反复熔铸对牙科烤瓷合金显微结构的影响

目的: 探讨反复熔铸对钴铬、纯钛、钯铜镓、金铂烤瓷合金显微结构的影响。方法: 在真空加氩气保护环境下,将4种烤瓷合金单纯反复熔铸1~3次。每次再熔铸前,烤瓷合金均经过课题组前期研究所得“烤瓷合金再熔铸前最佳处理方法”处理,根据金属显微组织检验方法（GB/T13298-2015）,分别对熔铸前、熔铸1~3次后的烤瓷合金进行研磨、抛光、浸蚀,采用金相显微镜或扫描电镜检测金相显微结构。结果: 随着熔铸次数增加,钴铬烤瓷合金晶粒粗化、晶粒间基质和晶界间化合物增多。纯钛烤瓷合金随熔铸次数增加,晶粒粗化明显。2次熔铸后,晶粒有等轴化倾向,3次熔铸则出现针刺状β相。钯铜镓烤瓷合金在2、3次熔铸后,晶粒结构略有长大。金铂烤瓷合金晶粒结构未随熔铸次数发生明显改变。结论: 反复熔铸显著改变钴铬、纯钛、钯铜镓烤瓷合金的显微结构,建议由厂家回收再利用烤瓷合金废旧料。     

Knochenwachstum in porösen,keramischen Implantaten beim Hund

Zusammenfassung Definiert poröse zylindrische (Radius 2,5 mm) und halbzylindrische (Radius 6,5 mm) Implantate aus resistenter Aluminiumoxidkeramik mit den Porendurchmessern 0,4 bis 0,6 mm, 0,6 bis 0,8 mm, 0,8 bis 1,0 mm und 1,0 bis 1,2 mm wurden in die Tibia von Hunden implantiert. In den Poren bildete sich in zunehmendem Maße Knochengewebe, und nach einer Verweilzeit von 7 Monaten enthielten fast alle Poren vorwiegend Knochen-gewebe. In zylindrischen Implantaten aus Calciumphosphat (Radius 2,5 mm) mit 0,8 bis 1,0 mm Porendurchmesser erfolgte die Knochenbildung innerhalb der zweimonatigen Verweilzeit deutlich schneller als in vergleichbaren Implantaten aus A1203 und in Implantaten aus Calciumphosphat-Calciumaluminat mit 0,8 bis 1,0 mm Porendurchmesser.Zwischen Knochen und Calciumphosphat-Implantat entstand eine direkte Verbindung ohne erkennbaren Bindegewebssaum. Zwischen Knochen und Al₂O₃-Keramik hingegen war ein schmaler, zwischen Knochen und Calciumphosphat-Calciumaluminat ein vergleichsweise breiter Bindegewebssaum vorhanden.Die Gewebeverträglichkeit war bei Calciumphosphat optimal. In der Umgebung von Al₂O₃ traten nach mehrwöchiger Verweilzeit geringgradige Fremdkörperreaktionen auf, in der Umgebung von Calciumphosphat-Calciumaluminat nach 2 Monaten starke Fremdkörperreaktionen.

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Bone growth in porous ceramic implants in dogs

Summary Cylindrical (radius 2.5 mm) and semicylindrical (radius 6.5 mm) implants of nondegradable alumina of defined porosity (pore diameters 0.4 to 0.6 mm, 0.6 to 0.8 mm, 0.8 to 1.0 mm and 1.0 to 1.2 mm) were implanted in the tibiae of dogs. The pores were filled to an increasing extent with bone tissue, so that after a period of seven months almost all the pores contained bone tissue. Cylindrical implants (radius 2.<5 mm) of calcium phosphate with 0.8 to 1.0 mm pore diameter were more rapidly filled with bone tissue within 2 months than implants of A1₂O₃ and of calcium phosphate-calcium alumina with 0.8 to 1.0 mm pore diameter.Direct contact was established between the calcium phosphate implants and new bone, i.e. without any seam of connective tissue. Between the bone and the Al₂O₃ ceramic on the other band, there was a narrow seam of connective tissue, and a relatively broad seam was observed between the bone and the calcium phosphate-calcium alumina implant.The calcium phosphate implants had an excellent tissue compatibility. In the vicinity of the Al₂O₃ implants minor, and in the case of the calcium phosphate-calcium alumina implants major foreign body reactions occurred after 2 months.

Die Untersuchungen sind Teil einer Forschungsarbeit, die das Battelle-Institut, Frankfurt a. M., im Auftrag des Bundesministeriums für Forschung und Technologie durchführt.     

不同陶瓷托槽与金属弓丝间摩擦力的研究

目的 研究不同类型陶瓷托槽与金属弓丝间的摩擦力,为临床应用及研制摩擦性能优良的陶瓷托槽提供参考.方法 选取正畸临床上常用的三种陶瓷托槽作为研究对象,一种金属托槽作为对照组.利用MTSTytron250微力实验机检测托槽与三种金属弓丝在不锈钢丝结扎下的最大静摩擦力和平均动摩擦力.结果 金属托槽与不锈钢圆丝间的最大静摩...     

Esthetic and functional consideration in restoring endodontically treated teeth

The selection of the best restoration for an endodontically treated tooth in the aesthetic zone depends on strength and the ability to recreate the form, function, and aesthetics of the natural tooth. The increased use of all-ceramic materials is a result of improved ceramic materials and adhesive systems. However, the advent of the current variety of translucent ceramic systems makes the shade of the abutment important in achieving the desired aesthetic outcome. This article discusses the different types of posts used in the restoration.     

两种底板设计的国产陶瓷托槽拉伸粘接强度的研究

目的评价两种不同底板设计的国产多晶体氧化铝陶瓷托槽拉伸粘接强度是否满足临床使用的需要。方法实验组为国产沟槽底板（3条横沟）和网格底板（3×3网格）陶瓷托槽,对照组为临床常用多晶体氧化铝陶瓷托槽CrystalineIV。30颗离体下颌双尖牙随机分为3组,每组10颗,使用37%液体磷酸和京津釉质粘接剂,分别粘接上述三种托槽,在0.9%生理盐水中室温保存24h。使用WDW3050型微机控制电子万能试验机检测拉伸粘接强度。托槽脱落后记录粘接剂残留指数,陶瓷托槽的折断数目和釉质表面出现肉眼可见缺损的牙齿数目。结果国产沟槽底板陶瓷托槽的拉伸粘接强度显著低于网格底板和CrystalineIV,后两者间的差异无显著性意义。三种陶瓷托槽的主要去除部位均在粘接剂内,所有样本未出现陶瓷托槽折断和肉眼可见的釉质缺损。结论国产沟槽底板陶瓷托槽不能获得临床所需的拉伸粘接强度,网格底板的陶瓷托槽更具开发前景。     

80件CEREC3全瓷修复体的临床效果回顾分析

目的探讨应用数字椅旁全瓷修复系统（CEREC3）进行椅旁即刻全瓷修复的临床效果。方法采用数字椅旁全瓷修复系统（CEREC3）共完成75例患者的全瓷修复体80件。追踪观察1.0～1.5年,询问患者对全瓷修复的主观感受,记录全瓷修复体的变化等。回顾分析80件全瓷修复的临床疗效。结果患者对CEREC3全瓷修复体的主观评价满意率为95.00%（76/80）,崩瓷率为3.75%（3/80）。结论采用CEREC3,能制作出高质量并且具有天然牙色的全瓷修复体,方便快捷,临床效果满意。     

An effect of immediate dentin sealing on the shear bond strength of resin cement to porcelain restoration

PURPOSE

The aim of this study was to determine differences in shear bond strength to human dentin using immediate dentin sealing (IDS) technique compared to delayed dentin sealing (DDS).

MATERIALS AND METHODS

Forty extracted human molars were divided into 4 groups with 10 teeth each. The control group was light-cured after application of dentin bonding agent (Excite® DSC) and cemented with Variolink® II resin cement. IDS/SE (immediate dentin sealing, Clearfil™ SE Bond) and IDS/SB (immediate dentin sealing, AdapterTM Single Bond 2) were light-cured after application of dentin bonding agent (Clearfil™ SE Bond and Adapter™ Sing Bond 2, respectively), whereas DDS specimens were not treated with any dentin bonding agent. Specimens were cemented with Variolink® II resin cement. Dentin bonding agent (Excite® DSC) was left unpolymerized until the application of porcelain restoration. Shear strength was measured using a universal testing machine at a speed of 5 mm/min and evaluated of fracture using an optical microscope.

RESULTS

The mean shear bond strengths of control group and IDS/SE group were not statistically different from another at 14.86 and 11.18 MPa. Bond strength of IDS/SE group had a significantly higher mean than DDS group (3.14 MPa) (P < .05). There were no significance in the mean shear bond strength between IDS/SB (4.11 MPa) and DDS group. Evaluation of failure patterns indicates that most failures in the control group and IDS/SE groups were mixed, whereas failures in the DDS were interfacial.

CONCLUSION

When preparing teeth for indirect ceramic restoration, IDS with Clearfil™ SE Bond results in improved shear bond strength compared with DDS.     

The effect of different surface treatments on bond strength between leucite reinforced feldspathic ceramic and composite resin

Objectives

The aim of this study was to evaluate the effect of different surface treatments on the microtensile bond strength between a leucite reinforced glass–ceramic and composite resin.

Methods

Leucite reinforced ceramic blocks (n = 24) were constructed using the hot pressing technique. The blocks were assigned to 4 groups, which received the following surface treatments: G1: hydrofluoric (HF) acid and silane; G2: silane alone; G3: HF acid and silane then dried with warm air (100 °C); G4: silane alone then dried with warm air (100 °C). Unfilled resin was applied, followed by composite resin. Specimens were prepared and loaded in tension to determine the microtensile bond strength. Failure modes were classified by stereo- and scanning electron microscopy (SEM). Data was analysed using Kruskal–Wallis test followed by the Dunn's multiple range test.

Results

The groups including the warm air step (G3 and G4) achieved a significantly stronger adhesion than G1 and G2. Pre-treatment of the surface with hydrofluoric acid in G1 resulted in significantly higher bond strength than G2. Failures were mostly cohesive in the luting resin for G1, G3 and G4 and mainly adhesive at the ceramic–resin interface in G2.

Conclusions

The method of application of silane to the ceramic surface can have a significant influence on the adhesion between the ceramic restoration and the resin cement. Enhancing the condensation reaction by drying the silane with a 100 ?C warm air stream significantly improved the microtensile bond strength, possibly eliminating the need for the hydrofluoric acid etching step.     

Accuracy of additively manufactured zirconia four-unit fixed dental prostheses fabricated by stereolithography,digital light processing and material jetting compared with subtractive manufacturing

ObjectiveTo evaluate the manufacturing accuracy of zirconia four-unit fixed dental prostheses (FDPs) fabricated by three different additive manufacturing technologies compared with subtractive manufacturing.MethodsA total of 79 zirconia FDPs were produced by three different manufacturing technologies, representing additive (one stereolithography [aSLA] and one material jetting [aMJ] device, two digital light processing [aDLP1/aDLP2] devices) and subtractive manufacturing (two devices [s1/s2]), the latter serving as references. After printing, additively manufactured FDPs were debound and finally sintered. Subsequently, samples were circumferentially digitized and acquired surface areas were split in three Regions Of Interest (ROIs: inner/outer shell, margin). Design and acquired data were compared for accuracy using an inspection software. Statistical evaluation was performed using the root mean square error (RMSE) and nonparametric Kruskal-Wallis method with post hoc Wilcoxon-Mann-Whitney U tests. Bonferroni correction was applied in case of multiple testing.ResultsRegardless the ROI, significant differences were observed between manufacturing technologies (P < 0.001). Subtractive manufacturing was the most accurate with no significant difference regarding the material/device (s1/s2, P > 0.054). Likewise, no statistical difference regarding accurary was found when comparing s2 with aMJ and aSLA in most ROIs (P > 0.085). In general, mean surface deviation was< 50 µm for s1/s2 and aMJ and< 100 µm for aSLA and aDLP2. aDLP1 showed surface deviations> 100 µm and was the least accurate compared to the other additive/subtractive technologies.SignificanceAdditive manufacturing represents a promising set of technologies for the manufacturing of zirconia FDPs, but not yet as accurate as subtractive manufacturing. Methodological impact on accuracy within and in between different additive technologies needs to be further investigated.