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Five new ether-soluble resin glycosides (jalapins), simonins I-V, have been isolated from the roots of Ipomoea batatas and characterized on the bases of chemical and spectral data. Simonin I is the first example of resin glycoside with aromatic acid (trans-cinnamic acid) as a component organic acid.
Two new ether-insoluble resin glycosides named woodrosins I and II were isolated from the stems of Ipomoea tuberosa L., and their structures were determined on the basis of chemical and spectral data. Contrary to anticipation, they had an intramolecular cyclic ester structure similar to that of ether-soluble resin glycosides (Mayer's jalapin) hitherto isolated. It is proposed to use the terms, "jalapin" and "convolvulin," not according to the solubility in ether (Mayer's classification), but according to the structure, i.e., intramolecular esters and others, respectively.
Two new polypodane-type triterpenes, myrrhanol A and myrrhanone A, were isolated from the 50% aqueous methanolic extract of guggul-gum resin [the resin of Balsamodendron (=Commiphora) mukul HOOK]. The structures of the new constituents, including their absolute configurations, were determined on the basis of chemical and physicochemical evidence.
The aim of this study was to evaluate the effect of the post eruptive enamel maturation on the durability of polyacid-modified resin composite (PMRC; Dyract Seal) and resin composite (Fissurit F) sealant and understanding the effect of posteruptive enamel maturation on the sealant retention. To determine the possible effect of the enamel maturation to the sealant retention, the success of the sealants applied to the newly erupted mandibular first molars of the 6 to 7 years old children, who were in the fourth or fifth eruption stage according to Dennison's classification were compared with the sealants applied to first mandibular molars which were in the mouth at least for two years of the 9 years old children. The molars of the younger children were accepted as immature and the elders were posteruptively mature. The sealant retention was evaluated for two years. At the end of two years the retention rates of Dyract Seal were significantly lower. Maturation has no effect on the sealant retention. Dyract Seal application after NRC conditioning is not recommended.
Evaluation were made of the effect of different finishing procedures on the surface textures of a conventional composite material, two newly introduced microfiller composite resins, a visible light polymerized resin, and a glass ionomer cement. The two micro-filler composite materials appeared to be superior in finishability compared with those materials loaded with larger filler particles. The use of fine grit devices particularly resulted in smooth surfaces. This is in contrast to the other materials which always showed rough surface textures with protruding filler particles. The use of a polishing paste improved the surface finish of the micro-filler materials in contrast to the materials with larger filler particles.
The most undesirable characteristic of composite resin is its polymerization shrinkage. Two techniques developed to counter this problem are the composite inlay and the sandwich composite filling. The durability of 100 direct composite inlays and 34 closed and 16 open sandwich composite fillings made with a conventional glass ionomer cement were evaluated during a 6-year period in a group of low and high caries risk patients. Modified USPHS criteria were used. Six inlays (6%), 5 closed sandwich fillings (14.7%), and 12 open sandwich fillings (75%) needed replacement. Six other inlays and three closed sandwich fillings showed non-acceptable defects that could be repaired with composite resin. The direct composite inlays showed very good clinical durability, whereas the open sandwich filling with conventional glass ionomer cement as dentin replacement cannot be advocated as a class-II restoration.
Powder-liquid type metal-resin composites, using Ag-Sn irregular particles as the filler, 4-META as coupling agent and UDMA + TEGDMA as resin matrix, were experimentally prepared under 9 different conditions (three different particle sizes and three different filler contents). The flexural strength and flexural modulus were measured. Three different irregular particle size MRCs without redox-initiator at 94% filler content, as well as amalgam, conventional hybrid composite and Ag-Sn spherical particle MRC were evaluated for condensability. The flexural strength of the Ag-Sn irregular particle MRC was significantly influenced by both the filler particle size and filler contents (p < 0.01). It increased when either the filler content increased or the particles size decreased. The highest flexural strength (97.6 MPa) was obtained from the condition of particles size < 20 microns and 94% filler content. The flexural modulus was significantly influenced by filler content and it increased with increasing filler content. The condensability of the Ag-Sn irregular particle MRC was lower than that of amalgam but much higher than presently available conventional composites and spherical particle MRC.
This study investigated the effect of various solvents on resin composite bond strength to dentin with both wet and dry dentin. A generic dentin bonding system was created with HEMA as the resin in the primer. The highest bond strengths were obtained when acetone was used as the solvent on a wet dentin surface; the lowest bond strengths were obtained with water as the solvent and the primer placed on a wet dentin surface.
Microleakage has been a major concern in restorative dentistry. The curing contraction of composites still presents a problem with controlling microleakage and postoperative sensitivity. This study investigated the effect of flowable materials on gingival microleakage of microhybrid and packable resin composite restorations. Ninety Class II cavities with cervical margins 1 mm below the CEJ were prepared in 45 extracted human premolars. The teeth were randomly divided into three groups (n=15). In each group, one side of each tooth was restored incrementally with respective composites-SureFil, Filtek P60 and Tetric Ceram; whereas, on the other side, flowable materials-Dyract Flow, Filtek Flow or Tetric Flow-were placed respectively as a 1-mm thick gingival increment before the resin composite restoration. The restored teeth were stored for one week in distilled water at 37 degrees C, thermocycled between 5 degrees C and 55 degrees C and immersed in 0.5% basic fuchsin for 24 hours. Dye penetration was evaluated using a stereomicroscope at 10x magnification. The data were analyzed statistically by Kruskal-Wallis analysis of variance and Mann-Whitney U-tests. The effect of flowable increments on reducing the gingival microleakage was found to be statistically significant for all restorative materials tested (p<0.05).
Rats received 20 skin applications of heavy pyrolysis resin, containing about 30% of polycyclic aromatic hydrocarbons. The every exposure duration was 4 hours a day. Applications have been carried out daily 5 days a week in the course of 4 weeks. Induction of cytochrome P-450 (P-450) by 79%, significant induction of microsomal (GTm) and cytosol (GTc) glutathione-S-transferase activity (by 46 and 85%, respectively) and small increase of reduced glutathione level (by 9%) also were registered as a result of these exposures. Lipid peroxidation level determined by TBK-reactive products quantity didn't alter significantly. Close correlation between ratio values of P-450/GTm levels and P-450/GTc levels and toxic effect indices of heavy pyrolysis resin on rat immune and endocrine systems.
Studies were done to decrease both the water sorption and solubility of visible light cured resin. As monomer, three kinds of cyclophosphazene monomers and three kinds of commercial monomers were prepared to the visible light cured unfilled resins. When these set products were immersed in water, MeOH and THF, water sorption and solubility in water, MeOH sorption and solubility in MeOH, THF sorption, and mechanical properties were examined. Water sorption was increased by degrees for all the monomers. In the cases of 4 PN-(EMA)8, 4 PN-(TF)1-(EMA)7, 4 PN-(TF)2-(EMA)6, Tri-EDMA, BMPEPP and Bis-GMA + Tri-EDMA, the value of solubility in water after 30 days, was 0.16, 0.20, 0.51, 0.65, 0.17 and 0.81% respectively. MeOH sorption showed a tendency to increase, except for Bis-GMA + Tri-EDMA and 4 PN-(TF)2-(EMA)6. Solubility in MeOH after 30 days, for cyclophosphazene monomers and commercial monomers, was 0.09-0.36% and 1.36-5.40%. THF sorption after 30 days, for cyclophosphazene monomers, was small in comparison with that of commercial monomers. Compressive strength was 230-275 MPa in all cases. But, transverse strength, for all the cyclophosphazene monomers, was 45 MPa or below. In the cases of commercial monomers, the value of transverse strength was 55-90 MPa.
This study evaluated compressive strength, sealing ability and tensile bond strength of various materials of composite resin cores. 1. Compressive strength of the various materials, after they were placed in air for 24 hours, underwent thermal cycling testing, or were soaked in water for 2 weeks, ranged from 2000 kgf/cm2 to 2900 kgf/cm2. 2. The sealing ability after thermal cycling testing and being soaked in water for 2 weeks varied among the materials. 3. The bond strength of all composite resin core materials to dentin was less than 50 kgf/cm2. 4. In this study, no relationship was found between sealing ability and tensile bond strength.
Short peptides, three to eight amino acids in length, containing various combinations of alanine, arginine, lysine, histidine and tyrosine have been synthesized onto water-swellable polyamide resin by the solid phase peptide synthesis method. The amount of bilirubin adsorbed from aqueous buffer solution (pH = 7.8) by the resins increases with increasing basicity of the amino acids in the pendant. As the number of basic amino acids on the pendant is increased from one to five a 4.7 fold enhancement in the adsorption capacity is seen for arginine while a 9.3 fold enhancement is obtained for lysine. A corresponding increase in length for the non-basic histidine results in a 6 fold enhancement. With alanine the adsorption capacity is uneffected by an increase in pendant length.
Bonding between acrylic resin teeth and a denture base material was investigated after microwave and hot water-bath curing. The specimens were tested according to the methods of the International Organisation for Standardisation (ISO 3336-1977 Dentistry-Synthetic Resin Teeth) using a universal testing machine. Superior bonding was found after hot water-bath curing. The generation of more porosities during microwave curing is the most likely explanation for the bond failures in this group. This finding is of clinical importance as the choice of curing method could influence the risk of loosening of acrylic teeth from the denture. No statistically significant difference in the fracture load between the two types of curing was found, which was expected as the load at fracture is not only related to the binding forces but also to factors such as the contact area and the fracture type.
Four light-cured composite resins (Z100, Heliomolar RO, Herculite XRV, and Prisma APH) and two resin-modified glass ionomer restorative materials (Fuji II LC and VariGlas VLC) were placed in an uncooled, unheated outdoor storage shed for 12 months. Maximum and minimum ambient temperatures were recorded every 24 hours. Each month, samples were polymerized with a visible light source and alterations in polymerization were assessed using a scratch test. Problems with manipulation or changes in appearance were also monitored. Samples stored outdoors were compared to control samples maintained at room temperature [68-74 degrees F (20-23.3 degrees C)]. Results showed that polymerization of all materials tested was apparently unaffected to any significant clinical degree by outdoor storage at temperatures ranging from 20 to 112 degrees F (-6.6-44.4 degrees C) over 12 months. Eight months into the study, the VariGlas VLC liquid had separated into a viscous gel and watery component. None of the other remaining materials demonstrated any changes in manipulation or appearance. All materials tested except VariGlas VLC appear suitable for use during military deployment or field training exercises under similar environmental conditions.
Eight different conventional and resin-modified glass ionomers as well as a polyacid-modified composite were air polished and their fluoride release was determined in comparison to untreated controls. The air polishing was done with two different devices at medium and maximum setting for powder and water. Ninety discs of 1.5 mm thickness and 7.0 mm diameter were produced from each cement. These discs were stored in 5 ml deionized water at 37 degrees C. After 1 day and 1, 4, 8, 12, and 16 weeks, the specimens were transferred into new vials with fresh deionized water. From the 4th week onward, the specimens (except for the untreated controls) were air polished on half of their upper and lower surfaces for 2 s each before being put into a new vial. After 20 weeks the fluoride released during the previous 4 weeks was determined with a fluoride ion-sensitive electrode. With the exception of Ketac-Cem, all cements released significantly more fluoride ions after air polishing, irrespective of the devices' settings. The differences in the amount of fluoride released among the investigated materials were greater than the changes in fluoride release patterns caused by air polishing. Air polishing increased the fluoride release by 20-60% in most of the materials investigated.
PURPOSE: To quantify the internal free surface in various resin cements and glass-ionomer-based materials. MATERIALS AND METHODS: Materials tested were Nexus fluid (NXF) and viscous (NXV), Vitremer (VTM), Fuji II LC (FII), Vitremer Luting Cement (VLC), Dyract (DYR) and Compoglass (COM). Samples (n=5) were made of each material between two microscopic glass slides under same weight. With a transmitted light microscopy, four zones of each sample were evaluated, finding the number of porosities per mm2 (NP), the average radius of porosities (RP), the ratio of total area of surface porosities (micron2) to area (mm2) of specimen surface (TA) and the ratio of total volume of porosities (micron2) to area (mm2) of material surface (VP). RESULTS: Median test was used. NP: NXV, NXF and DYR had smaller NP than VTM and FII and (likely) than VLC (P> 0.0000001). RP was smaller for DYR than for VLC and (likely) than for NXV (P= 0.00019). TA: NXV, NXF and DYR had smaller TA than VTM, FII and VLC (P< 0.0000001). VP: NXV and DYR had smaller VP than FII and (likely) than VTM and VLC (P< 0.0000001).
The concentrations of total Na+ and of free Na+ were measured in solutions of Na+ polystyrene sulfonate (NaPSS). Free Na+ was determined using a Na+-sensitive glass electrode having a high degree of specificity for Na+. In a 5% PSS solution, 80% or more of the Na+ was not detected by the glass electrode and was adsorbed specifically onto the anionic sulfonate groups. The degree of adsorption increased with an increase in the concentration of PSS. These results were discussed in regard to the interpretation of NMR studies of Na+ in the cross-linked PSS resins (Dowex 50) and in living cells. The results show that the quadrupolar splitting of the Na+ NMR signal is caused by specific ionic adsorption onto fixed anionic sites and not by a diffuse charge gradient extending over large distances.