不饱和螺环原酸酯与牙科树脂基质的化学固化反应的研究

目的：研究一种不饱和螺环原酸酯与牙科树脂基质在室温化学固化条件下的引发体系、聚合性体积收缩率、聚合转化率、开环反应率以及固化时间。方法：MTOSN膨胀单体与Bis-GMA或BisS-GMA树脂基质单体混合后,加入过氧化苯甲酰（BPO）或过氧化二叔丁基（DTBP）热分解型引发剂进行热固化反应;加入由BPO或DTBP引发剂和N,N-二羟丙基对甲苯胺（DHPT）、N,N-二甲基对甲苯胺（DMT）、对甲苯亚磺酸钠（TSS）促进剂进行室温化学固化反应。用红外光谱仪以内标法测试固化物的聚合转化率和开环反应率,用示差热量扫描仪测定固化时间,用膨胀计法测试聚合性体积收缩率。结果：在本实验条件下,BisS-GMA实验组的性能均优于Bis-GMA实验组。DTBP只能做热分解型引发剂,不能做氧化还原引发剂。BPO∶DHPT=1∶1时,MTOSN/BisS-GMA组有较高的聚合转化率与开环反应率,有较低的体积收缩率和固化时间。加入TSS后,能明显降低开环反应率和固化时间。加入MTOSN膨胀单体,能明显降低体积收缩率。结论：当BPO∶DHPT=1∶1时,MTOSN膨胀单体和BisS-GMA树脂基质能发生室温化学固化反应,有较低的体积收缩率,可以作为新型口腔复合树脂的基体树脂。     

光固化粘接剂单体转化率的红外光谱分析及其临床意义

复合树脂在空气中聚合时受氧气的阻聚影响，在表层形成不固化层，尤其是低粘度树脂受影响更严重，并严重影响复合树指与牙釉质的粘接强度。本试验通过对粘接剂在不同状态下单体转化率的比较分析，进一步从理论上解释了光固化粘接剂与复合树脂一起固化的新方法可以提高树脂－釉质粘接强度的原因。提高了粘接修复效果，是值得在临床上大力推广的方法。     

热压处理对Artglass玻璃瓷力学性能和单体转化率的影响

目的探讨二期高温、高压处理对Artglass玻璃瓷材料力学性能和单体转化率的影响,并初步分析二者之间的内在联系。方法用Artglass DA3材料分别制作20个抗压强度和直径拉伸强度测试试件,每种试件随机分为等数的两组,一组在U-niXS频闪聚合机中常规聚合,另一组在聚合后用国产自控多用途牙用树脂聚合器进行二期热压处理,温度120℃,压力0.6MPa,时间7min;用Instron 1195万能拉力测试仪测得抗压强度和直径拉伸强度,对二期热压处理前后的测试值用单因素方差分析方法进行比较。另外用傅立叶变换红外色谱仪,分别测试常规固化的Artglass DA3材料和二次热压处理后的材料,在标准基线方法下得到各自的单体转化率并进行比较。结果二期热压处理后Artglass的抗压强度和直径拉伸强度都有了显著提高,提高幅度分别为16%和9%。常规固化和热压处理后材料的单体转化率分别为(73.2±2.2)%和(75.0±2.0)%,热压处理后单体转化率的提高幅度为2.5%。结论二期热压处理可以提高Artglass玻璃瓷材料的单体转化率,并改善材料的机械性能。     

氯已定预处理对两步法自酸蚀粘接剂牙本质粘接界面稳定性的影响

目的：探讨氯已定预处理对两步法自酸蚀粘接剂的牙本质粘接界面稳定性的影响.方法：40颗离体人磨牙沿垂直于牙长轴的方向切割,暴露冠中部牙本质作为粘接面,牙本质试件随机分为两组,一组在粘接处理前涂布0.2％氯已定为实验组,一组无预处理为对照组,两组经两步法自酸蚀粘接剂SE Bond处理后,堆积复合树脂制备成粘接试件.每组随机抽取2个试件借助微拉曼光谱仪分析粘接剂的双键转化率,剩余的18个试件随机分为两个亚组,分别于即刻和冷热循环5000次后检测微拉伸粘接强度和界面的纳米渗漏情况.结果：0.2％氯已定预处理对SE Bond的树脂双键转化率无显著性影响（P＞0.05）.即刻测试时,对照组和实验组间的微拉伸粘接强度和纳米渗漏差异无统计学意义（PP ＞0.05）.冷热循环老化处理后,实验组的微拉伸粘接强度显著高于对照组,纳米渗漏程度显著低于对照组（P＜0.05）.结论：0.2％氯已定预处理不会干扰SE Bond的树脂聚合,且可提高其与牙本质粘接界面的稳定性.     

二期处理对Ceramage瓷聚体机械强度和单体转化率的影响

目的:探讨二期高温、高压处理对Ceramage瓷聚体材料机械性能和单体转化率的影响,并初步分析二者之间的内在联系.方法:用Ceramage瓷聚体体部材料分别制作20个抗压强度和直径拉伸强度测试试件,所有试件均在Solidilite光聚合器中常规聚合,然后随机分为等数的两组,一组为对照组,另一组聚合后用国产自控多用途牙用树脂聚合器进行二期热压处理,温度120℃,压力0.6MPa,时间7min;用Bose公司ElectroForce3520多功能材料实验机测得抗压强度和直径拉伸强度,对二期处理前后的测试值用单因素方差分析方法进行比较.另外用傅立叶变换红外色谱仪,分别测试常规固化的Ceramage瓷聚体体部材料和二次热压处理后的材料,在标准基线方法下得到各自的单体转化率并进行比较.结果:二期热压处理后Ceramage瓷聚体体部材料的抗压强度和直径拉伸强度都有了显著提高,提高幅度分别为12.90%和10.84%(P<0.01).常规处理时Ceramage体部材料的单体转化率为72.7%12.2%,经二期热压处理后单体转化率为75.4%±1.5%,提高幅度为2.7%(P<0.01).结论:二期热压处理可以提高Ceramage瓷聚体材料的单体转化率,并改善材料的机械性能.     

光照强度对牙本质湿粘接微拉伸强度的影响

目的：探讨光照强度对牙本质湿粘接微拉伸强度的影响。方法：用WDW-100型电子万能试验机测试和比较粘接剂在不同强度光照后的微拉伸强度。结果：采用300mW/cm^2的光照强度。所得的微拉伸强度明显高于采用500mW/cm^2和800mW/cm^2固化的微拉伸强度；采用500mW/cm^2固化的微拉伸强度又明显高于采用800mW/cm^2固化的微拉伸强度。结论：较弱的光照强度能提高光固化树脂与牙本质之间的湿粘接微拉伸强度，提示采用较弱的光照强度对提高复合树脂与牙本质间的结合有积极作用。     

树脂加强型玻璃离子水门汀抗拉伸粘接性能的研究

目的 研究树脂加强型玻璃离子水门汀(RMGIC)在不同牙面处理条件下,其抗拉伸粘接强度随时间变化的情况,为临床更有效地应用树脂加强型玻璃离子水门汀粘接托槽提供参考.方法 取因正畸原因拔除的人前磨牙150颗,随机分为5组,树脂对照组,GC酸蚀+水润湿组,GC酸蚀+干燥组,GC不酸蚀+水润湿组,GC不酸蚀+干燥组.分别采用不同方式粘接托槽.检测其在粘接后30min、24h、30d的抗拉伸粘接强度及粘接剂残留指数.结果 除GC酸蚀+干燥组在粘接后30min外,两GC酸蚀组的抗拉伸粘接强度均高于同一时间任一GC不酸蚀组(P＜0.01).各实验组在粘接后30d时的抗拉伸粘接强度均高于相同条件下30min时的抗拉伸粘接强度(P＜0.01).GC酸蚀组粘接剂残留指数(ARI)与对照组相当(P＞0.05),而GC不酸蚀组ARI低于对照组(P＜0.01).结论 酸蚀处理有助于提升树脂加强型玻璃离子水门汀GC的抗拉伸粘接强度,其强度基本可以达到传统树脂类粘接剂水平.湿润的粘接环境较干燥的粘接环境更有助于加快RMGIC抗拉伸粘接强度的上升.     

复合树脂固化收缩应力对黏结强度影响的三维有限元分析

目的：分析复合树脂固化收缩后黏结层的应力变化。方法：建立三维环形有限元模块，分别采用釉质、黏结剂、树脂的材料参数，应用温度应力的原理，模拟树脂固化时产生的体积收缩。分析10GPa、20GPa弹性模量的复合树脂在1％、1，5％、2％、2．5％、3％、3．5％体积收缩率时黏结层的应力分布和变化规律。结果：树脂固化时体积收缩率越大，在黏结层产生的应力越大；树脂的弹性模量越大，黏结层的应力越大。结论：树脂固化时的体积收缩可在黏结层产生较大的应力，影响黏结强度。     

不同表面处理的纤维桩微拉伸粘接强度研究

目的:通过微拉伸粘接强度测试法测试在纤维桩表面经过6种不同的处理后与核树脂的粘接强度,探索何种表面处理方法能显著提高纤维桩与核树脂的粘接强度,为临床应用提供参考。方法:将30根石英纤维桩随机分成6组,每组5根。A组纤维桩表面涂布粘接剂,B组涂布硅烷处理剂,吹干后涂粘接剂,C组5%氢氟酸酸蚀30sec,流水冲洗吹干后处理同A组,D组5%氢氟酸酸蚀30sec,流水冲洗吹干后处理同B组,E组24%双氧水处理,后操作同A组,F组24%双氧水处理后操作同B组。在桩周分层固化核树脂,用低速锯沿纤维桩外周平行片切,再垂直粘接面片切成横截面约0.9mm×0.9mm的长方柱状试件,每组15个,用微拉伸粘接强度测试法测试纤维桩与核树脂的微拉伸粘接强度,体视显微镜观察断裂类型。结果:A组微拉伸粘接强度8.78±2.20MPa,B组9.35±1.92MPa,C组15.50±2.87MPa,D组22.98±3.24MPa,E组16.64±2.70MPa,F组24.88±3.9 0MPa。用氢氟酸酸蚀的C组和D组和用双氧水处理的E组和F组的微拉伸粘接强度明显高于A组B组(P<0.05)。用氢氟酸酸蚀后再硅烷化处理的D组比C组、用双氧水处...     

大块充填复合树脂修复后的临床效果的研究进展

目前大块充填复合树脂逐渐应用于牙科治疗中,一些研究发现其除了具有操作简单的优势外,还具有良好的临床效果。单体转化率是反映树脂固化程度的重要指标,也是决定树脂的机械性能和生物学性能的重要因素。牙尖变形、边缘微渗漏是由于复合树脂的聚合收缩产生的收缩应力造成的,对充填体的耐久度、边缘封闭性有一定的影响,可以认为是衡量树脂粘接修复后的临床效果的常见指标。该文主要通过单体转化率、牙尖变形和边缘微渗漏这三方面对大块充填复合树脂修复后的临床效果以及原因机理做一个总结描述。     

Comparison of two video-imaging instruments for measuring volumetric shrinkage of dental resin composites

OBJECTIVES: The purpose of this study was to measure the polymerization shrinkage of three dental resin composites using two commercially available video-imaging devices to determine if the devices produced equivalent results. METHODS: Small, semi-spherical specimens of a microhybrid (Venus), microfill (Filtek A110), and flowable (Esthet*X Flow) resin composite were manually formed and light activated for 40s using a light-curing unit. The volumetric polymerization shrinkage of fifteen specimens of each brand of resin composite was measured using the AcuVol and the Drop Shape Analysis System model DSA10 Mk2 (DSAS) video-imaging devices. Mean volumetric shrinkage values were calculated for each resin composite and equivalence was evaluated using the two one-sided tests approach. Differences between the means that were less than approximately 5% of the observed shrinkage were considered indicative of clinical equivalence. RESULTS: Mean volumetric shrinkage values measured for the resin composites were: Venus (AcuVol, 3.07+/-0.07%; DSAS, 2.90+/-0.07%); Filtek A110 (AcuVol, 2.26+/-0.10%; DSAS, 2.25+/-0.09%); and Esthet*X Flow (AcuVol, 5.01+/-0.17%; DSAS, 5.14+/-0.11%). Statistical analysis revealed that the two imaging devices produced equivalent results for Filtek A110 and Esthet*X Flow but not for Venus. CONCLUSIONS: Video-imaging systems provide an easy method for measuring volumetric shrinkage of resin composites. As with other methods for measuring volumetric shrinkage, however, they are best used to comparatively measure different materials within the same laboratory.     

The effect of resin matrix composition on the polymerization shrinkage and rheological properties of experimental dental composites.

OBJECTIVES: This study was undertaken to evaluate the effect of the resin matrix composition of experimental composites on their polymerization shrinkage and rheological properties. METHODS: Six experimental composites consisting of varying ratios of Bis-GMA, TEGDMA, and UDMA were made. All composites had the same amount of filler (barium-aluminum-silicate glass, 76.5 wt.%) and initiator concentrations (camphorquinone, 1.7 wt.%). To investigate the effects of different resin matrices on the polymerization shrinkage, a newly developed measurement method was used. Using a rotational rheometer, a dynamic oscillatory shear test was undertaken to evaluate the rheological properties, including the storage shear modulus (G'), loss shear modulus (G'), loss tangent (tandelta), phase angle (delta), and complex viscosity (eta*) of the experimental composites as a function of frequency (0.1-10Hz). RESULTS: The polymerization shrinkage and complex viscosity of the experimental composites ranged from 2.61 to 3.88 vol.% and from 3.8 to 181.4Pas, respectively. The experimental composite composed of 17.5% Bis-GMA and 4.4% TEGDMA showed the lowest shrinkage and highest viscosity. The composite composed of 8.7% Bis-GMA and 13.1% TEGDMA showed the highest shrinkage and lowest viscosity. With increasing TEGDMA content, the polymerization shrinkage increased but the viscosity decreased. The substitution of UDMA for TEGDMA reduced the shrinkage level but increased viscosity. There was an inverse relationship between the polymerization shrinkage and complex viscosity. All experimental composites exhibited pseudoplasticity. SIGNIFICANCE: Within the limitations of this study, resin matrix composition significantly affected the volumetric shrinkage and rheological properties of the experimental composites.     

Influence of irradiation time on volumetric shrinkage and flexural properties of flowable resins

The purpose of this study was to evaluate the influence of irradiation time on volumetric change and flexural properties of flowable resins. Four commercially available flowable resins were employed. For volumetric shrinkage measurement, resin pastes were inserted into a mold (2 mm in height, 4 mm in diameter) and put into a water-filled dilatometer. This was followed by light irradiation for 10, 20, or 30 seconds at 600 mW/cm2. Volumetric shrinkage of the specimens was then determined from the change in the height of water meniscus, and the percentage volumetric change thereof was calculated. For flexural strength measurement, resin pastes were filled into a stainless steel mold (25 x 2 x 2 mm), and the middle one-third of the specimen was first irradiated. The remaining two-thirds were irradiated under the same irradiation conditions as volumetric shrinkage measurement. After 24-hour storage in 37 degrees C water, three-point flexural tests were performed with a span length of 20 mm at a crosshead speed of 1.0 mm/min. One-way ANOVA followed by Tukey's HSD test were used for statistical analysis. For all materials tested except Estelite Flow Quick, both volumetric shrinkage and flexural strength increased with longer light irradiation time. Results of this study indicated that both volumetric shrinkage and flexural properties were influenced by light irradiation time and resin composite type.     

Polymerization shrinkage of index and pattern acrylic resins

Inadequate dimensional stability caused by polymerization shrinkage has been reported concerning the various applications of acrylic resins. The objective of the study was to evaluate dimensional changes of two self-curing acrylic resins marketed as pattern and index material. Early volumetric changes were measured with a dilatometer and late linear changes were recorded with an inductive transducer. After 24 hours the volumetric shrinkage was 7.9% for Duralay resin and 6.5% for Palavit G resin; 80% of the change appears before 17 minutes at room temperature. Shrinkage was significantly increased when the proportion of powder in the mix was diminished. Results suggest that these resins should be used with some method to compensate for the shrinkage, when used as index material. However, the dimensional change might provide significant advantages for intracoronal castings.     

Influence of light activation on the volumetric change of core foundation resins

A core foundation system is frequently used in endodontically treated teeth that suffer excessive loss of the coronal portion of their structure. The volumetric shrinkage of core foundation resins may create marginal gaps that influence the bonding ability and longevity of a restored tooth. Little is known about how activation conditions of resin core foundation resin pastes affect their volumetric shrinkage. This study evaluated the influence of light intensity and light activation duration on volumetric shrinkage of direct core foundation resins. Two dual- and one light-activated core foundation resin pastes were employed. The material was placed in a Teflon mold 4 mm in diameter and 2 mm in height and extruded into a water filled dilatometer. The specimens were then light activated and the change in height of the meniscus of water was recorded using a charged-coupled device camera. The average volumetric shrinkage of the core foundation resins after 180 seconds ranged from 1.53% to 2.63%. For all materials tested, there was a tendency for increased volumetric shrinkage with increased light activation time and intensity. The results of this study indicate that the volumetric change of core foundation resins is influenced by the time and intensity of light activation.     

Volumetric polymerization shrinkage of resin composites under simulated intraoral temperature and humidity conditions

This study measured the volumetric shrinkage of resin composites polymerized under temperature and humidity conditions simulating the oral cavity and compared them to those occurring under ambient room conditions. Small, semispherical specimens of a microhybrid (Z100), microfill (Filtek A110) and flowable microhybrid (4 Seasons Flow) resin composite were manually formed and light activated for 40 seconds using a halogen light-curing unit (Spectrum Curing Light). The volumetric polymerization shrinkage of 10 specimens of each brand of resin composite was measured using a drop shape analysis unit (Drop Shape Analysis System, model DSA10 Mk2) under each of two temperature/relative humidity conditions: room conditions (22 +/- 2 degrees C and 60 +/- 5%) and those simulating intraoral conditions (35 degrees C and 92 +/- 5%). Mean volumetric shrinkage values were calculated for each resin composite and the data were analyzed using two-way analysis of variance and t-test (a=0.05) to determine if significant differences existed between the amount of volumetric polymerization shrinkage that occurred under ambient room conditions and that which occurred under simulated intraoral conditions. Mean volumetric shrinkage values measured for the resin composites were: 2.26 +/- 0.04% (ambient) and 2.61 +/- 0.04% (intraoral) for Z100; 1.96 +/- 0.04% (ambient) and 2.28 +/- 0.04% (intraoral) for Filtek A110 and 4.53 +/- 0.06% (ambient) and 5.34 +/- 0.05% (intraoral) for 4 Seasons Flow. For each resin composite, statistical analysis indicated that the amount of volumetric shrinkage measured under simulated intraoral conditions was significantly greater than what was measured under ambient room conditions (p<0.0001).     

复合树脂固化收缩应力对釉质受力影响的三维有限元研究

解放军总医院老年口腔病科副主任医师目的:分析复合树脂固化收缩后釉质的应力变化。方法:建立三维环形有限元模块,分别采用釉质、粘结剂、树脂的材料参数,应用温度应力的原理,模拟树脂固化时的体积收缩。分别分析弹性模量10MPa树脂在1%、1.5%、2%、2.5%、3%、3.5%体积收缩率时釉质应力分布及变化规律。结果:树脂固化时体积收缩率越大,釉质受力越大;应力集中的部位在釉质粘结界面边缘;距粘结界面距离越大,应力越小;釉质部分的vonMises应力明显大于第一主应力。结论:树脂固化时,可以在釉质产生较大的应力,特别是vonMises应力。     

Polymerization shrinkage and contraction stress of dental resin composites

OBJECTIVE: The aim of this study was to evaluate the shrinkage, contraction stress, tensile modulus, and the flow factor of 17 commercially available dental resin composites. METHOD: The volumetric shrinkage measurements were performed by mercury dilatometry, and the contraction stress and tensile modulus were determined by means of stress-strain analysis. The statistical analysis was conducted by ANOVA and Tukey's post hoc test, and linear regression. RESULTS: Strong linear correlation for most resin composites were found for (i) contraction stress and shrinkage (ii) contraction stress and tensile modulus, and (iii) shrinkage and tensile modules. For most of the materials the unpolymerized resin content determines the amount of shrinkage, contraction stress and tensile modules. The pre-polymerized clusters in Heliomolar results in improved shrinkage/contraction stress properties. The shrinkage/contraction stress for Filtek Z100, Aelite Flo, and Flow-it was too high for the amount of resin in the resin composite. This was rationalized by high polymerization rates, a flow factor, and the nature of the resin. SIGNIFICANCE: High shrinkage and/or high contraction stress may lead to failure of the bond between the resin composites and the tooth structure. This study shows that the unpolymerized resin content determines the amount of shrinkage, contraction stress and tensile modules. Therefore, using pre-polymerized clusters will improve shrinkage/contraction stress properties, as was shown in Heliomolar, while high polymerization rates, and low flow factors have a deteriorative effect on the shrinkage/contraction stress properties.