茯苓皮总多糖提取纯化工艺研究

目的研究并确立茯苓皮总多糖的最佳提取和纯化工艺。方法用超声波辅助法提取总多糖,用苯酚-硫酸法测其含量并作为指标,经过单因素实验和正交试验确立最佳提取工艺;用大孔树脂纯化总多糖,以多糖保留率,脱色率和蛋白去除率为指标,经过静态和动态实验,确立最佳纯化工艺。结果以料液比1∶25,温度45℃,超声功率100w,超声时间10min为最佳提取工艺;以AB-8型大孔吸附树脂,溶液pH 5,转速180r·min^-1,上样流速24mL·min^-1,径高比1∶15为最佳纯化工艺。在此条件下静态吸附实验蛋白去除率65.29%,脱色率79.08%,多糖保留率59.50%;动态吸附实验蛋白去除率48.98%,脱色率76.84%,多糖保留率74.58%。结论茯苓皮总多糖的提取纯化工艺稳定可靠,可为其进一步开发提供参考。     

Flexible Removable Partial Denture Prosthesis: A Survey of Dentists’ Attitudes and Knowledge in Greece and Croatia

Purpose

The aim of this study was to investigate through a questionnaire the knowledge, attitudes and possible differences in the use of flexible RPDPs among dentists in Greece and Croatia.

Material and Methods

A questionnaire of 16 questions was originally created in English, translated into Greek and Croatian language following a two way translation and tested for apprehension, precision, clarity and homogeneity by a number of native English speaking Greek and Croatian dentists. Following the necessary corrections, the questionnaires replicated in two online surveys and their addresses with an informed consent were sent by emails to nearly 4000 dentists in each country to participate. Collected data were analyzed by chi-square tests at a= .05 level of significance.

Results

378 dentists from Greece and 304 from Croatia participated in the study. 137(36.2%) dentists from Greece and 56(18.4%) from Croatia provided flexible RPDPs to their patients. Statistical analysis for all providers indicated no significant difference between genders (P>.05), significant differences between age groups (P<.01), years of practice (P<.05), specialization (P <.001), and instruction on flexible prostheses (P <.001). The analysis between the two countries showed differences for gender and age groups (P<.01) but no differences between experienced, specialized or instructed groups (P >.05).

Conclusion

The survey indicated differences between the two countries in the percentages of dentists using, selecting and providing RPDPs for their patients. Practitioners’ age, years in practice and instruction were associated with the provision of the prostheses, while comfort, esthetics and cost were the reasons for deciding to use the flexible RPDPs.

Conclusion

Although dentists are not educated in their schools about flexible RPDPs, almost a third of them offer this treatment to their patients. Long term success of these devices depends on clinical education, more experience and definitely more research.     

Comparative study of anatomical specimens using plastination by araldite HY103, polypropylene resin, 6170H19 Orthocryl and silicone – A qualitative study

Background

Most of the organs and tissues are preserved in formalin with its own set of disadvantages. Plastination is a unique method of permanently preserving tissue in a life like state. Plastination developed by western authorities is a labour and equipment intensive affair. Most common polymer used is S10, however this study uses easily available alternative polymers for plastination.

Method

Various polymers like Epoxy resins, Polypropylene resins, Orthocryl and silicone were used in plastinating the anatomical specimens. Specific methods were used for solid, hollow organs and brain specimens. The specimens were made to undergo stages of fixation, dehydration, impregnation and curing. The results were studied and interpreted under various parameters.

Results

The results were interpreted under various parameters like shrinkage, retention of colour, odour, pliability and retention of gross anatomy. The study concluded that Orthocryl and Epoxy resins retained maximum colour with minimal shrinkage while maximum discolouration was with polypropylene plastinates. Brain sections were best preserved in Orthocryl.

Conclusion

The study concluded that indigenous methods and materials can produce quality plastinates which can be an important adjunct to traditional methods of teaching however more studies need to be done for refinement.     

不同表面处理方式对丙烯酸树脂表面性状和粘接强度的影响

目的探讨不同表面处理方式对丙烯酸树脂表面性状和粘接强度的影响。方法制备硅橡胶与丙烯酸树脂构成的重叠联合模型。根据树脂条的不同表面处理方式,将模型随机分为4组:对照组、MMA浸润组、喷砂组、MMA浸润+喷砂组。用扫描电镜观察各组树脂处理后的表面形态变化,用粗糙度仪检测其粗糙度,万能材料试验机测定树脂条和硅橡胶之间的粘接强度。结果 1.电镜观察显示,未经处理的树脂条表面打磨痕迹明显,经过MMA浸润后,表面出现溶解的痕迹,经过喷砂后,表面粗糙凸凹不平;2.粗糙度:喷砂组(3.12±0.02)μm和MMA浸润+喷砂组(3.11±0.01)μm>对照组(0.73±0.01)μm和MMA浸润组(0.71±0.01)μm,且差异有统计学意义(P<0.05);3.粘接强度:MMA浸润+喷砂组(2.34±0.03)MPa>喷砂组(2.02±0.01)MPa>MMA浸润组(1.81±0.02)MPa>对照组(1.50±0.01)MPa,且差异有统计学意义(P<0.05)。结论 MMA单体浸润与喷砂的处理方式可以使丙烯酸树脂表面的形貌发生变化,更有利于硅橡胶与丙烯酸树脂的结合,获到良好的粘接效果,可在临床推广使用。     

纤维树脂桩核系统修复牙根发育不完全牙后抗折强度的分析

目的通过对经根管治疗后使用玻璃纤维桩核进行修复的牙根发育不完全牙各部位抗折强度的测量比较,以期为临床使用桩核系统修复根尖诱导成形术后的牙降低根折风险提供依据。方法收集符合纳入标准的因正畸需要拔除的根尖发育不完全,根尖孔未形成的第1、2前磨牙45颗,随机分成3组。分别为纤维桩复合树脂水门汀组(实验组)、复合树脂水门汀组(阳性对照组)、根管充填后不作处理组(阴性对照组),每组样本15颗,常规桩道预备后用复合树脂和桩核系统进行修复,将修复后的样本牙进行包埋,采用TY-8000型电子万能测试机分别测量牙根颈1/3和中1/3区域的抗折强度,比较经纤维桩核系统修复后牙根不同部位的抗折强度。采用SAS软件包对所得数据进行统计学分析。结果实验组的牙根颈部、中部的抗折强度分别为(999±75.40)N和(799±21.77)N,阴性对照组分别为(501±38.4)N和(472±22.98)N,阳性对照组分别为(704±88.39)、(550±20.14)N。实验组的牙根各部位的抗折能力均最强,与阳、阴性对照组均有显著差异(P<0.0001)。结论纤维桩核系统对牙根抗折性能有显著影响,植入纤维树脂桩的牙齿在牙根颈1/3和中1/3区域都显示出比植入复合树脂粘接材料和仅经根管充填后的牙齿具有更大的抗折强度。     

Comparative study of the shear bond strength of various veneering materials on grade II commercially pure titanium

PURPOSE

To compare the shear bond strength of various veneering materials to grade II commercially pure titanium (CP-Ti).

MATERIALS AND METHODS

Thirty specimens of CP-Ti disc with 9 mm diameter and 10 mm height were divided into three experimental groups. Each group was bonded to heat-polymerized acrylic resin (Lucitone 199), porcelain (Triceram), and indirect composite (Sinfony) with 7 mm diameter and 2 mm height. For the control group (n=10), Lucitone 199 were applied on type IV gold alloy castings. All samples were thermocycled for 5000 cycles in 5-55℃ water. The maximum shear bond strength (MPa) was measured with a Universal Testing Machine. After the shear bond strength test, the failure mode was assessed with an optic microscope and a scanning electron microscope. Statistical analysis was carried out with a Kruskal-Wallis Test and Mann-Whitney Test.

RESULTS

The mean shear bond strength and standard deviations for experimental groups were as follows: Ti-Lucitone 199 (12.11 ± 4.44 MPa); Ti-Triceram (11.09 ± 1.66 MPa); Ti-Sinfony (4.32 ± 0.64 MPa). All of these experimental groups showed lower shear bond strength than the control group (16.14 ± 1.89 MPa). However, there was no statistically significant difference between the Ti-Lucitone 199 group and the control group, and the Ti-Lucitone 199 group and the Ti-Triceram group. Most of the failure patterns in all experimental groups were adhesive failures.

CONCLUSION

The shear bond strength of veneering materials such as heat-polymerized acrylic resin, porcelain, and indirect composite to CP-Ti was compatible to that of heatpolymerized acrylic resin to cast gold alloy.     

Evaluation of the bond strength between aged composite cores and luting agent

PURPOSE

The aim of this study was to evaluate effect of different surface treatment methods on the bond strength between aged composite-resin core and luting agent.

MATERIALS AND METHODS

Seventy-five resin composites and also seventy-five zirconia ceramic discs were prepared. 60 composite samples were exposed to thermal aging (10,000 cycles, 5 to 55℃) and different surface treatment. All specimens were separated into 5 groups (n=15): 1) Intact specimens 2) Thermal aging-air polishing 3) Thermal aging- Er:YAG laser irradiation 4) Thermal aging- acid etching 5) Thermal-aging. All specimens were bonded to the zirconia discs with resin cement and fixed to universal testing machine and bond strength testing loaded to failure with a crosshead speed of 0.5 mm/min. The fractured surface was classified as adhesive failure, cohesive failure and adhesive-cohesive failure. The bond strength data was statistically compared by the Kruskal-Wallis method complemented by the Bonferroni correction Mann-Whitney U test. The probability level for statistical significance was set at α=.05.

RESULTS

Thermal aging and different surface treatment methods have significant effect on the bond strength between composite-resin cores and luting-agent (P<.05). The mean baseline bond strength values ranged between 7.07 ± 2.11 and 26.05 ± 6.53 N. The highest bond strength of 26.05 ± 6.53 N was obtained with Group 3. Group 5 showed the lowest value of bond strength.

CONCLUSION

Appropriate surface treatment method should be applied to aged composite resin cores or aged-composites restorations should be replaced for the optimal bond strength and the clinical success.     

大孔树脂纯化北五味子中总木脂素的工艺研究

目的:研究大孔树脂纯化北五味子中总木脂素的工艺条件。方法:以吸附量和解析率为指标,通过静态吸附-解析试验,从不同型号的大孔树脂中筛选出最佳型号的树脂;以解析率为指标,采用单因素试验考察乙醇体积分数、乙醇用量、上样浓度及上样量等对北五味子总木脂素大孔树脂纯化工艺的影响。采用紫外分光光度法测定总木脂素含量。结果:最佳纯化工艺为:取AB-8型树脂20 m L(湿体积)湿法上柱,上样液浓度1.5 mg/m L,上样量6 BV,加5 BV的95%乙醇按3 BV/h的流速进行洗脱。结论:AB-8型大孔树脂对五味子中总木脂素有良好的纯化效果。