Evaluation of an experimental dental porcelain

The aim of this study was to evaluate fracture toughness, hardness, ceramic/metal bond strength and microstructure of experimental dental porcelain and compare it with commercial type. Specimens of specific dimensions were prepared. Fracture toughness was assessed by a three-point bending test. The Vickers hardness was measured using a microhardness tester. The ceramometal bond strength was measured using a universal testing machine. The load was applied at the porcelain/metal interface via a chisel edged blade with a crosshead speed of 2.0 mm/min until fracture. The polished specimens of dental porcelain were chemically etched and the microstructure was analyzed with a scanning electron microscope. The results showed comparable fracture toughness and bond strength for both materials, while the experimental porcelain exhibited higher hardness. The experimental porcelain showed uniform cohesive failure while the commercial type showed mixed mode of failure. The microstructure of the experimental porcelain was tetragonal leucite crystals dispersed randomly in a glass matrix. The leucite crystals exist in two forms, acicular and rod like structures. It was concluded that the experimental porcelain has adequate fracture toughness and ceramic/metal bond strength that can resist the rapid crack propagation and its consequent catastrophic failure, which indicates a material serviceability in the oral cavity.     

Characteristics and porcelain bond strength of (Ti,Al)N coating on dental alloys

The effect of a novel titanium-aluminum nitride film, or (Ti,Al)N film, on the bond strength between a dental porcelain and two nickel-based dental alloy substrates was investigated. A thin layer of (Ti,Al)N film was deposited on flat metal samples using a reactive radio-frequency sputtering method. A uniform thickness of porcelain was applied to the film- coated metal samples. Metal-ceramic specimens were subjected to three-point bending, and failure loads were recorded. Bond strengths between the porcelain and (Ti,Al)N-coated metal alloys ranged from 159.0 +/- 11.7 N to 278.0 +/- 12.3 N. These values were significantly greater (p< 0.05) than bond strengths recorded for control samples that did not incorporate the (Ti,Al)N film. An electron probe microanalyzer with a line profile mode was used to characterize the interface between the (Ti,Al)N film and the porcelain. Results of this investigation suggest that the (Ti,Al)N film (1) increases the flexural bond strength between dental porcelain and nickel-based alloy substrates by permitting elemental diffusion, (2) interferes with the surface oxide formation that characteristically originates from the nickel-based metal alloy substrate, and (3) provides an appropriate oxide layer for porcelain application.     

应用烤瓷套冠修补崩瓷冠桥的可行性研究

背景：有临床科室采用瓷套冠方法对烤瓷冠桥崩瓷患者进行崩瓷修补,取得了不错效果。 目的：检测烤瓷套冠单冠黏结强度的大小,判断烤瓷套冠在修补崩瓷临床应用中的可行性,同时观察烤瓷套冠修复崩瓷过程中喷砂处理和硅烷偶联剂处理金属黏结表面对其黏结强度的影响。 方法：用失蜡法铸造相同规格钴铬合金套冠,选择表面无气孔、无铸造缺陷的试件20件,常规打磨,超声清洗后随机分为4组,分别进行喷砂处理、硅烷偶联剂处理及喷砂+硅烷偶联剂处理,以未作任何处理的为对照组。将处理后的试件用聚羧酸锌水门汀进行黏结,采用万能力学测试仪测试拉伸强度。 结果与结论：对照组、喷砂组、硅烷偶联剂组、喷砂+硅烷偶联剂组的拉伸强度分别为(0.68±0.04),(1.00±0.02),(1.31±0.08),(1.09±0.04) kN,各组间比较差异有显著性意义(P均< 0.01)。对照组金属表面光滑,可见一些不规则的表浅细小纹络;喷砂组金属表面呈现出不规则的鳞状突起,有利于黏结剂的渗入;硅烷偶联剂组金属表面表现为规则的蜂窝状结构,有利于黏结剂的嵌合;喷砂+硅烷偶联剂组金属表面表现为大小不等的金属突起,金属表面粗糙,利于黏结。说明喷砂和硅烷偶联剂均能显著提高金属套冠间的黏结强度,并且硅烷偶联剂处理效果最好,其次为喷砂联合硅烷偶联剂处理。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：     

Effects of airborne-particle abrasion, sodium hydroxide anodization, and electrical discharge machining on porcelain adherence to cast commercially pure titanium

The aim of this study was to determine the effect of airborne-particle abrasion (APA), sodium hydroxide anodization (SHA), and electrical discharge machining (EDM) on cast titanium surfaces and titanium-porcelain adhesion. Ninety titanium specimens were cast with pure titanium and the alpha-case layer was removed. Specimens were randomly divided into three groups. Ten specimens from each group were subjected to APA. SHA was applied to the second subgroups, and the remaining specimens were subjected to the EDM. For the control group, 10 specimens were cast using NiCr alloy and subjected to only APA. Surfaces were examined by using scanning electron microscope and a surface profilometer. Three titanium porcelains were fused on the titanium surfaces, whereas NiCr specimens were covered with conventional porcelain. Titanium-porcelain adhesion was characterized by a 3-point bending test. Statistical analysis showed that the porcelain-metal bond strength of the control group was higher than that of the titanium-porcelain system (p < 0.05). There were no significant differences between the bond strengths of titanium groups (p 0.05), except the bond strengths of Noritake Super Porcelain TI-22 groups on which APA and SHA were applied (p < 0.05). SHA and EDM as surface treatment did not improve titanium-porcelain adhesion when compared to APA.     

Effect of an acidulated fluoride etchant on bonding between titanium and two luting materials

Adhesive bonding between resin and titanium is useful for resin-bonded prostheses. The purpose of this study was to investigate the efficacy of an etchant, consisting of ammonium hydrogen fluoride (AHF) and phosphoric acid (PA), in titanium bonding. Cast specimens of commercially pure titanium were air-abraded with alumina and etched for 30 s, after which a primer (ALP) was applied. An acrylic rod was bonded to the specimen with one of the two luting agents being examined (Super-Bond QUICK and Panavia F2.0). Shear bond strengths were determined following 10,000 thermocycles. When Panavia F2.0 was applied, neither the etchant nor the ALP primer showed significant effect on bond strength. The postthermocycling bond strength of Super-Bond QUICK was significantly improved with the use of an etchant and ALP primer. Although microscopic observation revealed that considerable numbers of submicron pits were created on the specimens etched using AHF with PA, no significant difference in bond strength was detected in the application of AHF, with or without PA. The present findings suggested that the improved bonding durability was due to the micromechanical retention between the resin and the microscopically roughened titanium surface.     

Interface reactions between machinable bioactive glass-ceramics and bone

A new biomaterial for bone substitution, a "machinable bioactive glass-ceramic" has been developed. The material contains two main crystal phases, mica and apatite, and is therefore machinable and bioactive. It has the advantage to be workable by the surgeon, if necessary, during operation. The preparation method of this glass-ceramic is described. Different types of the material can be produced in dependence of the composition, nucleation, and crystallization of the basic glass. In vivo and in vitro investigations showed a characteristic solubility of the material. A Ca-phosphate-rich interface layer with apatite crystals (from the basic glass-ceramic) and a thickness of about 5-10 micrometers grows as solid-state reaction between glass-ceramic and bone. This interface reaction is interpreted as a chemical process which includes a slight solubility of the glass-ceramic and a solid state reaction between the stable apatite crystals in the glass-ceramic and the bone.     

Shear bond strength of a hot pressed Au-Pd-Pt alloy-porcelain dental composite

Objectives: The purpose of this study was to evaluate the effect of hot pressing on the shear bond strength of a Au-Pt-Pd alloy-porcelain composite. Methods: Several metal-porcelain composites specimens were produced by two different routes: conventional porcelain fused to metal (PFM) and hot pressing. In the latter case, porcelain was hot pressed onto a polished surface (PPPS) as well as a roughened one (PPRS). Bond strength of all metal-porcelain composites were assessed by the means of a shear test performed in a universal test machine (crosshead speed: 0.5?mm/min) until fracture. Interfaces of fractured specimens as well as undestroyed interface specimens were examined with optical microscope, stereomicroscope, Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS). The data were analyzed using one-way ANOVA followed by Tuckey's test (p<0.05). Results: Shear bond strength of conventional PFM specimens were in line with the upper range of literature data (83±14?MPa). Hot pressing proved to significantly increase bond strength between metal and porcelain (p<0.05). For both polished and roughened surface the shear bond strength values for hot pressed specimens were 120±16?MPa and 129±5?MPa, respectively, which represents an improvement of more than 50% relatively to a conventional PFM. Roughened surface did not have a significant effect on bond strength of hot pressed specimens (p>0.05). Significance: This study shows that it is possible to significantly improve metal-porcelain bond strength by applying an overpressure during porcelain firing.     

Apatite formation on the surface of Ceravital-type glass-ceramic in the body.

Previous studies on surface structural changes in vitro as well as in vivo of bioactive A-W-type glass-ceramics and Bio-glass-type glasses showed that the essential condition for glasses and glass-ceramics to bond to living bone is formation of a bonelike apatite layer on their surfaces in the body. Gross et al., however, had explained the bone-bonding mechanism of Ceravital-type apatite-containing glass-ceramic without mentioning formation of the surface apatite layer. In the present study, apatite formation on the surface of one of Ceravital-type glass-ceramics was investigated in vitro as well as in vivo. An apatite-containing glass-ceramic of the composition Na2O 5, CaO 33, SiO2 46, Ca(PO3)2 16 wt%, which was named KGS by Gross et al., was soaked in an acellular simulated body fluid which had ion concentrations almost equal to those of the human blood plasma. The same kind of glass-ceramic was implanted into a rabbit tibia. Thin-film x-ray diffraction, Fourier transform infrared reflection spectroscopy, and scanning electron microscopic observation of the surfaces of the specimens soaked in the simulated body fluid showed that Ceravital-type glass-ceramic also forms a layer of carbonate-containing hydroxyapatite of small crystallites and/or a defective structure on its surface in the fluid. Electron probe x-ray microanalysis of the interface between the glass-ceramic and the surrounding bone showed that a thin layer rich in Ca and P is present at the interface. These findings indicated that Ceravital-type glass-ceramics also form the bonelike apatite layer on its surface in the body and bond to living bone through the apatite layer.     

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.     

Titanium-porcelain system. Part III: effects of surface modification on bond strengths

During its development, titanium was found to be incompatible with conventional dental porcelains due to weak bond strength brought about by titanium's high yet oxidative nature. In spite of the development of new low-fusing porcelains designed for titanium application, previous studies have shown that sandblasting pre-treatment prior to porcelain application led to weakening of the metal-ceramic bonding. The aim of this study is to search for an effective alternative to sandblasting for the surface treatment of the titanium substrate in the titanium-porcelain system. The research evaluated the bond strength of 165 samples of titanium-porcelain systems divided into 11 groups. A three-point flexural bend test was conducted to measure the force required to fracture the porcelain on the titanium substrate. A correlation between the type of surface treatment and the bond strengths of each group was evaluated if it resulted to significant differences. The study found significantly differences in the energy-to-break of titanium-porcelain systems treated with hydrochloric acid and sandblasting compared with the control group. The bonds strength achieved by the titanium-porcelain system when treated with hydrochloric acid is comparable to that of conventional metal-ceramic alloy system. Hydrochloric acid treatment of the titanium substrate is a promising alternative to sandblasting for the surface treatment of the titanium substrate in the titanium-porcelain system.     

Bond strength of binary titanium alloys to porcelain

The purpose of this study was to investigate the bond strength between porcelain and experimental cast titanium alloys. Eleven binary titanium alloys were examined: Ti-Cr (15, 20, 25 wt%), Ti-Pd (15, 20, 25 wt%), Ti-Ag (10, 15, 20 wt%), and Ti-Cu (5, 10 wt%). As controls, the bond strengths for commercially pure titanium (KS-50, Kobelco, Japan) and a high noble gold alloy (KIK, Ishifuku, Japan) were also examined. Castings were made using a centrifugal casting unit (Ticast Super R, Selec Co., Japan). Commercial porcelain for titanium (TITAN, Noritake, Japan) was applied to cast specimens. The bond strengths were evaluated using a three-point bend test according to ISO 9693. Since the elastic modulus value is needed to evaluate the bond strength, the modulus was measured for each alloy using a three-point bend test. Results were analyzed using one-way ANOVA/S-N-K test (alpha = 0.05). Although the elastic moduli of the Ti-Pd alloys were significantly lower than those of other alloys (p = 0.0001), there was a significant difference in bond strength only between the Ti-25Pd and Ti-15Ag alloys (p = 0.009). The strengths determined for all the experimental alloys ranged from 29.4 to 37.2MPa, which are above the minimum value required by the ISO specification (25 MPa).     

Micromechanical versus chemical bonding between CoCr alloys and methacrylate resins

INTRODUCTION: As adhesive systems for bonding to metals have developed in dentistry, considerable importance is attached to the preparation of the metal alloy for both mechanical and chemical bonding. Different grit sizes when sandblasting Cobalt Chromium (CoCr) will provide a different three-dimensional surface for bonding. Previous reports have shown that 4-Methacryloyloxyethyl trimellitic anhydride (4-Meta) resins offer high bond strengths to CoCr alloy, with various surface preparations providing varying bond strengths. The relevance of this to bond strength was assessed. Objectives: The aim of the study was to evaluate the importance of grit size of alumina in the preparation of CoCr alloy and to determine the effect on the tensile bond strength of four different acrylic resins to the CoCr alloy. METHODS: Ten specimens were prepared within each group of four resins. Four grit sizes were assessed, 50, 110, 250 microm, and a range from 180 to 330 microm. The specimens were tested both within one day of production after storing at 37 degrees C in phosphate-buffered saline for seven days and after thermocycling. RESULTS: Grit size resulted in a change in average contact surface area available for bonding. A significant difference (p < 0.01) existed in bond strengths between each of the materials, but no significant difference (p = 0.0673) was determined when different grit sizes were included. SIGNIFICANCE: It was concluded that grit size determined the available contact surface area of CoCr alloy for bonding but did not determine the bond strength that could be achieved between acrylic resins and CoCr alloy as a result of the poor adaptation of the resin to the complex surface topography.     

A new glass-ceramic for bone replacement: evaluation of its bonding to bone tissue

Glass powders (350 mesh) of the composition MgO, 4.6; CaO, 44.9; SiO, 34.2; PO, 16.3; CaF, 0.5 in weight ratio were compacted, heated to 1050 degrees C at a rate of 5 degrees C/min and kept at 1050 degrees C for 2 h. The resultant glass-ceramic having oxyapatite, fluoroapatite, and wollastonite crystals showed high bending and compressive strengths of 157 and 1060 MPa, respectively. The biocompatibility and bonding ability of this new glass-ceramic to the bone tissue was evaluated using rabbit tibial bones, and the failure load to break the bonding of several ceramics (the new glass-ceramic, dense hydroxyapatite, 45S5 Bioglass, alumina-ceramic) to bone tissues was measured. The new glass-ceramic showed tight bonding to bone comparable with dense hydroxyapatite, and in 25 weeks its load was 70% of that of bone tissue.     

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.     

Pyruvic acid as an etching agent in clinical dentistry

The objective of this study was to evaluate the use of pyruvic acid as an alternative etching agent to phosphoric acid (H3PO4). Solutions containing 5, 10, 15, 20, 25, and 30 m/m % pyruvic acid and 50% m/m H3PO4 were prepared. The tensile bond strengths of a composite resin to enamel surfaces etched with the respective etching agents were determined. The rates of etching of enamel surfaces by each of the etching solutions were evaluated. Unground and polished enamel surfaces were etched with the respective etching solutions and the surfaces examined by scanning electron microscopy. The tensile bond strengths of the resin to enamel surfaces etched with 10-30% pyruvic acid exceeded those obtained on enamel surfaces etched with 50% H3PO4. The rates of etching of all the pyruvic acid solutions were significantly less than of H3PO4. Well-defined etching patterns were observed on the enamel surfaces etched with all the etching solutions. The results of this laboratory study suggest that pyruvic acid may be a suitable alternative to phosphoric acid as an etching agent in clinical dentistry.     

The effect of a silane coupling agent on the bond strength of bone cement and cobalt-chrome alloy

Debonding of the cement-implant interface has been hypothesized to be the leading initial indicator of failed total hip prostheses. Many attempts have been made to increase the bond strength of this interface by precoating the implant, increasing the implant's surface roughness, and creating macro-grooves or channels on the implant. However, each of these approaches introduces new complications. This study introduces a unique silane coupling agent used to chemically bond the bone cement to the implant. Cylindrical cobalt-chrome samples were treated with the silane coupling agent, bonded to polymethylmethacrylate, and pushed out to failure. The mean shear strengths were compared to the failure strengths of untreated samples. Half of the specimens were tested immediately following cement curing, and the other half were tested after immersion in saline solution for 60 days. The mean shear strength of the silane-coated samples ranged from 18.2 to 24.1 MPa, and the mean shear strength of the uncoated samples ranged from 7.6 to 15.0 MPa. The increase in strength following silane coating noted in this study may increase the longevity of the implant by decreasing debonding at the interface and, therefore, subsequent failure due to loosening.     

添加剂对可切削生物微晶玻璃结构的影响

本研究分析了ZnO、Fe2O3和ZrO2添加剂对KO-MgO-CaO-SiO2-P2O5-F系统可切削微晶玻璃的结构和性能的影响,并初步探讨了添加剂影响的机理.     

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。     

Microperoxidase primer promotes adhesion of butylborane-polymerized resin to dentin

The purpose of this study was to investigate the effect of dentin primers containing microperoxidase (MP-11) with 2-hydroxyethyl methacrylate (HEMA) on the bond strength between a tri-n-butylborane-initiated self-polymerizing resin and dentin. Bovine dentin surfaces were etched with 10 wt % phosphoric acid, primed, and then bonded with stainless steel rods. Tensile bond strength after 24 h of storage in water was significantly influenced by both MP-11 and HEMA. Groups with no MP-11 showed the lowest values. Without HEMA, the bond strengths of groups using 0.01, 0.1, and 1.0 micromol/g MP-11 were statistically identical, and also greater than that of the no MP-11 control. In the presence of HEMA, the bond strength was significantly enhanced with an increasing concentration of MP-11. The highest bond strength of 29.0 MPa was obtained with aqueous HEMA primer, containing 1.0 micromol/g MP-11. Microscopic observation showed the formation of a hybrid layer at the bonded interface. Polymerization of the resin was significantly accelerated with the MP-11 primer. In conclusion, MP-11 has a potential for adhesive bonding promoter between the resin and the demineralized dentin surface.     

Bonding characteristics of newly developed all-in-one adhesives

This study evaluated the microtensile bond strength and the interfacial morphology of newer adhesives. The occlusal surfaces of extracted teeth were ground flat for random allocation to four equal groups. Resin composite was bonded to each surface using either Clearfil SE Bond [SEB], Clearfil Protect Bond [PB], G-Bond [GB], or an experimental adhesive, SSB-200 [SSB]. After storage for 24 h in water at 37 degrees C, they were sectioned into beams (cross-sectional area 1 mm(2)) for microtensile bond strength testing (muTBS) at a crosshead speed of 1 mm/min. The load at failure of each was recorded; the data were analyzed by one-way ANOVA and Games Howell tests. The surfaces of the fractured specimens were observed using SEM. For the ultra-morphology of the interface, the occlusal surfaces of four more teeth were prepared as before and a thin layer of flowable resin composite was bonded to each surface using one of the four adhesives.The mean muTBS ranged from 39.68 MPa (GB) to 64.97 MPa (SEB). There were no statistical differences between SEB and SSB, or between PB and GB (p > 0.05). The muTBS of SEB and SSB were significantly greater than that of PB and GB (p < 0.05). SEMs of the fractured surfaces revealed a mixed (cohesive/interfacial) failure. TEM examination highlighted differences in the hybrid layer; SEB had a thicker layer than the others. In conclusion, the newer all-in-one adhesives produced a thin hybrid layer but varied in their bond strengths. The 2-step self-etching adhesives do not necessarily produce higher bond strengths than that of the all-in-one systems.