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At least 1,405 records · Page 78Linked to original sources
PubMed1986

Improved accuracy by reheating addition-reaction silicone impressions.

Addition-reaction silicone impressions were made at 37 degrees C in two cylindrical trays of a truncated-cone-shaped chromium-steel die. One tray size was used to obtain impressions with 1 mm thickness from tray to the buccal and lingual surface of the steel die while the second tray permitted a thickness of 4 mm. Stone dies were made from impressions after (1) cooling to 22 degrees C for 10 minutes or (2) cooling to 22 degrees C for 10 minutes and reheating to 37 degrees C for 30 minutes. Results revealed that reheating the impressions to mouth temperature before pouring the dies improved their accuracy.

Dental Impression Technique↗
PubMed1986

Movement of artificial teeth in waxed trial dentures.

Movements of artificial teeth during the wax trial denture stage was investigated in three dimensions by means of a traveling microscope. Fixed points of reference were devised for accurate measurements of teeth movements. Porcelain and plastic anterior and posterior teeth set in five wax trial dentures were tested at 2, 4, 7, and 24 hours. Tooth movements in wax trial dentures invariably occurred and lacked correlation in direction and time.

Dental Occlusion↗
PubMed1989

The effect of clinical experience on dental students' ability to design removable partial denture frameworks.

To determine whether clinical experience influenced dental students' ability to correctly design removable partial denture frameworks, four combinations of six casts depicting various partially edentulous situations were used in the study. The authors independently rated the casts as to the degree of difficulty on a three-point scale. Only those casts for which there were 100% agreement were used. All of the casts that were used had a moderate degree of difficulty rating (level 2). The dental student sample consisted of 34 second-year students who had just completed 98 hours of instruction in removable partial dentures. Each student was given six casts on which to design removable partial denture frameworks. The students were evaluated before clinical experience in removable prosthodontics and after 1 year of removable prosthodontic experience. The results indicated that the dental students made significantly fewer errors in framework design after clinical experience. Errors on two of 13 framework design items were increased postclinically. The increase in errors on these two items may have been the result of a lack of attention to detail or a lack of reinforcement in learning certain basic concepts.

Clinical Clerkship↗
PubMed1991

Dimensional stability of a polyvinylsiloxane impression material following ethylene oxide and steam autoclave sterilization.

Polyvinlsiloxane impressions were made from a stainless steel master die machined to stimulate five full veneer crown preparations symmetrically placed in an arch form. Three groups of 10 impressions each were made. Treatment groups were sterilized using an ethylene oxide gas and a conventional steam autoclave. Casts were poured and intrapreparation, height, and diameter measurements were made using a stereomicroscope, a digital electronic caliper, and a 1-inch travel dial indicator. Analysis of dimensional changes for the two groups showed that casts made from impressions sterilized by ethylene oxide are acceptable for use in the construction of fixed or removable prostheses. Casts made from impressions sterilized in a steam autoclave can be used for the fabrication of diagnostic casts and some transitional prostheses, but not for routine construction of crowns or fixed partial dentures.

Analysis of Variance↗
PubMed1992

A soft tissue simulated cast for implant prosthesis.

A master cast that simulates the mucosa around implant fixtures and abutments facilitates implant prosthesis fabrication. It is helpful if this simulation is not altered during laboratory procedures. A technique is described for a master cast that includes a removable mucosal component. This technique can be applied when either implant or abutment analogs are positioned in the cast.

Dental Implants↗
PubMed1993

Evaluation of three impression techniques for osseointegrated oral implants.

The purpose of this in vitro investigation was to determine the accuracy of gypsum casts produced from impressions made with polyether, polyether and impression plaster, or polyether and acrylic resin for the fabrication of osseointegrated implant prostheses. Strain gauges were attached to a master framework to determine the passivity of fit of the framework to sample casts made by the three impression techniques. Strain values were statistically compared by one way analysis of variance and Duncan's multiple range test. A statistically significant difference was found between the three impression techniques tested (p < 0.05). The results of this investigation revealed that none of the impression techniques resulted in an absolutely passive framework fit. However, of the techniques tested, the polyether alone resulted in the closest duplication of the master cast.

Acrylic Resins↗
PubMed1993

A multidie technique for the fabrication of porcelain laminate veneers.

Porcelain veneers are a challenge for the dentist and dental technician when they are an integral part of complex restorative treatment plans. A multidie technique is described that allows construction of laminate veneers on removable refractory dies in a stone master cast. This system provides flexibility and accuracy with less chair time when used in combination with epoxy resin dies. Multiple restorative techniques can be used simultaneously with one master cast, and emphasis is directed to harmonious working relationships between the dentist, dental technician, and patient.

Dental Casting Investment↗
PubMed1994

An in vitro study of a surface wetting agent for addition reaction silicone impressions.

The aims of this study were to determine whether the use of a topical surfactant (Hydrosystem) reduced the number of air bubbles visible on the surface of polyvinyl siloxane impressions and stone dies. The impressions exhibited a mean of 1.4 +/- 2.1 bubbles when Hydrosystem wetting agent was used, which was significantly less (p < 0.001) than when it was not used (mean 5.5 +/- 4.7 bubbles). Dies prepared with Hydrosystem surfactant contained a mean of 0.4 +/- 0.8 bubbles, which was significantly (p < 0.001) less than when Wax-Mate surface agent was used (mean 3.5 +/- 5.2 bubbles). In conclusion, in vitro use of Hydrosystem surfactant reduced the number of air bubbles on the surface of silicone impressions and stone dies.

Dental Impression Materials↗
PubMed1975

Relations between tooth positions and focal troughs of panoramic machines.

A comparison of the established focal troughs of three panoramic machines with positions of the teeth in the dental arches of 240 patients. The patients, divided into twelve cells, were selected on the basis of race, sex, age, number of teeth, and occlusion. Occlusal registrations were made in fast-set acrylic. Tooth centers were identified and, with the midline-incisal point as a reference point, various composite drawings of tooth positions of patients were made. The total composite of all teeth revealed the striking similarity of the arches. Superimposition on the focal troughs showed that the focal trough of the Panorex easily encompassed all tooth positions. The focal trough of the Orthopantomograph encompassed all tooth positions, although tooth centers lie on the edges of the trough. The focal trough of the GE-3000 with profile index 10 extended so far buccally that many teeth are positioned lingual to the trough. The focal trough of the GE-3000, when reduced uniformly to profile index 7.5, encompasses all tooth positions although some positions fall quite near the borders of the trough.

Adolescent↗