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At least 325 records · Page 18Linked to original sources
PubMed1989

[Clinical study on the prognosis of complete denture wearers covering 10 years. 3. Fitness test of the complete denture base].

The purpose of this study was to estimate the clinical condition of complete denture wearers. 72 patients came to our Dental Hospital according to our recall. The examination consisted of a questionnaire and clinical examinations. For objective evaluation, the fitness test of lower complete denture base was taken place and was classified into four groups by the thickness of the white-silicone film (A-zone 0-30 microns, B-zone 30-70 microns, C-zone 70-130 microns, D-zone 130 microns-). Results 1. The average ratio of four groups of the white-silicone film were A-zone 9.3%, B-zone 35.8%, C-zone 24.5% and D-zone 30.4%. 2. The fitness of anterior portion was ill fit in comparison with posterior portion. 3. There was statistically significant difference between the fitness of lower complete denture and dentist's judgment diagnosed as ill fit denture. 4. There was significant difference between the fitness test and the patients who complained about loose fit of the denture.

Denture Bases↗
PubMed1975

[Pathological and histological changes in the gingival mucosa under the action of denture bases with and without palatal scraping].

Histological examination showed that denture bases with palatal scraping ("Frankfurt Radierung") do not strain the palatal mucosa any more than is the case with any other palate-covering denture. If the irritation produced by the dental replacement is within the tolerance limits of the palatal mucosa, there will be no pathological changes in epithelium and submucosa in the area of the scraping borders. If the load put on the denture exceeds the tolerance level of the palatal mucosa, so that a denture stomatopathy is resulting, the changes observable in the entire palatal mucosa are also found in the areas where the scrapinb borders are located.

Denture Bases↗
PubMed1985

Cultivable microflora of plaque from full denture bases and adjacent palatal mucosa.

Anaerobic cultural techniques and rapid biochemical identification tests normally employed for periodontal plaque were utilized for the analysis of plaque samples taken from denture bases and corresponding adjacent mucosa. Results were compared with those or more comprehensive microbiological investigations. Forty four samples were obtained from the denture bases and adjacent palatal mucosa of 12 patients wearing full upper dentures. The specimens were then collected in Reduced Transport Fluid and processed in the anaerobic glove box. Samples were plated on Enriched Trypticase Soy Agar (ETSA) and cultured under both aerobic and anaerobic conditions. In addition plaque samples were plated on Sabouraud medium. Facultative bacteria predominated in both denture and palatal plaques. Significantly greater numbers of cocci were recovered in the samples from palatal mucosa. More rods were found in denture plaque. Anaerobes were present in both instances. Among the anaerobes, saccharolytic Bacteroides were identified with the highest frequency, while Veillonella species were present in the greatest quantity. Recovery of yeasts was similar for both ETSA and Sabouraud media incubated aerobically. As has been found in other microbiological studies Candida albicans represented only a minor part of the total cultivable flora.

Actinomyces↗
PubMed1991

Effect of the curing cycle on acrylic denture base glass transition temperatures.

Glass transition temperature of a polymer is an important physical property which may have a major effect on the dimensional stability of denture base materials. Thermomechanical analysis has been used to determine the glass transition temperature of specimens of denture base materials which had been produced by various selected curing cycles. It was found that different curing cycles produced variations in glass transition temperature of up to 20 degrees C.

Acrylic Resins↗
PubMed1983

Bending strength of intact and repaired denture base resins.

Results of bending strength and deflection at fracture of intact and repaired denture base resin specimens were obtained. Both heat-cured and cold-cured resins of two different products were used. After storage in distilled water at 37 degrees C for 1 month, some of the intact heat-cured specimens were dried in air at 21 +/- 1 degree C for 24 h before testing. This induced a lowering of the bending strength. There was no difference in strength between the two products. However, the intact heat-cured specimens of SR 3/60 showed higher results of deflection at fracture than Vertex. Repaired specimens had a bending strength between 42.9% and 61.2% compared with the intact heat-cured specimens tested immediately after storage in water. The repair performed with the low-viscosity self-cured resin resulted in higher bending strength values than when using repair material with the higher initial viscosity. Drying the broken heat-cured specimens for 24 h at 21 +/- 1 degree C before the repair and painting with monomer liquid on the fractured surfaces of the heat-cured resin was without effect on the bending strength of the repaired specimens.

Acrylic Resins↗
PubMed1997

The effect of untreated UHMWPE beads on some properties of acrylic resin denture base material.

OBJECTIVES: To evaluate the effect of surface untreated ultra high molecular weight polyethylene (UHMWPE) beads on a range of properties of the polymerised acrylic resin denture base material. METHODS: UHMWPE in the form of surface untreated beads was added to acrylic resin denture base material in various percentages (2.5%, 5%, 7.5% and 10%) to form a composite material. The influence on doughing and manipulation times, transverse and impact strength and hardness characteristics were examined. RESULTS: The results indicated that the manipulation and setting times gradually increased as the percentage of UHMWPE beads in the acrylic resin powder increased. By increasing the percentage of incorporated UHMWPE beads, there was a decrease in modulus of rupture and impact fracture resistance. There was also an effect on the hardness with an increasing percentage of beads lowering the hardness value, although this was not consistent. CONCLUSION: It was concluded that the use of untreated UHMWPE beads is of no significant benefit to the properties of acrylic resin.

Acrylic Resins↗
PubMed2001

A pilot clinical evaluation of a new injection denture base system.

The purpose of this pilot study was to determine if clinically acceptable complete denture prostheses can be consistently fabricated with a new injection system. In the first part of this investigation, 14 patients requiring complete denture fabrication had one prosthesis made with the new injection system and one made with the compression-pack technique. Polish, porosity, and esthetics were evaluated by one of three investigators at the placement visit. The percentage of the intaglio surface in contact with the mucosa before adjustment was also measured. One week after placement, the patients were questioned regarding the prostheses' stability, the presence of any undesirable taste, and overall satisfaction. The second portion of the study involved materials property testing of flexural strength and Izod toughness of conventionally packed and injection-packed specimens processed by the fast cycle or the long cycle. In every case, acceptable results were obtained for the resin's polishability, its lack of porosity, esthetics, stability, lack of unpleasant taste, and overall patient satisfaction with the prostheses. No difference in clinical adaptation was observed. These results indicated that no clinical difference was detectable between the conventionally packed and injection-packed denture bases by the investigators or patients in this study. Physical property testing indicates that the differences between groups may be more affected by the polymerization cycle used than the way that the resin was placed in the mold space.

Acrylic Resins↗
PubMed2000

The effect of continuous poly (methyl methacrylate) fibres on some properties of acrylic resin denture base material.

This study investigated the effect of continuous poly (methyl methacrylate) fibres on the transverse strength and impact strength of poly (methyl methacrylate) denture base resin. The fibres were added in three arrangements, a single unidirectional (longitudinal in the length of the specimen) layer, two longitudinal layers and in cross ply form (a combination of an inferior longitudinal layer and a superior transverse layer). The results indicated that the transverse bend and impact strengths of poly (methyl methacrylate) denture base resin, were not significantly improved by the addition of poly (methyl methacrylate) fibres.

Acrylic Resins↗
PubMed2004

Effect of metal strengthener length on stress distribution in acrylic denture bases: a finite element study.

This study investigated the influence of metal strengthener length on stress created in acrylic denture bases in relation to location of the vertical support to the dentures. Finite element analysis was conducted to calculate stress generated in the straps of 2 mm-thickness and 18 mm-width that were reinforced with metal strengtheners of five different lengths. A vertical biting force of 60 N was directed on one end of each strap, while the other end was fixed. Vertical movements were restricted at one of the three support locations between the centre of the strap and the loading site. When the straps were vertically supported near the loading site, greater maximum tensile stresses were seen in the straps with relatively short strengtheners than those shown in the straps with longer strengtheners. The metal strengtheners with sufficient length may provide a preventive denture design against the acrylic fractures.

Acrylic Resins↗
PubMed1989

Complete denture retention. Part II: Wettability studies on various acrylic resin denture base materials.

The objective of this study was to characterize in vitro selected acrylic resin denture base materials by water-contact angle measurements. The sessile drop method and the underwater-bubble method were used. The results obtained from these measurements are discussed in terms of contact angle and polymer-water work of adhesion hysteresis. On polished heat-polymerized samples this hysteresis results from the reorientation of superficial polymer chains. The combined effect of increased sample roughness and of the entrapment of water droplets in the pores of material gives rise to the highest contact-angle hysteresis observed on sand-abraded samples. On the basis of physical analysis of the mechanism involved in complete denture retention, developed in Part I of this work, it is believed that the sand-abraded material is the most convenient for the retention of the complete denture.

Acrylic Resins↗
PubMed1993

Longitudinal study on torque transmitted from denture base to an abutment tooth of lower distal-extension removable partial dentures with conus crown telescopic system.

The purpose of this study was to make a longitudinal analysis of torque transmitted to a direct abutment tooth of a lower distal-extension removable partial dentures constructed with the conus crown telescopic system. Torque around the vertical and lateral axes of the tooth were measured during chewing of food at the time of insertion of the new dentures to about three months after. The maximal mean value of torque (Max.MT) was calculated from the peak level of all chewing strokes at the minimum of the interocclusal distance. The integration values of torque (I) and time (T) from initiation of chewing to swallowing were obtained, then the average value of torque (Ave.T) was calculated (Ave.T = I/T). The results are summarized as follows: (a) There were no remarkable changes of Max.MT around the both axes; (b) Max.MT around the lateral axis was 7-47 x 10(-3) kgm (mean: 25 x 10(-3) kgm) (1 kgm = 9.8 Nm) in the downward direction and Ave.T around the lateral axis was 6-14 x 10(-3) kgm ss-1 (mean: 10 x 10(-3) kgm ss-1) in the downward direction; (c) There were marked differences of Max.MT and Ave.T around the vertical axis between subjects. Max.MT around the vertical axis was less than 24 x 10(-3) kgm and Ave.T around the vertical axis was less than 6 x 10(-3) kgm ss-1.

Aged↗