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PubMed1997

Dental impressions.

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Dental Impression Materials↗
PubMed1998

Soft tissue transfer models: the patient-dentist-laboratory connection.

The dental technician must have an accurate impression of gingival contour, in order to apply porcelain correctly to a metal-ceramic restoration. This article describes a technique for making an accurate model of the soft tissues around a restoration. The technique involves taking a transfer impression and making a soft tissue model.

Communication↗
PubMedDate not supplied

Unsuspected foreign body aspiration.

Aspiration of foreign bodies is a serious complication that may occur during the course of dental treatment. A case report of a 60-year-old man with recurrent pneumonia is presented. One year after the onset of his initial symptoms, a hard substance that made a complete mold of the bronchial tree at the inferior right lobe was extracted with a rigid bronchoscopy. This green material of elastic consistency was dental impression material (polyvinylsiloxane). On careful questioning, the patient indicated that he had dental impressions taken 2 months before the onset of the symptoms. Surgery was indicated and lobectomy of the inferior right lobe was performed without incident. To avoid this complication, some preventive precautions such as identifying high-risk patients; using rubber dam; tethering any small instrument with a ligature; placing a gauze screen to protect the oropharynx in sedated patients; and using custom impression trays to minimize the amount of impression material required have been suggested. In case of a suspected aspiration, the patient must be referred to appropriate medical care.

Bronchi↗
PubMed2002

Laser digitization of casts to determine the effect of tray selection and cast formation technique on accuracy.

UNLABELLED: STATEMENT OF PROBLEM; Several studies have attempted to determine the ideal combination of dental materials and laboratory techniques to produce the most accurate dental cast. Most have made use of 2-dimensional manual measuring devices, which neglect to account for the dimensional changes that exist along a 3-dimensional surface. PURPOSE: The purpose of this study was to determine the effect of impression tray selection and cast formation techniques on the dimensional change of a dental cast with the use of new, 3-dimensional optical digitizing technology. MATERIAL AND METHODS: Multiple impressions of a machined steel die that resembled a dental arch were made with custom and stock impression trays and vinyl polysiloxane impression material. The impressions were poured in type V artificial dental stone and allowed to set with the tray inverted or noninverted. The steel master die and stone casts were digitized with the Steinbichler Comet 100 Optical Digitizer, which was developed at the Minnesota Dental Research Center for Biomaterials and Biomechanics. Three-dimensional images of the stone casts were aligned to the 3-dimensional image of the master die and analyzed with AnSur-NT software. Multiple measurements of the master die and stone casts were analyzed to determine the accuracy of the 3-dimensional technology and of the impression and cast fabrication techniques. Planar distances between the center of each crown preparation were measured, as were crown heights. Data were analyzed with analysis of variance (P<.05), and root mean square error values were determined. RESULTS: Casts were compared with a total of 45 significance tests, of which only 4 yielded P<.05. There was no pattern to these results, which suggests that they were false-positive findings. CONCLUSION: Results obtained with the use of new optical digitizing technology indicated that neither impression tray type nor cast formation technique affected the accuracy of final casts.

Analysis of Variance↗
PubMed1984

Technique for making flexible impression trays for the microstomic patient.

This impression technique can be used for patients in whom routine use of stock impression trays is hindered by microstomia. Putty wash material can be manipulated with minimal effort and time. Placing the completed preliminary impression in a free-flowing mix of dental stone stabilizes the impression material and facilitates boxing and pouring of the impression. The resultant preliminary casts can then be used for diagnostic purposes and for making rigid sectional trays for final impressions.

Dental Impression Materials↗
PubMed1994

Effect of disinfection of custom tray materials on adhesive properties of several impression material systems.

The effects of impression tray disinfection procedures on the bond strength of impression-material adhesives to two types of resin trays were evaluated with a tensile test. Autopolymerizing acrylic resin and a visible light-curing resin were formed into one-half inch cubes. A screw eye was attached to each cube before polymerization. Perforated trays were fabricated with stops to maintain an even one-eighth inch of impression material over the resin block. Hooks on the opposite side permitted attachment of the metal plate to a mechanical testing machine. Before adhesive was applied, one third of the resin specimens were immersed in a 1:213 iodophor solution; one third in a 10% sodium hypochlorite solution, and one third were kept in the "as fabricated" condition. Polysulfide, polyether, and polyvinyl siloxane impression material-adhesive systems were evaluated. The resin-impression material-metal plate couples were attached to a mechanical testing machine and tensile forces were applied at a separation rate of 5 inches per minute. Mean values for adhesive strength ranged from 3.49 kg/cm2 for the autopolymerizing acrylic resin/iodophor/polyether combination to 10.55 kg/cm2 for the autopolymerizing acrylic resin/untreated/polyvinyl siloxane combination. Differences were detected among materials and disinfecting procedure. Clinically, disinfection of resin trays may adversely affect retention of the impression material to the tray.

Acrylic Resins↗
PubMed1985

Allergic stomatitis from dental impression compounds.

Two women experienced a severe stomatitis following brief contact with Impregum, a dental impression material. In one patient it was shown that the sensitizer was the catalyst 2,5 dichlorobenzene sulfonate. This dental impression material is widely used in the United States, and has been reported as a sensitizer in Europe. The catalyst in Scutan, another dental impression compound sometimes used instead of the methacrylates, has also been reported in Europe as being a sensitizer.

Aziridines↗
PubMed1984

Tear strength of non-aqueous impression materials.

Examples from each of the four major groups of dental impression materials (polysulfides, polyethers, condensation polysiloxanes, and addition polysiloxanes) were subjected to a trouser-leg tear test. Tear energies were determined, and materials were ranked with respect to each other. Polysulfides displayed the highest tear energy, while condensation polysiloxanes were the lowest, with the addition polysiloxanes occupying an intermediate position.

Dental Impression Materials↗
PubMed1986

An investigation into the compatibility of some irreversible hydrocolloid impression materials and dental gypsum products. Part I. Capacity to record grooves on the international standard die.

Some alginate impression materials produce rough, chalky, soft surfaces on gypsum casts. This is recognized by various standards, which include tests for an alginate's compatibility with gypsum, and its capacity to record details and impart these to a gypsum cast. These qualities were looked at in this study. The method used closely followed that laid down by International Standard ISO 1563-1978(E) for alginate impression materials. Ten alginates and seven gypsum products were tested. Using the criteria specified by this Standard, it was found that none of the materials tested was able to record the finest (0.020 mm) line on the test block. However, two elastomeric impression materials tested in the same manner also failed to reproduce this line, as did all the gypsum products when tested directly against the block. These findings cast some doubt on the efficacy of utilising such a fine line in the classification of these materials. Only thirty-four of the seventy possible combinations were able to reproduce the 0.050 mm line. Eight combinations reproduced the 0.075 mm line as the finest line, and the remainder (thirty-eight) failed to record any of the lines. Some of the alginate materials were treated with fixing solutions of varying concentrations of potassium sulphate and alum. The results obtained varied, sometimes producing marked improvement, sometimes deterioration in the surface quality of the subsequent gypsum casts, despite the fact that none of the manufacturers of the alginates recommended the use of fixing solutions.

Alginates↗
PubMed1985

Viscoelastic properties of setting elastomeric impression materials.

An instrument was introduced to determine the relationship between induced and permanent tensile deformation of selected elastomeric dental impression materials during and after setting. The method accurately recorded viscoelastic properties of impression materials.

Chemical Phenomena↗
PubMed1993

Accuracy, detail reproduction, and hardness of gypsum casts produced from silicone impressions treated with glow discharge.

Plasma treatment has been reported to improve the wettability of silicone impression materials. This study investigated whether plasma treatment of silicone impressions influenced the linear dimensional accuracy, detail reproducibility, and surface hardness of models produced from a type IV dental die stone. Five silicone impressions materials were used in this study. Linear dimensional accuracy and detail reproduction were tested according to ISO standards. Surface hardness was evaluated with a Vickers hardness test. The results indicated that plasma-treated impressions from Xantopren and Provil silicone impression materials had significantly smaller dimensional change than their respective controls, and the other materials were not influenced. The detail reproduction was superior in casts produced from plasma-treated impressions from President silicone. Surface hardness was not influenced by the treatment. Plasma treatment of silicone impressions has no negative influence on the tested physical properties of die stone models.

Analysis of Variance↗
PubMedDate not supplied

[Elastomeric impression materials].

A review of the literature on elastomeric impression materials, is presented in this paper. The article mentions the composition and the most important properties of the elastomeric impression materials used in dental practice. The clinical significance of these materials, physical and mechanical properties are also emphasized. In addition some new elastomeric impression materials with improved properties and a new (experimental) light-cured impression material, are mentioned. Another part of this article is the biocompatibility of these materials. In the end the great significance of handling is outlined.

Biocompatible Materials↗