[Observation of intracutaneous reaction in Behçet's disease and its clinical application].
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Adult↗
Biomedical subjects
F Kawano
Publications and source records attributed to F Kawano.
[Serum immunoglobulins in Behçet's disease].
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Adult↗
Influence of occlusal scheme on the pressure distribution under a complete denture.
PURPOSE: The purpose of this study was to estimate which occlusion offers the best conditions of pressure distribution on the supporting structure under a complete denture when crushing food. MATERIALS AND METHODS: Simulated maxillary and mandibular complete dentures with three different posterior occlusal schemes--fully balanced occlusion, lingualized occlusion, and monoplane occlusion--were fabricated. Eight pressure transducers were placed in the basal surface of a mandibular denture. The pressure distribution on the mandibular edentulous mouth model with 1.5-mm-thick artificial tissue under a complete denture was recorded when crushing three different foods: soft food (kamaboko), peanuts, and carrot. The mean pressure values at each measurement point and the force required for each test were compared using one-way analysis of variance with P < or = 0.05 representing statistical significance. RESULTS: The required force for crushing a soft food or carrot in the left molar region in monoplane occlusion was significantly larger than that required in fully balanced occlusion or lingualized occlusion. In crushing soft food, fully balanced occlusion showed significantly higher pressure values on the working side than in monoplane occlusion or lingualized occlusion. In crushing the carrot, the pressure values in fully balanced occlusion and in lingualized occlusion were significantly lower than those in monoplane occlusion. CONCLUSION: These results demonstrate that with fully balanced occlusion and lingualized occlusion a large occlusal force is not needed for crushing hard food, and the stress to the supporting tissues is smaller than with monoplane occlusion.
Alveolar Process↗
Reinforcing effect of a Ni-Cr alloy plate on an acrylic resin denture base.
The authors previously reported on the strengthening effect of a thin Ni-Cr plate on an acrylic resin test specimen in the three-point bending test. This study evaluated the reinforcement of acrylic resin denture bases by measuring the strain distribution in the palate of a maxillary complete denture. It was found that this reinforcing technique led to a uniform distribution of strain in the palatal area of the maxillary denture and a reduction of strain in the midpalatal area.
Acrylic Resins↗
Reinforcement of acrylic resin denture base with a Ni-Cr alloy plate.
A pilot study was conducted to evaluate the strengthening effect of a Ni-Cr metal plate on an acrylic resin test specimen. Test specimens were retained using a mechanical method and adhesion with 4-META resin. Three positions of the metal plate were evaluated: on the compression surface, on the tension surface, and in the middle layer. A three-point bend test was used to compare physical properties of the specimens with metal-plate reinforcement to a resin specimen without reinforcement. No advantage was derived from placing the metal plate in the center of the resin. Both methods of retention produced improved physical properties when placed on either the compressive or tensile side, but the greatest advantages were gained when an adhesive-retained plate was placed on the side in tension.
Acrylic Resins↗
Effect of soft denture liner on stress distribution in supporting structures under a denture.
This study examined the effect of a soft denture liner on the distribution of stresses in the denture-supporting structures. Dentures without a linear and with three configurations of a soft liner were simulated by using a two-dimensional viscoelastic finite-element stress analysis. The stress intensity at functional force-bearing areas decreased when a soft denture liner was used. However, the stresses in the bone increased remarkably up to 3.0 seconds after loading. Because of the time-dependent effect of stresses applied to soft denture liners, denture patients who clench or brux may not benefit as greatly from soft denture liners. The study indicates that viscoelastic finite-element analysis is helpful for evaluating soft denture liners. Soft denture liners appear to be useful for improving the stress distribution in the supporting structures under dentures.
Alveolar Process↗
An in vitro study of the influence of occlusal scheme on the pressure distribution of complete denture supporting tissues.
This study compared lingualized occlusion and completely balanced occlusion using a simulation device. Sixteen pressure transducers were placed in the simulated residual ridge area supporting the test dentures. Lingualized occlusion was found to transfer stresses from the occluding side to the opposite, nonworking side to stabilize the mandibular denture.
Dental Articulators↗
Bond strength of six soft denture liners processed against polymerized and unpolymerized poly(methyl methacrylate).
The bond strength of six commercial soft denture liners was evaluated by a two-phase tensile test. The soft denture liners investigated were VinaSoft, Prolastic, Flexor, Molloplast-B, Novus, and SuperSoft. The samples were fabricated by processing them (1) against polymerized poly(methyl methacrylate), and (2) against unpolymerized poly(methyl methacrylate). The soft denture liners were processed according to the manufacturers recommendations. The samples were tested using an Instron Universal Testing Machine. The mode of failure, adhesive or cohesive, was also recorded. The bond strength when processed against unpolymerized poly(methyl methacrylate) ranged from 0.48 to 2.60 MPa, and when processed against polymerized poly(methyl methacrylate) the bond strength ranged from 0.94 to 2.56 MPa. A two-way analysis of variance (P = .05) revealed a significant increase in bond strength when the liners were processed against polymerized poly(methyl methacrylate), except for Novus, which had no change, and VinaSoft, which decreased. The Tukey interval between materials was .22 and between methods of polymerization was .08. Four of the six liners investigated demonstrated increased bond strength when processed against polymerized poly(methyl methacrylate). It was concluded that bonding can be influenced by the processing method.
Acrylic Resins↗
Impact absorption of four processed soft denture liners as influenced by accelerated aging.
The cushioning effect of soft denture liners was evaluated by using a free drop test with an accelerometer. Materials tested included SuperSoft (Coe Laboratories, Chicago, IL), Kurepeet-Dough (Kreha Chemical, Tokyo), Molteno Soft (Molten, Hiroshima, Japan), and Molloplast-B (Molloplast Regneri, Karlsruhe, Germany). All materials were found to reduce the impact force when compared to acrylic denture base resin. A 2.4-mm layer of soft denture material demonstrated good impact absorption, and Molloplast-B and Molteno had excellent impact absorption. When the soft denture liner was kept in an accelerated aging chamber for 900 hours, the damping effect recorded increased for all materials tested. Aging of all materials also affected the cushioning effect.
Acrylic Resins↗