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PubMed1995

Custom tinting denture bases by visible light cure lamination.

A urethane dimethacrylate and tinting powder lamination, chemically bonded to a methyl methacrylate denture base, produces a natural-appearing distribution of the tints. The characterization is protected by a hard, clear layer of urethane. Procedures are described that achieve this lamination either in the laboratory, before processing the dentures, or after the dentures have been fabricated.

Acrylic Resins↗
PubMed1983

The development of modified denture base materials.

This work has been undertaken in an attempt to develop improved materials for the construction of dentures. In particular, a material was sought that would combine radiopacity with high impact resistance. Eight particulate radiopaque glasses were prepared and incorporated into poly(methyl methacrylate) denture base material, and the properties of the resultant composites were measured. Experiments were also carried out with glass fiber fillers, which were found to increase impact strength. It was shown that the incorporation of both a particulate radiopaque glass and glass fiber, 20% of each, yielded composites with improved properties.

Dental Materials↗
PubMedDate not supplied

Color changes of denture base materials after disinfection and sterilization immersion.

This study evaluated the effects of chemical disinfectants on the color of denture base materials. Materials tested included Paladon 65 (Kulzer, Friedrichdorf, Germany), Triad VLC (Dentsply Int, York, PA), and ProBase Cold (Ivoclar, Schaan, Liechtenstein). The disinfectants were Klinex (Lever Hellas, Athens, Greece), Cidex-7 (Johnson & Johnson, East Windsor, NJ), Hibitane (Imperial Chemical, Macclesfield, UK), and Cabadol (Detax Karl Huber, Ettlingen, Germany). Denture material samples were placed in the various disinfectants and evaluated for color changes (delta E*) at intervals of 10 minutes, 10 hours, and 7 days. Changes in color were measured using a tristimulus colorimeter on 10 samples for each denture material and disinfectant combination. It was concluded that if the recommended disinfecting times are followed, no observable color changes should be anticipated for the denture materials tested. Even the long-term (7-day) immersion caused observable color changes only with Cabadol, a phenol-based disinfectant, and ProBase and Triad denture materials.

Acrylic Resins↗
PubMed1992

The dimensional accuracy of rectangular acrylic resin specimens cured by three denture base processing methods.

The dimensional accuracy of rectangular acrylic resin specimens was examined when they were processed by three methods: a conventional method, the SR-Ivocap system, and a microwave curing method. The dimensional accuracy was evaluated by the change of the distance vector V, which is calculated by means of measurements of the distances between fixed points on specimens. The specimen cured by the SR-Ivocap system exhibited less dimensional change (p less than 0.05) than those cured by the conventional and the microwave curing methods. The SR-Ivocap system might produce a more accurate denture base than the conventional and the microwave curing methods.

Acrylic Resins↗
PubMed1984

Stereochemistry of poly(methyl methacrylate) acrylic resin denture base material.

Nuclear magnetic resonance (NMR) 13C has been used to determine the tacticity of poly(methyl methacrylate) (PMMA) denture base materials. Curing cycle has no effect on tacticity. A tendency towards a mainly syndiotactic arrangement is shown. Industrially produced PMMA showed the same tacticity as the dental products.

Acrylic Resins↗
PubMed2004

Effect of powder to liquid ratio on tensile strength and glass transition temperature of alumina filled poly methyl methacrylate (PMMA) denture base material.

The aim of this study was to evaluate the mechanical properties and glass transition temperature (Tg) of a denture base material prepared from high molecular weight poly methyl methacrylate (PMMA) and alumina (Al2O3). The glass transition temperature was studied by using differential scanning calorimetry (DSC). The effect of powder-to-liquid ratio was investigated. The result showed that the tensile properties and the Tg were slightly effected by the powder-to-liquid ratio. The ratio of 2.2:1 by weight of powder to liquid was found to be the best ratio for mixing the material to give the best result in this formulation.

Aluminum Oxide↗
PubMed2002

A simplified numerical simulation method of bending properties for glass fiber cloth reinforced denture base resin.

The purpose of this study was to propose a new numerical modeling of the glass fiber cloth reinforced denture base resin (GFRP). The proposed model is constructed with an isotropic shell, beam and orthotropic shell elements representing the outmost resin, interlaminar resin and glass fiber cloth, respectively. The proposed model was applied to the failure progress analysis under three-point bending conditions, the validity of the numerical model was checked through comparisons with experimental results. The failure progress behaviors involving the local failures, such as interlaminar delamination and resin failure, could be simulated using the numerical model for analyzing the failure progress of GFRP. It is concluded that the model was effective for the failure progress analysis of GFRP.

Acrylic Resins↗
PubMed2004

Effect of packing types on the dimensional accuracy of denture base resin cured by the conventional cycle in relation to post-pressing times.

This study investigated the dimensional stability of denture bases influenced by packing methods, in relation to post-pressing times, in the Clássico acrylic resin which was prepared according to manufacturer recommendations. Forty maxillary wax bases were made and randomly assigned into 2 groups of 20 specimens each according to the conventional and RS system packing methods. In each method, the specimens were subdivided into immediate, 6, 12 and 24 h post-pressing times. The dough of the acrylic resin was packed in metallic flasks and processed in a water bath curing cycle at 74 masculine C for 9 h. After cooling at room temperature, the bases were removed from the flasks, finished and fixed on stone casts with instantaneous adhesive. The resin base-stone cast sets were transversally sectioned into 3 sections and the base-stone gap measured at 5 points in each section. The data were submitted to ANOVA and Tukey's test, which showed that the RS system had a smaller base distortion compared to conventional packing, with the exception of the 24-h post-pressing time. There was a statistically significant difference between the packing methods only in section C (posterior palatal zone). In the conventional packing method, the immediate and 6 h times demonstrated values with no statistically significant difference between them, as well as between the 12 and 24 h post-pressing times.

Acrylic Resins↗
PubMed1991

Evaluation of the level of residual monomer in acrylic denture base materials having different polymerization properties.

The aim of this study was to evaluate the level of residual monomer in acrylic denture base materials having different polymerization properties. The investigation included a conventional-type acrylic cured under heat and pressure, as well as a pour-type resin polymerized by an injection-moulding technique at room temperature and under pressure. It was found that the residual monomer content ranged from 0.22-0.54% in pour-type resin, and from 0.23-0.52% in routinely used resins when the specimens were analysed by high performance liquid chromatography. These findings revealed that there were no significant differences between the two types of acrylic in terms of their residual monomer content.

Acrylic Resins↗
PubMedDate not supplied

Cytotoxicity of denture base resins.

This in vitro study examined the effect of eluate from heat-activated, chemically activated, and microwave-activated denture base resins on cell viability of primary cultures of human gingival fibroblasts. Eluates corresponding to 24, 48, 72, and 96 hours of resin disk immersion were prepared. Fibroblasts were plated at a density of 3 x 10(4) cells in 96-well plates and exposed to a medium containing eluate. After 24 hours, the cytotoxic effect was determined by cellular mitochondrial function. The effect of eluates was compared to control cultures containing culture medium without eluate. Results indicated that at all time periods tested, all three resins leached materials that were cytotoxic to the fibroblasts. Eluate from chemically activated resin disks was more cytotoxic than eluate from heat-activated and microwave-activated disks. In general, cytotoxicity appeared to diminish as disk immersion time was increased. The greatest cytotoxic effect on cell viability was observed with eluates recovered after 24 hours of disk immersion, and the least cytotoxic effect was observed with eluates recovered after 96 hours of immersion.

Acrylic Resins↗
PubMed1998

[Influence of covering gingival sulcus with denture base on periodontal tissue--pH value in gingival sulcus and amount of gingival crevicular fluid].

The purpose of this study was to clarify the effect of covering gingival sulcus with denture base on periodontal tissue. Six subjects participated in this study. An experimental denture was inserted to a test tooth of each subject that was prepared for a full crown. Each experimental denture was designed to cover the gingival sulcus around the tooth. All subjects used them for two weeks. The parameters were as follows: 1) pH in gingival sulcus, 2) amount of gingival crevicular fluid, 3) tooth mobility, 4) temperature in gingival sulcus, 5) probing depth, 6) GI, and 7) P1I. Measurements were performed during the following periods: 1) pre-examination, 2) after cementation of provisional restoration, 3) during insertion of experimental denture, 4) after cementation of final restoration. A repeated-measures ANOVA was used for statistical analysis. The results were as follows: 1. pH value and amount of GCF increased after insertion of the experimental denture, and returned to same level as pre-examination after cementing of the final restoration. 2. Tooth mobility decreased during insertion of the experimental denture. 3. The changes of the other parameters were not significant. These results suggested that subclinical inflammatory change occurred in periodontal tissue in an early stage accompanied with covering of the gingival sulcus.

Adult↗
PubMed1997

Effect of alcoholic drinks on surface quality and mechanical strength of denture base materials.

The effect of pure alcohol as well as several alcoholic drinks on the static and dynamic strength and surface quality of denture base poly (methyl methacrylate) was investigated. Wetting tensile specimens with alcohol led to a reduction of their static strength by 16.1% and their fatigue strength by 14.3%. Polished specimens immersed in various alcoholic drinks with over 40% alcohol exhibited considerable surface corrosion, which was capable of reducing the fatigue strength of the material.

Beverages↗
PubMed1989

[Development of denture base resin. 2. Manufacturing of visible-light cured prepreg and physical properties of FRP].

To develop the visible light-cured FRP denture base, we investigated the physical properties and the warp of FRP plate by using various combinations of matrix resin and reinforcement. From the results of the bending test, hardness test and manipulation processing, the matrix resin of Bis-GMA/UDMA/3 G at 48/48/4 wt% was determined. The sateen weave's glasscloth as the reinforcement of the prepreg was used. The maximum plies included FRP of 0.5 mm, 0.8 and 1.0 mm thickness have the same maximum bending strengths of 45 kgf/mm2, which is about 5 times larger than that of conventional acrylic resin. The warp of these FRP plates were not found.

Bisphenol A-Glycidyl Methacrylate↗