Hardness and fracture toughness of four commercial visible light-cured composite resin veneering materials

summary Four commercial visible light (VL)-cured composite resin veneering materials with a dentine shade were examined for their Knoop hardness and fracture toughness. Composite specimens were classified into three groups. The first group was cured by VL only, the second group was cured by VL and postcured by VL and the third group was cured by VL and post-cured by heat. It became evident that one composite containing four-functional urethane monomer had both hardness and fracture toughness greater than those of the other three composites containing two-functional urethane monomer. The filler content (vol%) in the composite tended to be linearly proportional to both hardness and fracture toughness. Post-curing by VL and heat were proven to effectively increase both hardness and fracture toughness of once light-cured composites. These results suggest that the clinical performance (e.g. wear resistance and colour stability) of VL-cured composite resin veneering materials might be improved with the aid of post-curing.     

Glass fiber reinforced composite resin as an intracanal post--a clinical study

Restoration of primary incisors, which have been severely damaged by early childhood caries or trauma, is a difficult task for the pediatric dentist. With the introduction of new adhesive systems and restorative materials, alternative approaches for treating these teeth have been proposed. MATERIALS: Ten healthy children aged between 3-4 years who had 28 grossly destructed primary maxillary incisors requiring intra canal retention were selected for the study. Following root canal treatment, either a Glass Fiber Reinforced Composite Resin (GFRCR everStick,, Finland) or an omega shaped stainless steel wire were placed as intracanal posts in these teeth. Flowable composite was used for cementation of posts and also to build up the coronal structure using celluloid strip crowns. Both types of intracanal posts were evaluated for retention and marginal adaptation at 1, 6 and 12 months. The data obtained was subjected to statistical analysis. CONCLUSION: GFRCR intracanal posts showed better retention and marginal adaptation than omega shaped stainless steel wire posts.     

光固化复合树脂颜色稳定性的研究进展

随着口腔材料学的快速发展和进步,光固化复合树脂在现代牙科美容修复中占据越来越重要的地位,其颜色稳定性成为治疗效果评判的重要检验标准之一。本文旨在对光固化复合树脂的色彩性能、颜色稳定性及其影响因素作一综述。     

新型聚酰亚胺碳纤维复合树脂桩钉材料的研制

目的：研究碳纤维增强聚酰亚胺树脂的机械性能、生物安全性;探索复合树脂桩钉材料的成型方法.方法：用缠绕法制得单向预浸布料,热压成型制作单向聚酰亚胺/碳纤维复合层压板复合材料,并测试其弯曲强度、弹性模量.采用机械加工方法根据尺寸要求制备桩钉材料.并采用MTT法进行生物学评价.结果：复合材料的弯曲强度比金属材料明显提高,弹性模量更接近于天然牙根的弹性模量（其中复合材料弯曲强度在1160-1550 MPa之间,弹性模量在6.4-8.8 GPa之间）.细胞毒性均为1级,溶血率小于均5%.结论：连续碳纤维增强聚酰亚胺树脂复合材料,具有优良的机械性能及良好的生物相容性和生物安全性,可以满足临床需要.     

两种充填方式对不同光固化复合树脂充填体内孔隙的影响

目的 探讨光固化复合树脂的稠度及充填方式对充填体内孔隙的影响,以期为复合树脂的临床应用提供参考.方法 6位操作者将3种复合树脂(树脂A:Prodigy;树脂B:Tetric EvoCeram;树脂C:Tetric Ceram HB)以器械充填和注射充填的方式充填入模拟I类洞中,将充填体纵向片切成0.5 mm厚的切片,测定切片内孔隙数量;并测试未进行充填的复合树脂内的固有孔隙数量.结果 未充填的复合树脂内固有孔隙数量极少(≤5个);稠度居中的树脂B的孔隙数量[器械充填和注射充填分别为(1137.1±365.0)和(566.1±206.4)个]远多于稠度最大的树脂C[分别为(193.1±35.8)和(156.3±33.0)个]和稠度最小的树脂A[分别为(241.0±116.1)和(195.8±28.7)个,P<0.05).树脂B器械充填的孔隙数量明显多于注射充填(P<0.05),而树脂A和C两种充填方式的孔隙数量差异均无统计学意义(P>0.05).结论 复合树脂充填体内的孔隙基本是在充填过程中形成的,孔隙数量与复合树脂稠度无线性关系;并非所有复合树脂用注射充填均能显著减少充填体内孔隙数量.     

Fiber reinforced composite resin systems

The Targis/Vectris and Sculpture/FibreKor systems were devised to create a translucent maximally reinforced resin framework for fabrication of crowns, bridges, inlays, and onlays. These materials are esthetic, have translucency similar to castable glass-ceramics such as OPC and Empress, and have fits that are reported to be acceptable in clinical and laboratory trials. These restorations rely on proper bonding to the remaining tooth structure; therefore, careful attention to detail must be paid to this part of the procedure. Cementation procedures should involve silane treatment of the cleaned abraded internal restoration surface, application of bonding agent to the restoration as well as the etched/primed tooth, and finally use of a composite resin. Each manufacturer has a recommended system which has been tested for success with its resin system. These fiber reinforced resins are somewhat different than classical composites, so not all cementation systems will necessarily work with them. Polishing of the restoration can be accomplished using diamond or alumina impregnated rubber wheels followed by diamond paste. The glass fibers can pose a health risk. They are small enough to be inhaled and deposited in the lungs, resulting in a silicosis-type problem. Therefore, if fibers are exposed and ground on, it is extremely important to wear a mask. Also, the fibers can be a skin irritant, so gloves also should be worn. If the fibers become exposed intraorally, they can cause gingival inflammation and may attract plaque. The fibers should be covered with additional composite resin. If this cannot be accomplished, the restoration should be replaced. The bulk of these restorations are formed using a particulate filled resin, similar in structure to conventional composite resins. Therefore, concerns as to wear resistance, color stability, excessive expansion/contraction, and sensitivity remain until these materials are proven in long-term clinical trials. They do hold the promise of minimizing tooth reduction and may be particularly useful in preserving sound tooth structure. Although not the primary intended use, an excellent application is long-term temporization, such as for patients requiring full mouth rehabilitation. The belleGlass/Connect, Ribbond, and GlasSpan materials rely on nonimpregnated polyethylene fibers which have mechanical properties inferior to Vectris and FibreKor. These fibers may be used to greater success as splinting materials, in provisional restorations, and in repair of complete and partial removable dentures.     

Clinical evaluation of light-cured composite resin inlays in primary molars

A study was carried out to evaluate the clinical potential of a visible light-cured composite resin inlay (P-30) cemented with an adhesive resin cement (Panavia-EX) in primary molars. The inlays were placed in Class I complex, Class II MO, DO, MOD and more extensive cavity preparations in primary molars. Fifty restorations were placed in 40 patients and evaluated at baseline, 3 months, 6 months, 1 year and 2 years. The evaluations were carried out according to the U.S. Public Health Service Clinical Rating System. The results showed the composite resin inlay cemented with an adhesive resin cement to be a highly effective combination.     

二期处理光固化复合树脂的单体转化率

３种光固化复合树脂光固化４０ｓ后，分别作光照５ｍｉｎ，１４０℃热处理７．５ｍｉｎ和０．６ＭＰａ１２０℃加热加压处理７ｍｉｎ３种二期处理，用红外分光光度计测量其单体转化率。结果发现，经过二期处理的光固化复合树脂，除后牙用复合树脂和ＲｅｓｔｏｒａｔｉｖｅＺ１００光照５ｍｉｎ组只比对照组（光照４０ｓ）的单体转化率增加１～１．２％外，其余组单体转化率比对照组高４．８～８．５％，且以１４０℃热处理７．５ｍｉｎ组为最好。     

Comprehensive properties of a novel fiber reinforced composite with a UEDMA-based resin matrix

The traditional fiber reinforced composite (FRC) contains bisphenol A glycidyl methacrylate (bis-GMA) in the resin matrix, which is thought to have some disadvantages. This research aimed at replacing bis-GMA with another monomer—urethane dimethacrylate (UEDMA), with the desired properties for dental use still retained. Four groups were prepared with light-curing (n = 30), one Control group with a bis-GMA-based resin matrix and three experimental groups with UEDMA-based matrices (Exper 1, Exper 2 and Exper 3 with a varying UEDMA weight percentage). Specimens were stored in dry conditions for 24 h or in deionized water for 1, 3, 6 or 12 months prior to the tests. Water sorption (n = 6), Vicker’s hardness (n = 6) and flexural properties (n = 6) after each storage time were investigated. Scanning electron microscopy (SEM) images were taken at the fracture sites after 3-point bending. All the results were statistically analyzed (α = 0.05). The Exper 1 group exhibited the lowest weight increase after water storage among the experimental groups. As for dry conditions, 1- and 6-month storage, different resin matrix compositions made no significant difference to hardness, while for 3- and 12-month storage, “Control” possessed the highest hardness. The Control group’s strength and modulus, Exper 1 and Exper 2’s modulus were stable during water storage. Compared to other experimental groups, Exper 1 had the highest strength and modulus values with most of the storage times. SEM images showed relatively good adhesion between the fiber and the matrix. With all the tested properties considered, the Exper 1 group had superior performance among all the three experimental groups.     

高强度玻璃纤维/树脂复合材料桩钉的临床应用

目的 :探讨自行研制的高强度玻璃纤维 /树脂复合材料桩钉的临床应用效果。方法 :观察 13例 19件修复体的使用情况 ,并对临床应用的有关问题进行分析。结果 :经过 0 .5 -3年的临床观察 ,无一例桩钉折断或脱落 ,修复效果满意。结论 :高强度玻璃纤维树脂桩钉具有较好的美观效果和强度 ,有较好临床应用价值。     

Bonded orthodontic retainer and fixed partial denture made with fiber reinforced composite resin

Retention is the phase of orthodontic treatment which maintains teeth in their orthodontically corrected positions, following the cessation of active orthodontic tooth movement. Development of resin-impregnated, fiber-reinforced composite materials has provided the potential to develop new approaches for stabilizing teeth and replacing teeth conservatively. This case report describes the rehabilitation of a patient with orthodontic and prosthetic problems. The long-term behavior of glass fibers splint must be evaluated in clinical studies.     

酸蚀时间对树脂加强型玻璃离子粘结性能的影响

目的 比较光固化树脂加强型玻璃离子水门汀和复合树脂在几种粘结条件下，不同酸蚀时间后的粘结强度，探求减少釉质脱钙的粘结方法。方法 120颗因正畸拔除的健康双尖牙分成8组，酸蚀30秒或90秒后在几种条件下(干燥／被水或唾液潮湿)粘结脱槽，做冷热循环实验后，测剪切强度。结果 复合树脂酸蚀90秒较酸蚀30秒的粘接强度明显增强；光固化树脂玻璃在几种粘接条件下酸蚀90秒和酸蚀30秒粘接强度无明显区别，水潮湿组粘接强度最高。结论 复合树脂可通过延长酸蚀时间增加粘接强度；光固化树脂玻璃酸蚀30秒足够，延长酸蚀时闻不能增加粘接强度，白白造成釉质丢失。     

Two-year clinical evaluation of light-cured composite resin restorations in primary molars

The restorations were evaluated at baseline, and at 6, 12, and 24 months by two trained examiners. In the system used, the highest, most desirable rating is Alfa. Of the restorations evaluated at 24 months, 99% had Alfa ratings for color match, 87% had Alfa ratings for no discoloration at cavosurface margins, and 86% had Alfa ratings for no loss of anatomic form. In addition, 75% of the restorations had Alfa ratings for margin adaptation, and 91% had Alfa ratings for no recurrent caries at the 24-month evaluation. In conclusion, the light-cured composite resin restorative material functioned well at the 12- and 24-month evaluation periods, when used in primary molars.