十种纳米填料光固化复合树脂聚合收缩性能的比较与评价

目的 探讨10种纳米填料光固化复合树脂的聚合收缩情况,评价纳米填料在光固化复合树脂聚合收缩性能中的作用.方法 采用激光位移传感器进行非接触式测量,实时监测10种纳米填料光固化树脂(CM:Clearfil Majesty; CX:Ceram·X;F:Fulfil;E:Estelite α;PM:Premisa; TN:Tetric N-Ceram restorative;S:Spectrum TPH3;TB:Tetric Bulk Fill;Z:Z350XT;P:P90)的聚合收缩情况.测量光固化时的体积收缩率、收缩速率峰值以及到达峰值的时间.采用单因素方差分析10种材料的差异.结果 10种纳米填料光固化树脂的体积收缩率差异有统计学意义(P＜0.01).10种纳米填料光固化树脂的体积收缩率范围为1.20％ ～ 3.09％,P＜PM ＜Z≈E ＜TN≈CM≈TB ＜CX ＜S ＜F,其中Z与E、TN与CM间差异无统计学意义,体积收缩率较接近.收缩速率峰值范围为2.14～ 14.76 μm/s,到达峰值的时间范围为3.29～5.39 s.结论 10种纳米填料复合树脂的聚合收缩差异显著,填料含量和粒径对复合树脂聚合收缩有一定影响作用,增加填料含量,减小纳米填料的粒径,有助于降低聚合收缩率.     

Clinical evaluation of six composite resins in posterior teeth

Six different composite resin restorative materials were placed in posterior Class I and Class II cavities and evaluated at one and two years after placement for colour, marginal discoloration, and wear. Wear was determined by comparison with standard models and by SEM. All materials darkened over the study period but remained an acceptable match. Marginal discoloration increased. The trend of relative wear was in accordance with predictions from fracture mechanics. Insufficient restorations in one material were available at two years for it to be included in the results. The microfine materials used in this study suffered surface damage (micro-chipping) in high stress areas, again consistent with fracture mechanics predictions.     

Effects of surface conditioning on repair bond strengths of non-aged and aged microhybrid,nanohybrid, and nanofilled composite resins

This study evaluates effects of aging on repair bond strengths of microhybrid, nanohybrid, and nanofilled composite resins and characterizes the interacting surfaces after aging. Disk-shaped composite specimens were assigned to one of three aging conditions: (1) thermocycling (5,000×, 5–55°C), (2) storage in water at 37°C for 6 months, or (3) immersion in citric acid at 37°C, pH 3 for 1 week; a non-aged group acted as the control. Two surface conditionings were selected: intermediate adhesive resin application (IAR-application) and chairside silica coating followed by silanization and its specific IAR-application (SC-application). Composite resins, of the same kind as their substrate, were adhered onto the substrates, and repair shear bond strengths were determined, followed by failure type evaluation. Filler particle exposure was determined by X-ray photoelectron spectroscopy and surface roughness analyzed using scanning electron and atomic force microscopy. Surface roughness increased in all composite resins after aging, but filler particle exposure at the surface only increased after thermocycling and citric acid immersion. Composite resin type, surface conditioning, and aging method significantly influenced the repair bond strengths (p < 0.05, three-way analysis of variance) with the least severe effects of water storage. Repair bond strengths in aged composite resins after IAR-application were always lower in non-aged ones, while SC-application led to higher bond strengths than IAR-application after thermocycling and water storage. In addition, SC-application led to more cohesive failures than after IAR-application, regardless the aging method.     

Micro-sized erosions in a nanofilled composite after repeated acidic beverage exposures: consequences of clusters dislodgments

Objective

To evaluate the hardness (KHN), color stability (DE), and superficial micromorphology of two categories of composites after immersion in either distilled water or grape juice for up to 45 days.

Material and Methods

Cylindrical specimens (6 mm diameter x 2 mm thick) were obtained according to the factors: composite [Opallis (FGM) and Filtek Z350XT (3M ESPE)]; immersion solution (distilled water and grape juice); and evaluation time: 24 h and 7, 14, 21, 28, and 45 days. After photoactivation, the specimens were stored at 37ºC for 24 h. KHN (50 g/15 s) and ΔE were then repeatedly assessed according to the immersion solutions. Data were analyzed (three-way ANOVA/Tukey''s test). Scanning electron microscopy (SEM) topographic analysis was also performed.

Results

In general, KHN of both composites reduced after 24 h, irrespective of the immersion solution and time. A significantly lower KHN was noted for Opallis compared with Filtek Z350XT in all parameters. An increase in ΔE over time was noted for both composites, irrespective of the immersion solution. Significantly higher ΔE was noted for Filtek Z350XT immersed in grape juice compared with Opallis, regardless of the evaluation time. The grape juice caused significantly higher DE compared with water in all periods. SEM analysis showed eroded areas for Filtek Z350XT but not for Opallis.

Conclusions

The compositions and immersion solutions influence the composite hardness and the color stability. In spite of the higher hardness, the nanofilled composite is more susceptible to color change than the microhybrid when immersed in an acidic dyed solution.     

Curing depth of (polyacid-modified) composite resins determined by scraping and a penetrometer

OBJECTIVES: The present study aimed to compare the curing depth of polyacid-modified composite resins (PAM-C) and some representative composite resins as a function of shade and post-cure using a scraping method and a penetrometer. METHODS: The curing depth of the PAM-C Hytac, F2000, Glasiosite, Dyract, Dyract AP, and Compoglass F and of the composite resins Durafill VS and Z100 were determined for shade A2 and A4 using a scraping method based on ISO 4049:2000 and a digital penetrometer. Samples were light-cured (800 mW/cm2 at 40 s) in bulk in split stainless steel molds. Immediately after light-curing or after a 24 h post-cure, the height of the cylinder of cured material was measured and taken as the curing depth. RESULTS: For both test methods, the curing depth was independent of post-cure (P > or = 0.05) but differed significantly among materials and shade (P<0.001). Moreover, there was a significant interaction between the latter (P<0.001). Regression analysis generally demonstrated that there was no significant systematic or proportional difference between the test methods. The curing depths of the PAM-C F2000 and Glasiosite were comparable to that of the hybrid composite Z100, but greater than the curing depth of the microfilled composite Durafill VS. The PAM-C Dyract AP, Dyract, Compoglass F and Hytac had a curing depth smaller than that of the microfilled composite. SIGNIFICANCE: The scraping method based on ISO 4049:2000 and a digital penetrometer give comparable curing depths for PAM-C. The curing depth greatly varies among the materials and can be considerably smaller than that of a microfilled composite resin. Shade A2 results in significantly greater values for the curing depth compared to shade A4, the effect depending quantitatively on the formulation of the material.     

Some factors influencing the depth of cure of visible light-activated composite resins

Some of the factors influencing the depth of cure of four composite resins of different composition were examined. Knoop hardness measurements were carried out at the surface and 1, 2, 3, 4 and 6 mm below the surface to which the light was applied. The hardness of the composites decreased with increasing depth and shorter exposure times. The composites continued to polymerize after removal of the light source. Composition of the composite resin has a major effect on the surface hardness and depth of polymerization.     

An in vitro quantitative antibacterial analysis of amalgam and composite resins

OBJECTIVES: Antibacterial properties of restorative dental materials such as amalgam and composite resins may improve the restorative treatment outcome. This study evaluates the antibacterial properties of three composite resins: Z250, Tetric Ceram, P60 and a dental amalgam in vitro. METHODS: Streptococcus mutans and Actinomyces viscosus served as test microorganisms. Three quantitative microtiter spectrophotometric assays were used to evaluate the effect of the restorative materials on: (i) early-stage biofilm using a direct contact test (DCT); (ii) planktonic bacterial growth; (iii) bacterial growth in the materials' elute. For comparison purposes, agar diffusion test (ADT) was also performed. RESULTS: The effect of the composite resins on bacterial growth was minimal and limited to a few days only. One-week-aged composites promoted growth of S. mutans and A. viscosus. The antibacterial properties in direct contact were more potent than in planktonic bacterial growth. Amalgam showed complete inhibition of both bacteria in all phases, and the effect lasted for at least 1 week. The materials' elute had no effect on both bacterial growth with the exception of complete inhibition of S. mutans in amalgam. The later results correlated with the ADT. CONCLUSIONS: The present findings demonstrate potent and lasting antibacterial properties of amalgam, which are lacking in composite resins. This may explain the clinical observation of biofilm accumulated more on composites compared to amalgams. It follows that the assessment of antibacterial properties of poorly-soluble materials has to employ more than one assay.     

Effect of different composite modulation protocols on the conversion and polymerization stress profile of bulk-filled resin restorations

ObjectiveThe aim of this in vitro study was to test the effect of different composite modulation protocols (pre-heating, light-curing time and oligomer addition) for bulk filling techniques on resin polymerization stress, intra-pulpal temperature change and degree of conversion.MethodsClass I cavities (4 mm depth × 5 mm diameter) were prepared in 48 extracted third molars and divided in 6 groups. Restorations were completed with a single increment, according to the following groups: (1) Filtek Z250XT (room temperature – activated for 20 s); (2) Filtek Z250XT (at room temperature – activated for 40 s); (3) Filtek Z250XT (pre-heated at 68 °C – activated for 20 s); (4) Filtek Z250XT (pre-heated at 68 °C – activated for 40 s); (5) Filtek BulkFill (at room temperature – activated for 20 s); (6) Filtek Z250XT (modified by the addition of a thio-urethane oligomer at room temperature – activated for 40 s). Acoustic emission test was used as a real-time polymerization stress (PS) assessment. The intra-pulpal temperature change was recorded with a thermocouple and bottom/top degree of conversion (DC) measured by Raman spectroscopy. Data were analyzed with one-way ANOVA/Tukey's test (α = 5%).ResultsPre-heating the resin composite did not influence the intra-pulpal temperature (p = 0.077). The thio-urethane-containing composite exhibited significantly less PS, due to a lower number of acoustic events. Groups with pre-heated composites did not result in significantly different PS. Filtek BulkFill and the thio-urethane experimental composite presented significantly higher DC.SignificanceResin composite pre-heating was not able to reduce polymerization stress in direct restorations. However, thio-urethane addition to a resin composite could reduce the polymerization stress while improving the DC.     

五种光固化后牙复合树脂三年疗效评定

为研究后牙光固化复合树脂的临床疗效及效果评定，我们采用两种疗效评价方法对５种后牙可见光固化复合树脂充填的１６９颗成人后牙Ⅰ类洞进行了１年及３年随访及疗效评定。结果表明：两种评价法各有优点。本组中疗效随时间延长呈下降趋势。治疗失败及缺陷主要发生在术后３年。失败的主要原因是继发龋、充填体脱落及边缘出现墨浸现象。３年成功率比１年有明显下降，故长期疗效尚需进一步观察。     

水的含量对硼酸铝晶须-二氧化硅熔附体填料复合树脂弯曲性能的影响

目的：研究正硅酸乙酯（TEOS）水解、缩聚过程中水与TEOS的摩尔比对硼酸铝晶须（AlBw）与SiO2熔附体填料复合树脂弯曲性能的影响。方法：采用TEOS溶胶-凝胶法,通过控制水与TEOS的摩尔比,制得不同粒径大小及分布的纳米SiO2,高温烧结使其熔附于AlBw表面,制作试样并测试其弯曲强度和弯曲弹性模量;利用透射电镜（TEM）观察AlBw-SiO2熔附体形貌。结果：水与TEOS摩尔比对牙科复合树脂的弯曲强度有显著性影响,但对弯曲弹性模量无显著性影响。SiO2纳米粒子的粒径大小及分散程度将影响牙科复合树脂的弯曲性能;不同粒径大小的纳米粒子不会影响牙科复合树脂的弯曲弹性模量。M水/TEOS=22时复合树脂的弯曲强度达149.59±12.86Mpa。结论：水与TEOS摩尔比可改善AlBw-SiO2熔附体填料复合树脂的弯曲性能。     

Effects of air-polishing powders on color stability of composite resins

Objectives

The purpose of this study was to investigate the effect of different air-polishing powders on the color stability of different types of composite resin restorative materials.

Material and methods

Thirty cylindrical specimens (15×2 mm) were prepared for each of 7 composite resin restorative materials. All specimens were polished with a series of aluminum oxide polishing discs (Sof-Lex). The prepared specimens of each composite resin were randomly divided into 3 groups of 10 specimens each, for control (Group-C) and two air-powder applications (Group-CP: Cavitron Prophy-Jet; Group-PS: Sirona ProSmile prophylaxis powder). A standard air-polishing unit (ProSmile Handly) was used. All specimens were air-powdered for 10 s at 4-bar pressure. The distance of the spray nosel from the specimens was approximately 10 mm and angulation of the nosel was 90º. Specimens were stored in 100 mL of coffee (Nescafe Classic) for 24 h at 37ºC. Color measurement of all specimens was recorded before and after exposure to staining agent with a colorimeter (Minolta CR-300). Color differences (∆E*) between the 2 color measurements (baseline and after 24 h storage) were calculated. The data were analyzed with a 2-way ANOVA test, and mean values were compared by the Tukey HSD test (p≤0.05).

Results

According to the 2-way ANOVA results, composite resin restorative materials, air-polishing powders, and their interaction were statistically significant (p<0.05) For Aelite Aesthetic Enemal, Filtek Z250, Grandio, CeramX Mono, and Quixfil composite resin restorative materials, no significant difference was observed between Group-PS and Group-CP (p>.05) and these groups demonstrated the highest ∆E* values. For Filtek Silorane and IntenS, the highest ∆E* values were observed in Group-PS. The lowest ∆E* values for all composite resin groups were observed in Group-C. When comparing the 7 composite resin restorative materials, Aelite Aesthetic Enemal demonstrated significantly less ∆E* values than the other composite resins tested. The highest ∆E* values were observed in Quixfil.

Conclusion

Except for Quixfil, all control groups of composite resins that were polished Sof-Lex exhibited clinically acceptable ∆E values (<3.7). Air-polishing applications increased the color change for all composite resin restorative materials tested. Composite restorations may require re-polishing after air-polishing.     

磨损过程中pH值改变对复合树脂磨耗性能的影响

目的:研究4种充填用复合树脂材料:Beautifit(B),SureFilTM(S),TE-Econom(T),Charisma(C)与牙釉质对磨,改变人工唾液pH值,对树脂材料与牙釉质磨耗性能的影响.方法:利用UMT-2微摩擦磨损实验机模拟复合树脂与牙釉质磨耗,计算树脂磨耗质量丧失量,扫描电镜观察磨耗后表面形貌.结果:SEM显示,B、S树脂中无机填料颗粒体积较大,C树脂相埘较小且均匀.4种树脂无机填料颗粒周围均出现裂纹和脱落迹象,牙釉质在酸性环境浸泡时磨损表面出现特征性变化.S,C,T 3种树脂较耐磨损;人工唾液pH值南6.8降为4.0时,B、S、T 3种树脂磨损量显著增加,C磨损量变化不显著.结论:不同品牌的复合树脂与牙釉质对磨时,耐磨性不同;降低pH值可以加速某些复合树脂的磨损.     

Effect of lipstick on composite resin color at different application times

Objectives

The aim of this study was to evaluate the influence of the contact of two lipsticks, one with common fixer and one with ultra fixer, on the color of a composite resin immediately, 30 min and 24 h after photoactivation.

Material and methods

Ninety specimens were prepared with a composite resin, Filtek-Z350. Specimens were polished and divided into 9 groups (n=10) according to time elapsed after photoactivation (A- immediately; B- 30 min; C- 24 h) and the contact with lipstick (UF- lipstick with ultra fixer; F- lipstick with common fixer). The control group was represented by specimens that did not have any contact with lipstick (C- without lipstick). Color measurements of the specimens were carried out using a spectrophotometer (Easyshade - CIE L* a* b* system). For UF and F groups, the baseline color of the specimens was measured immediately before pigmentation and the lipsticks were applied dry after 1 hour. The excess lipstick was removed with absorbent paper and final color checking was performed, including the control group. Differences between the final and baseline color measurements were calculated and data were analyzed statistically by the Kruskal-Wallis test at 5%.

Results

The means between the differences of color values were: AUF: 16.0; AF: 12.4; AC: 1.07; BUF: 9.51; BF: 8.3; BC: 0.91; CUF: 17.7; CF: 12.41; CC: 0.82.

Conclusion

Groups where lipstick was applied showed greater staining than the control group at the three evaluation times. The lipstick with ultra fixer stained more than the lipstick with common fixer. Time elapsed between photoactivation and contact with lipstick had a similar influence on the groups that received lipstick application.     

光固化复合树脂凝胶玻璃化后固化收缩量评价

目的 评价光固化复合树脂在凝胶点后特别是玻璃化后的固化收缩量,以期为深入研究光固化复合树脂的固化收缩特性提供新的评价方法.方法 利用本实验室自主研制开发的一种基于激光测距技术的固化收缩测量仪,获得5种光固化复合树脂自光照开始后300 s内的固化收缩量一时间曲线和固化收缩速率-时间曲线,并通过收缩速率-时间曲线计算凝胶点和转变点V以及凝胶点后及玻璃化后的固化收缩量.结果 5种光固化复合树脂的凝胶点为0.77 ～ 1.59 s,差异有统计学意义(P＜0.01);转变点V为1.99～6.33 s,差异有统计学意义(P＜0.01);凝胶点后收缩量为33.35～53.18 μm,差异有统计学意义(P＜0.01);玻璃化后收缩量为16.43～30.58 μm,差异有统计学意义(P＜0.01);总收缩量为39.25～64.84μm,差异有统计学意义(P＜0.01).5种光固化复合树脂凝胶点后收缩量及玻璃化后收缩量的顺序与总收缩量的顺序有所不同.结论 通过动态测量光固化复合树脂固化收缩量,可推测凝胶点和转变点V,从而获得更具有实用意义的复合树脂固化收缩特性评价参考值.     

Immediate repair bond strengths of microhybrid,nanohybrid and nanofilled composites after different surface treatments

Objectives

To evaluate immediate repair bond strengths and failure types of resin composites with and without surface conditioning and characterize the interacting composite surfaces by their surface composition and roughness.

Methods

Microhybrid, nanohybrid and nanofilled resin composites were photo-polymerized and assigned to four groups: (1) no conditioning (Control), (2) no conditioning, polymerized against a Mylar strip (Control, with strip), (3) intermediate adhesive resin (IAR) application, and (4) chair-side silica coating, silanization and intermediate resin application (SC). Resin composites, similar as their substrates, were adhered onto the substrates. Shear force was applied to the interface in a universal testing machine and failure types were evaluated under light microscopy. Surface characterization was done by contact angle measurements, X-ray photoelectron spectroscopy, scanning electron and atomic force microscopy.

Results

Significant effects of the resin composite type and surface conditioning were observed. Conditioning the composites with their IARs does not result in significant improvements in bond strength compared to the control with strip (bond strengths between 14.5 and 20.0 MPa). SC increased the bond strength in all composites except TE by an average 8.9 MPa, while in all composites the surface roughness increased from 7 to 384 μm. Failure types in this group were exclusively cohesive. Physico-chemical modelling of the composite surfaces showed that the surfaces were dominated by the resin matrix, with a major increase in silica-coverage after SC for all composites.

Conclusion

Intermediate adhesive resin conditioning did not improve the composite-to-composite immediate repair strength. Silica coating and silanization followed by its corresponding IAR, strongly increased repair bond strengths and provided exclusively cohesive failures in the substrate in all composites.     

含氟涂料对光固化复合树脂腐蚀作用的探讨

目的评估不同含氟涂料对5种光固化复合树脂表面的腐蚀作用。方法选取5种光固化复合树脂[微填料复合树脂（Ar）、纳米混合复合树脂（Gr）、纳米复合树脂（Su）、复合体（GI）和聚硅氧烷复合树脂（Ad）]制成φP6mm×3mm试样各25个。表面磨平抛光后分别用4种含氟涂料（F、G、D、B）于37℃100％相对湿度下处理30min，单次蒸馏水作为对照。扫描电镜观察试样表面的形态改变，并行激光共聚焦显微镜分析。结果含氟涂料对4种复合树脂均产生腐蚀作用（Su除外），腐蚀程度由强到弱的顺序为F、G、D、B。试样腐蚀形式均为表面粗糙。含氟涂料F和G作用于Ad后其改变最明显。经激光共聚焦显微镜分析，含氟涂料处理后复合树脂表面参数数值均增大。Su表面参数改变不明显。结论含氟涂料对复合树脂有腐蚀作用，腐蚀程度与复合树脂的类型、含氟涂料的种类相关。     

Micro-Raman spectroscopic analysis of the degree of conversion of composite resins containing different initiators cured by polywave or monowave LED units

Objectives

To determine the degree of conversion (DC) over 48 h post-curing of resin mixtures containing trimethylbenzoyl-diphenylphosphine oxide (TPO) initiator cured by a polywave or a monowave LED light-curing unit (LCU).

Methods

In resin mixtures based on equal weight percent (wt%) of BisGMA and TEGDMA the following initiators were added: 0.2 wt% camphorquinone (CQ) + 0.8 wt% ethyl-4-dimethylaminobenzoate (EDMAB) (Group 1); 1 wt% TPO (Group 2) and 0.1 wt% CQ + 0.4 wt% EDMAB + 0.5 wt% TPO (Group 3). Half of the samples in each group (n = 5) were cured using a polywave (bluephase^® G2, Ivoclar Vivadent) or a monowave LED LCU (bluephase^®, Ivoclar Vivadent). The DC was measured using micro-Raman spectroscopy within 5 min and then 1, 3, 6, 24 and 48 h post-irradiation. The data were analysed using general linear model and two-way ANOVA for the factors ‘time’, ‘material’, ‘surface’ and ‘LCU’ at α = 0.05.

Results

The initial DC values obtained upon light curing remained similar over a 48 h period. bluephase^® G2 produced the highest DC in Group 2 followed by Group 3, and Group 1. bluephase^® resulted in the highest DC in Group 1, followed by Group 2 and Group 3 (p < 0.05).

Conclusions

Unfilled resin materials containing both TPO– and CQ–amine initiators are effectively cured using bluephase^® G2. Resin mixture with the same wt% of initiators is better cured when TPO is the only initiator, compared to CQ–amine only or combined TPO and CQ–amine system. After initial light cure, no additional conversion of uncured monomers was detected in an unfilled resin material over 48 h at 37 °C.     

复合树脂的不同固化方法对抗压强度影响

目的 探讨不同固化方法处理后对复合树脂抗压强度的影响。方法 采用光固化、光固化＋光固化、光固化＋热固化,3种不同固化方法处理3M和贺利氏复合树脂,在万能验试机上测试抗压强度。结果 2次处理的复合树脂抗压强度均比1次处理的复合树脂有较大提高,范围在51.8%-91.6%之间。不同的2次固化方法相比,统计学无显著差异。结论 复合树脂经2次固化方法处理,其抗压强度高于1次光固化方法的处理。     

弱光引导固化对复合树脂收缩应力影响的研究

目的通过对比弱光引导固化和传统方式固化两种方式下复合树脂收缩应力的差异，探讨弱光引导固化减小树脂收缩应力的机制。方法自制环氧树脂圆盘，在其中心制备直径为4mm的圆孔，使用3种复合树脂A（Charisma）、B（TPH Spectrum）和C（Esthet-X）各充填16个样本，其中每种树脂8个样本使用弱光引导固化（弱光引导固化组），8个样本使用传统方式固化（传统方式固化组）。于固化后不同时间用光弹法测量和计算收缩应力的大小。结果树脂A、B、C弱光引导固化组收缩应力的变化趋势与传统方式固化组基本相同，固化后24h收缩应力分别为（3．80±0．31）MPa、（3．21±0．40）MPa、（2．84±0．22）MPa，而传统方式固化组收缩应力分别为（4．19±0．24）MPa、（3．69±0．33）MPa、（3．14±0．28）MPa。3种树脂两种固化方式固化后24h的收缩应力差异均有统计学意义（P〈0．05）。结论弱光引导固化能降低复合树脂固化后的收缩应力。