Background: Effective polymerization of the composite resin is essential to obtain long term clinical success and has a great importance obtaining improved mechanical properties. The purpose of this study was to measu...Background: Effective polymerization of the composite resin is essential to obtain long term clinical success and has a great importance obtaining improved mechanical properties. The purpose of this study was to measure the effect of the light intensity of LED and QTH curing devices in relation to the light distances, on the hardness (KHN) of two light cure nano-resin composite. Material and Methods: The top and bottom surfaces of the two nanofill composite specimens were evaluated. Two LED and two QTH light curing devices were used at nine different distances. Light intensity was measured with two radiometers placed at these same distances from the curing tip. 360 pvc dies were prepared with circular cavity 3 mm in diameter and 2 mm thick. The tested materials were placed in each cavity. The different light curing distances were standardized by adding pvc spacers dies at different height matching the different distances. Top and bottom surface microhardness were evaluated with a Micro Hardness Tester in knoop hardness numbers (Kg/mm2). Data were statistically analyzed using: Three-way ANOVA, Tukey and Pearsons test. Results: It was revealed that there was a statistically significant difference in microhardness between the composites (p < 0.001), between the nine distances (p < 0.001) and between the four light curing devices (p < 0.001). Increasing the distance of the light source from composite resin, the light intensity and the microhardness values at the top and bottom surface decrease. LED light curing devices produced a greater microhardness results at the bottom surface of the specimens. The Filtek Ultimate nanocomposite (3 m) showed highest microhardness values on the top and bottom surfaces, polymerized with all four curing devices and all nine distances compared to Empress Direct nano composite (Ivoclar vivadent). Clinical significant: Even with high power LED curing light, the distance between the tip of the light source and the restoration surface should be as close as possible. In this study, Filtek Ultimate showed better results (highest microhardness values) than Empress Direct.展开更多
Objectives: Resin-based composites are the most widely used dental restorative materials. Bulk-fill resin composites are of rising interest as they can be clinically applied in thicker increments compared to conventio...Objectives: Resin-based composites are the most widely used dental restorative materials. Bulk-fill resin composites are of rising interest as they can be clinically applied in thicker increments compared to conventional composites. The purpose of the study was to evaluate the flexural fatigue strength of a conventional and bulk-filled resin composite placed incrementally or non-incrementally. Methods: Resin composite specimens were fabricated using either a conventional (Brilliant EverGlow?) or a bulk-fill (Fill-Up!<sup>TM</sup>) resin composite by either non-incremental filling (2 × 2 × 25 mm<sup>3</sup>) or in increments of (1 × 2 × 25 mm<sup>3</sup>). Specimens were stored in distilled water for 24 h or thermocycled for 5000 cycles. The static flexural strength (σ), flexural fatigue limit (FFL) after 105 cycles and post-fatigue flexural strength (PFσ) were measured. Data were analyzed using ANOVA, with a post-hoc Tukey’s test to compare mean FFL (p σ and PFσ compared to conventional composites regardless of incremental cure or thermocycling (p σ and FFL for conventional composites but not bulk-filled composites. There was no significant difference in PFσ compared to σ after 24 h storage, but a significant increase in PFσ after thermocycling (p < 0.05). Conclusions: The type of composite rather than incremental placement had a greater effect on flexural strength, suggesting that operator placement technique had less influence than material selection. Thermocycling in combination with cyclic loading caused a strengthening effect in the composites, likely due to the absorption and dissipation of stresses, thereby enhancing resistance to fracture.展开更多
目的在离体牙牙本质上涂布粘接剂后分别予以声波技术充填Sonicfill树脂及分层充填P60树脂,评估应用两种复合树脂与牙本质的剪切粘接强度。方法选择因牙周病拔除的磨牙40颗,制成40个牙本质试件,随机分为2组。A组为Sonicfill树脂组,B组为...目的在离体牙牙本质上涂布粘接剂后分别予以声波技术充填Sonicfill树脂及分层充填P60树脂,评估应用两种复合树脂与牙本质的剪切粘接强度。方法选择因牙周病拔除的磨牙40颗,制成40个牙本质试件,随机分为2组。A组为Sonicfill树脂组,B组为P60树脂组。每组涂布粘接剂后,A组采用声波技术充填树脂,B组采用分层技术充填树脂。经过循环温度为5℃及55℃的冷热循环疲劳试验,每个循环为3 min,共循环500次后,测试2组的剪切粘接强度(Shear Bond Strength,SBS)。结果A组的SBS为(10.32±1.13)MPa,B组的SBS为(8.43±0.98)MPa,两者差别有统计学意义(P<0.05)。结论运用声波技术的Sonicfill树脂充填体相比采用分层充填的P60树脂拥有更高的剪切粘接强度。因此,在修复过程中使用声波充填技术不亚于传统分层充填树脂,且临床操作时间更短。展开更多
An experimental procedure was designed to monitor the preform thickness change real-time throughout the vacuum assisted resin infusion( VARI) process. Two kinds of liquid with different viscosity were infused with dif...An experimental procedure was designed to monitor the preform thickness change real-time throughout the vacuum assisted resin infusion( VARI) process. Two kinds of liquid with different viscosity were infused with different post-filling time. The variation of the part thickness during the VARI process was studied. And the effect of the post-filling time on the part thickness was investigated.The results indicate that the compaction behavior of the preform can be divided into three stages,and the fiber volume fraction varies with the post-filling time in a similar sinusoid form. In addition,the post-filling should be overtime for the greatest fiber volume fraction,and when the resin is infused with higher viscosity,the greatest fiber volume fraction is higher.展开更多
文摘Background: Effective polymerization of the composite resin is essential to obtain long term clinical success and has a great importance obtaining improved mechanical properties. The purpose of this study was to measure the effect of the light intensity of LED and QTH curing devices in relation to the light distances, on the hardness (KHN) of two light cure nano-resin composite. Material and Methods: The top and bottom surfaces of the two nanofill composite specimens were evaluated. Two LED and two QTH light curing devices were used at nine different distances. Light intensity was measured with two radiometers placed at these same distances from the curing tip. 360 pvc dies were prepared with circular cavity 3 mm in diameter and 2 mm thick. The tested materials were placed in each cavity. The different light curing distances were standardized by adding pvc spacers dies at different height matching the different distances. Top and bottom surface microhardness were evaluated with a Micro Hardness Tester in knoop hardness numbers (Kg/mm2). Data were statistically analyzed using: Three-way ANOVA, Tukey and Pearsons test. Results: It was revealed that there was a statistically significant difference in microhardness between the composites (p < 0.001), between the nine distances (p < 0.001) and between the four light curing devices (p < 0.001). Increasing the distance of the light source from composite resin, the light intensity and the microhardness values at the top and bottom surface decrease. LED light curing devices produced a greater microhardness results at the bottom surface of the specimens. The Filtek Ultimate nanocomposite (3 m) showed highest microhardness values on the top and bottom surfaces, polymerized with all four curing devices and all nine distances compared to Empress Direct nano composite (Ivoclar vivadent). Clinical significant: Even with high power LED curing light, the distance between the tip of the light source and the restoration surface should be as close as possible. In this study, Filtek Ultimate showed better results (highest microhardness values) than Empress Direct.
文摘Objectives: Resin-based composites are the most widely used dental restorative materials. Bulk-fill resin composites are of rising interest as they can be clinically applied in thicker increments compared to conventional composites. The purpose of the study was to evaluate the flexural fatigue strength of a conventional and bulk-filled resin composite placed incrementally or non-incrementally. Methods: Resin composite specimens were fabricated using either a conventional (Brilliant EverGlow?) or a bulk-fill (Fill-Up!<sup>TM</sup>) resin composite by either non-incremental filling (2 × 2 × 25 mm<sup>3</sup>) or in increments of (1 × 2 × 25 mm<sup>3</sup>). Specimens were stored in distilled water for 24 h or thermocycled for 5000 cycles. The static flexural strength (σ), flexural fatigue limit (FFL) after 105 cycles and post-fatigue flexural strength (PFσ) were measured. Data were analyzed using ANOVA, with a post-hoc Tukey’s test to compare mean FFL (p σ and PFσ compared to conventional composites regardless of incremental cure or thermocycling (p σ and FFL for conventional composites but not bulk-filled composites. There was no significant difference in PFσ compared to σ after 24 h storage, but a significant increase in PFσ after thermocycling (p < 0.05). Conclusions: The type of composite rather than incremental placement had a greater effect on flexural strength, suggesting that operator placement technique had less influence than material selection. Thermocycling in combination with cyclic loading caused a strengthening effect in the composites, likely due to the absorption and dissipation of stresses, thereby enhancing resistance to fracture.
文摘目的在离体牙牙本质上涂布粘接剂后分别予以声波技术充填Sonicfill树脂及分层充填P60树脂,评估应用两种复合树脂与牙本质的剪切粘接强度。方法选择因牙周病拔除的磨牙40颗,制成40个牙本质试件,随机分为2组。A组为Sonicfill树脂组,B组为P60树脂组。每组涂布粘接剂后,A组采用声波技术充填树脂,B组采用分层技术充填树脂。经过循环温度为5℃及55℃的冷热循环疲劳试验,每个循环为3 min,共循环500次后,测试2组的剪切粘接强度(Shear Bond Strength,SBS)。结果A组的SBS为(10.32±1.13)MPa,B组的SBS为(8.43±0.98)MPa,两者差别有统计学意义(P<0.05)。结论运用声波技术的Sonicfill树脂充填体相比采用分层充填的P60树脂拥有更高的剪切粘接强度。因此,在修复过程中使用声波充填技术不亚于传统分层充填树脂,且临床操作时间更短。
基金The Fundamental Research Funds for the Central Universities,China(No.2232014D3-26)Innovation Fund of the Chinese National Engineering Research Center,China(No.SAM C14-JS-15-049)Science and Technology Commission of Shanghai Municipality,China(No.14DZ1100402)
文摘An experimental procedure was designed to monitor the preform thickness change real-time throughout the vacuum assisted resin infusion( VARI) process. Two kinds of liquid with different viscosity were infused with different post-filling time. The variation of the part thickness during the VARI process was studied. And the effect of the post-filling time on the part thickness was investigated.The results indicate that the compaction behavior of the preform can be divided into three stages,and the fiber volume fraction varies with the post-filling time in a similar sinusoid form. In addition,the post-filling should be overtime for the greatest fiber volume fraction,and when the resin is infused with higher viscosity,the greatest fiber volume fraction is higher.
