Sealing effectiveness of light-cured glass ionomer cement liners

Glass ionomer materials have been used as liners or bases beneath restorations, but light-cured varieties have recently been introduced. Microleakage at the restoration/tooth interface in cervical cavities was used to test the adhesion to dentin of two new light-cured glass ionomer cement lining materials, XR-Ionomer and Fuji Lining LC. Wedge-shaped cervical cavities were prepared on extracted teeth with a gingival cavosurface margin involving dentin, and the specimens were assigned randomly to three groups. The experimental groups were restored with two light-cured glass ionomer cements, the controls were restored with a chemically cured glass ionomer cement; and marginal leakage was assessed by dye penetration. The two light-cured glass ionomer cements displayed some adhesion to dentin in class V test cavities, but there was no significant difference between the two materials.     

Bond strength of a light-cured and two auto-cured glass ionomer liners

Ninety-nine extracted human molar teeth were used in this study comparing the shear bond strengths on dentine of one light-cured and two auto-cured polyalkenoate (glass ionomer) cements. Bond strength can be influenced by differences in tooth structure. A balanced-incomplete block design (Hull and Nie, 1981) was used to reduce variation attributable to such differences. Cements were applied to paired dentine surfaces in combinations such that 66 tooth sides were treated with each material. A light-cured dentinal adhesive and composite resin restorative material were then placed and shear bond strength testing was conducted exactly 24 h after the completion of each specimen. Mean forces (MPa) for the three materials were compared using an appropriate analysis of variance model (balanced-incomplete-blocks) The shear bond strengths (MPa) of the light-cured liner (Espe, Seefeld/Oberbay, FRG) was 4.71 +/- 1.16. Vitrabond showed the greatest variance of all three materials tested, however this material's average bond strength was greater than the maximum achieved for the other materials. Student-Newman-Keuls comparison of means showed that all cements differed significantly from each other (alpha = 0.05). It is concluded that the light-cured glass ionomer liner exhibited significantly better shear bond strength performance than the two auto-cured glass ionomers tested.     

Pulpal response to an anhydrous glass ionomer luting cement

Abstract This investigation was designed to study the pulpal responses to Aquacem®, an anhydrous glass ionomer luting cement, and to compare the results with those previously obtained for a conventional glass ionomer luting cement, Chembond®. The study was carried out according to the BSI (1980) recommendations for testing restorative materials in vivo. Aquacem caused more pulpal inflammation than the control material, Kalzinol®, though by an indirect mechanism. The statistical model demonstrated a significant association between bacterial presence within the experimental cavity and pulpal inflammation. The type of restorative material has no direct association with the degree of inflammation, but the model suggests that it exerts an indirect influence via its antibacterial properties and hence its influence on microbial microleakage.     

Pulpal response to two semihydrous glass ionomer luting cements

This study compared the pulpal responses to two innovative semihydrous glass ionomer luting cements (STA and ZIN) with those previously obtained for a conventional anhydrous glass ionomer luting cement, Aquacem. ZIN contained zinc oxide in the formulation. The study was conducted according to the BSI (1989) recommendations for testing restorative materials in vivo. ZIN was associated with minimal pulpal changes and microbial microleakage, and differed little from the control material, Kalzinol. The pulpal response to STA was similar to that observed for Aquacem, but was associated with less microbial microleakage. The statistical model demonstrated a significant association between bacterial presence within the experimental cavity and pulpal inflammation. The closer that bacteria were to the pulp, the more severe was the ensuing inflammation.     

Pulpal response to an anhydrous glass ionomer luting cement

This investigation was designed to study the pulpal responses to Aquacem, an anhydrous glass ionomer luting cement, and to compare the results with those previously obtained for a conventional glass ionomer luting cement, Chembond. The study was carried out according to the BSI (1980) recommendations for testing restorative materials in vivo. Aquacem caused more pulpal inflammation than the control material, Kalzinol, though by an indirect mechanism. The statistical model demonstrated a significant association between bacterial presence within the experimental cavity and pulpal inflammation. The type of restorative material has no direct association with the degree of inflammation, but the model suggests that it exerts an indirect influence via its antibacterial properties and hence its influence on microbial microleakage.     

A comparative study of microleakage below cemento-enamel junction using light cure and chemically cured glass ionomer cement liners

Posterior composite resins have gained considerable importance over last few years. However, improper placement techniques continue to be a prime cause of failure of these restorations. This study was done to compare the microleakage at the tooth restoration interface extending below cementoenamel junction when posterior composite restorations were placed directly in the cavity or when placed over a glass ionomer cement liner, both chemically cured and light cured. The results have shown that light cured glass ionomer when used as a liner under a composite restoration used below gingival cementum/dentin margin has the best sealing capability.     

Comparison of the shear bond strength of a light-cured glass ionomer and a chemically cured glass ionomer for use as an orthodontic bonding agent.

Light-cured glass ionomers with an initial set of 20 seconds may produce higher initial bond strengths, as well as decreased sensitivity to moisture contamination and desiccation, than chemically cured glass ionomers making them attractive for use as orthodontic bonding agents. The purpose of this study was to determine and compare the shear bond strength of stainless steel orthodontic attachments to enamel with a light-cured glass ionomer (Zionomer) tested at 60 minutes and 24 hours, and a rapidly setting chemically cured glass ionomer (Ketac-Bond) tested at 60 minutes and 24 hours. Fifty-two recently extracted human premolars were randomly divided into four groups--1-hour and 24-hour light-cured glass ionomer groups and 1-hour and 24-hour chemically cured glass ionomer groups. Stainless steel lingual buttons were bonded to prepared enamel surfaces, and the samples were placed in a water bath at 37 degrees C until ready for testing. The shear bond strength of each sample was determined with a universal testing instrument. Results from the study conclude: (1) The mean shear bond strength of the light-cured glass ionomer is greater than that of the chemically cured glass ionomer at 1 and 24 hours. (2) The mean shear bond strength of both glass ionomers increases from 1 to 24 hours. (3) The mean shear bond strength of the light-cured glass ionomer is not significantly different from 1 to 24 hours, but the shear bond strength of the chemically cured glass ionomer cement is different.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pulpal effects of glass ionomer cements

Summary. The incidence of pulpal damage beneath cavities filled with ASPA, Chemfil and Chembond was studied in class I cavities in human premolar teeth after 1–10 days, 11–30 days, and 31 or more days. Cavities filled with Kalzinol or zinc oxide/eugenol acted as controls. All glass ionomer cements were accompanied by more pulpal damage than controls, but Chemfil was associated with the least changes. Bacteria were demonstrated at the material/cavity wall interface in a number of cavities with all materials, although no significant correlation was demonstrated between them and pulpal inflammation. The use of a base is recommended in cavities where large numbers of previously unaffected dentinal tubules are present.     

Bonding of light-cured glass ionomer cement to polycarbonate resin treated with experimental primers

The effect of experimental primers on the shear bond strength of polycarbonate composite resin with light-cured glass ionomer cements was investigated. Mixtures of methylmethacrylate (MMA) with the comonomers 2-hydroxyethyl methacrylate (HEMA), triethyleneglycol methacrylate (TEGDMA), and bisphenol-A-glycidymethacrylate (bisGMA) were used as primers. Polycarbonate composite resin rods of circular cross section and plates were bonded, with and without precured and nonprecured primers, using 2 light-cured glass ionomer cements (commercially available [LC] and experimental [EX]). In addition, commercial polycarbonate composite resin brackets with precured 50% TEGDMA/MMA primer were bonded to etched human enamel with both cements. Shear bond strengths were measured. Results were compared by ANOVA and Scheffe's tests at P = .05. The 30% HEMA/MMA, 50% TEGDMA/ MMA, 10% bisGMA/MMA, and 30% bisGMA/MMA primers produced the higher shear bond strengths (9.5 to 20.8 MPa) with LC and EX to polycarbonate composite resin. The 50% TEGDMA/MMA primer was most effective in improving the shear bond strengths of both LC and EX. Precured 50% TEGDMA/ MMA primer on a commercial resin bracket was effective in providing good shear bond strength to enamel.     

Adaptation to the cavity floor of the light-cured glass ionomer cement base under a composite restoration

The study attempted to assess methods of prevention of the formation of a contraction gap in a cylindrical enamel and dentine cavity. The influence has been investigated of the tensile bond strength of cement/dentine and cement/composite resin and the direct tensile strength during setting of light-cured glass-ionomer cements. The interface between composite resin/cement and cement/dentine were viewed and photographed by replica techniques under an SEM (Scanning Electron Microscope). The most noticeable finding was that an enamel and dentine cavity applicated with light- and auto-cured glass-ionomer cement generally presented with a small construction gap at the tooth restoration interface. However, the light-cured glass-ionomer base (Vitrabond) exhibited significantly better tensile bond strength to dentine and resin performance than the conventional glass-ionomer tested. This study revealed that there was no clear relationship between the adhesion to dentine and the adaptation to the dentine cavity floor.     

Shear bond strength of light-cured glass ionomer to enamel and dentin

The shear bond strengths of a light-cured glass-ionomer cement to enamel and dentin were determined with use of extracted human maxillary permanent canines and molars. Bonding sites on the ground, etched enamel and ground dentin surfaces were demarcated by the punching of a hole, 3 mm in diameter, in an adhesive tape. The mixed glass-ionomer cement was transferred to the demarcated site, cured by exposure to visible light for 30 s, and the cement surface treated with Scotchprep Dentin Primer followed by Scotchbond 2 Light Cure Dental Adhesive. The embedded teeth were positioned in an assembly apparatus, and Silux composite was bonded to the glass-ionomer-cement surfaces. The specimens were disassembled after 15 min and subjected to a shear load (in an Instron machine) immediately after disassembly; after storage in water at 37 degrees C for 24 h, without and with temperature cycling; and after storage in water for four weeks, without and with temperature cycling. The shear bond strength of the glass-ionomer cement to etched enamel was in the order of 12 MN.m-2, and to dentin it was 9 MN.m-2. Temperature cycling and duration of storage had no adverse effect on the shear bond strength. The enamel and dentin aspects of fractured test specimens were examined, and the percentage of the bonding area that failed in the cement was estimated. Most of the test specimens failed partly at the enamel and dentin interfaces and within the glass-ionomer cement.     

光固化型玻璃离子水门汀的体外细胞毒性

目的：比较８种光固化型玻璃离子水门汀的体外细胞毒性。方法：采用牙髓细胞体外培养技术和四唑盐（ＭＴＴ）显色分光光度法。结果：除１种含金属离子的加强型玻璃离子水门汀外，其余７种玻璃离子水门汀呈较弱的体外细胞毒性。８种玻璃离子水门汀的体外细胞毒性从小到大依次为：Ｄｙｒａｃｔ，ＦｕｊｉⅡＬＣ，Ｇｅｒｉｓｔｏｒｅ，ＣｈｅｍＦｉｌⅡ，ＰｈｏｔｏＦｉｌ，Ｖｉｔｒｅｍｅｒ，Ｒｅｓｉｎｏｍｅｒ，Ｈｉ－Ｄｅｎｓｅ．结论：光固化型玻璃离子水门汀的体外细胞毒性较弱，但金属离子加强型玻璃离子水门汀体外毒性较强     

Marginal leakage of visible light-cured glass ionomer restorative materials

This study examined the sealing of two visible light-cured glass ionomer restorative materials and a conventional glass ionomer. Class V cavity preparations were completed at the cementoenamel junction on the facial and lingual surfaces of extracted human molars. The cavity preparations were restored with either VariGlass VLC, GC Fuji II LC, or GC Fuji II glass ionomer cements. The restored teeth were thermocycled, immersed in fuchsin dye for 24 hours, sectioned, and evaluated with a measuring microscope. No microleakage occurred at the enamel/glass ionomer or dentin/glass ionomer cement interfaces of any samples, but the enamel adjacent to the VariGlass glass ionomer cement restorations exhibited crazing and staining.     

Microleakage in restorations with glass ionomer liners after thermocycling

The purpose of this study was to compare microleakage around two types of restorations lined with polyalkenoate (glass ionomer) cements after thermocycling. Preparations were made in 48 molars to a diameter and depth of 2.0 mm. Half of the preparations were lined with glass ionomer, and the remainder were not lined. Dental amalgam or glass ionomer restorative material was placed and the amalgams were left unburnished and unpolished. Selected restorations were thermocycled 625 times between 4 degrees C and 50 degrees C. Teeth were immersed in 0.5 per cent methylene blue solution, sectioned and visually scored for microleakage at X 100 magnification. Data analysis indicated significant differences in microleakage because of: thermocycling (chi 2 = 103.38, d.f. = 19,2P less than 0.0004); presence of glass ionomer liners (chi 2 = 53.28, d.f. = 19,2P less than 0.0001); and type of restorative material (chi 2 = 103.44,d.f. = 19,2P less than 0.0004). The use of a glass ionomer liner significantly reduced microleakage in both amalgam and glass ionomer restorations when subjected to thermocycling.     

Short- and long-term fluoride release from glass ionomer based liners

Abstract— The aim of the study was to measure the fluoride release from glass ionomer based liners/bases after storing the specimens for 24 h and for 6 months in running water. The fluoride release was greater in the beginning than after half a year. From most liner materials the initial and the long-term release was greater than from the glass ionomer filling material studied for comparison. From two liners the release was minimal, just at the detection limit.     

Pulpal response to a hybrid composite resin inlay bonded with a newly developed resin-modified glass ionomer luting cement

This study evaluated the pulpal response of hybrid composite resin inlay luted with a resin-modified glass ionomer cement, and compared it with a glass ionomer cement and an amalgam. Cervical cavities were prepared in monkey teeth. A resin-modified glass ionomer luting cement (Ionotite F, Tokuyama Dental Corp.) was applied to the teeth in one of the experimental groups, and then hybrid composite resin inlays (Estenia, Kuraray Medical Inc.) were bonded to the cavities. The teeth were extracted after 3, 30, and 90 days and stained with Hematoxylin and Eosin staining or Brown and Brenn gram stain for bacterial observation. No serious inflammatory reaction of the pulp, such as necrosis or abscess formation, was observed in any of the experimental groups. No bacterial penetration along the cavity walls was detected in the resin-modified glass ionomer luting cement group. Hence, the resin-modified glass ionomer luting cement showed an acceptable biological compatibility with monkey pulp.     

Pulpal responses to ionomer cements--biological characteristics

When glass ionomer cements were initially introduced, the pulpal responses were considered milder relative to other cements. However, the results mainly came from the application of glass ionomer cements as restorative materials. When ultimately tested with the basic laws of biocompatibility required of other cements, especially a luting agents, little difference has been shown. The judicious use of calcium hydroxide is highly recommended.     

树脂加强型玻璃离子黏结剂黏结力的实验研究

目的 了解光固化树脂加强型玻璃离子水门汀的剪切强度能否满足临床需要;并比较不同条件下其剪切强度的变化.方法 收集离体前磨牙50颗,随机均分为5组.第1组(对照组):35%磷酸酸蚀30s,冲洗、干燥,涂黏结剂,采用京津釉质黏结剂黏结托槽.第2、4组:35%磷酸酸蚀30s,冲洗,湿润,采用光固化型的Fuji Ortho Lc树脂加强型玻璃离子黏结托槽.第3、5组:不酸蚀,采用光固化型的Fuji Ortho Lc树脂加强型玻璃离子黏结托槽.1、2、3组用电子万能实验机测24h的抗剪切强度,4、5组测30 min的抗剪切强度.并统计牙面上的黏结剂残留量.结果 第2、3、4组的抗剪切强度均能满足临床需要,第5组的抗剪切强度不能满足临床需要,第2组的抗剪切强度与其它各组相比差别有显著性.结论 光固化树脂加强型玻璃离子在酸蚀和免酸蚀后24h,以及酸蚀黏结30min后的剪切强度均能满足临床需要;而免酸蚀黏结30min的抗剪切强度不能满足临床需要;酸蚀后光固化树脂加强型玻璃离子的剪切强度明显增强.