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Results for “TOOTH, ARTIFICIAL”

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At least 397 records · Page 22Linked to original sources

PubMedDate not supplied

Effects of denture teeth on the dimensional accuracy of acrylic resin denture bases.

The Michigan Computer-Graphics Coordinate Measurement System was used to determine the effects of artificial denture teeth on the accuracy of acrylic resin denture bases. Two poly(methyl methacrylate) acrylic resins and two processing techniques were tested. Groups processed with denture teeth reproduced more accurate points than groups processed without denture teeth. Groups processed with a conventional heat-polymerized acrylic resin reproduced more accurate points than groups polymerized with an injection pressing type of acrylic resin.

Acrylic Resins↗

PubMed2002

Complications and failures in removable partial dentures: a clinical evaluation.

The design of removable partial dentures (RPDs) is an important factor for good prognostication. The purpose of this study was to clarify the effectiveness of denture designs and to clarify the component that had high rates of failure and complications. A total of 91 RPDs, worn by 65 patients for 2-10 years, were assessed. Removable partial dentures were classified into four groups: telescopic dentures (TDs), ordinary clasp dentures (ODs), modified clasp dentures (MDs) and combination dentures (CDs). The failure rates of abutment teeth were the highest and those of retainers were the second highest. The failure rates of connectors were generally low, but they increased suddenly after 6 years. Complication and failure rates of denture bases and artificial teeth were generally low. Complication and failure rates of TDs were high at abutment teeth and low level at retainers. Complication and failure rates of ODs were high at retainers.

Adult↗

PubMed1991

Denture materials and acrylic base materials.

Modifications in denture plastics, including acrylics containing butadiene-styrenes, block copolymers to increase toughness, and those with added soluble heavy-element salts to increase radiopacity are described. Developments in processing of denture bases by microwave, laser, and injection methods are described. Also reviewed are acrylics and their dimensional stability, including the effect of artificial salivas on properties. In addition, the rheological, glass transition, dynamic, impact, and fatigue properties of denture acrylics are presented. Adhesion of polymers to plastics and metals is reviewed, as well as the biocompatibility and adhesion of organisms to denture plastics. Soft denture materials are reviewed with respect to research on new materials and to clinical evaluations of existing products. Finally, studies on the wear of denture teeth are summarized.

Acrylic Resins↗

PubMed2002

The selection of anterior teeth appropriate for the age and sex of the individual. How variable are dental staff in their choice?

As part of the development of a guide to aid the undergraduate in the selection of artificial teeth, the aim of this study was to investigate the variability in choice of dental staff to select teeth appropriate to the age and sex of the individual with the aid of a series of three-dimensional guides. Four three-dimensional guides were produced for use in the study. Fifty dentists were asked to complete a questionnaire designed to assess the variability in selection of anterior teeth appropriate for the age and sex of an individual. From this study it can be concluded that there was little consistency in the selection of the shade, mould and arrangement of anterior teeth appropriate for the age and sex of the individual by qualified dental staff. The development and implementation of an aesthetic proforma to guide dental staff, dental undergraduates and patients through the process of choosing tooth mould, shade and arrangement based on age and sex may be helpful.

Adult↗

PubMedDate not supplied

[Adhesion of artificial teeth to polymethacrylate resins].

UNLABELLED: In this study the microleakage is first tested between the poly-methylméthacrylate resins used in removable partial denture and the artificial teeth after storage in 100% humidity at 37 degrees C or after aging by an hydrothermal fatigue stress. Then the porcelain butt joint was improved by pyrolytic silanization. MATERIALS: A metallic flask was realized, in this study, to polymerize strictly identical samples. RESULTS: Due to polymerization in 100% humidity, the silane bond will be destroyed. Thermo-or chemopolymerizing resins are the only resins to allow the bonding with porcelain teeth by means of the sandwich technic.

Adhesiveness↗

PubMed1989

[Number and frequency of upper anterior artificial teeth].

By this study, a survey has been made of the number and frequency (percentage) of the selections made by form of Trubyte Bioblend artificial teeth applied to 1,507 cases of removable denture fitted for 17 years from Number, 1971, to November, 1988, at Department of Prosthodontics, Dental hospital in Nihon Univ. School of Dentistry at Matsudo. As a result, significantly high selecting frequency was observed of all forms as: 2 forms of Square Tapering in 548 cases (36.4%) and Tapering Ovoid in 270 cases (17.9%); and by sex, single form of Square Tapering in 253 male cases (48.8%) and 2 forms of Square Tapering in 295 cases (29.9%) and Tapering Ovoid in 234 cases (23.7%).

Denture Design↗

PubMed2006

Concept and development of a computerized positioning of prosthetic teeth for complete dentures.

To date, CAD/CAM technology has made no noteworthy inroads into removable dentures. We want to present a new area of application for this in our study. Models of the maxilla and edentulous mandible were 3D scanned. The software detects and automatically reconstructs the reference structures that are anatomically important for the set-up of artificial teeth, such as the alveolar ridge centerlines and the interalveolar relations between the alveolar ridges. In a further step, the occlusal plane is semiautomatically defined and the front dental arch is designed. After these design features have been determined, artificial teeth are selected from a database and set up automatically. The dental technician can assess the esthetics and function of the suggested dental set-up on the computer screen and make slight corrections if necessary. Summarizing: The interplay of hardware and software components within on integrated solution including conversion of the "virtual" into a real positioning of prosthetic teeth is presented.

Alveolar Process↗

PubMed1990

[Teeth arrangement of anterior artificial teeth. 1. Age and teeth exposure].

In selecting and arranging anterior artificial teeth for edentulous patients, it is necessary to consider their sex, personality, age and other factors. The relation of upper and lower lip lines to incisal edge has been one of the standards for the selection and the arrangement of anterior artificial teeth. The purpose of this report was to establish and to evaluate decision bases for the selection and arrangement. We recorded and measured the exposure rate of anterior natural teeth (48 men, 46 women) during function, such as smile, pronunciation, by means of the image analysis. Following results were obtained. 1. As the age of patients increased, upper anterior teeth appeared less than lower's. 2. Differences in exposure ratio between upper and lower teeth were found more remarkable in smiling rather than in pronunciation.

Adult↗

PubMedDate not supplied

Complications after treatment with implant-supported fixed prostheses: a retrospective study.

PURPOSE: The aim was to retrospectively evaluate the frequencies of different complications, as well as the number of visits to dentists because of such complications, after treatment with implant-supported fixed prostheses. MATERIALS AND METHODS: The study group comprised 75 patients who had been treated with implant-supported fixed prostheses 3 years earlier. All case records were scrutinized, and notes of complications in association with implants and superstructures were registered. RESULTS: The most common intervention made was occlusal adjustment/selective grinding of the prostheses. Complications in association with both implants and superstructures were fairly common. The most frequent complication was fractures of the acrylic resin matrix, including artificial acrylic resin teeth. Consultations because of periimplant mucosal inflammation were much more common among women compared to men, while complications that could be attributed to heavy loading tended to be more common in men. CONCLUSION: Complications with both implants and superstructures are fairly common after treatment with implant-supported fixed prostheses. Regular follow-ups to maintain optimal function in these patients are thus mandatory.

Acrylic Resins↗

PubMed1997

Debridement by operators with varying degrees of experience: a comparative study on manikins.

The treatment of periodontally diseased root surfaces with power-driven instruments is becoming increasingly important as an alternative to the use of hand instruments. Root surfaces of artificial teeth on a manikin were debrided under simulated flap operation conditions to determine if effectiveness was dependent on the instrument used (curettes or a modified sonic scaler tip) and/or the operator's degree of experience. Two quadrants were treated with each instrument. A morphometric evaluation followed. Debridement was faster with the diamond-coated sonic scaler tip than with hand instruments. With the sonic scaler, the time necessary for treatment was reduced by 30%. The experienced operators treated about 80% of the root surface, while the inexperienced operators treated only about 65%. Treatment quality depended on the operator and not on the instrument used.

Clinical Competence↗

PubMed1993

[Identification of artificial teeth by fluorescent examination with an emphasis on metal bond porcelains].

Artificial teeth look similar to natural teeth under natural light, but under the black light blue or fluorescent light (365 nm, 254 nm), they showed different features from those of natural teeth. These characteristic are available to identify various dental porcelain products. Using the metal bond porcelains produced by different manufacturers, we prepared samples showing the same color tone as that of the VITASHADE A3, and examined then with the black light blue or fluorescent examination lamp (365 nm, 254 nm). The results suggest possibility of discrimination of several porcelain products; Ceramco II, Vintage, Vita VMK68, Duceram, Noritake and Biodent. We applied this method to identify porcelain products of coronae on the anterior teeth of unknown bodies in four actual cases.

Dental Porcelain↗

PubMed1993

Mechanical properties of artificial teeth.

In selecting the teeth for fabrication of complete or partial dentures, each patient's anatomic and physiologic requirements and the properties of the artificial teeth themselves should be taken into consideration. The purpose of this study was to evaluate the mechanical properties of the artificial teeth by the static compression test and the impact test. Specimens were the lower first molar porcelain and resin teeth (Livdent FB-20 teeth by G. C. Co., Tokyo, Japan). All were of the same shape. In the static compression test, the fracture load and deformation of the artificial teeth were measured with an Instron-type universal testing machine at a cross-head speed of 1.0 mm/min. Elastic modulus, ultimate strength and absorbed energy were calculated. In the impact test, the acceleration of a falling impactor was measured with a drop impact apparatus. The load applied to the specimen was equivalent to 300N. Absorbed energy and deformation were calculated. The resin teeth showed a lower elastic modulus, higher fracture toughness and shock-absorbing ability than the porcelain teeth. Resin teeth should be selected when the first requisite is high shock-absorbing ability, and porcelain teeth should be selected when the first requisite is high masticating efficiency.

Dental Porcelain↗

PubMed1999

[Functional mobility measurement of removable partial dentures using newly-developed analyzing system in six degrees of freedom--effect of cusp inclination of molar artificial teeth on denture displacement in function].

A measuring system to record three-dimensional displacement of removable partial dentures (RPDs) in six degrees of freedom has been developed. The system employed three pairs of photodiode and LED that were set up in a triangle. This system was capable of recording the in vivo RPD displacement with a recording sensitivity of 0.1 mm. In vivo displacement of upper RPDs with unilateral distal extension saddle was investigated using this measuring system to determine the effect of artificial cusp inclination of molar teeth on denture mobility. Two groups of different artificial dentition were switched to be attached to each of three experimental RPDs. The artificial teeth with cusp inclinations were calibrated to contact with opposing natural dentition during lateral grinding of the mandible, while the other artificial teeth were prepared to disclude with the mandibular teeth (flat-cusp group). Displacement range and average position of a reference point at the first molar of the RPDs during mastication were measured and analyzed as a function of the cusp inclination and the test food. As a result, the average displacement of the RPDs toward the edentulous ridge was smaller in the cusp group than that in the flat-cusp group, while the range of horizontal displacement in the buccal-palatal direction was greater in the former group than the latter. The denture wearers demonstrated typical grinding strokes at the end of the closing phase of the mandiblar movements when they chewed a peanut, which was attributed to a wide range of horizontal displacement of the dentures.

Denture, Partial, Removable↗

PubMed1989

[Selection error of upper anterior artificial teeth].

Seventy two cases of selection error of upper anterior artificial teeth due to the esthetic factors were investigated out of the 1,507 cases of removable dentures, which were made at the Prosthodontics department of Nihon University school of dentistry at Matsudo for 17 years from November, 1971 to November, 1988. The following were the results of the investigation. 1. Frequency of the selection errors amounted to 4.8% of the total selected cases as broken down in 1.6% by Shade and 4.0% by Mould, the rate of selection errors of the Mould being significantly high. 2. By Mould, selection errors in Ovoid type occupied a significantly high rate. 3. Regarding frequency of Mould after re-selection ST and TO occupied a high rate of 45.9%. 4. Mould of re-selection were almost uniformly small, showing a trend of intumescence becoming emphatically.

Denture, Partial, Removable↗

PubMed2001

The influence of surface configuration on the retention of posts designed for use with a cast-on technique.

OBJECTIVES: The combination of an individually cast core and a prefabricated metal post is one of the many techniques to restore endodontically treated teeth. The surface characteristics of commercially available posts vary considerably and likely influence retention. In this study, the surface configuration of 11 castable prefabricated post systems and their retention at the post-cement interface were investigated. METHOD AND MATERIALS: Scanning electron microscopic photos were made to assess surfaces of the posts. Etchant residues or applied surface layers were also analyzed with an electron beam microprobe. For the retention measurements, 6 posts from each system were cemented in artificial root canals with a zinc phosphate cement. Retention was measured on a universal testing machine. RESULTS: Analysis of variance and the Ryan-Einot-Gabriel-Welsch F test revealed significant differences in retention between posts; these differences were related to the microstructure of the surfaces of the posts. In general, the coarser the surfaces, the better the retention. Gold plating of the etched surface for one manufacturer resulted in less retention compared to posts of the same type and size that were not plated. CONCLUSION: The surface configuration of a post could be an important factor when selecting a prefabricated post system.

Acid Etching, Dental↗

PubMed2000

Adding silanes to MMA: the effects on the water absorption, adhesive strength and mechanical properties of acrylic denture base resins.

The adhesive strength of porcelain artificial teeth and polymethylmethacrylates (PMMAs), which contained silanes with various number of vinyl or ethoxy groups, and the mechanical and physical properties of the PMMAs were measured. Four types of PMMAs with silanes showed high adhesive shear strength and caused fractures in the porcelain. Water absorption of the PMMAs increased with the addition of silane, but that of one type with silane was almost the same as the PMMA only type. The flexural strengths of the PMMAs with silane, except for one type, showed no significant differences compared with that of PMMA (p < 0.05). The Tg levels of all PMMAs with silane fell less than that of PMMA. From these results, it was found that PMMA with silane from three vinyl groups and one ethoxy group showed excellent chemical bonding to porcelain and low water absorption.

Absorption↗

PubMed1997

Adhesive composite resins for artificial teeth: a laboratory investigation of bond strength to a cobalt-chromium alloy.

Adhesive resin systems are reported to improve the bond strength between resins and cast cobalt-chromium alloy. This investigation compares the behaviour of three resin systems. Cylinders and beams of cobalt-chromium, with 0.6-mm-diameter retention beads regularly cast onto the bonding surfaces, were air-abraded and ultrasonically cleaned. Resin veneers 4 mm deep on the cylinders and 2 mm on the bars were polymerized by heat and pressure or by light. Specimens were water-stored for 7 or 90 days, including thermocycling between 4, 37 and 60 degrees C, before testing in a Universal Testing Machine to examine the shear bond strength or the effect of the bonded resin spine on the flexural strength of the beams using a three-point bend test. Specimens were examined with an optical microscope to attempt to determine the nature of the failures that occurred. The investigation showed that, overall, the heat- and pressure-cured urethane dimethacrylate resin with and adhesive based upon methacrylic acid performed significantly less well than a conventional acrylic resin, or a hybrid composite resin with and adhesive monomer.

Chromium↗

PubMed2001

A laboratory comparison of the efficacy of battery-operated, non-rechargeable power toothbrushes.

PURPOSE: To evaluate the cleaning efficacy of three battery-operated, non-rechargeable, oscillating/rotating power toothbrushes, using a robot system to simulate normal clinical toothbrush use. MATERIALS AND METHODS: The study compared the cleaning efficacy of the new Braun Oral-B D4/EB4 with the Actibrush and the Dr. Best Powerclean in two independent experiments. Plaque substitute was applied to the artificial teeth of typodonts, which were cleaned by the robot system for a total of 2 minutes at a brushing force of 1.95 N. The remaining plaque substitute on buccal + lingual/palatal and occlusal surfaces, as well as gingival margin and interproximal sites, was measured using a computerized vision system. RESULTS: The new D4/EB4 was found to remove more plaque substitute than the Actibrush at all sites, and for all surfaces, lingual surfaces and occlusal surfaces the difference in favor of the D4/EB4 was statistically significant (P < 0.05). In comparison with the Powerclean toothbrush, the D4/EB4 was significantly more effective at all sites (P < 0.001). These results indicate that not all battery-operated oscillating/rotating power toothbrushes have equal efficacy with respect to plaque removal and that, in this series of laboratory experiments, the Braun Oral-B D4/EB4 was more effective than the Actibrush and the Dr. Best Powerclean.

Dental Plaque↗