不同包埋材料对铸钛适合性的影响

目的比较不同包埋材料对铸钛适合性的影响。方法制作10个统一规格的全冠蜡型,一组用铸钛专用包埋料(T-InvestC &     

液相沉积涂层对纯钛烤瓷修复体边缘适合性的影响

目的:研究液相沉积纯钛表面纳米二氧化硅涂层对烤瓷修复体边缘适合性的影响。方法:用纯钛在统一规格的基牙预备代型上制作铸造基底冠28个,按照表面处理与否、烤瓷与否两因素两水平随机平分为4组,各组试件经过处理后用同一种粘结剂粘固于代型上,环氧树脂包埋后沿纵轴切开,测各组试件边缘间隙。结果:涂层烤瓷组边缘间隙(94.57±7.86μm)小于烤瓷组边缘间隙(109.13±11.28μm),其差异有统计学意义(P<0.05),涂层组边缘间隙(81.43±6.49μm)与对照组边缘间隙(74.53±5.60μm)的差异无统计学意义(P>0.05)。结论:通过液相沉积处理可提高纯钛烤瓷修复体的边缘适合性。     

3D打印多单位固定桥蜡型熔模基底冠适合性研究

［摘要］目的 分析与探讨3D打印制作多单位固定桥基底冠熔模蜡型的适合性。方法 统一制作相同前牙6个单位固定桥模型50个, 随机分成两组,其中实验组25个,对照组25个。实验组用3D打印制作基底冠树脂蜡型,对照组用传统手工浸蜡方式制作基底冠蜡型。采用扫描电镜比较基底冠与模型的密合性,每个模型取4点,分别为固定桥两端基牙的唇侧、舌侧边缘,同时对两组金属基底冠就位与外形修整技师所耗时间进行比较。 结果 3D打印制作的多单位前牙固定桥其基底冠的稳定性、适合性均优于传统手工浸蜡法,并可以显著缩短技师操作时间。 结论 3D打印制作固定桥熔模蜡型具有良好的适合性和稳定性,值得在口腔修复工艺中应用与推广。     

口腔铸钛包埋料的研制

目的:对自行研制的铸钛包埋料的性能、铸钛全冠精度及钛铸件反应层结构进行检测和分析。方法:对包埋料凝固膨胀、热膨胀和抗拉强度及铸钛全冠间隙值进行测量,并利用金相显微镜、扫描电镜观察钛铸件反应层结构,利用能谱分析仪检测包埋料中的元素在钛铸件表面的分布。结果:自行研制的铸钛包埋料凝固膨胀为0.19%,铸模温度200℃时热膨胀0.58%,抗拉强度为0.31MPa;其铸钛全冠颈缘间隙值颊舌向为0.040mm±0.002mm,近远中向为0.033mm±0.003mm;钛铸件反应层厚度为50μm,其结构由外向内分为5层:烧结层、α层、富硅层、针状结晶层、钛基体。结论:自行研制的铸钛包埋料各项性能优良,铸钛全冠精度达到ADA25-40μm的国际标准;磷酸盐包埋料中加入适当比例的ZrO2可降低钛铸件反应层厚度。     

不同厚度纯钛基底冠适合性的比较研究

目的 探讨纯钛基底冠厚度对钛烤瓷冠适合性的影响.方法 在统一规格树脂基牙模型上制作厚度分别为0.3、0.5、0.7 mm的纯钛基底冠试件各10个,共30个,分为6组,每组5个.又按饰瓷与否,分为不饰瓷和饰瓷两类,即0.3、0.5、0.7 mm纯钛基底冠不饰瓷试件3组;0.3、0.5、0.7 mm纯钛基底冠饰瓷试件3组.所有试件黏固于代型上,测量冠与代型的垂直边缘间隙.而后自凝树脂包埋,唇舌向片切,测量冠与代型的绝对边缘间隙及内间隙.结果 垂直边缘间隙、唇侧中点绝对边缘间隙、舌侧中点绝对边缘间隙、轴壁内间隙及切端内间隙在3组不同厚度纯钛基底冠不饰瓷试件间的差异无统计学意义.基底冠饰瓷试件中,0.7 mm组纯钛基底冠饰瓷试件在垂直边缘间隙和唇侧中点绝对边缘间隙同0.3、0.5mm组纯钛基底冠饰瓷试件的差异具有统计学意义(P＜0.05);舌侧中点绝对边缘间隙、轴壁内间隙及切端内间隙在3组不同厚度纯钛基底冠饰瓷试件间均无明显差异.结论 0.3、0.5、0.7 mm厚铸造纯钛基底烤瓷冠适合性基本符合临床要求,其中纯钛基底冠厚度为0.5mm最佳.     

激光焊接多单位固定桥精度的研究

目的：比较激光焊接和整铸的多单位非贵金属烤瓷合金固定桥精度,探讨激光焊接是否能改进多单位固定桥粗度,为临床应用提供依据。方法：分别制作整铸和激光焊接４单位ＣＷ＝ＰＡ烤瓷合金固定桥,分别就位于金属模具,观察就位情况、测试边缘间隙、外形尺寸即近远中桥长线距变化。结果：（１）整铸桥由于铸造变形而不能完全就位;（２）焊接桥的边缘间隙是７４μｍ,符合临床适合性标准,近远中桥长线距比整铸桥明显接近于金属模具（     

非贵金属烤瓷合金整铸固定桥的适合性研究

采用 CW—PA(Ni-Cr-Nb)烤瓷合金和 HCAEST(?)磷酸盐结合系包埋料,比较有圈包埋与无圈包埋两种包埋方法和蜡型立即包埋与存放24小时后包埋两种蜡型存放时间,考察三单位金属烤瓷固定桥整铸支架的适合性。结果,在本实验条件下,使用非贵金属烤瓷合金制作的整铸固定桥适合性较差;有圈包埋与无圈包埋之间无统计差异;蜡型不存放与存放24小时之间基本无统计差异;表明铸件的变形是不可避免的,这与固定桥的特殊形状有密切关系。     

饰瓷对不同材料基底冠边缘适合性的影响

目的:比较金合金、纯钛、镍铬合金基底冠饰瓷前后的冠边缘适合性的变化以及临床意义。方法:在按统一标准机加工预备的树脂基牙模型上分别制作3组共24个全冠蜡形,严格按金合金、纯钛以及镍铬合金3种材料的要求分别进行铸造。对所得铸件在就位完全后,分别测量基底冠的颊侧、远中、腭侧以及近中边缘中点至基牙预备终止线的垂直距离,然后分别以相匹配的瓷粉饰瓷,再测量上述4点,得到饰瓷后的边缘间隙数据。以金合金组为对照组,纯钛组和镍铬合金组为实验组,用SAS统计软件对测量所得数据进行统计学分析。结果:金合金、纯钛以及镍铬合金各组饰瓷后4个点位的边缘间隙较饰瓷前均有明显的增大,各组差值有统计学差异,其中纯钛组4点间隙差值明显小于镍铬合金组和金合金组,而镍铬合金组与金合金组之间4点的间隙差值无明显差异。以上3组的饰瓷后的各点边缘间隙均小于120μm。结论:饰瓷对纯钛基底冠边缘适合性的影响最小。3组基底冠饰瓷后的冠边缘适合性均在临床可接受的范围内。     

不同包埋材料对Ti-6Al-7Nb合金铸造全冠适合性的影响

目的：研究不同包埋材料对Ti-6Al—7Nb合金铸造全冠适合性的影响,筛选出适合于临床应用的包埋材料。方法：采用氧化镁系、磷酸盐系、氧化锆系包埋材料包埋模拟后牙牙冠的帽状蜡型,用Ti-6Al—7Nb合金铸造,铸件组织面经喷砂后就位于各自的不锈钢代型上,在金相显微镜下分别测试铸件的边缘适合性和组织面密合度,统计分析各组均值之间的差异。结果：3种包埋料各点间隙均小于120μm,氧化镁系组和磷酸盐系组包埋材料铸出试件的各测量点间隙没有显著性差异（P〉0．05）,氧化镁系组和磷酸盐系组边缘间隙值明显小于氧化锆系组边缘间隙值（P〈0．05）。结论：3种包埋料均适合于Ti-6Al—7Nb合金的包埋铸造,但氧化镁系组包埋料精度更高。     

ZrP99铸钛包埋材料的铸模温度对铸造精度的影响

目的：研究ZrP99铸钛包埋材料的铸模温度对铸造精度的影响。方法：利用代型模具，制作30个超硬石膏全冠预备体代型．并制作相应的全冠蜡型，随机分为5组，每组6个样本，其中4组为实验组，采用ZrP99铸钛包埋材料进行包埋，分别在铸模温度为600℃、450℃、300℃、150℃条件下进行铸造；另外一组为对照组，采用Titavest—CB包埋材料进行包埋．在铸模温度为600℃条件下进行铸造。利用显微图像分析技术．在实体显微镜下分别测量蜡型及相应的铸件边缘与代型肩台之间在标志点处的间隙，两者差值即代表铸造精度。采用t检验及单因素方差分析进行统计学处理。结果：Titavest—CB包埋材料组的铸造精度显著优于在不同铸模温度下ZrP99包埋材料组：当ZrP99包埋材料的铸模温度低于450℃时，随着温度升高，铸造精度显著提高。结论：ZrP99铸钛包埋材料的铸模温度必须高于300℃．才有可能满足临床精度要求。     

The fit of fixed partial dentures joined by infrared soldering.

This study determined the accuracy of fit of three-unit fixed partial dentures joined by an infrared soldering technique compared with one-piece fixed partial denture castings and individually cast crowns. Wax patterns of prepared Ivorine teeth, maxillary left central incisor and maxillary left canine, were injection molded; a plastic rod was used as a pontic. One group of patterns was cast as one-piece dentures; the other group was sectioned in the connector area, cast individually and then joined by infrared soldering. Castings were seated on their respective dies, embedded in epoxy resin, and sectioned. Gap distances between the casting and the die were measured at specified marginal sites with a profile projector. Results showed that the fit of infrared-soldered fixed partial dentures was significantly better than that of one-piece castings and was comparable with the fit of single crowns. The gap openings measured in all castings were within the range of clinical acceptability.     

Marginal and internal adaptation of commercially pure titanium and titanium-aluminum-vanadium alloy cast restorations

AIM: The purpose of this in vitro study was to investigate the marginal accuracy and internal fit of complete cast crowns and three-unit fixed partial dentures (FPDs) cast with commercially pure titanium (CPTi) and Titanium-Aluminum-Vanadium alloy (Ti-6Al-4V). METHODS AND MATERIALS: CPTi and Ti-6Al-4V alloy were used to cast twelve single crowns and twelve three-unit FPDs. A traveling microscope was used to measure marginal gap and discrepancies in internal fit. Two and one-way analysis of variance (ANOVA) analyses were used to determine the effects of the marginal and internal fit discrepancies. RESULTS: The Ti-6Al-4V alloy demonstrated a significantly smaller marginal gap than CPTi (P<0.0001). The recorded marginal discrepancies for both metals were within a clinically accepted range (<100 microm). The single crown fit discrepancy was significantly smaller than the three-unit FPD for both the CPTi and the Ti-6Al-4V alloy (P<0.0001). For the internal fit discrepancy, the occlusal surface showed the greatest gaps. CONCLUSIONS: The Ti-6Al-4V alloy demonstrated a better fit than CPTi. Single crowns showed an improved fit when compared with the three-unit FPD. Mid-occlusal internal gap demonstrated greater values than the axial internal gap. CLINICAL IMPLICATIONS: This in vitro study suggested marginal fit of complete crowns and three-unit FPDs cast by CPTi or Ti-6Al-4V alloy were within the range of what is clinically acceptable for longevity of restorations.     

In vitro investigation of marginal accuracy of implant-supported screw-retained partial dentures

Mismatch occurring during the fabrication of implant-supported dentures may induce stress to the peri-implant bone. The purpose of this study was to investigate the influence of two different alloys and the fabrication method on the marginal accuracy of cast partial dentures. Two laboratory implants were bonded into an aluminium block so that the distance between their longitudinal axes was 21 mm. Frameworks designed for screw-retained partial dentures were cast either with pure titanium (rematitan) or with a CoCr-alloy (remanium CD). Two groups of 10 frameworks were cast in a single piece. The first group was made of pure titanium, and the second group of a CoCr-alloy (remanium CD). A third group of 10 was cast in two pieces and then laser-welded onto a soldering model. This latter group was also made of the CoCr-alloy. All the frameworks were screwed to the original model with defined torque. Using light microscopy, marginal accuracy was determined by measuring vertical gaps at eight defined points around each implant. Titanium frameworks cast in a single piece demonstrated mean vertical gaps of 40 microm (s.d. = 11 microm) compared with 72 microm (s.d. = 40 microm) for CoCr-frameworks. These differences were not significant (U-test, P = 0.124) because of a considerable variation of the values for CoCr-frameworks (minimum: 8 microm and maximum: 216 microm). However, frameworks cast in two pieces and mated with a laser showed significantly better accuracy in comparison with the other experimental groups (mean: 17 microm +/- 6; P < 0.01). (i) The fit of implant-supported partial dentures cast with pure titanium in a single piece is preferable to that of those made with the CoCr-alloy and (ii) the highest accuracy can be achieved by using a two-piece casting technique combined with laser welding. Manufacturing the framework pieces separately and then welding them together provides the best marginal fit.     

Casting titanium partial denture frameworks: a radiographic evaluation

STATEMENT OF PROBLEM: Titanium is the most biocompatible metal available for dental castings. However, there is some concern about the castability of titanium used on a daily basis. PURPOSE: A radiographic evaluation of titanium partial denture frameworks was undertaken to ascertain whether these castings were technically acceptable for clinical use. MATERIAL AND METHODS: Three hundred Grade II titanium removable partial denture frameworks were cast in a Titec 205M casting machine. All materials were used as directed by the manufacturer, and all castings were made by an experienced titanium specialist. Each casting was evaluated by radiograph. Based on the number, location, and size of argon inclusions, the frameworks were rated as follows: technically acceptable for clinical use as cast; technically acceptable after laser welding modifications; or unacceptable as cast, with remake necessary. RESULTS: Of the 300 titanium frameworks cast, 97% were rated technically acceptable for clinical use in terms of castability. SUMMARY: Within the limitations of this radiographic evaluation, it was determined that the castability of titanium was such that technically acceptable castings could be made on a daily basis.     

Nonprecious cast-metal alloys in dentistry.

This review of selected articles from October 1989 to October 1990 is divided into two sections: a review of clinical studies and a review of laboratory studies for nonprecious cast metals. The clinical articles are centered on biological compatibility issues, such as taste anomalies (dysgeusia) attributed to cast metals and allergy correlation to base metals, and on technique and longevity evaluations involving resin-bonded fixed partial dentures. Laboratory articles are mainly devoted to metal preparation before bonding of etched or resin-bonded fixed partial dentures and the estimated bond strengths of the metal castings. Other selected articles are based on studies of physical properties and physical testing of nonprecious alloys, such as modulus of rupture, to determine ceramic compatibility, castibility testing, marginal fit of fixed partial dentures, and flexure testing of of traditional and experimental designs for cast major connectors. Additionally, a low-cost method of titanium casting is reviewed.     

Porosity and accuracy of multiple-unit titanium castings

The objective of this investigation was to determine whether titanium could be used to cast reproducible multiple-unit dental restorations. A metal analog was machined to simulate preparations for a three-unit fixed partial denture. Castings were made with four different sprue designs at three temperatures. Marginal accuracy and porosity were evaluated. A total of 70 titanium castings were made with an argon/electric arc/vacuum/pressure casting machine. Ten castings were made in the conventional manner by use of gold-palladium alloy as a control to compare the marginal gap. The results revealed that the porosity was less when a large individual sprue (6-gauge) was used. It was also noted that the lower pattern burnout temperatures of 910 degrees C and 920 degrees C exhibited significantly smaller marginal gaps than did the higher temperature of 930 degrees C.     

Custom-made laser-welded titanium implant prosthetic abutment

A technique to create an individually modified implant prosthetic abutment is described. An overcasting is waxed onto a machined titanium abutment, cast in titanium, and joined to it with laser welding. With the proposed technique, a custom-made titanium implant prosthetic abutment is created with adequate volume and contour of metal to support a screw-retained, metal-ceramic implant-supported crown.     

Comparative accuracy of fixed partial dentures made as one-piece castings or joined by solder.

Four-unit fixed partial dentures were fabricated as a one-piece casting or as two-piece castings joined by soldering prior to the addition of porcelain. The accuracy of the two techniques was compared and evaluated using an anatomic cast-metal master model. All procedures, including SEM measurements, were performed directly on the master model. The cast one-piece units had smaller vertical marginal openings than did the soldered units. The rigid nature of the abutments evokes the problems occurring with osseointegrated implants.     

Fitness accuracy and retentive forces of additive manufactured titanium clasp

PurposeLaboratory and clinical assessment of cast titanium dentures were reported, little is known about additive manufacturing (AM) frameworks. This study evaluated in vitro AM titanium alloy clasps for clinical use.MethodsAfter scanning the stainless steel dies to simulate the first molar, an Akers clasp was designed by CAD. AM clasp specimens were manufactured using laser sintering and AM machines from CP titanium grade 2 (CPTi), Ti-6Al-4V (Ti64), and Ti-6Al-7Nb (Ti67) powders. As controls, cast titanium clasps were conventionally made with same three titanium alloys. After nondestructive inspection and surface element analysis, surface roughness, fitness accuracy, initial retentive forces, and changes in retentive forces were measured.ResultsAlthough few porosities and little contamination of AM clasps were confirmed, the AM clasp arm and tip indicated slightly worse fitness accuracy as compared to cast clasps. The initial retentive forces of all titanium clasps showed appropriate retentive forces within the acceptable ranges, AM clasps tended to have lower decreases in retentive forces with up to 10,000 insertion/removal cycles as compared to those of the cast clasps.ConclusionsAM titanium clasps would be acceptable for clinical use similar to that of cast titanium clasps.     

Comparison of accuracy of multiunit one-piece castings

An investigation was conducted to evaluate the accuracy of one-piece castings of FPDs consisting of three, four, and five units with a ceramometal alloy cast in a large circular ring. A three-piece aluminum mold with stainless steel dies simulating the various lengths of the FPDs was used. A total of 18 castings, six castings for each FPD, were fabricated. Marginal discrepancies of the castings on the dies and the length of the castings were compared before and after sectioning the castings at the connectors. The following conclusions were drawn from the study. Seating of the castings improved approximately 50% after sectioning, which indicates that the castings were distorted. The distortion was a three-dimensional phenomenon, with the greatest discrepancy on the mesiogingival surface of the anterior retainer and on the distolingual surface of the posterior retainer. The distortion was least for the three-unit FPDs and greatest for the five-unit FPDs. The lingual-facial diameter of the castings at the gingival axial line angle was significantly larger than the dies in most cases. The mesiodistal diameter of the castings at the gingival axial line angle was smaller than that of the dies but was only significant with the three-unit FPDs. Although the castings were slightly oversized or undersized, the primary reason the castings did not seat was warpage.