环氧乙烷对牙科手机灭菌效果及机械性能影响的实验研究

目的 探讨环氧乙烷对人工污染牙科手机灭菌效果和机械性能的影响.方法 采用实验室代表菌种污染牙科手机,经环氧乙烷气体灭菌后,无菌检查法检查牙科手机的灭菌效果,用酶联免疫吸附实验(ELISA)法检测HBsAg;牙科手机每经20次灭菌后进行机械性能检测.结果 环氧乙烷灭菌法对实验室污染的牙科手机可全部达到灭菌效果,乙型肝炎表面抗原(HBsAg)抗原性全部灭活;经200次灭菌后10支牙科手机中,2支转速下降至30万r/min以下,仍高于16万r/min的标准转速.结论 牙科手机用环氧乙烷灭菌效果可靠,并可满足机械的使用性能.     

两种清洗方式对污染牙科手机洗涤效果分析

目的比较2种清洗方式对污染牙科手机上标准微生物的清洗效果。方法分别用标准试验菌株枯草杆菌黑色变种芽孢和大肠杆菌的菌悬液污染牙科手机机头各23支;3支污染后直接放入洗脱液,取洗脱液作为清洗前对照;另外20支分别采取手工刷洗10支,超声波清洗10支,再分别放入洗脱液,收集清洗后的洗脱液,分别接种培养,计数存活的标准试验菌菌落数,计算清除率。结臬对人工污染枯草杆菌黑色变种芽孢和大肠杆菌的牙科手机,手工刷洗后2种细菌清除率分别为86．66％、88．82％;超声波清洗后2种细菌清除率分别为90．68％、93．56％,2种方法的清除率有非常显著性差异（P〈0．01）。结论对人工污染2种标准试验菌株的牙科手机,超声波清洗效果优于手工刷洗效果。     

五种灭菌器对牙科手机灭菌效果的研究

目的检测5种灭菌器对牙科手机的灭菌效果.方法用酶联免疫吸附(ELISA)法检测5种压力蒸汽灭菌器灭菌后的HBsAg人为污染的牙科手机,并对5种灭菌器灭菌后的临床污染的牙科手机进行无菌检测,同时用嗜热脂肪杆菌芽胞检测5种压力蒸汽灭菌器的灭菌效果.结果 5种灭菌器生物监测均合格,5种压力蒸汽灭菌器杀菌效果都可达100%,其中2种灭菌器灭菌的所有牙科手机HBsAg抗原性检测均为阴性,其他3种灭菌器灭菌的牙科手机各有1支HBsAg抗原性检测为阳性.结论压力蒸汽灭菌器效果可靠,乙肝病毒是否灭活,还需做其他检测.牙科手机应严格遵守灭菌保养流程,灭菌后应洁净存放.     

两种消毒方法对牙科手机灭菌效果的评价

目的 :比较含氯消毒剂浸泡法和环氧乙烷气体灭菌法对牙科手机的灭菌效果。方法 :利用枯草杆菌黑色变种芽孢和乙肝表面抗原阳性血清污染牙科手机 ,消毒后进行定量杀菌实验 ,用酶联免疫吸附实验 (ELISA)法检测HBsAg 结果 :牙科手机浸泡在有效氯含量为 30 0 0× 10 -6的消毒剂中 30分钟 ,细菌杀灭率及乙肝表面抗原的抗原灭活率均未达到 10 0 % ,而环氧乙烷灭菌法可达到 10 0 %。结论 :环氧乙烷灭菌牙科手机效果可靠。     

常用消毒方法灭活藻酸盐印模表面乙肝病毒的效果

目的:观察几种常用消毒方法灭活藻酸盐印模表面乙肝病毒的效果.方法:采用ADA建议的消毒方法,对表面污染有乙肝病毒血清的藻酸盐印模进行消毒实验,采用酶联免疫分析法(Elisa)对乙肝病毒表面抗原灭活效果进行检测.结果:1500mg/L的NaClO消毒液浸泡消毒10min或喷涂消毒25min可完全灭活HBsAg;2%中性强化戊二醛消毒液浸泡消毒40min可完全灭活HBsAg;2%中性强化戊二醛消毒液喷涂消毒60min灭活HBsAg效果不可靠;臭氧消毒60min仍无效.结论:浓度为1500mg/L的NaClO消毒液浸泡消毒10min或喷涂消毒25min、2%中性强化戊二醛消毒液浸泡消毒40 min三种消毒方法可灭活印模表面的乙肝病毒.     

3种方法用于三用枪消毒的效果比较

目的比较3种方法用于三用枪消毒的效果。方法采用现场采样检测方法,对用消毒剂表面擦拭消毒、2%碱性戊二醛浸泡消毒和高温高压蒸气灭菌法灭菌效果进行观察。结果使用消毒剂表面擦拭消毒法,三用枪细菌总数超标率为9.09%;使用戊二醛浸泡消毒和高温高压灭菌法消毒,三用枪全部无菌生长。结论消毒剂表面擦拭法的消毒效果较差;高温高压蒸汽灭法消毒临床应用最为方便,效果最好。     

B级脉动真空压力蒸汽台式灭菌器对牙科手机灭菌效果分析

目的探讨B级脉动真空压力蒸汽台式灭菌器对牙科手机的灭菌效果。方法分析牙科手机灭菌器的选择、灭菌处理流程及灭菌效果监测,并对监测结果及牙科手机有效的灭菌方法进行评价。结果四川大学华西口腔医院采用B级脉动真空压力蒸汽台式灭菌器对牙科手机进行灭菌处理,其化学监测、生物监测指标均符合要求,灭菌有效率100%;对灭菌后牙科手机进行需氧培养、厌氧培养、乙型肝炎标志物监测均为阴性。结论对牙科手机采用B级台式灭菌器脉动真空压力蒸汽灭菌是行之有效的方法。     

消毒液浸泡对牙科石膏模型尺寸的影响

目的:探讨消毒液浸泡3种牙科石膏模型后对其尺寸稳定性的影响.方法:用临床常用的3种不同类型石膏(Ⅲ型、Ⅳ型、Ⅴ型)制作50 mm×15 mm×10 mm 3组共24个试件.1h后脱模,静置24 h后,用数显卡尺测量石膏模型尺寸.以蒸馏水浸泡作为对照,设戊二醛消毒剂、麦瑞斯消毒液浸泡为实验组,浸泡0.5 h取出,静置0.5、1、2、24 h后,用数显卡尺测量模型尺寸.采用SPSS10.0软件包对数据进行统计学分析.结果:浸泡前,3组石膏模型长度分别为(50.073±0.017) mm、(50.048±0.015) mm和(50.027±0.015)mm;浸泡后,各实验组、各时间点的模型尺寸基本无变化,石膏模型的尺寸变化小于0.01％.结论:消毒液浸泡对牙科石膏模型尺寸基本无影响.     

不同消毒处理对改良型硅橡胶印模润湿性的影响

目的 :评价 3种改良型亲水性硅橡胶印模材料经 4种常用消毒液不同时间浸泡处理后其表面润湿性的变化。方法 :对每一种材料 ,各制取 80个相同的印模 ,以 2 0个为一组分别接受 2 %碱性戊二醛、0 .5 %碘伏、0 .0 2 %二氧化氯、5 .2 5 %次氯酸钠的浸泡处理。在每个处理组的 2 0个印模中 ,5个不做处理作为对照组 ,15个接受浸泡处理作为实验组 :以 5个为一组分别浸泡 10min、30min、6 0min ,处理完毕后用液滴法测其接触角 ,比较各材料处理前后接触角的变化。结果 :所有材料经浸泡 10min、30min、6 0min后 ,其接触角与处理前接触角相比 ,均有所增大 ,在统计学上有显著性差异 (P <0 .0 5 )。结论 :3种改良型亲水性硅橡胶印模材料经 4种消毒液不同时间浸泡处理后 ,其表面润湿性均有所降低     

关于减少牙探针污染的研究

牙科常规使用的无菌探针检查一颗牙后能培养出3～7×10~个细菌的,即被污染。Loesche等通过实验证明在检查牙齿的过程中,牙探针可把变链菌接种到同一口腔的其他牙齿上。Bielak也发现在临床牙科检查后,被变链菌集聚的牙面数增加。这些资料表明,检查牙齿时,探针可以把变链菌传播到整个牙列。但在检查口腔时,不可能每检查一颗牙齿都换一根无菌探针。因此作者对受污染探针的清洁方法进行了研究。     

INFLUENCE OF IODOFORM ON ANTIMICROBIAL POTENTIAL OF CALCIUM HYDROXIDE

The purpose of this research was to verify the influence of Iodoform on antimicrobial potential of calcium hydroxide. S. aureus, E. faecalis, P. aeruginosa, B. subtilis, C. albicans were the biological indicators. The substances tested were: calcium hydroxide + saline; calcium hydroxide + Iodoform + saline; Iodoform + saline. For the agar diffusion test, 18 Petri plates with 20 ml of BHI agar were inoculated with the microbial suspensions. Fifty-four cavities were made and filled with the substances tested. The diameters of microbial inhibition were then measured. In direct exposure test, 162 #50 sterile absorbent paper points were immersed in the experimental suspensions for 5 min, and covered with the pastes. At intervals of 24, 48 and 72 hours, the paper points were immersed in 10 ml of Letheen Broth, followed by incubation at 37°°C for 48h. Microbial growth was evaluated by turbidity of the culture medium. A 0.1 ml inoculum obtained from the Letheen Broth was transferred to 7 ml of BHI, and incubated at 37°°C for 48h. Bacterial growth was again evaluated by turbidity of the culture medium. The calcium hydroxide associated with the saline or the iodoform plus saline showed antimicrobial effectiveness in both experimental methods. The iodoform paste presented antimicrobial ineffectiveness for the agar diffusion test on all biological microorganisms and for the direct exposure test on B. subtilis and on the mixture.     

THE IMPACT OF FLUORIDATION ON PATTERNS OF DENTAL TREATMENT

Dr. Douglas and his group have tackled the problem of determining the impact on patterns of practice which develop in areas of fluoridated water.     

聚乳酸在颌骨缺损修复中的应用

聚乳酸 (polylactic acid,PLA)因其良好的生物相容性 ,可降解性和骨引导活性 [1,2 ] ,在各类骨缺损修复中均得以广泛应用。在颌骨缺损修复中的应用包括 :PLA引导组织再生膜 (guided tissue regener-ation,GTR)、颗粒自体骨移植支托、坚固内固定夹板螺钉、骨形成蛋白 (BMP)载体、组织工程细胞附着支架 ,此外 ,PLA还可用于解除疤痕挛缩和外形重建。用途不同 ,PLA材料的性能要求也各不相同。本文将 PLA在颌骨缺损修复中的应用综述于下。1　PLA引导组织再生膜早期 GTR膜多为聚四氟乙烯 (e- PTFE) ,随着可降解材料研究的深入和生产…     

热疗对鼠肿瘤细胞代谢的影响

本研究通过酶组织化学的方法观察热疗对鼠肿瘤细胞各种酶活性的作用。结果显示热疗（４３℃，４０ｍｉｎ）能使肿瘤细胞线粒体酶、内质网酶、胞液内的酶和肿瘤组织中毛细血管内皮细胞酶活性下降；溶酶体酶活性升高。上述酶活性的改变相应地导致肿瘤细胞的有氧代谢，无氧酵解和核酸合成代谢功能降低，同时使肿瘤组织的毛细血管损伤。因此，认为热疗杀伤肿瘤细胞的机制是热疗损伤了肿瘤细胞膜结构和肿瘤的毛细血管。     

EFFECTS OF POLISHING PROCEDURES ON COLOR STABILITY OF COMPOSITE RESINS

The purpose of this study was to investigate the effect of different polishing methods on color stability of posterior, universal and nanohybrid composite resin restorative materials upon exposure to a staining agent. Twenty-five specimens were prepared for each of 5 different composite resins (Filtek Z250, Filtek P60, Quadrant LC, Grandio and Filtek Supreme). Specimens were divided into 5 groups and different polishing procedures, including polishing discs (Pd), polishing discs then diamond polishing paste (PdP), polishing discs then a liquid polishing system (Biscover) (PdB), and combinations of these (PdPB) were used. Unpolished specimens served as the control (C). The specimens were stored for 48 h in a coffee solution. The color of all specimens was measured before and after exposure with a colorimeter, and total color change ∆E*) were calculated. The data were analyzed with a two-way ANOVA and the means were compared by Tukey HSD test (α=0.05). The lowest color difference was observed in the groups PdP and C, while the highest color difference was observed in PdPB, and PdB. When comparing the five different restorative materials, no significant difference was observed between FiltekP60 and FiltekZ250, and these materials demonstrated significantly less color change than Quadrant LC and the nanohybrid materials (Grandio, Filtek Supreme). The posterior (Filtek P60) and universal (Filtek Z250) composite resin restorative materials, which do not contain tetraethyleneglycol dimethacrylate (TEGDMA), were found to be less stainable than the nanohybrid (Grandio, Filtek Supreme) and universal (Quadrant LC) composite resins, which contain TEGDMA. The use of diamond polishing paste after polishing with polishing discs significantly decreased staining when compared to the groups that used polishing discs alone, for all restorative materials tested. The highest color change values were obtained for the specimens that were polished with the Biscover liquid polish system (PdB and PdPB groups).     

面积对陶瓷修复体体瓷色度学的影响

目的：探讨陶瓷修复体的色彩与其面积的关系。方法：分别制作厚度为2mm，直径为8mm、12mm、16mm、20mm的圆盘状B3色体瓷试件，在D65光源条件下，以分光光度计分别测试各组试件在黑色背景和在白色背景条件下的混合色。结果：随陶瓷试件直径由8mm增加至20mm，试件中心的色度值变化表现为：①彩度增加，色调趋向红色。②明度在黑色底板下增加，在白色底板下减小。②陶瓷试件直径由16mm增加至20mm时，试件色度值变化不明显。结论：陶瓷试件色度值随直径增大而趋向稳定。     

EFFECT OF STORAGE PERIOD ON THE ACCURACY OF ELASTOMERIC IMPRESSIONS

Aims:

To investigate the effect of the storage period on the accuracy of recently developed elastomeric materials.

Methods:

Simultaneous impressions of a steel die were taken using a polyether (I: Impregum Soft Heavy and Light body, 3M ESPE) and vinyl polysiloxane (P: Perfectim Blue Velvet and Flexi-Velvet, J.Morita). The trays were loaded with the heavy-bodied impression materials while the light-bodied impression materials were simultaneously spread on the steel die. The impressions were poured after 2 hours, 24 hours, and 7 days. Impressions were stored at approximately 55% relative humidity and room temperature. Ten replicas were produced for each experimental condition (n=60). Accuracy of the stone dies was assessed with a depth-measuring microscope. The difference in height between the surface of the stone die and a standard metallic ring was recorded in micrometers at four demarcated points, by two independent examiners. Dxata were submitted to two-way ANOVA and Tukey test (α = 0.05).

Results:

Significant differences were found among the groups. Smaller discrepancies were observed when pouring was performed up to 24 hours (I-2h= 65.0 ± 15.68 μm; I-24h= 81.6 ± 11.13 μm) for the polyether, and up to 7 days for the vinyl polysiloxane (P-2h= 79.1 ± 13.82 μm; P-24h= 96.8 ± 6.02 μm; P-7d= 81.4 ± 4.3 μm). Significant dimensional discrepancies, however, were observed when polyether was stored for 7 days (I-7d= 295.3 ± 17.4 μm).

Conclusion:

Storage may significantly affect the dimensional accuracy of impressions and, thus, a maximum period and storage condition should be specified for the recently developed materials.     

INFLUENCE OF THERMAL STRESS ON MARGINAL INTEGRITY OF RESTORATIVE MATERIALS

The aim of this study was to evaluate the influence of thermal stress on the marginal integrity of restorative materials with different adhesive and thermal properties. Three hundred and sixty Class V cavities were prepared in buccal and lingual surfaces of 180 bovine incisors. Cervical and incisal walls were located in dentin and enamel, respectively. Specimens were restored with resin composite (RC); glass ionomer (GI) or amalgam (AM), and randomly assigned to 18 groups (n=20) according to the material, number of cycles (500 or 1,000 cycles) and dwell time (30 s or 60 s). Dry and wet specimens served as controls Specimens were immersed in 1% basic fuchsine solution (24 h), sectioned, and microleakage was evaluated under x40 magnification. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests: Thermal cycling regimens increased leakage in all AM restorations (p<0.05) and its effect on RC and GI restorations was only significant when a 60-s dwell time was used (p<0.05). Marginal integrity was more affected in AM restorations under thermal cycling stress, whereas RC and GI ionomer restoration margins were only significantly affected only under longer dwell times.