The effect of cycling deflection on the injection-molded thermoplastic denture base resins

Objective. The aim of this study was to evaluate the effect of cycling deflection on the flexural behavior of injection-molded thermoplastic resins. Materials and methods. Six injection-molded thermoplastic resins (two polyamides, two polyesters, one polycarbonate, one polymethyl methacrylate) and, as a control, a conventional heat-polymerized denture based polymer of polymethyl methacrylate (PMMA) were used in this study. The cyclic constant magnitude (1.0 mm) of 5000 cycles was applied using a universal testing machine to demonstrate plasticization of the polymer. Loading was carried out in water at 23ºC with eight specimens per group (n = 8). Cycling load (N) and deformation (mm) were measured. Results. Force required to deflect the specimens during the first loading cycle and final loading cycle was statistically significantly different (p < 0.05) with one polyamide based polymer (Valplast) and PMMA based polymers (Acrytone and Acron). The other polyamide based polymer (LucitoneFRS), polyester based polymers (EstheShot and EstheShotBright) and polycarbonate based polymer (ReigningN) did not show significant differences (p > 0.05). None of the materials fractured during the loading test. One polyamide based polymer (Valplast) displayed the highest deformation and PMMA based polymers (Acrytone and Acron) exhibited the second highest deformation among the denture base materials. Conclusion. It can be concluded that there were considerable differences in the flexural behavior of denture base polymers. This may contribute to the fatigue resistance of the materials.     

不同基托树脂抗弯性能的比较

目的 为临床医生在基托树脂的选择上提供一个参考依据。方法 选用5种义齿基托材料，错成试件。在一定的实验条件下对试件加力，记录试件的断裂弯曲载荷。结果 不碎胶树脂断裂弯曲载荷最大，除常规热凝树脂组和BPS树脂组之间无显著性差异外，其余各组间均有显著性差异。结论 不碎胶基托树脂、BPS基托树脂和常规热凝树脂是较为理想的基托材料。大面积义齿基托不宜采用自凝和光聚合基托树脂。     

Properties of injection-molded thermoplastic polyester denture base resins

Objective. This study investigated the properties of injection-molded thermoplastic polyester denture base resins. Materials and methods. Two injection-molded thermoplastic polyester denture base resins (polyethylene terephthalate copolymer and polycycloalkylene terephthalate copolymer) were tested. Specimens of each denture base material were fabricated for flexural properties testing, Charpy impact testing and shear bond testing (n = 10). The flexural strength at the proportional limit, elastic modulus, Charpy impact strength and the shear bond strength of the two denture base materials were estimated. Results. The polycycloalkylene terephthalate copolymer denture base resin had significantly lower flexural strength at the proportional limit, lower elastic modulus, higher impact strength and lower shear bond strength compared to the polyethylene terephthalate copolymer denture base resin. Conclusion. The properties of the injection-molded thermoplastic denture base resins composed of polyethylene terephthalate copolymer and polycycloalkylene terephthalate copolymer were different from each other. The polycycloalkylene terephthalate copolymer denture base resin had significantly lower flexural strength at the proportional limit, lower elastic modulus, higher impact strength and lower shear bond strength compared to the polyethylene terephthalate copolymer denture base resin.     

Influence of water sorption on mechanical properties of injection-molded thermoplastic denture base resins

Objective. This study investigated the influence of water sorption on certain mechanical properties of injection-molded thermoplastic denture base resins. Materials and methods. Six thermoplastic resins (two polyamides, two polyesters, one polycarbonate, one polymethylmethacrylate) and a polymethylmethacrylate (PMMA) conventional heat-polymerized denture-based polymer, selected as a control, were tested. Specimens of each denture base material were fabricated according to ISO 1567 specifications and were either dry or water-immersed for 30 days (n = 10). The ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of the denture base materials were calculated. Results. Water sorption significantly decreased the ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of one of the polyamides and the PMMAs. It also significantly increased the ultimate flexural strength of the polycarbonate. Conclusion. The mechanical properties of some injection-molded thermoplastic denture base resins changed after water sorption.     

三种义齿基托材料抗白色念珠菌黏附性能的比较

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。     

不同热凝义齿基托树脂对基托表面亲水性及力学性能的影响

目的 研究不同热凝义齿基托树脂对基托表面亲水性及力学性能的影响,以提高义齿基托的表面特性及弯曲特性的新思路和新方法。方法 选择平均分子量及平均粒径不同的4种粉剂：D-100M(甲基丙烯酸甲酯聚合物粉）,聚甲基丙烯酸甲酯聚合(D-250M）,聚甲基丙烯酸甲酯/丙烯酸乙酯共聚物(D-300）,聚甲基丙烯酸乙酯聚合物(D-250E）,作为研究对象,将各组粉剂和4种单体(MMA,i-BMA,EHMA,HEMA）分别配对聚合成15种不同材料的试件,进行周期性浸泡,随后置于恒温干燥箱0、14、30、90、180、360天后,测定表面接触角及弯曲性能。结果 浸泡前各组试件之间的差异有统计学意义(P<0.05）。浸泡后各材料之间的接触角变化显著不同;弯曲强度及弯曲弹性模量的差异有统计学意义(P<0.05）。随着时间推移,甲基丙烯酸甲酯组(MMA）的弯曲强度显著高于其他组(P<0.05）;单体MMA和EHMA+HEMA组浸泡至360天时弯曲强度无显著变化;其余组的样本浸泡至30天后弯曲强度明显上升。结论 适当组成成分的搭配对热凝义齿基托的表面亲水性、弯曲强度及弯曲弹性模量有很大影响,恰当的组合能改进热凝义齿基托的表面特性及力学性能。     

Shear bond strength of an autopolymerizing repair resin to injection-molded thermoplastic denture base resins

Abstract

Objective. This study investigated the shear bond strength of an autopolymerizing repair resin to injection-molded thermoplastic denture base resins. Materials and methods. Four injection-molded thermoplastic resins (two polyamides, a polyethylene terephthalate copolymer and a polycarbonate) were used in this study. The specimens were divided into eight groups according to the type of surface treatment given: (1) no treatment, (2) air abrasion with alumina, (3) dichloromethane, (4) ethyl acetate, (5) 4-META/MMA-TBB resin, (6) alumina and 4-META/MMA-TBB resin, (7) tribochemical silica coating or (8) tribochemical silica coating and 4-META/MMA-TBB resin. Half of the specimens in groups 1, 5, 6 and 8 were thermocycled for 10,000 cycles in water between 5–55°C with a dwell time of 1 min at each temperature. The shear bond strengths were determined. Results. The shear bond strengths to the two polyamides treated with alumina, dichloromethane and ethyl acetate and no treatment were very low. The greatest post-thermocycling bond strengths to polyamides were recorded for the specimens treated with tribochemical silica coating and 4-META/MMA-TBB resin (PA12: 16.4 MPa, PACM12: 17.5 MPa). The greatest post-thermocycling bond strengths to polyethylene terephthalate copolymer and polycarbonate were recorded for the treatment with alumina and 4-META/MMA-TBB resin (22.7 MPa, 20.8 MPa). Conclusion. Polyamide was exceedingly difficult to bond to an autopolymerizing repair resin; the shear bond strength improved using tribochemical silica coating followed by the application of 4-META/MMA-TBB resin. Both polyethylene terephthalate copolymer and polycarbonate were originally easy to bond to an autopolymerizing repair resin. However, with 4-META/MMA-TBB resin, the bond was more secure.     

Factors affecting the bond strength of denture base and reline acrylic resins to base metal materials

Objective

The shear bond strengths of two hard chairside reline resin materials and an auto-polymerizing denture base resin material to cast Ti and a Co-Cr alloy treated using four conditioning methods were investigated.

Material and Methods

Disk specimens (diameter 10 mm and thickness 2.5 mm) were cast from pure Ti and Co-Cr alloy. The specimens were wet-ground to a final surface finish of 600 grit, air-dried, and treated with the following bonding systems: 1) air-abraded with 50-70-µm grain alumina (CON); 2) 1) + conditioned with a primer, including an acidic phosphonoacetate monomer (MHPA); 3) 1) + conditioned with a primer including a diphosphate monomer (MDP); 4) treated with a tribochemical system. Three resin materials were applied to each metal specimen. Shear bond strengths were determined before and after 10,000 thermocycles.

Results

The strengths decreased after thermocycling for all combinations. Among the resin materials assessed, the denture base material showed significantly (p<0.05) greater shear bond strengths than the two reline materials, except for the CON condition. After 10,000 thermocycles, the bond strengths of two reline materials decreased to less than 10 MPa for both metals. The bond strengths of the denture base material with MDP were sufficient: 34.56 MPa for cast Ti and 38.30 for Co-Cr alloy.

Conclusion

Bonding of reline resin materials to metals assessed was clinically insufficient, regardless of metal type, surface treatment, and resin composition. For the relining of metal denture frameworks, a denture base material should be used.     

抗菌涂层材料对义齿基托吸水性和溶解性与单体渗出的影响

目的研究义齿基托树脂表面抗菌涂层对基托吸水性和溶解性以及单体渗出的影响。方法根据YY 0270-2003 标准,测量4种基托树脂涂膜前、后的吸水值和溶解值,应用索氏提取法测量固化后基托树脂的交联度;利用气相色谱法测量基托树脂涂膜前、后的单体渗出量。采用SPSS17.0软件包对数据进行统计学分析。结果具有抗菌涂层的基托材料的吸水值、溶解值和单体渗出量明显减少。4种材料中,贺利氏树脂的交联度最高,日进和山八树脂次之,新世纪树脂最低。结论义齿基托树脂的吸水值、交联度和单体渗出量之间存在一定联系,即交联度较大时,吸水值减少,甲基丙烯酸单体渗出量也相应降低。抗菌涂层可以提高树脂基托的综合性能。     

义齿基托树脂PMMA的化学改性研究

目的通过对义齿基托复合树脂PMMA的改性来提高其自身机械性能,解决长期以来义齿基托尤其是上颌总义齿基托容易断裂的问题.方法用不同浓度的活性单体二甲基丙烯酸一缩乙二醇酯(DD)与MMA接枝共聚.在Instron1125和Instron3365万能测试机上测量其弯曲强度、拉伸强度、弹性模量和断裂伸长率,用SPSS进行统计学分析.用示差扫描量热法(DSC)分析研究其热性能,结合扫描电镜(SEM)分析研究其结构性能.并且与未改性的义齿基托树脂进行对比研究.结果在MMA中加入25%的活性单体DD共聚后的基托树脂的弯曲强度增加了9.36%;拉伸强度提高了9.02%;弹性模量提高了13.12%;断裂伸长率提高了44.87%,统计学分析有显著性差异(P＜0.05).DSC分析显示玻璃化转变温度提高了3.54%.SEM观察断裂面为韧性断裂.结论用25%的活性单体DD改性的基托树脂力学性能和热稳定性都有一定的提高.     

纳米载银无机抗菌剂在树脂基托中应用的研究进展

近年来,载银纳米无机抗菌剂在医学生物领域得到了广泛应用,本文介绍载银纳米无机抗菌剂在树脂基托中应用的研究进展,分析其在树脂基托中的抗菌作用、生物安全性及对基托性能、颜色的影响。     

Mechanical properties of denture base resin cross-linked with methacrylated dendrimer

Objectives

The aim of this study was to investigate the mechanical properties of denture base resin cross-linked with methacrylated dendrimer.

Methods

The test specimens (3 mm × 10 mm × 65 mm) were fabricated from autopolymerizing resin with the powder/liquid ratio of 10 g/7 ml. The monomer liquid of resin was applied with the mixture of methylmethacrylate and crosslinker dendrimer (DD1) or crosslinker ethyleneglycol dimethacrylate (EGDMA) with five different volume percentages (vol%). The dendrimer crosslinker in this study is a methacrylated molecule (MW = 3617 g/mol) with 12 methacrylate groups. Quantity of crosslinkers varied from 1.1 to 9.1 vol%. The specimens (n = 8/group) were polymerized in distilled water maintained at 55 °C under pressure of 0.4 MPa for 20 min. Test specimens were stored dry at room temperature before testing. The flexural strength (MPa) and flexural modulus (GPa) was measured with three-point bending test at a crosshead speed of 5 mm/min. Surface microhardness (MHN) of matrix area of polymer (n = 8/group) was measured with a load of 245.3 mN by 10 s. Data were analyzed with two-way ANOVA.

Results

ANOVA showed that the addition of DD1 had a significantly higher effect (p < 0.05) on flexural modulus and hardness of matrix area than EGDMA but on flexural strength (p > 0.05). The effect of quantity differences of crosslinker was statistically significant only on flexural strength (p < 0.05).

Significance

The results of this study suggest that dendrimer-crosslinked resin gives better stiffness than that of EGDMA.     

Elastic modulus and flexural strength comparisons of high-impact and traditional denture base acrylic resins

Background

Fractures of acrylic resin dentures are a common occurrence in clinical dentistry. The denture may be fractured accidentally when dropped or while in service in the mouth due to flexural fatigue.

Objectives

The aim of this study was to compare the elastic modulus and the flexural strength between two heat-cured acrylic resins used in denture bases: a high-impact resin (Lucitone 199) and a traditional resin (Rodex).

Materials and methods

Rectangular strips of Lucitone 199 and Rodex (10 samples each) were fabricated and stored in artificial saliva at 37 °C for 2 weeks. The specimens were subjected to a three-point flexural test. The data were statistically analysed with Student’s t-test (p ⩽ .05).

Results

The high-impact acrylic resin had a lower elastic modulus (p = .000) and higher flexural strength (p = .001) compared to the traditional acrylic resin.

Conclusion

Within the limitations of this study, it can be concluded that the high-impact acrylic resin is a suitable denture base material for patients with clinical fracture of the acrylic denture.     

微波凝固型塑料制作的全口义齿精度变化

目的：了解微波凝固型塑料制作的全口义齿精度变化。方法：应用三维座标测定仪对微波凝固型塑料及热凝塑料制作的全口义齿进行精度测量并比较。结果：塑料凝固后即时变化显示微波凝固型塑料比热凝塑料收缩率大,至３或４ 周呈现时间性变化。结论：微波凝固型塑料在凝固后３ 或４ 周存在时间性变化。     

Flexural properties of denture base resins subjected to long-term water immersion

Abstract

Objective. The aim of this study was to investigate the flexural properties of denture base resins subjected to long-term water immersion. Materials and methods. Four denture base resins (one conventional heat-processed, one microwave energy-processed and two pour-type autopolymerizing) were selected for this study. The specimens of each denture base material tested were fabricated according to the manufacturers' instructions (n = 10). The flexural properties of the denture base resins were measured according to ISO 20795-1. The ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of the specimens were evaluated. Results. The ultimate flexural strengths of the heat-processed resin and the two pour-type autopolymerizing resins significantly decreased after 6 months water immersion. The flexural strength at the proportional limit of the heat-processed resin significantly decreased after 6 months water immersion, but the microwave energy-processed denture base resin and two pour-type autopolymerizing resins did not change after 6 months water immersion. The elastic moduli of the heat-processed resin, the microwave energy-processed denture base resin and one pour-type autopolymerizing resin significantly increased after 6 months water immersion. Conclusion. The flexural properties of denture base resins significantly changed after long-term water immersion.     

不同类型义齿清洁剂对着色热凝基托树脂和树脂人工牙的清洁效果

目的:比较不同类型义齿清洁剂对着色热凝基托树脂和树脂人工牙的清洁效果.方法:将40块规格相同的热凝基托树脂试件和40颗贺利氏树脂人工中切牙,浸泡于咖啡、绿茶和酱油的混合液中4周,各随机分为4组(n=10),按使用说明分别浸泡在Polident、Steradent清洁片配成的溶液、质量分数为0.5％次氯酸钠溶液和蒸馏水(对照组)中4h,使用色差仪和电子比色仪分别测量热凝基托树脂和树脂人工牙着色前后、清洁剂浸泡后的色度值,计算试件处理前后的色差(△E)并进行统计学分析.结果:在着色前后,4组热凝基托树脂和4组树脂人工牙△E无统计学差异(P＞0.05).在着色后与清洁后的△E值,0.5％次氯酸钠组＞ Polident组和Steradent组＞蒸馏水组(P＜0.05);Polident组与Steradent组之间无统计学差异(P＞0.05).在着色前与清洁后,蒸馏水组的△E大于其他3组(P＜0.05);其他3组之间无统计学差异.结论:0.5％次氯酸钠、Polident和Steradent对着色热凝基托树脂和树脂人工牙均有有效的清洁效果,其中0.5％次氯酸钠优于Polident和Steradent,Polident和Steradent效果相同.     

Comparative study of the transverse strength of three denture base materials

OBJECTIVES: Fracture resistance of recently introduced denture base resins has not been compared to traditional denture base materials. This study compared the transverse strength of three denture base materials, namely, Lucitone 199, Triad VLC, and the newly introduced Eclipse. MATERIALS AND METHODS: A total of 30 specimens (50mmx25mmx2.5mm) were fabricated, 10 from each material. The specimens were loaded until failure on an Instron universal testing machine using a three point flexural test. One-way analysis of variance (ANOVA) was used to compare the mean transverse strength between the three materials tested. RESULTS: The transverse strength values showed significant differences between the three denture base materials (P<0.0001). The mean transverse strength and standard deviations (MPa) were as follows: Eclipse 116.13+/-17.7, Lucitone 87.12+/-8.1, and Triad VLC 57.96+/-7.3. CONCLUSIONS: Within the limitations of this study, Eclipse showed the highest transverse strength among the materials tested. Eclipse denture base material may provide a stronger alternative to traditional denture base resins.     

Assessing the physical and mechanical properties of 3D printed acrylic material for denture base application

ObjectiveThree-dimensional (3D) printing is increasingly being utilised in the dental field because of its time-saving potential and cost effectiveness. It enables dental practitioners to eliminate several fabrication steps, achieve higher precision, and attain consistency in complex prosthetic models. The properties of 3D-printed resin materials can be affected by many factors, including the printing orientation (PO) and insufficient post-curing time (CT). This study aimed to investigate the effect of PO and CT on the mechanical and physical properties of a 3D-printed denture base resin (NextDent).Methods3D-printed specimens were fabricated in 0°, 45°, and 90° POs, followed by three CTs (20, 30, and 50 min). The microhardness was tested using a Vickers hardness test, while the flexural property was evaluated using a three-point bending test. Sorption and solubility were measured after the specimens had been stored in an artificial saliva for 42 days, and the degree of conversion during polymerisation was analysed using Fourier Transform Infra-red (FTIR) spectroscopy.ResultsThe flexural strength of the material significantly increased (p < 0.05) when the printing orientation was changed from 0° to 90°. A similar increase was observed in the hardness, degree of conversion, and water sorption results. In general, no significant difference (p > 0.05) in any of the tested properties was found when the post-curing times were increased from 20 to 50 min.SignificanceThe highest physical and mechanical properties of the 3D-printed denture base resin can be obtained by printing vertically (90° angle to the platform base). The minimal post-curing time to achieve ideal results is 30 min, as further curing will have no significant effect on the properties of the material.     

齿科树脂基托热压注塑成型机的研制及应用

目的 研制齿科树脂基托热压注塑盛开时机,探讨应用前景。方法 由压机部件、液压部件和电器控制部件三部分组成齿科树脂基托热压注塑成型机,运用ＰＭＭＡ试量口嘶托。结果 使用ＰＭＭＡ树脂由齿科树脂基托注塑成型机制成全口义齿基托。结论 齿科树脂基托热压注塑成型机方便实用,初步观察义齿基托制品性能良好。