正畸托槽粘接剂对细菌粘附影响的临床试验研究

目的：评价不同正畸托槽粘接剂对口腔细菌粘附的差异。方法：采用临床实验的方法。观察三种常用正畸托槽，粘接剂在口内戴用二个月后的细菌粘附情况及种类。结果：三种粘接材料的细菌粘附能力有显著性差异。结论：从粘附口腔细菌的数量来看，所选三种常用粘接材料存在差异。光固化玻璃离子粘固剂为最少，其次为高粘度聚羧酸粘固剂和复合树脂釉质粘接剂。     

消毒剂对印模材料尺寸稳定性的影响

目的　比较质量分数为 2 %戊二醛溶液与新型有机氯消毒剂———爱尔施消毒液浸泡两种藻酸盐和两种硅橡胶印模材料后 ,对材料尺寸稳定性的影响。方法　用 6 0mm× 10mm× 10mm金属试件制取印模 ,分别在质量分数为 2 %戊二醛溶液与爱尔施消毒液中浸泡 10、2 0、30min ,用JXD - 2 5 0B型数显读数显微镜测量浸泡前和浸泡后各时段印模材料的线性长度。每种印模材料分成 2组 ,每组 10个 ,用SPSS 10 .0统计软件包对结果作统计学分析。结果　爱尔施消毒液对各种印模材料尺寸稳定性的影响与质量分数为 2 %戊二醛溶液相比无显著性差异(P >0 .0 5 ) ;ImpregumF硅橡胶和ExpressPutty硅橡胶印模材料浸泡后的体积变化小于红叶和Cavex藻酸盐印模材料。结论　爱尔施消毒液不会影响印模材料的尺寸稳定性 ,可试用于临床印模的浸泡消毒 ;硅橡胶印模材料的尺寸稳定性优于藻酸盐印模材料     

无机活性元素组织工程支架材料重建修复山羊颌骨缺损的扫描电镜观察

目的:用扫描电镜观察无机活性元素组织工程支架材料构建的组织工程骨及其修复羊大面积颌骨缺损的体内成骨状况.方法:实验组对15只山羊下颌角缺损(30 mm×25 mm×10 mm大小)以支架材料修复,左侧为实验组,右侧为空白对照组,术后分别于1、3、6个月处死5只动物行扫描电镜及生物化学检查,观察无机活性元素组织工程支架材料体内成骨情况.结果:实验组骨缺损新生骨在1、3、6个月显著优于对照组,空白对照组6个月骨缺损区均无明显骨修复现象.结论:应用扫描电镜观察到无机活性元素组织工程支架材料具有优良的成骨效果.     

SY-28、SY-20和MDX4-4210硅橡胶机械性能的对比测定

目的:对比SY-28、SY-20和MDX4-4210硅橡胶的机械性能。方法:以MDX4-4210硅橡胶为对照,对SY-28、SY-20硅橡胶扯断强度、扯断伸长率、永久变形率(3分钟)、撕裂强度、硬度(邵氏A)进行测试,对其机械性能加以评价,并进行统计学分析。结果:SY-28硅橡胶的扯断伸长率、撕裂强度和邵氏硬度优于MDX4-4210硅橡胶;扯断强度和永久变形率与之相似。SY-20硅橡胶的邵氏硬度优于MDX4-4210硅橡胶;扯断强度、扯断伸长率、永久变形率和撕裂强度与之相似。结论:①SY-28、SY-20硅橡胶可以满足颌面软组织缺损赝复材料的机械性能要求。②在硬度上,SY-28硅橡胶适合用于耳、鼻等缺损的修复;SY-20硅橡胶适合颌面部软组织缺损的修复。③应用硅橡胶并用技术弥补现有硅橡胶的性能缺陷,可以获得更适合临床应用的硅橡胶赝复材料。     

The effect of thermocycling on the bonding of different restorative materials to access opening through porcelain fused to metal restorations

PURPOSE

Porcelain fused to metal (PFM) crowns provide the best treatment option for teeth that have a large or defective restoration. More than 20% of teeth with PFM crowns or bridges require non-surgical root canal treatment (NSRCT). This may be due to the effect of restorative procedures and the possible leakage of bacteria and or their by-products, which leads to the demise of the tooth pulp. Thus, this study was planned to compare the ability of the restorative materials to seal perforated PFM specimens.

MATERIALS AND METHODS

The study evaluates the ability of amalgam, composite or compomer restorative materials to close perforated PFM specimen''s in-vitro. Ninety PFM specimens were constructed using Ni-Cr alloys and feldspathic porcelain, and then they were divided into 3 groups: amalgam (A), composite + Exite adhesive bond (B) and compomer + Syntac adhesive bond (C). All the PFM samples were embedded in an acrylic block to provide complete sealing of the hole from the bottom side. After the aging period, each group was further divided into 3 equal subgroups according to the thermocycling period (one week for 70 cycles, one month for 300 cycles and three months for 900 cycles). Each subgroup was put into containers containing dye (Pelikan INK), one maintained at 5℃ and the other at 55℃, each cycle for 30 sec time. The data obtained was analyzed by SPSS, 2006 using one way ANOVA test and student t-test and significant difference level at (P<.01).

RESULTS

The depth of dye penetration was measured at the interfaces of PFM and filling materials using Co-ordinate Vernier Microscope. The lowest levels of the dye penetration for the three groups, as well as subgroups were during the first week. The values of dye leakage had significantly increased by time intervals in subgroups A and C.

CONCLUSION

It was seen that amalgam showed higher leakage than composite while compomer showed the lowest level of leakage.     

The potential of three-dimensional printing technologies to unlock the development of new ‘bio-inspired’ dental materials: an overview and research roadmap

Purpose

Bio-inspiration is an approach in engineering aimed at optimizing artificial systems by borrowing biological concepts from nature. This review sets out to summarize the fundamental aspects employed by nature to avoid premature dental failures. On the basis of these findings, it then defines and evaluates rules for ‘post-modern’ manufacturing processes to imitate or regenerate complex biological systems.

几种市售商品充填材料密合度的实验研究

选用几种市售牙体充填复合树脂和玻璃离子水门汀充填Ⅴ类洞(龈壁由牙骨质和牙本质组成),采用染色法观察其边缘微漏的离体牙实验。发现不同充填材料存在不同程度的边缘微漏,酸处理洞缘可显著降低边缘微漏(P<0.05),窝洞的牙釉质壁渗漏显著低于牙骨质壁渗漏(P<0.01)。实验结果提示,充填材料的粘附性能,窝洞边缘的位置以及酸处理技术,都将影响牙体充填的治疗效果。     

不同树脂界面处理对义齿软衬材料粘结强度的影响

目的:考察不同界面处理对义齿软衬材料粘结强度的影响.方法:用不同粒度的砂纸打磨甲基丙烯酸树脂粘结面并采用不同浓度的乙醇进行清洁脱脂.根据不同的处理方法将材料分为4组,一半试件进行冷热循环.采用拉式剪切强度试验法分别测试冷热循环前及循环后各处理方式组试件的抗剪切强度,所得试验数据经统计学分析(a=0.05),考察不同界面处理方式对义齿软衬材料粘结强度的影响.结果:冷热循环前,各处理方式组之间剪切强度无统计学差异(a>0.05).经冷热循环后,各组粘结强度均有下降,各组之间剪切强度之间有统计学差异(a<0.05).各组冷热循环前后粘结破坏形式均以软衬材料内聚破坏为主.结论:不同界面粗糙度和脱脂乙醇浓度对软衬材料与甲基丙烯酸树脂粘结强度无影响.     

Microtensile bond strength tests: scanning electron microscopy evaluation of sample integrity before testing

The failure of a certain number of microtensile specimens during their preparation and before loading is a common and undesirable occurrence. This study was aimed at observing, under a scanning electron microscope, enamel and dentin microtensile specimens, in order to find structural faults that might be responsible for their premature failure. In a sample of 80 sticks, none of the specimens was found to be free of defects. These may consist of microcracks in enamel, most often at the periphery of the stick, or in dentin at the level of hybrid layer. Gaps were often seen at the interfaces between the substrates. Voids were sometimes visible within the resin composite thickness. Enamel specimens tended to exhibit more defects than dentin specimens. It is fair to suspect that, because of the brittleness of the tissue, enamel microtensile specimens are intrinsically more prone to failure, thus yielding bond strengths which are not significantly higher than those measured on dentin specimens. This leads one to question the reliability of the microtensile method for testing adhesion on enamel. It seems sensible to develop a method for a quantitative assessment of specimens integrity before loading as a possible predictor for their performance under load.     

Influence of surface modification techniques on shear bond strength between different zirconia cores and veneering ceramics

PURPOSE

Veneering porcelain might be delaminated from underlying zirconia-based ceramics. The aim of this study was the evaluation of the effect of different surface treatments and type of zirconia (white or colored) on shear bond strength (SBS) of zirconia core and its veneering porcelain.

MATERIALS AND METHODS

Eighty zirconia disks (40 white and 40 colored; 10 mm in diameter and 4 mm thick) were treated with three different mechanical surface conditioning methods (Sandblasting with 110 µm Al₂O₃ particle, grinding, sandblasting and liner application). One group had received no treatment. These disks were veneered with 3 mm thick and 5 mm diameter Cercon Ceram Kiss porcelain and SBS test was conducted (cross-head speed = 1 mm/min). Two and one way ANOVA, Tukey''s HSD Past hoc, and T-test were selected to analyzed the data (α=0.05).

RESULTS

In this study, the factor of different types of zirconia ceramics (P=.462) had no significant effect on SBS, but the factors of different surface modification techniques (P=.005) and interaction effect (P=.018) had a significant effect on SBS. Within colored zirconia group, there were no significant differences in mean SBS among the four surface treatment subgroups (P=0.183). Within white zirconia group, "Ground group" exhibited a significantly lower SBS value than "as milled" or control (P=0.001) and liner (P=.05) groups.

CONCLUSION

Type of zirconia did not have any effect on bond strength between zirconia core and veneer ceramic. Surface treatment had different effects on the SBS of the different zirconia types and grinding dramatically decreased the SBS of white zirconia-porcelain.