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At least 55 records · Page 3Linked to original sources

[Three dimensional changes of the denture base of the complete denture following polymerization].

The objective of this study was to clarify some of the dimensional change patterns of the denture base of the complete denture following polymerization. Dimensional changes of three polymerization method types were compared. The complete dentures were measured by using the three dimensional measurement system. The results obtained were summarized as follows. 1. Dimensional changes from the original model immediately after polymerization of complete upper and lower dentures were recorded and all three polymerization methods produced shrinkage on all three axes toward the center. Heat cured resin samples and microwave cured resin samples showed the same shrinkage with pour type resin samples only showing 1/2 that amount. 2. The gradual dimensional changes occurring after polymerization up until 4 weeks were also recorded. The heat cured resin samples showed no additional changes but remained in its shrunken state. The pour-type resin samples began to enlarge until almost all of them reached the original model size within 4 weeks. The microwave cured resin samples began to enlarge but only slightly and then soon stopped changing. 3. All polymerization method types showed more dimensional change in the lower plate than in the upper plate.

Acrylic Resins↗

Visible light-cured denture base resin used in making dentures with conventional teeth.

A visible light-cured denture base can be made to serve as a custom record base and as the final denture base. After individual conventional denture teeth are set in wax, a matrix can be made to hold the teeth in relation to the denture base and cast after the wax is removed and during the time the light-cured resin is being added and partially cured. When the matrix is removed, additional light-cured resin can be added to establish the denture contours and the denture can be processed without flasking.

Acrylic Resins↗

Flexural strength at the proportional limit of a denture base material relined with four different denture reline materials.

This study evaluated the resistance to plastic deformation under a flexural load (PLf) of a denture base material relined with four different types of denture reline materials. A heat-processed poly(methyl methacrylate) denture base was relined with varying thicknesses of denture reline materials and subjected to a flexural load. The flexural load at the proportional limit (PLf) was recorded. The PLf of the bulk denture base and denture reline materials were also measured for comparison. All relined denture bases showed significantly lower PLf than the bulk denture base. Generally, the PLf of the reline-denture base composite progressively decreased with an increasing proportional thickness of the reline material.

Analysis of Variance↗

[A study on the improvement of denture base resin. Epoxy dimethacrylate-polybutadiene dimethacrylate-MMA monomers as the liquid of denture base resin].

The dimethacrylates, EpDMA and BdDMA, which have a bisphenol type epoxy chain and butadiene chain in their main chains, respectively, were synthesized. The properties of the terpolymer composed of EpDMA, BdDMA and MMA monomers were examined. The monomer mixture of EpDMA, BdDMA and MMA was used as the liquid of denture base resin, and the properties of the cured resin were examined. The polymerization shrinkage of the terpolymer of EpDMA-BdDMA-MMA decreased with the increase in the EpDMA concentration in the cured resin, and the transverse strength and the elastic modulus were greatest at the BdDMA concentration of 0.3-1 vol%. The denture base resin produced using a monomer mixture as the liquid, the transverse strength and the impact strength showed the highest values of about 110 MPa and 14 KJ/m2, respectively, at the liquid composition of 10 vol% EpDMA, 1 vol% BdDMA and 89 vol% MMA.

Butadienes↗

[Radiograph stress measurement of metallic denture base formed by wire explosion energy. 1. Stress changes during various stages of manufacturing metallic denture base].

The radiograph stress measurement method is the only known means of a non-destructive measurement, and this method is used to assess the residual stresses of various metals. This study was made to evaluate the possibility of radiograph stress measurement of the metallic denture base formed by the wire explosion energy. Radiograph stress measurements of stress changes during various stages of manufacturing metallic denture base were successfully obtained.

Dental Stress Analysis↗

The evolution of the complete denture base. Theories of complete denture retention--a review. Part 4.

The history of denture base materials and the accompanying development of impression techniques are traced from the earliest times to the present day (Part 1) as a prelude to a study (Part 2-4) of the various theories that have been advanced to explain retention of the base without mechanical support. These theories are critically reviewed and tabulated in chronological order. Some areas for further investigation are identified.

Denture Bases↗

The evolution of the complete denture base. Theories of complete denture retention--a review. Part 2.

The history of denture base materials and the accompanying development of impression techniques are traced from the earliest times to the present day (Part 1) as a prelude to a study (Part 2-4) of the various theories that have been advanced to explain retention of the base without mechanical support. These theories are critically reviewed and tabulated in chronological order. Some areas for further investigation are identified.

Adhesiveness↗

The evolution of the complete denture base. Theories of complete denture retention--a review. Part 3.

The history of denture base materials and the accompanying development of impression techniques are traced from the earliest times to the present day (Part 1) as a prelude to a study (Part 2-4) of the various theories that have been advanced to explain retention of the base without mechanical support. These theories are critically reviewed and tabulated in chronological order. Some areas for further investigation are identified.

Adhesiveness↗

Application of carbon fiber (CF)-cloth reinforcement to upper complete denture base.

The acrylic resin denture base is used more than the usual metal denture base because of the low cost, simple process to make and easy rebasing. But, as the strength of the resin is weaker, the upper resin denture base is three to four times as thick as the metal denture base. So, a study was made to make the upper complete resin denture base thinner while maintaining the strength of the resin denture bases currently in use now. To make the palatal area of the denture base thinner was made possible by the application of carbon fiber (CF)-cloth reinforcement. The resin denture base reinforced by the CF-cloth was of a thickness of 0.7 mm and was evaluated for the mechanical properties of bending. As a result, it was found that both the stiffness and strength were improved by 10% or more as compared with those of the ordinary resin denture bases.

Carbon↗

Custom-made denture teeth and denture base material for removable partial dentures.

A method that uses Isosit material to fabricate custom-made denture teeth and denture base has been described. The advantages of this technique are the denture teeth can be made to function in harmony with dynamics of the stomatognathic system; any type of occlusal scheme can be used; the material is esthetically pleasing; it can be characterized; it can be used as a denture base material, which can also be characterized; it can be repaired, relined, or rebased with little difficulty; and laboratory procedures can be accomplished in the dental office or laboratory.

Acrylic Resins↗

Influence of thermal and mechanical stresses on the strength of intact and relined denture bases.

STATEMENT OF PROBLEM: Denture bases may become increasingly weaker as a result of thermal stress and flexural cyclic loading. Information regarding this potential problem and its relationship to the denture base reline is limited. PURPOSE: This study evaluated the influence of thermal and mechanical stresses on the strength of intact and relined denture bases. MATERIAL AND METHODS: Twenty-eight microwave-polymerized (Acron MC) intact denture bases were prepared in the shape of a 3-mm-thick maxillary denture. Additionally, fifty-six 2-mm-thick denture bases were relined with 1 mm of autopolymerizing resin (Tokuyama Rebase Fast II or New Truliner) (n=28). Intact and relined specimens were divided into 4 groups (n=7) as follows: without stress (control); a mechanical stress at 0.8 Hz for 10,000 cycles; 5000 thermal cycles between 5 degrees C and 55 degrees C; or a combination thermo-mechanical stress. The specimens were vertically loaded in compression with a rounded rod at 5 mm/min until failure, using a universal testing machine. Data on maximum fracture load (N), deflection at fracture (%), and fracture energy (N.mm) were analyzed by 2-way analysis of variance and Student-Newman-Keuls tests (alpha=.05). RESULTS: The strength of the denture bases relined with New Truliner was not significantly affected by any of the experimental conditions, but comparing the control groups, New Truliner exhibited the lowest maximum fracture load values. The maximum fracture load of intact denture bases (P=.002) and those relined with Tokuyama Rebase Fast II (P=.01) showed a significant decrease after thermal stress. Additionally, cyclic loading significantly decreased the maximum fracture load (P<.001), deflection at fracture (P=.025), and fracture energy (P<.001) of intact denture bases and those relined with Tokuyama Rebase (P values of .002, .039, and .001, respectively). CONCLUSION: Thermal and mechanical stresses exert deleterious effects on the strength of intact and/or relined denture bases, which vary according to the relining material used.

Acrylic Resins↗

The evolution of the complete denture base. Theories of complete denture retention--a review. Part 1.

The history of denture base materials and the accompanying development of impression techniques are traced from the earliest times to the present day (Part 1) as a prelude to a study (Part 2-4) of the various theories that have been advanced to explain retention of the base without mechanical support. These theories are critically reviewed and tabulated in chronological order. Some areas for further investigation are identified.

Aluminum↗

Some flexural properties of a nylon denture base polymer.

Nylon denture base material could be a useful alternative to poly (methyl methacrylate) (PMMA) in special circumstances such as patient allergy to the monomer. The aim of this study was to evaluate the flexural properties of a nylon denture base material (Lucitone FRS), a conventional compression-moulded heat-polymerized (Meliodent), a compression-moulded microwave-polymerized (Acron MC) and an injection-moulded microwave-polymerized (Lucitone 199) PMMA polymers. The effect of aldehyde-free, oxygen releasing disinfectant solution (Perform) on these properties was also investigated. The flexural modulus and the flexural strength were assessed with a three-point bending test. Specimens were stored in water at a temperature of 37 degrees C for 30 days. For each material, half of the prepared specimens were randomly selected and immersed in the disinfectant 24 h prior to testing. Results were compared statistically at a confidence level of 95%. The result showed that in both the control and disinfected groups, the flexural modulus of nylon was significantly lower than the three PMMA polymers. The flexural strength of nylon was significantly lower than those of Meliodent and Acron MC but was comparable with Lucitone 199. A 24-h immersion in the disinfecting solution increased the rigidity of nylon denture base material.

Acrylic Resins↗

Effect of water sorption on the resistance to plastic deformation of a denture base material relined with four different denture reline materials.

PURPOSE: The effect of water sorption on the flexural strength at the proportional limit (FSp) of a denture base material relined with four different denture reline materials was studied. MATERIALS AND METHODS: Denture base specimens were relined either after 24 hours or 30 days of water immersion. The relined specimens were tested after another period of 24 hours or 30 days of water immersion. RESULTS: Relined denture specimens generally exhibited lower FSp with an increase in water immersion time and an increase in the thickness of the reline material. CONCLUSIONS: The plasticizing effect of absorbed water molecules explains the general decrease in FSp of immersed relined specimens. The absence of a significant effect that water immersion had on some relined specimens under certain immersion conditions was explained by water sorption into the denture base achieving an equilibrium after a period of water immersion, and the resistance of some reline materials to the effect of water immersion.

Analysis of Variance↗