesive resin cements according to the dentin region

The aim of the study is to evaluate the effectiveness and level of chemical interaction of self-adhesive resin cements (SRCs) according to the dentin region. One hundred eight sound human third molars and three SRCs were selected: Bifix SE (Voco), Maxcem Elite (Kerr), and RelyX U200 (3M ESPE). Ninety human molars were used for the bond strength test and 18 teeth for the X-ray diffraction (XRD) characterization. A flat surface of superficial, deep, or axial dentin was exposed. For bond strength evaluation, 90 indirect composite resin restorations (10 mm in diameter, 2.0 mm-thick) were built and cemented with one of the SRCs according to the manufacturer's instructions. The restored teeth were then cut into sticks with cross-sectional areas of 0.8 mm² and tested in tensile at a speed of 0.5 mm/min (n=10). The results of bond strength were statistically analyzed by two-way ANOVA and Tukey's test (α=0.05). The fractured specimens were classified under SEM. The remaining teeth were further sectioned in order to build dentin fragments with 2.0 mm² of area and 0.2 mm in thickness for XRD analysis. In general, significantly higher bond strength was found when bonding to axial and deep dentin compared to superficial dentin. Comparing the bonding effectiveness of the SRCs, taking into account the mean bond strength obtained in the 3 dentin regions, the study found no significant difference (p>0.05). Although RelyX U200 showed similar bond strength irrespective of the dentin region (p>0.05), the bonding results of the other 2 SRCs varied significantly (p<0.05). There was a higher incidence of cohesive failure in the SRCs for all groups. The XRD analysis detected different perceptual reductions of hydroxyapatite crystallinity for all SRCs, indicating a particular chemical interaction in each experimental condition. Thus, it can be concluded that the bond strength and chemical interaction of the SRCs can vary significantly according to the dentin region.     

Influence of Surface Finish on Flexural Strength and Microhardness of Indirect Resin Composites and the Effect of Thermal Cycling

This study investigated the effect of surface finish and thermal cycling procedures on flexural strength and surface microhardness of three indirect resin composites, Artglass®, Signum®, and Solidex®. The specimens were prepared in sufficient number and size according to flexural and microhardness test requirements (n = 10). Scanning electron microscopy-energy dispersive x-ray (SEM-EDX) analysis was also used for studying the morphology, dispersion, and elemental compositions of fillers. The EDX results showed that Artglass contained 1.57% aluminium oxide (Al₂O₃), 53.29% silicon dioxide (SiO₂), and 2.62% barium oxide (BaO); Signum had 55.69% silicon dioxide (SiO₂) and Solidex had 44.99% silicon dioxide (SiO₂) of total mass. Artglass appeared to display the best flexural strength values under all the test conditions employed (range: 116.8 ± 32.18 to 147.8 ± 47.97 MPa), and it was followed by Signum (range: 93.7 ± 22.84 to 118.0 ± 33.45 MPa). Thermal cycling did not seem to have affected the flexural strength of Artglass and Signum (p > 0.05); however, it led to a significant decrease, from (110.5 ± 20.69 MPa) to 74.0 ± 13.30 MPa (p < 0.001), in the strength of polished Solidex specimens. While surface microhardness of the three materials increased by polishing (Artglass: 55.7 ± 2.64/74.1 ± 8.63 Vickers Hardness Numbers (VHN); Signum: 44.8 ± 3.12/60.7 ± 4.50 VHN; Solidex: 44.0 ± 2.31/53.4 ± 3.58 VHN for unpolished/polished specimens), thermal cycling had a deleterious effect on this property (p < 0.001).     

Microtensile Bond Strength of Self-Adhesive Resin-Based Dental Cement to Bleached Enamel

This study investigated the effectiveness of bleaching agents on the micro tensile bond strength (µTBS) of self-adhesive luting cement and enamel. A total of 126 samples were prepared from the labial surfaces of permanent human maxillary central incisors and assigned into three groups with 42 samples each as: control, enamel bleached with 10% hydrogen peroxide (HP), and enamel bleached with 10% carbamide peroxide (CP). Rely X Unicem® (3 M, ESPE) was used as self-adhesive resin cement. The total testing period for bleaching was selected as 14 days and the bleaching agents were applied 8 hours a day. The statistical one-way ANOVA model and Tukey HSD multiple comparison test (α = .01) were used to assess the differences. The control group demonstrated the highest value (18.245 MPa) while HP and CP showed the much lower values of 11.150 and 14.222 MPa, respectively. Bleaching agents affect the µTBS negatively. Failure analysis of the fracture surfaces demonstrated that almost all samples showed adhesive failures at the cement-enamel interface.     

Bond Strength and Interfacial Ultramorphology of Current Adhesive Systems

This study evaluated the bond strength and ultramorphology of the resin-dentin interfaces produced by current dental adhesive systems. Nine dentin bonding agents were investigated. Restored teeth were vertically, serially sectioned to obtain bonded slices for interfacial TEM analysis or to produce bonded beams for the microtensile bond strength test. The one-step self-etching adhesives (Futurabond® NR and Hybrid Bond®) showed lower bond strength values than the three-step etch-&-rinse adhesive system All-Bond 3. Most bonding agents presented statistically similar mean bond strength values, which ranged from 41.3 ± 17.9 to 35.0 ± 5.3 MPa. The thickness of the hybrid layer varied according to the type of adhesive system used. While the etch and rinse adhesives with alcohol as organic solvent showed bond strength means higher than 40 MPa, the self-etching systems showed bond strength lower than 40 MPa. Resin-dentin interdifusion zone and resin tags were noted in all bonded interfaces.     

NA—5聚氨酯胶粘剂对金属粘接强度的影响

以ＮＡ－５型氨酯胶粘剂作为金属五ＰＵ弹性胶料之间的胶粘剂，制作钢／ＰＵ橡胶／铝静件。研究了影响制件粘接强度的主要因素，给出了ＮＡ－５最佳粘接工艺。     

外加剂对含镁铝尖晶石新型铝酸盐水泥结合强度的影响

以轻烧白云石粉和工业氧化铝粉为原料,采用烧结法制备了含镁铝尖晶石的新型铝酸盐水泥.利用X射线衍射(XRD)检测了新型铝酸盐水泥及其水化产物的物相组成,并采用扫描电子显微镜(SEM)观察和分析了其水化产物的形貌.研究了不同外加剂(CaCl2,Na2SO4,Li2CO3)对新型铝酸盐水泥结合高铝矾土浇注料早期强度的影响.结果表明:新型水泥的物相组成为一铝酸钙(CA)、二铝酸钙(CA2)和镁铝尖晶石(MA);水化产物主要以C2AH8为主,提供了水泥的早期强度;所选外加剂早强效果由强到弱为:Li2CO3>CaCl2>Na2SO4.当新型铝酸盐水泥中添加0.01%的Li2CO3时,水泥结合的浇注料早期强度可提高40%左右.而其与萘系减水剂共同作用的效果更为明显.     

Physical properties of a bisphenol-F epoxy containing a silica filler treated with silane coupling agents

A model epoxy system consisting of a diglycidyl ether of bisphenol-F epoxy resin, 1,4-butanediol, and cured with 4-methyl-2-phenylimidazole has been investigated. Thermal analysis indicated that 3 parts per hundred resin (phr) is the optimum amount of curing agent for this system. The influence of silane-treated amorphous fumed silica fillers on properties of the cured epoxy was also examined. Silica particles were treated with 3-aminopropyldiethoxymethylsilane (APDS) and3-aminopropyltriethoxysilane (APTS) coupling agents. No change in glass transition temperatures was observed with the addition of the filler (with or without coupling agents) to the epoxy. Addition of the filler led to a slight increase in the activation energy for the glass transition; however, no change in activation energy was observed when using the coupling agent. Addition of either coupling agent to the filler surface led to an increase in cooperativity. Fumed silica also did not significantly affect moisture diffusion properties, but a small decrease was observed in the moisture saturation mass with the addition of silica particles treated with APDS.     

Effect of Microwave Treatment on the Shear Bond Strength of Denture Tooth/Acrylic Resin

This study investigated the effect of microwave treatment on the shear bond strength of the denture tooth to acrylic resin adhesion, when the glossy ridge laps were unmodified, abraded, grooved, or etched by monomer. Eighty specimens (n = 10) were polymerized in a hot bath at 74°C for 9 hours, and deflasked after flask cooling. Specimens were soaked in 150 mL of distilled water and submitted to microwave treatment in a domestic microwave oven calibrated at 650 W for 3 minutes. Control specimens were not microwave treated. The shear bond strength test was performed in an Instron machine with a cross-speed of 1mm/minute. The ultimate fracture load value was transformed into shear bond strength as a function of the bonding area. Collected data were submitted to ANOVA and Tukey's test (α = .05). Treatment by microwave energy significantly decreased (p < .05%) the shear bond strength values in all ridge lap conditions used for the denture tooth/resin adhesion.     

Influence of Surface Nano-roughness of Dental Alumina Ceramic on Bond Strength to Dual-Cure Resin Cements

The goal of this research is to evaluate the effect of sandblasting and silica coating on the nano-roughness and on the microtensile bond strength (MTBS) of glass-infiltrated alumina bonded to different resin cements. Six slabs of In-Ceram Alumina (Vita) were randomly treated according to the following groups: (1) no treatment; (2) sandblasting (125 μm Al₂O₃-particles); and (3) tribochemical silica-coating (50 μm silanated silica particles). Nano-roughness (Ra) was assessed under an atomic force microscope (AFM). Such surface treatments were also applied to nine In-Ceram Alumina CAD/CAM blocks. Ceramic blocks were duplicated in composite resin, and composite samples were bonded to the conditioned surfaces. Each pre-treatment group was divided into three subgroups depending on the resin cement system: (1) Clearfil Ceramic Primer plus Clearfil Esthetic Cement (CEC, Kuraray); (2) RelyX Unicem (RXU, 3M); and (3) Calibra Silane plus Calibra Resin Cement (CAL, Dentsply). After 24 h, the bonded specimens were cut into 1±0.2 mm² sticks. The MTBS values (MPa) were obtained using a universal testing machine (crosshead speed: 0.5 mm/min). Failure modes were recorded using a scanning electron microscope (SEM). Nano-roughness and MTBS data were analyzed by ANOVA and Student–Newman–Keuls tests (α =0.05). No significant changes in nano-roughness occurred after conditioning. The MTBS of CEC and RXU were comparable despite the surface treatment. All CAL-sticks debonded prematurely. Ceramic pre-treatments, such as sandblasting or silica coating, do not affect the alumina's surface nano-roughness or bond strength. The MDP monomers dissolved in the CEC Primer and the functional dimethacrylate monomers present in the self-adhesive RXU may be the key to successful bonds to alumina.     

Bond strength evaluation of composite resin bonded to glass ionomer cements after different periods of setting

This study investigated the time elapsed after setting of glass ionomer cements on the bond strength to composite resin restorations. Bovine incisors received cavity preparations on the buccal surface (6 mm×6 mm×2 mm) and the specimens were tested according to cement type (conventional and resin-modified) and time elapsed before performing the restorations: GC10m: conventional glass ionomer cement and 10 min time elapsed after setting; GC24h: conventional cement and 24 h after setting; GC7d: conventional cement and 7 days after setting; GRM10m: resin-modified glass ionomer cement and 10 min after setting; GRM24h: resin-modified cement and 24 h after setting; and GRM7d: resin-modified cement and 7 days after setting. Specimens were subjected to micro-shear testing and the data were analyzed by Analysis of Variance and Tukey′s test (p=0.05). Bond strength of restorations performed on conventional cement after 10 min of time elapsed presented the lowest mean values and differed statistically from values at 24 h and 7 days. Resin-modified cement after 24 h presented the highest mean values and differed statistically from values at 10 min and 7 days. The time elapsed after setting of glass ionomer cement may interfere in the bond strength to composite restorations.     

Shear bond strengths of six different porcelain laminate veneer materials cemented to enamel with two different MDP-containing resin cements

Purpose: To compare the shear bond strengths of six different porcelain laminate veneer (PLV) materials cemented to enamel with two different MDP-containing resin cements. Materials and methods: Totally 120 disc specimens were fabricated with In-Ceram alumina (ICA), Turkom-Cera^TM (TCR), IPS Empress (IPS), IPS Empress-II (IPS2), Finesse (FNS), and Ceramco-3 (CER) ceramic systems (n = 20). Sixty specimens were cemented with self-adhesive resin cement (Clearfil SA), and 60 specimens were cemented with self-etch resin cement (Panavia F2.0) to enamel. Thus, 120 PLV–enamel specimens were assigned to 12 experimental groups (ICA/Pv, ICA/Cf, TCR/Pv, TCR/Cf, IPS/Pv, IPS/Cf, IPS2/Pv, IPS2/Cf, CER/Pv, CER/Cf). Shear force was applied on PLV–enamel interfaces until failure. Obtained data were statistically analyzed with ANOVA and t-tests. Results: Obtained shear bond strength values (SBSV) ranged as follows, respectively; TCR/Cf (7.70 MPa), FNS/Cf (7.57 MPa), TCR/Pv (6.91 MPa), ICA/Pv (5.05 MPa), CER/Pv (4.75 MPa), IPS2/Cf (4.66 MPa), FNS/Pv (4.43 MPa), IPS2/Pv (3.97 MPa), CER/Cf (3.82 MPa), IPS/Pv (3.62 MPa), ICA/Cf (3.59 MPa), IPS/Cf (3.11 MPa). Highest SBSV were obtained in TCR groups (7.70 MPa for TCR/Cf and 6.91 MPa for TCR/Pv) and lowest SBSV were obtained in IPS groups (3.11 MPa for IPS/Cf and 3.62 MPa for IPS/Pv) in both resin cements. No significant bond strength difference was found between two resin cements. Conclusions: TCR groups showed highest SBSV; lowest SBSV were obtained with both IPS PLVs. The resin cement type did not significantly affect the bond strength value of a ceramic type, except for the Finesse system.     

Evaluation of different desensitizing agents effect on shear bond strength of adhesive resin cement to dentin

Desensitizing agents can inhibit the bonding strength between dentin and adhesive resin cement. This study evaluated the effects of different desensitizing agents on the shear bond strength of adhesive resin cement to dentin. Sixty freshly extracted and caries free teeth were classified into five experimental groups, randomly (n?=?12). Each group was treated with a different desensitizing agent (Teethmate, Shield Force Plus, Admira Protect and Ultra-Ez) respectively, except for an untreated control group. After desensitizing agents and adhesive resin cement were applied to each dentin surface, all specimens were stored in incubator at 37?°C for 24?h. The shear bond strength was tested with a Universal testing machine at a 0.5?mm/min crosshead speed. Data were analysed by using a statistical software (SPSS 22). The results of the measurements were analysed by Kruskal Wallis test with Bonferroni correction and multiple comparisons were made by Wilcoxon test (p???.01). Specimens were examined by a scanning electron microscope, additionally. The Shield Force Plus showed significantly the highest shear bond strength compared with other groups (p?<?.01). Ultra-Ez showed the lowest shear bond strength (p?>?.01). There was no significant difference among Teethmate and Admira Protect groups (p?>?.01). Desensitizing agents containing resin monomers increased the bonding strength, however desensitizers containing calcium phosphate, potassium nitrate and fluoride did not effect the bonding strength of resin cement to dentin.     

Shear Bond Strength Evaluation of Orthodontic Brackets Bonded to Fluorotic Teeth with a Self-Etching Primer and a New Generation of Color Bonding

The objective of this work was to evaluate the shear bond strength (SBS) and bond failure site of brackets bonded to teeth with fluorosis treated with and without microabrasion before placement of a self-etching primer (SEP) and a color-changing composite and to compare with a control group. This in vitro study included 120 premolars with and without dental fluorosis, divided into six groups: (1) healthy enamel etched for 15 sec and fifth generation primer, (2) healthy enamel, (3) mild fluorosis (MIF) enamel, (4) MIF enamel microabraded, (5) moderate fluorosis (MOF) enamel, and (6) MOF enamel microabraded. For groups 2–6, an SEP was used. All samples were evaluated with the SBS test and the modified adhesive remnant index (ARI). The highest SBS mean value was for healthy enamel etched for 15 sec and fifth generation primer and the lowest SBS mean value was for healthy enamel with SEP. Significant differences were found in the ARI between healthy and MOF groups. SBS of orthodontic brackets bonded on fluorotic teeth with an SEP and a new generation of color bonding could be clinically acceptable as the value obtained was above the suggested minimum required for orthodontic bonding.     

新型复合早强剂对水泥砂浆力学性能的影响

本文试验研究了两种新型复合早强剂(甲酸钙-晶胚、甲基丙烯酸-晶胚)对水泥砂浆新拌性能和力学性能的影响,并通过X射线衍射仪(XRD)和扫描电子显微镜(SEM)进行了微观分析。结果表明,随着早强剂掺量增加,新拌水泥砂浆的流动度略有降低,凝结时间提前。两种复合早强剂均能够加速水泥早期水化,显著提高水泥砂浆的早期强度。甲酸钙-晶胚、甲基丙烯酸-晶胚两种复合早强剂可使水泥砂浆的12 h抗压强度分别提高96.7%和89.3%,抗折强度分别提高192.2%和211.1%;同时,对水泥砂浆28 d抗压强度的提高幅度仍高达50.0%左右,说明两类早强剂对水泥砂浆后期强度发展无负面影响。XRD和SEM分析均证实,掺两类复合早强剂使水泥水化程度提高,水化产物增多,结构密实度提高。     

纤维热处理对C/C-SiC复合材料剪切强度的影响

对T300碳纤维在真空环境下,在600、900、1200、1500℃进行热处理,用液硅熔渗反应法(liquid silicon infiltration,LSI)制备了不同微观组织结构的C/C-SiC复合材料。采用光电子能谱分析了热处理对纤维表面结构的影响,用光学显微镜和扫描电子显微镜对材料微观形貌进行了观察分析。采用双槽口剪切法(DNS)测试了C/C-SiC复合材料层间剪切强度(interlaminar shear strengh,ILSS),并分析了纤维热处理对材料剪切性能影响的微观机理。结果表明：碳纤维经热处理后,表面化学成分发生变化,氧含量显著降低,改变了碳纤维增强树脂基复合材料(carbon fiber reinforced resin matrix composite,CFRP)先驱体中纤维/树脂界面结合强度,从而在CFRP裂解后形成了具有不同微观结构的C/C预制体,通过液Si对不同微结构的C/C预制体进行熔渗,获得具有不同微观结构的 C/C-SiC复合材料;DNS 测试发现碳纤维热处理能够有效改善 C/C-SiC复合材料的层间剪切强度,主要是由于纤维经热处理后制备的C/C-SiC复合材料中,SiC基体相分布较均匀并包裹在碳纤维周围,导致纤维/基体界面结合强度高。经1500℃热处理纤维增强的C/C-SiC复合材料,其剪切强度为34 MPa,与未处理的相比,ILSS提高了33%。     

Short Exposure to 1% Hydrofluoric Acid to Improve the Repair Bond Strength of Dental Resin Composites

Application of 1% hydrofluoric acid (HFA) to improve the repair bond strength of a microhybrid (Z250; 3 M/ESPE) and a nanofilled dental composite (Supreme XT, 3 M/ESPE) was investigated. Aged composites were etched using 1% HFA for 10, 30, or 60 s. Negative (non-etched) and positive (10% HFA for 60 s) control groups were tested. The surfaces received a layer of a silane and adhesive (Single Bond 2; 3 M/ESPE). Cylinders of fresh composite (n = 15 per group) were built up and a shear bond strength test was carried out after water storage for 24 hr or 6 months. Surface topography was assessed using atomic force microscopy (AFM). For the nanofill at 24 hr, all etching regimens yielded higher bond strengths than the negative control. After 6 months, the negative and positive controls showed lower bond strength than 1% HFA for 30 s. For the microhybrid, the negative control generally showed lower bond strength at 24 hr, while all groups had similar results after 6 months. Only the positive controls showed lower bond strengths after 6 months. AFM analysis showed that the nanofill was more susceptible to acid-etch roughening. In conclusion, exposure to 1% HFA may improve the repair bond strength of dental composites.     

Effect of Different Application Techniques of All-in-One Adhesives on Microtensile Bond Strength to Sound and Caries-Affected Dentin

The aim of this study was to evaluate the microtensile bond strength of two all-in-one self-etch adhesives applied to sound and caries-affected dentin with four different application techniques. Forty extracted third molars with occlusal caries were randomly divided into four groups for G-Aenial Bond and S3 Bond: (1) according to manufacturer's instructions; (2) with acid etching before applying adhesives; (3) doubling adhesive application time; and (4) doubling adhesive coating. Teeth were sectioned to obtain 1-mm- ± 0.2-mm-thick dentin sticks and subjected to a tensile force. For G-Aenial Bond, doubling the time and application of two consecutive coats produced significantly higher strength than that obtained by following manufacturers' instructions and acid etching application to sound dentin. Prior acid etching and application of two consecutive coats to caries-affected dentin generated significantly higher bond strength than that using other techniques. For S3 Bond, there was no significant difference between application techniques in caries-affected dentin. For sound dentin, double-time application of S3 Bond produced significantly higher strength than application according to the manufacturers' instructions. Compared to the application according to manufacturer's instructions, acid etching before applying adhesives, doubling application time, and doubling the coating had a positive effect on bond strength to caries-affected dentin for all-in-one adhesives.     

Bond Strength of Porcelain Bonded to Enamel and Dentin Surfaces Prepared with Different Surface Treatments

Although acid etching is routinely used to condition tooth surfaces, it increases the caries susceptibility of enamel and enhances enamel demineralization; thus the role of alternative surface treatments such as alumina air abrasion and erbium-doped yttrium aluminium garnet (Er:YAG) laser irradiation for tooth conditioning is controversial. This study was undertaken to compare the effects of different conditioning methods on the shear bond strength (SBS) of resin cement on enamel and dentin. Prepared permanent human dentin and enamel samples (N = 210) embedded in clear acrylic resin were conditioned by 37% phosphoric acid etching, 50-µm alumina air abrasion, Er:YAG laser irradiation (120 mJ, 10 Hz, medium short pulse mode), or their combinations. Porcelain laminates were cemented by using photopolymerizing luting composite. SBS was evaluated after thermal cycling (10,000 cycles, 5–55°C) and fracture types (adhesive, cohesive, or mixed) were observed by stereomicroscopy. Data were analyzed by Kruskal–Wallis analysis of variance and followed by Tamhane's test (p < 0.05). Enamel and dentin specimens showed significant differences in SBS (p < 0.000). Er:YAG laser etching presents successful alternatives to acid etching on dentin surfaces; it does not enhance adhesion of the resin cement on enamel surfaces.