Visible Light-cured Composite Resin Research Articles

可視光線重合型コンポジットレジンのフィラーに関する研究 : I. 機械的性質に及ぼす各種シリカフィラーの影響

To investigate the effect of silica fillers on the mechanical properties of visible light-cured composite resins, Bis-GMA-based composites with four types of silica fillers were prepared. The mechanical properties of the composites with splinter-shaped silica fillers increased with increasing the filler fraction. Although the spherical silica filler could be filled more with resin monomer than the splinter-shaped silica filler, the mechanical properties of spherical silica-filled composite were relatively lower than those of the composite with splinter-shaped silica fillers. The micro particle silica-filled composite showed no obvious increase in the mechanical properties in either the dry or wet conditions. SEM observations of the fractured resin surface revealed that fracture occurred through the resin matrix as well as the resin/filler interface and the mechanical properties of each composite resin were correlated with the nature of crack propagation.

A Study on Effect of Surface Treatments on the Shear Bond Strength between Composite Resin and Acrylic Resin Denture Teeth

Visible light-cured composite resins have become popular in prosthetic dentistry for the replacement of fractured/debonded denture teeth, making composite denture teeth on partial denture metal frameworks, esthetic modification of denture teeth to harmonize with the characteristics of adjacent natural teeth, remodelling of worn occlusal surfaces of posterior denture teeth etc. However, the researches published on the bond strength between VLC composite resins and acrylic resin denture teeth is very limited. The purpose of this study is to investigate the effect of five different methods of surface treatments on acrylic resin teeth on the shear bond strength between light activated composite resin and acrylic resin denture teeth. Ninety cylindrical sticks of acrylic resin with denture teeth mounted atop were prepared. Various treatments were done upon the acrylic resin teeth surfaces. The samples were divided into six groups, containing 15 samples each. Over all the treated and untreated surfaces of all groups, light-cured composite resin was applied. The shear strengths were measured in a Universal Testing Machine using a knife-edge shear test. Data were analyzed using one way analysis of variance (ANOVA) and mean values were compared by the F test. Application of bonding agent with prior treatment of methyl methacrylate on the acrylic resin denture teeth resulted in maximum bond strength with composite resin.

Influence of Background Color on the Chromatic Value of Four All-Ceramic System Core Materials

This study aims to investigate the effect of background color on the chromatic value of four all-ceramic system core materials at clinically appropriate thicknesses. Disc specimens with 15 mm in diameter and thicknesses ranging from 0.5±0.01mm In-Ceram zirconia core, Cercon base zirconia core, and Cercon base color zirconia core) to 0.8±0.01mm (Empress II) were fabricated. A colorimeter (CIE- 1976-Lab) measured the chromatic value of all samples placed on a high-noble metal-ceramic alloy and a visible light-cured dental composite resin (A2 color) background, after which the color difference was calculated. The color difference of Empress II samples was more than 1.5 among different background color groups, while that of Zirconia was less than 1.5. The influence of background color on the Empress II dentin was visible, such that it could be used on a tooth color post. Meanwhile, the influence of background color was invisible for the three kinds of Zirconia core materia1s, such that the materials developed excellent color-masking abilities and could be adapted for use on any color background.

Current concepts and techniques in complete denture final impression procedures.

In 2001, a survey of U.S. dental schools was conducted to determine which concepts, techniques and materials are currently prevalent in the teaching of final impression procedures for complete dentures in the predoctoral clinical curriculum. The questionnaire was mailed to the chairperson of the prosthodontic/restorative departments of 54 U.S. dental schools. Of these, 44 schools returned the completed survey resulting in a response rate of 82%. Results from this survey show that the majority of schools (71%) teach the selective-pressure technique for final impression making; the majority of the schools (64%) use modeling plastic impression compound for border molding the final impression tray; 39% of the schools do not place vent holes in the final impression tray, 30% of schools place more than one hole and 27% place one hole only; the majority of the schools (98%) are using custom trays for final impressions. Ninety-eight percent of the schools are border molding the custom tray and 70% of schools are using a visible light-cured (VLC) composite resin material to make the trays. Thirty-six percent of the schools are teaching the Boucher impression technique and 34% are teaching the modified Boucher impression technique. Predoctoral clinical complete denture educational programs agree on many aspects of final impression making, however, there is variability in their teachings regarding the impression philosophy and the materials used.

Polymerization of dental composite resins using plasma light

Five visible light-cured composite resins used as restoration or adhesive materials in dentistry, were irradiated with high energy plasma light (1300 mW/cm 2), and contraction, rate of contraction, irradiation-induced temperature were analysed. A comparison was carried out with the same materials irradiated with a conventional halogen light (400 mW/cm 2). The exposure to the photoactivating lights was either continuously or sequentially in three or more intervals with 10 min between intervals. Comparing the lengths of exposure of both lights, which induced the same contraction in a given material, it was found that the exposure length to the plasma light was greatly reduced, when compared with the exposure length of the halogen light (1 : 10). Frequently, the final contraction of plasma-irradiated materials was lower, whereas the rate of contraction, as indicated by the linear dimensional variation curves obtained by laser beam scanning method, did not show significant differences between the two lights. The temperature increase induced by plasma light on the material did not exceed the temperature induced by conventional light.

Effects of Uncontrolled Outdoor Storage on the Polymerization, Manipulation, and Appearance of Visible Light-Cured Composite Resin and Resin-Modified Glass Ionomer Materials

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.

In vivo corrosion behavior of gold-plated versus titanium dental retention pins

Two types of titanium dental retention pins and a gold-plated stainless steel pin were tested for their in vivo corrosion behavior. Six paired samples of titanium and gold-plated pins were placed in box preparations of 12 periodontally involved premolars. Half of the samples were restored with a high copper admixed type amalgam while the rest were restored with a BisGMA-POCl 2 bonding resin and a hybrid visible light-cured composite resin. After 3 months in vivo, the teeth were extracted, and the pins were removed and examined with an electron microprobe. The surface of the titanium pins was found to be smooth and without defects. Only traces of Ca and P could be identified from dentin. The gold-plated pins demonstrated cracks and pores, especially at the outer part of the serrations, resulting in disruption of the electroplated film. Traces of Hg, Sn, Cu, S, Zn, Ca, K, Cl, P, and S were detected at the gold-plated pin/amalgam interface, while Cl and P were found at the gold-plated pin/composite resin interface. The in vivo corrosion resistance of the titanium pins was found to be superior to that of the gold-plated stainless steel pins.

光重合型コンポジットレジンの開発に関する研究 ー シクロホスファゼン系モノマーに混合するフィラーの種類およびその量と物性について ー

光重合型コンポジットレジンの開発に関する研究 ー シクロホスファゼン系モノマーに混合するフィラーの種類およびその量と物性について ー

Mechanical properties and cure depth of UDMA-based composite resins

Mechanical properties and cure depth of visible light-cured composite resins based on six types of UDMA (IP-HEMA, IP-HPMA, XY-HPMA, MC-HPMA, UEDMA and UPDMA) monomers were investigated. Under wet conditions, the mechanical properties of the composite resins based on aliphatic UDMA (UEDMA and UPDMA) monomers were inferior to those based on the other UDMA monomers containing aromatic or cyclohexane rings in their chemical structures. The cure depth for these UDMA-based composite resins increased with increasing irradiation time. The composite resin based on the XY-HPMA monomer showed a cure depth and transmission coefficient superior to the other composite resins.

Durability of commercial composite resin. Chronological change in transverse strength and transverse elastic modulus of composite resin immersed in MeOH

The durability of visible light-cured composite resin was examined. Five kinds of commercial redox type composite resin and 7 kinds of visible light-cured composite resin were used and their base monomers were analyzed by HPLC. After the set products were immersed in MeOH, transverse strength and transverse elastic modulus were measured. Furthermore, the MeOH sorption, solubility in MeOH and main soluble component were examined. The main component of the base monomer in all 5 kinds of redox type was Bis-GMA. Seven kinds of visible light-cured composite resin consisted of 4 kinds of Bis-GMA (including BMPEPP) and 3 kinds of UDMA. Both cases of redox type and visible light-cured type of composite resin, when they were immersed in MeOH, transverse strength and transverse elastic modulus decreased. In the case of redox type (Clearfil posterior new bond), the decrease of transverse strength and transverse elastic modulus was small, that is, its base monomer was Bis-GMA, and large quantities of hybrid type filler were mixed. In the case of redox type, transverse strength and transverse elastic modulus showed a tendency to decrease with the increase of MeOH sorption. Solubility of 12 kinds of these composite resins was 0.25-4.78% and its main component in Pyrofil light bond A was BMPEPP, the residual were coincident with the main component of base monomer.

Dynamic mechanical properties of an inlay composite

A visible light-cured composite resin (Brilliant DI) has been studied over a wide range of temperature and frequency by a dynamic mechanical flexural method. The derived data of logarithmic modulus and loss tangent (tan δ) show considerable changes following a secondary-cure process applied to the material. This involved the application of heat and intense light with temperatures rising to 120°C in 7 min. Following this oven-cure the resin phase exhibited enhanced stiffness with the activation-energy barrier for molecular motion at the glass-transition rising from 220 to 291 kJ/mol. This study clarifies the nature and extent of the internal molecular changes which may be produced in the fabrication of a composite inlay.

Marginal sealing of visible light-cured composite resins in cervical cavities : Hotta Masato (1988) Jap. J. Conserv. Dent.31, 1371–1388

Marginal sealing of visible light-cured composite resins in cervical cavities : Hotta Masato (1988) Jap. J. Conserv. Dent.31, 1371–1388

Effect of filler system on the mechanical properties of light-cured composite resins. II. Mechanical properties of visible light-cured composite resins with binary filler system

To improve the fracture resistance of the composite resin system under highly stressed conditions, a variable amount of microfiller was incorporated into the light-cured composite resins containing splinter-shaped silica filler. With the increasing the microfiller content (10-30 wt%) in the resin matrix, the elastic modulus, compressive proportional limit and compressive fracture strength of the composite resin were increased. The plastic deformation of the composite resins under compressive stress were decreased with increasing microfiller content. These findings suggested that the combination of a larger silica filler and microfiller would increase the compressive fracture resistance of the composite resin systems.

A Study on Disintegration of Visible Light-cured Composite Resins Caused by Long-term Water Immersion

A Study on Disintegration of Visible Light-cured Composite Resins Caused by Long-term Water Immersion

各種歯科材料の疲労に関する研究 Ｉ 合着用セメントおよび支台築造用コンポジットレジンの圧縮強さについて

In this study, we investigated compressive strength of various luting cements and composite resin cores in both dry and wet condition, and then influences of repeating load on compressive strength in wet condition of distilled water at 37 degrees C. As frequency of repeating load increased, compressive strength of all materials decreased. It means that the repeated load cycling test used in this study is adequate for evaluating durability of various dental materials. The results were as follows: 1. In the condition of no loading in both dry and wet condition, resin cement indicated the highest compressive strength of all cements examined and was followed by glass ionomer cement, zinc phosphate cement and polycarboxylate cement. Glass ionomer cement was notably influenced in wet condition. 2. After 10,000 cycles of loading in wet condition, resin cement indicated the highest compressive strength again and was followed by glass ionomer cement, polycarboxylate cement and zinc phosphate cement. In particular, compressive strength of zinc phosphate cement decreased remarkably. 3. In the condition of no loading, visible light-cured composite resin core was superior to chemical one. Visible light one was notably influenced in wet condition. 4. After 10,000 cycles of loading, visible light-cured composite resin core was superior to chemical one.

The shear impact retentive strengths of four dentine bonding agents to human and bovine dentine

The purpose of this study was to determine the shear impact retentive strengths of four dentine bonding agents to human and bovine dentine. The bonding agents were used to attach a visible light-cured composite resin to extracted human and bovine teeth. The shear impact bond strength was determined using a hydraulic tester running at close to maximum chewing speed. Statistically significant differences in bond strength were found using the different dentine bonding agents. There were no significant differences in bond strengths between the dentine substrate species for each agent.

Shear bond strength of a new dentin bonding restorative system

A new visible light-cured composite restorative resin, Lumifor, used in conjunction with a dentin bonding agent, Gluma, has recently become commercially available in Europe. The objective of this study was to determine the shear bond strength of the restorative system to dentin. Extracted human permanent molars were stored in 1% chloramine, and the test specimens prepared within 24 h after extraction. The teeth were embedded in cold-cure acrylic and the exposed surfaces ground wet on 600-grit silicon-carbide paper to expose dentin. Gluma Cleanser was applied to the dentin for 30 s and washed for 15 s. Gluma Dentin Bond was applied to dentin for 30 s and blown dry. A split Teflon mold with an inner diameter of 3.5 mm was mounted on the dentin surface in a special device. A thin layer of the low viscosity sealer was applied to the demarcated dentin surface and cured with visible light for 30 s. The composite resin was transferred to the split mold and cured for 2 min. The 75 test specimens were stressed to failure in an Instron machine at a crosshead speed of 0.02 inch.min −1, immeditely after specimen preparation (A), 24 h after specimen preparation (B), 24 h after specimen preparation and subjected to 250 temperature cycles between 5°C and 55°C with a dwell time of 30 s (C), 4 weeks after specimen preparation (D), 4 weeks after specimen preparation and subjected to 250 temperature cycles between 5°C and 55°C with a dwell time of 30 s (E). The shear bond strengths were expressed in MN.m −2, and the data were analyzed by an analysis of variance at the 5% level of significance. The following bond strengths were obtained (mean±SD): A: 8.9±2.3; B: 10.8±3.0; C: 10.8±2.3; D: 10.8±2.1; E: 10.3±1.4. The Gluma/Lumifor system effectively bonds to dentin and the shear bond strength is not adversely affected by storage and temperature cycling.

Five-year study of two lightcured posterior composite resins

Two visible light-cured composite resins, Ful-Fil and X-55, were used to restore 136 Class I and Class II cavity preparations in adult teeth. After 5 years the ratings for color matching, interfacial staining, secondary caries, and marginal adaptation remained good, using USPHS criteria (ranging from 75% to 100% Alfa). The average surface loss due to occlusal wear was 158 and 169 micrometers for Ful-Fil and X-55, respectively. Significant differences in occlusal wear were noted depending on tooth and restoration type. These results indicate that both composite resins meet the current ADA Council on Dental Materials specifications for full acceptance in adult posterior teeth.

Effect of exposure time on the depth of polymerization of a visible light-cured composite resin.

The effect of exposure time of a visible light source on the depth of polymerization and degree of hardness of a sample of Occlusin posterior composite resin was investigated. The border between cured and non-cured composite resin was identified by a change in colour and by applying pressure with a scalpel. Knoop hardness tests were performed perpendicular to the long axis of illumination. The composite resin nearer to the light source underwent more complete polymerization. Increased exposure time resulted in greater depth of cure. The rate of polymerization was greatest in the first 10 s. Maximum hardness measured up to a depth of 1 mm obtained after 80 s of exposure time. At greater depth, a decrease in Knoop hardness was observed. At exposures under 80 s, maximum hardness was not achieved even at a depth of only 1 mm.

The Development of Visible Light-cured Composite Resin -Selection of Monomers to be Mixed with Cyclophosphazene Monomer and the Relationship between the Mixed Amount of Filler and Physical Properties-

The Development of Visible Light-cured Composite Resin -Selection of Monomers to be Mixed with Cyclophosphazene Monomer and the Relationship between the Mixed Amount of Filler and Physical Properties-