Effect of surface conditioning methods on the bond strength of luting cement to ceramics

OBJECTIVES: This study evaluated the effect of three different surface conditioning methods on the bond strength of a Bis-GMA based luting cement to six commercial dental ceramics. METHODS: Six disc shaped ceramic specimens (glass ceramics, glass infiltrated alumina, glass infiltrated zirconium dioxide reinforced alumina) were used for each test group yielding a total number of 216 specimens. The specimens in each group were randomly assigned to one of the each following treatment conditions: (1) hydrofluoric acid etching, (2) airborne particle abrasion, (3) tribochemical silica coating. The resin composite luting cement was bonded to the conditioned and silanized ceramics using polyethylene molds. All specimens were tested at dry and thermocycled (6.000, 5-55 degrees C, 30 s) conditions. The shear bond strength of luting cement to ceramics was measured in a universal testing machine (1 mm/min). RESULTS: In dry conditions, acid etched glass ceramics exhibited significantly higher results (26.4-29.4 MPa) than those of glass infiltrated alumina ceramics (5.3-18.1 MPa) or zirconium dioxide (8.1 MPa) (ANOVA, P<0.001). Silica coating with silanization increased the bond strength significantly for high-alumina ceramics (8.5-21.8 MPa) and glass infiltrated zirconium dioxide ceramic (17.4 MPa) compared to that of airborne particle abrasion (ANOVA, P<0.001). Thermocycling decreased the bond strengths significantly after all of the conditioning methods tested. SIGNIFICANCE: Bond strengths of the luting cement tested on the dental ceramics following surface conditioning methods varied in accordance with the ceramic types. Hydrofluoric acid gel was effective mostly on the ceramics having glassy matrix in their structures. Roughening the ceramic surfaces with air particle abrasion provided higher bond strengths for high-alumina ceramics and the values increased more significantly after silica coating/silanization.     

氧化铝-羟基磷灰石修复兔骨腔隙性骨缺损的CT观察

目的通过CT摄片观察致密型氧化铝-羟基磷灰石人工骨材料修复兔骨腔隙性骨缺损的效果。方法采用放电等离子烧结(SPS,SparkPlasmaSintering)技术制备氧化铝-羟基磷灰石(Al2O3-HA)人工骨,植入兔股骨腔隙性骨缺损模型中,术后1天、12周通过CT摄片,观察人工骨与兔骨结合状况。结果术后12周宿主骨缺损完全愈合。结论SPS技术烧结的氧化铝-羟基磷灰石人工骨具有良好的生物相容性,是一种理想的承重骨人工骨替代材料。     

氧化铝/羟基磷灰石修复兔桡骨缺损模型的手术方法学研究

目的通过对运用两种方法建立氧化铝/羟基磷灰石纳米陶瓷骨替代材料修复兔桡骨缺损模型研究,探讨因手术方式、材料的固定模式等因素对实验建模的影响。方法把20只成年中国家兔随机分为A、B两组,采用不同的术式将双侧桡骨制造成10-14mm长的骨缺损模型,分别植入氧化铝/羟基磷灰石纳米陶瓷A、B两型骨替代材料,术后进行一般情况观察和1、2周X线平片检查。结果术式A的建模成功率为60.0%,术式B建模成功率为89.5%,两者有显著性差异(χ2=4.439,P<0.05)。结论术中创伤小,对兔前臂组织结构破坏少的B术式和具有内固定功能B型材料的组合是良好的建模方式。     

A novel diaphragm-to-housing junction adhesive method: alumina ball milling

An alumina ball milling method was applied to enhance the adhesiveness and smoothness of the diaphragm-to-housing (D-H) junction. The impact produced by the three rotating alumina balls along the meshed junction made the surface of the junction uniform and smooth. The quality of the D-H junction was evaluated by various methods, such as inspection using an optical microscope and a scanning electron microscope, smoothness examination by an atomic force microscope, and measurement of the tensile strength. All the evaluations revealed marked improvements, and the platelet adhesion test revealed that the alumina ball milling method plays an important role in the blood compatibility enhancement of the D-H junction.Part of this paper was presented at the poster session of the ASAIO (2002) meeting     

调整氧化铝内冠轴壁聚合度对全瓷冠强度的影响

目的 探讨在全瓷冠基牙预备轴壁聚合度偏大的情况下,调整氧化铝内冠轴壁聚合度对全瓷冠抗压强度的影响.方法 将离体的上颌左中切牙制备成轴壁内聚12°的基牙预备体,并制作A、B、C组轴壁聚合度(4°、8°、12°)的氧化铝内冠.内冠上堆筑饰面瓷恢复牙冠形态,通过加载实验测试其抗压强度.结果 A组抗压强度最高,A、B组间无统计...     

Effect of different surface treatments on In-Ceram Alumina roughness. An AFM study

Objectives

The aim of this study was to evaluate the influence of different treatments on the surface roughness of In-Ceram Alumina (VITA, Säckingen, Germany).

Methods

The ceramic blocks were polished (4000 grit) and sandblasted (SB) with airborne particle abrasion Al₂O₃; 110 μm particle size; 2.8 bar; 20 s. The following treatments were performed: (1) no treatment; (2) Rocatec System (RC): after SB treatment, sandblasting with silica powder; 30 μm particle size; 2.8 bar; 20 s. (3) Neodymium:yttrium–aluminium–garnet (Nd:YAG) laser (ND) application of graphite powder (stain) on the ceramic surface and Nd:YAG laser irradiation (distance: 1 mm, 100 mJ, 20 Hz, 2 W, and 141.54 J/cm²). (4) Nd:YAG laser plus Rocatec System: after ND treatments, RC was applied. Digital images (20 μm × 20 μm) from the surfaces were obtained by means of an AFM microscope in taping mode (Nanoscope IIIa, Digital Instruments). Roughness was measured in 10 μm × 10 μm boxes. Roughness (R_a) data (nm) were analyzed by one-way ANOVA (p < 0.05).

Results

No differences in ceramic surfaces roughness occurred after any of the tested treatments (p = 0.54).

Conclusions

High-alumina ceramic surface roughness was not increased with any of the tested treatments.     

某铝电公司铝合金项目扩建工程职业病危害预评价

目的识别、分析某铝电公司铝合金项目及配套预焙阳极系统的建设项目在生产过程中可能产生的职业病危害因素。方法采用检查表法与类比法相结合的原则对该建设项目进行评价。结果该项目的选址、总体布局、生产工艺和设备布局、建筑卫生学要求、辅助用室等符合国家有关法规。主要存在氧化铝尘、氟化氢、二氧化硫、噪声、工频电磁场、高温、热辐射、沥青烟等职业病危害因素。类比企业车间粉尘TWA检测,仅铸造车间清包操作位超标2.52倍。该项目属于职业病危害严重的建设项目。结论该项目在生产过程中可能产生的职业病危害是可以预防的,从职业卫生角度分析该项目是可行的。     

人工膝关节表面置换术后的X线学评价

目的；随访调查了ＮＣＵ型ＴＫＡ对术后各假体经时的Ｘ线学变化，比较性评价使用骨水泥固定与非水泥固定ＴＫＡ术后各假体组件的稳定性。方法：１９８９年至１９９５年在ＯＡ和ＲＡ患者中共施行６８例１０３关ＮＣＵ型ＴＫＡ，获得较完整的随访资料６５例９９关节，采用Ｘ线学评价法计测了术后即时最终调查时的ＦＰＡ，ＴＰＡ，ＦＰＴＡ，ＴＰＴＡ，并观察评价了Ｘ线透亮线，假体下沉及无菌性松动等项目。     

Towards long lasting zirconia-based composites for dental implants. Part I: Innovative synthesis,microstructural characterization and in vitro stability

In order to fulfill the clinical requirements for strong, tough and stable ceramics used in dental applications, we designed and developed innovative zirconia-based composites, in which equiaxial α-Al₂O₃ and elongated SrAl₁₂O₁₉ phases are dispersed in a ceria-stabilized zirconia matrix. The composite powders were prepared by an innovative surface coating route, in which commercial zirconia powders were coated by inorganic precursors of the second phases, which crystallize on the zirconia particles surface under proper thermal treatment. Samples containing four different ceria contents (in the range 10.0–11.5 mol%) were prepared by carefully tailoring the amount of the cerium precursor during the elaboration process. Slip cast green bodies were sintered at 1450 °C for 1 h, leading to fully dense materials. Characterization of composites by SEM and TEM analyses showed highly homogeneous microstructures with an even distribution of both equiaxial and elongated-shape grains inside a very fine zirconia matrix.Ce content plays a major role on aging kinetics, and should be carefully controlled: sample with 10 mol% of ceria were transformable, whereas above 10.5 mol% there is negligible or no transformation during autoclave treatment.Thus, in this paper we show the potential of the innovative surface coating route, which allows a perfect tailoring of the microstructural, morphological and compositional features of the composites; moreover, its processing costs and environmental impacts are limited, which is beneficial for further scale-up and real use in the biomedical field.