2种不同印模方法制取间接桩核的临床效果评价

目的比较硅橡胶印模法与琼脂/藻酸盐联合印模法制取铸造间接桩核的临床效果。方法将牙体大面积缺损、根管治疗后要求桩核冠修复的389颗牙随机分为A、B组,A组采用硅橡胶印模法制取间接桩核,B组采用琼脂/藻酸盐联合印模法制取间接桩核,对2种印模法制取间接桩核的效果进行评价。结果硅橡胶印模法制取间接桩核的临床成功率高于琼脂/藻酸盐联合印模法,二者之间差异具有统计学意义（P<0.05）。其中,2种不同印模方法制取前牙间接桩核的成功率之间差异无统计学意义（P>0.05）,制取前磨牙和磨牙间接桩核的成功率之间差异有统计学意义（P<0.05）。结论采用硅橡胶印模法制取间接桩核的临床效果优于琼脂/藻酸盐联合印模法。     

Elastic and plastic properties of elastic dental impression materials

Strain in compression, compression set, stiffness and Shore A hardness of 36 brands of elastic dental impression materials have been determined. There was no correlation between compression set and the other properties tested, while statistically highly significant correlations were found between strain in compression, stiffness and Shore A hardness. It is recommended to routinely determine Shore A hardness for a sufficiently accurate prediction of stiffness and strain in compression. The stiffness is directly proportional to the force necessary to remove an impression from undercut areas in the mouth.     

The release of fluoride from alginate impression materials

Abstract Alginate material used as a vehicle for fluoride gives, after 18 hours exposure, a fluoride uptake of human enamel of 620 ± 0.26 parts/10⁶.     

Physical properties and compatibility with dental stones of current alginate impression materials

This study examined physical properties and compatibility with dental stones of two types of alginate impression materials. Five powder-type alginate impression materials (Alginoplast EM, Aroma Fine, Algiace Z, Coe Alginate, Jeltrate Plus) and a paste-type alginate impression material (Tokuso AP-1) were used. The dynamic viscosity immediately after mixing was measured by means of a controlled-stress rheometer. The gelation times were determined according to Japanese Industrial Standards (JIS) T6505, and recovery from deformation, strain in compression and compressive strength were determined according to the International Organization for Standardization (ISO) specification 1563. Detail reproduction and surface roughness of type III dental stones (New Plastone, New Sunstone) and a type IV dental stone (Die Stone) were evaluated using a ruled test block as specified in the ISO specification 1563 and a profilometer, respectively. The alginate impression materials evaluated in this study were all in compliance with the ISO specification 1563 and JIS T6505. The alginate impression materials had similar mechanical properties after gelation, whilst a wide range of dynamic viscosity immediately after being mixed, gelation times and compatibility with dental stones were found among the materials. The paste-type material had a higher dynamic viscosity and a shorter gelation time than the powder-type materials. The best surface quality was obtained with the paste-type material/type III dental stone cast combinations. The materials should be selected in consideration of initial flow, setting characteristics and compatibility with dental stones. The results suggested that a paste-type material would better meet the requirements of an alginate impression material.     

琼酯和藻酸盐印模材联合印模法在冠桥修复中的应用

目的：探讨琼脂和藻酸盐印模材料联合印模法失败的原因。方法：对临床上186例，478颗基牙应用寒天印模材与藻酸盐类印模材联合印模法取印模，进行分析、总结，找出主要影响联合印模成功的因素。结果：联合印模法在前牙区、上后牙区、下后牙区的成功率分别为：90．3％、89．3％和76．4％；在前牙区1－3个牙的成功率分别为：98．4％、97．4％、94．4％。随着基牙数的增加，联合印模法的成功率下降。结论：琼酯／藻酸盐类印模材联合印模法是一种操作简单、成功率高、价格低廉的精密印模法。     

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目的评价硅橡胶加预成胶针精密印模法间接制作铸造桩核的临床效果。方法选取2005年1月至2007年10月广东省深圳牙科医疗中心门诊289例患者的400颗经完善根管治疗的前牙及前磨牙残根、残冠,随机分成试验组(248颗)和对照组(152颗),规范制备根管根面。试验组通过根管内注入硅橡胶并插入预成胶针制取根管根面精确印模,技工室完成铸造桩核。对照组常规以嵌体蜡加金属丝制取根管根面印模并完成桩核铸造。临床试戴,检查桩核的就位性、密合性、固位性。结果试验组242颗临床检查为优秀(97.6%),对照组136颗临床检查为优秀(89.5%),两组修复效果差异有统计学意义(P<0.05)。结论硅橡胶加预成胶针精密印模法间接制作铸造桩核,精密度高,临床效果好,值得推广使用。     

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数字印模技术是随着计算机辅助设计与制作（CAD／CAM）技术逐渐发展起来的,与模型扫描相比存在更大的难度,对系统本身的要求更高。常见的口腔数字印模系统包括CEREC蓝光系统（德国Sirona公司）、CERECOmicam系统（德国Sirona公司）、LavaC．O．S．系统（美国3M公司）、iTero系统（美国Cadent／Straumann公司）和E4D系统（美国E4D公司）,这些系统获取印模的方式和软件不同,各有优势。数字印模在效率、精度和舒适性方面与传统印模技术相比具有很大的优势,但需要在牙体预备、干燥隔湿和喷粉取像方面注意操作技巧。     

3种方式调拌Jeltrate藻酸盐印模材料的气泡含量及物理性能比较

目的：评价全自动印模调拌机、半自动印模调拌机、手动调拌3种调拌方法调拌藻酸盐印模材料的气泡含量及物理性能。方法在同种条件下（室温、水粉比、蒸馏水温度）,分别采用全自动印模调拌机调拌法、半自动印模调拌机调拌法、手动调拌法调制藻酸盐印模材料。比较各调拌方法所调制材料的气泡数量、气泡总面积、压应变值、弹性回复值、流动性。结果3种调拌方法的气泡量和气泡面积之间差异有统计学意义。全自动调拌机调拌的材料气泡最少,半自动调拌机调拌的材料次之,手动调拌的材料气泡最多。3种调拌方法调拌的材料物理性能均符合国家相关标准,手工调拌法的弹性回复值低于半自动调拌法及全自动调拌法,全自动调拌法印模流动性最好。结论在本实验条件下,藻酸盐印模材料调拌方法对材料气泡含量及其物理性能有影响;不同调拌方法所调材料物理性能均符合国家相关标准,全自动调拌法所调材料性能最佳。     

两种调拌方法对藻酸盐印模材尺寸稳定性的影响

目的：比较2种调拌方式（人工,机调）下,2种藻酸盐印模材（金玛克专用,普通藻酸钾）精度的变化。方法：按调拌方式和印模材种类分4组：A组为自动调拌机调拌金玛克印模材;B组为自动调拌机调拌藻酸钾印模材;C组为人工调拌金玛克印模材：D组为人工调拌藻酸钾印模材。采用特制的金属模具取模后灌注石膏模型,再测量模型尺寸变化差值,所得数据进行统计分析。结果：采用机调的2种印模材精度均好于人工调拌组;而金玛克专用印模材在机调组中的精度好于普通藻酸钾印模材;人工调拌下金玛克印模材与普通藻酸钾印模材的精度差值差别并不显著。结论：使用自动调拌机调拌的印模材精度优于人工调拌,而以专用的印模材精度最高。     

DTG thermal analyses and viscosity measurements of three commercial agar impression materials

Three commercial agar impression materials, two for clinical uses and one for dental laboratory, were examined for their thermal properties by differential thermogravimetric (DTG) thermal analyses and viscosity measurements. On DTG profiles, an endothermic peak along with weight loss at around 100 degrees C was observed on all three agar impression materials as a result of water evaporation. Two clinical agar impression materials were more susceptible to this trend than the remaining one dental laboratory agar impression material. The viscosity of three agar impression materials could be expressed in the exponential function of temperature. Viscosity at 46 degrees C of one dental laboratory agar impression material far exceeded those of two clinical agar impression materials. Monitoring the viscosity could facilitate the detailed analysis of setting process of agar impression materials upon cooling, and might be useful for future development of agar-based dental impression materials.