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41.
《Dental materials》2020,36(7):829-837
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. 相似文献
42.
43.
Caroline COTES Mayra CARDOSO Renata Marques de MELO Luiz Felipe VALANDRO Marco Antonio BOTTINO 《Journal of applied oral science : revista FOB》2015,23(1):71-78
Objective
The purpose of this study was to assess the influence of conditioning methods and thermocycling on the bond strength between composite core and resin cement.Material and Methods
Eighty blocks (8×8×4 mm) were prepared with core build-up composite. The cementation surface was roughened with 120-grit carbide paper and the blocks were thermocycled (5,000 cycles, between 5°C and 55°C, with a 30 s dwell time in each bath). A layer of temporary luting agent was applied. After 24 h, the layer was removed, and the blocks were divided into five groups, according to surface treatment: (NT) No treatment (control); (SP) Grinding with 120-grit carbide paper; (AC) Etching with 37% phosphoric acid; (SC) Sandblasting with 30 mm SiO2 particles, silane application; (AO) Sandblasting with 50 mm Al2O3 particles, silane application. Two composite blocks were cemented to each other (n=8) and sectioned into sticks. Half of the specimens from each block were immediately tested for microtensile bond strength (µTBS), while the other half was subjected to storage for 6 months, thermocycling (12,000 cycles, between 5°C and 55°C, with a dwell time of 30 s in each bath) and µTBS test in a mechanical testing machine. Bond strength data were analyzed by repeated measures two-way ANOVA and Tukey test (α=0.05).Results
The µTBS was significantly affected by surface treatment (p=0.007) and thermocycling (p=0.000). Before aging, the SP group presented higher bond strength when compared to NT and AC groups, whereas all the other groups were statistically similar. After aging, all the groups were statistically similar. SP submitted to thermocycling showed lower bond strength than SP without thermocycling.Conclusion
Core composites should be roughened with a diamond bur before the luting process. Thermocycling tends to reduce the bond strength between composite and resin cement. 相似文献44.
Endodontic complications in teeth with vital pulps restored with composite resins: a systematic review
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Composite resin is used extensively for restoration of teeth with vital pulps. Although cell culture studies have disclosed harmful effects on pulpal cells, any untoward clinical effects, manifest as adverse pulpal responses, have yet to be determined. This study comprises a systematic review, designed to address the question of whether the risk of endodontic complications is greater with composite resin restorations than with other restorative materials, such as amalgam. The study methodology involved (i) formulation of the research question, (ii) construction and conduct of an extensive literature search with (iii) interpretation and assessment of the retrieved literature. A search of the medical database PubMed was complemented with a search of the Controlled Trials Register (CENTRAL). The initial search yielded 1043 publications, the abstracts of which were read independently by the authors. After additional searches, 10 studies were included in the review. In all the included studies, the level of evidence was assessed as low. No conclusions could therefore be drawn. The included studies reported few, if any, endodontic complications. Little or no differences emerged between teeth restored with composite resins and those restored with amalgam. To determine whether composite resin restorations of teeth with vital pulps are associated with an increased risk for development of endodontic complications such as apical periodontitis, further evidence is needed, from well‐constructed studies with a large number of participants. 相似文献
45.
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。 相似文献
46.
47.
目的比较3种义齿基托材料的抗白色念珠菌黏附性能。方法将热凝基托树脂、不碎胶树脂、弹性材料树脂义齿基托材料制备成粗糙度相同的标准试样,每组10个。用白色念珠菌(ATCC 90028)菌液对各试样黏附培养24h、48h、168h后,分析白色念珠菌对试件表面的黏附。结果在培养24h时,3组试件白色念珠菌黏附量差异无统计学意义(P0.05);培养48h时,除不碎胶树脂组和弹性材料树脂组外,其余两两之间差异均有统计学意义(P0.05);培养168h时,3组试件两两之间差异均有统计学意义(P0.05),白色念珠菌黏附量计数,热凝基托树脂不碎胶树脂弹性材料树脂。结论与传统热凝树脂基托相比较,不碎胶树脂基托和弹性材料树脂基托能减少白色念珠菌的黏附。 相似文献
48.
Coelho-De-Souza FH Camargo JC Beskow T Balestrin MD Klein-Júnior CA Demarco FF 《Journal of applied oral science : revista FOB》2012,20(2):174-179
Objective
This randomized double-blind clinical trial compared the performance of posterior composite restorations with or without bevel, after 1-year follow-up.Material and Methods
Thirteen volunteers requiring at least two posterior composite restorations were selected. Twenty-nine cavities were performed, comprising 14 without bevel (butt joint) and 15 with bevel preparation of the enamel cavosurface angle. All cavities were restored with simplified adhesive system (Adper Single Bond) and composite resin (Filtek P60). A halogen light curing unit was used through the study. Restorations were polished immediately. Analysis was carried out at baseline, after 6 months and after 1 year by a calibrated evaluator (Kappa), according to the FDI criteria. Data were statistically analyzed by Mann-Whitney test (p<0.05).Results
Beveled and non-beveled cavities performed similarly after 1 year follow-up, regarding to fractures and retention, marginal adaptation, postoperative hypersensitivity, recurrence of caries, surface luster and anatomic form. However, for surface and marginal staining, beveled cavities showed significantly better performance (p<0.05) than butt joint restorations.Conclusions
It was concluded that the restorations were acceptable after 1 year, but restorations placed in cavities with marginal beveling showed less marginal staining than those placed in non-beveled cavities. 相似文献49.
Ribeiro BC Boaventura JM Brito-Gonçalves Jd Rastelli AN Bagnato VS Saad JR 《Journal of applied oral science : revista FOB》2012,20(2):212-217
Objective
This study aimed at evaluating the degree of conversion (DC) of four composite resins, being one nanofilled and 3 microhybrid resins, photo-activated with second- and third-generation light-emitting diodes (LEDs).Material and methods
FiltekTM Z350 nanofilled composite resins and Amelogen® Plus, Vit-l-escenceTM and Opallis microhybrid resins were photo-activated with two second-generation LEDs (Radii-cal and Elipar Free LightTM 2) and one third-generation LED (Ultra-Lume LED 5) by continuous light mode, and a quartz halogen-tungsten bulb (QHT, control). After 24 h of storage, the samples were pulverized into fine powder and 5 mg of each material were mixed with 100 mg of potassium bromide (KBr). After homogenization, they were pressed, which resulted in a pellet that was evaluated using an infrared spectromer (Nexus 470, Thermo Nicolet) equipped with TGS detector using diffuse reflectance (32 scans, resolution of 4 cm-1) coupled to a computer. The percentage of unreacted carbon-carbon double bonds (% C=C) was determined from the ratio of absorbance intensities of aliphatic C=C (peak at 1637 cm-1) against internal standard before and after curing of the specimen: aromatic C-C (peak at 1610 cm-1).Results
The ANOVA showed a significant effect on the interaction between the light-curing units (LCUs) and the composite resins (p<0.001). The Tukey''s test showed that the nanofilled resin (FiltekTM Z350) and Opallis when photo-activated by the halogen lamp (QTH) had the lowest DC compared with the other microhybrid composite resins. The DC of the nanofilled resin (FiltekTM Z350) was also lower using LEDs. The highest degrees of conversion were obtained using the third-generation LED and one of second-generation LEDs (Elipar Free LightTM 2).Conclusions
The nanofilled resin showed the lowest DC, and the Vit-l-escenceTM microhybrid composite resin showed the highest DC. Among the LCUs, it was not possible to establish an order, even though the second-generation LED Radii-cal provided the lowest DC. 相似文献50.
RP Bueno PS Viaro PC Nascimento RT Pozzobon 《Journal of applied oral science : revista FOB》2012,20(3):335-339