Effect of filler type and polishing on the discoloration of composite resin artificial teeth.

In this study, the effects of filler type and polishing on the discoloration of composite resin artificial teeth were examined. Four types of experimental resins were prepared: one was a matrix resin, while the others were composite resins containing three different types of fillers (nano-sized silica filler with or without silanization, and prepolymerized filler). Specimens were immersed in distilled water, coffee, red wine, or curry.

Development of soft denture lining materials containing fluorinated monomers.

Purpose: To develop a new fluorine-containing soft denture lining material, the influences of fluorinated monomers on physical properties and contamination resistance were examined.

Methods: Five experimental materials of different chemical compositions in fluorinated monomer and two plasticized acrylics (Supersoft, VertexSoft) were used to evaluate water sorption, solubility, staining resistance, Shore A hardness, and contact angle. Five specimens for each test were fabricated.

Evaluation of denture retention and ease of removal from oral mucosa on a new gel-type denture adhesive.

Purpose: The purpose of this study was to evaluate the effect of a new gel-type denture adhesive on denture retention and ease of removal from the oral mucosa after use.

Methods: Eleven complete denture wearing patients (3 males and 8 females; age range, 58-84 years; mean age, 73.7 years) with compromised maxillary denture-bearing tissues were included in the study.

Reinforcement of denture base resin with short-rod glass fiber.

The present study investigated the feasibility of a high short-rod fiber content in denture base resins using polymethylmethacrylate (PMMA) powder with a small particle diameter. The effects of fiber contents on mechanical properties of composite resins were studied. A commercial denture base PMMA powder (AC; average particle size, 150 microm) and an industrial PMMA powder (MB; average particle size, 4 microm) were selected.

Compositional characteristics and hardness of acrylic and composite resin artificial teeth.

Statement Of Problem: New types of artificial teeth are commercially available; however, evidence-based information regarding composition and properties is lacking.

Purpose: The purpose of this study was to qualify the compositional characteristics and hardness of new commercially available types of acrylic resin and composite resin artificial teeth.

Material And Methods: Twelve brands of 3 types (2 conventional acrylic resins, 3 cross-linked acrylic resins, and 7 composite resins) of artificial teeth were examined.

Finite element analysis of stress-breaking attachments on maxillary implant-retained overdentures.

Purpose: The purpose of this study was to examine the effect of stress-breaking attachments at the connections between maxillary palateless overdentures and implants.

Materials And Methods: Three-dimensional finite element models were used to reproduce an edentulous human maxilla with an implant-retained overdenture. Two-implant models (in the canine tooth positions on both sides) and four-implant models (in the canine and second premolar tooth positions on both sides) were examined.

Effect of degradation of denture base resin on bond strength to relining resins.

The purpose of this study was to evaluate the effect of degradation of a denture base resin on bond strength to relining resins. Denture base resin specimens were immersed under various conditions to simulate degradation. Tensile bond strength of denture base resin after immersion to relining resins was measured with or without surface grinding.

Evaluations of masticatory performance of complete denture wearers using color-changeable chewing gum and other evaluating methods.

We have been investigating and developing a color-changeable chewing gum, that tends not to adhere to dentures. The aim of this study was to investigate the color change of the chewing gum comparing to other methods while evaluating post-insertion changes of masticatory performance of complete denture wearers. Color-changeable chewing gum, the peanuts sieve test, a patient satisfaction questionnaire and a food questionnaire were applied to 26 edentulous subjects.

In vitro study of reduction of stress transferred onto tissues around implants using a resilient material in maxillary implant overdentures.

The purpose of this in vitro study was to investigate the effect of hardness on the reduction of stress transferred to tissues around implants using a resilient material applied to the female parts of the ball attachment in maxillary implant overdentures. A cast chrome-cobalt framework was mounted onto a maxillary acrylic edentulous model, which contained two implants and four strain gauges attached to the implant. Ball abutments were screwed into the implant.

Physical properties of a new denture lining material containing a fluoroalkyl methacrylate polymer.

Statement Of Problem: A new fluoride-containing, methacrylate-based denture lining material has been introduced. Because of the fluoride content, this material is expected to demonstrate low water sorption and solubility and high stain resistance, but these attributes remain untested.

Purpose: This study investigated a wide range of clinically relevant properties for a new fluoroalkyl methacrylate denture base liner product (Maxfit) and compared these properties with those of 3 other commercial products.

Palatal coverage disturbance in masticatory function.

Oral sensorimotor function is essential for mastication. We hypothesized that palatal coverage would disturb mastication and sensorimotor function. Masticatory efficiency, which was expressed by the declination rate of particle size, and oral stereognosis ability (OSA) were measured for 20 dentate subjects.

Antifungal effects of a tissue conditioner coating agent with TiO2 photocatalyst.

Tissue conditioners are susceptible to colonization by microorganisms. Therefore, the prevention of biofilm formation are important for oral hygiene. However, mechanical and chemical cleaning methods may cause clinical problems such as deformation or surface degradation of tissue conditioners.

Occlusal pressure pattern analysis of complete dentures for evaluation of occlusal adjustment.

The purpose of this study was to investigate occlusal pressure patterns of complete denture wearers to evaluate progress of occlusal adjustment of dentures. Thirty three edentulous subjects volunteered to participate in this study. A computer-based device was used to measure occlusal pressure sequence while tapping with their new dentures.

Effect of denture adhesive on stability of complete dentures and the masticatory function.

This study examines the effects of denture adhesive on the retention and stability of complete dentures and the masticatory function. The authors estimated the stability of complete dentures from 3-dimensional (3-D) denture movement and rotational denture movement and additionally the masticatory function from cycle time and chewing time. Six edentulous subjects who participated in this study had old and newly fabricated complete dentures.

Effects of cyclic loading on viscoelastic properties of soft lining materials.

The cyclic loadings during mastication supposedly accelerate degradation of soft lining materials. The purpose of this study was to investigate the effects of cyclic loading on viscoelastic properties of soft lining materials. Two plasticized acrylics, two silicones and one isoprene-based monomer contained elastomer were selected.

A new polyisoprene-based light-curing denture soft lining material.

Objectives: The purpose of this study was to investigate some clinically relevant properties of Clearfit LC, a newly developed polyisoprene-based light-curing lining material. Its properties were compared with those of other four commercial products.

Materials And Methods: Five soft lining materials, Clearfit LC, two plasticised acrylics (Super-soft, Soften) and two silicones (Molloplast B, Sofreliner) were used to determine water sorption, solubility, staining resistance, Shore A hardness and shear bond strength to denture base.

Impressions for complete dentures using new silicone impression materials.

This article describes a convenient technique for making impressions of complete dentures using two newly developed silicone materials. One of these materials, a heavy-bodied silicone material, is used for simultaneous molding of all borders. The material is available in automatic mixing systems, so it can be easily and evenly applied on the tray borders.

Effects of a denture adhesive on masticatory functions for complete denture wearers--consideration for the condition of denture-bearing tissues--.

The purpose of this study was to examine effects of a denture adhesive on masticatory functions for complete denture wearers considering the condition of denture-bearing tissues. Sixteen edentulous subjects wearing well-fitting complete dentures volunteered to participate in this study. According to the condition of denture-bearing tissues, subjects were divided into two groups; "good group" and "poor group".

Improving a self-curing dental resin by eliminating oxygen, hydroquinone and water from its curing process.

Self-curing dental resins are always manipulated in the presence of curing inhibitory factors such as oxygen, hydroquinone, water and another contaminants such as saliva and blood. The purpose of this study was to elucidate the effects of eliminating these curing inhibitory factors on resin properties. Several clinically relevant characteristics of an experimental resin cured in the absence of inhibitory factors (purified group) were determined and compared with the resin cured conventionally (control group).

[A clinical application of the T-Scan II system--usefulness for evaluating occlusal contacts of complete denture wearers].

The purpose of this study was to assess the reproducibility of the T-Scan II system and its clinical usefulness for evaluating occlusal contacts of complete denture wearers. The occlusal contacts of 13 dentate subjects, and 14 complete denture wearers, were recorded using a T-Scan II system during maximum voluntary clenching. The recordings for complete denture wearers were taken after each treatment for the new denture, and continued until the completion of all corrections.

[Fundamental study on the development of a measuring device using an accelerometer].

It is important to clarify stomatognathic functions. To diagnose them, some measuring devices, such as MKG and the Gnatho-hexagraph, were developed. Such equipment, however, is not widely diffused, due to cost.

A new approach to evaluating occlusal support by analyzing the center of the bite force.

The aim of this study was to create a standard for occlusal support in the diagnosis and evaluation of prosthetic treatment. In experimental occlusion, the maximal bite force of eight normal dentates was measured by pressure-sensitive film over the whole dentition using splints divided into nine pieces. The occlusal contact was altered by exchanging splint pieces according to the shortened dental arch concept.

[In vitro study on accuracy and repeatability of the T-Scan II system].

The T-Scan system has been used to analyze the distribution of occlusal loading forces, and occlusal contact variability. An enhanced version, the T-Scan II system, has been developed with clinical significance of its center of force. The T-Scan II system was also found to be clinically useful for measuring simultaneous occlusal contacts bilaterally.

[A study on evaluation methods of masticatory ability for complete denture wearers--correlation between evaluation using a questionnaire and masticatory performance].

The purpose of this study was to investigate the relation between evaluation by a questionnaire on masticatory aspects of 20 foods, and masticatory performance obtained using the sieving method, previously used in many studies. After replacement of upper and lower complete dentures made newly, 28 edentulous patients voluntarily participated in this study. The basal seat area of each patient was scored and divided into two groups, and masticatory ability was evaluated by two methods: using a questionnaire and the sieving method.