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At least 1,063 records · Page 59Linked to original sources
PubMed2000

Surgical guide for dental implant placement.

Restorative problems with less than desirable implant placement can be challenging. A procedure is presented for the fabrication of a surgical guide stent that dictates placement of dental implants. This surgical guide can enhance implant placement in an efficient and acceptable manner so that final restorations can be properly contoured and esthetic.

Dental Implantation, Endosseous↗
PubMed1995

The accuracy of a high-precision digitizer for CAD/CAM of crowns.

An alternative method for manufacturing fixed prostheses that uses machine digitalization and a combination of milling and spark erosion has been developed. The digitizer used has a contact probe with a ball-shaped tip. This study evaluated the accuracy of the device and the transfer of data from the individual die to the computer. The dimensions of a square gauge as read by the machine were compared with the known dimensions of the object with a computer, which allowed determination of the accuracy of the digitalization. Procera machining and the implications for reliable prosthodontic treatment are discussed.

Analog-Digital Conversion↗
PubMed1995

Measurement (in vitro) of the amount of force required to dislodge specific clasps from different depths of undercut.

A fundamental principle in clasp selection for a specific abutment is the reduction of the transmission of excessive forces to that abutment. The flexibility of a clasp was believed to directly affect the reduction of such forces. This study compares the average measurements of forces required to dislodge two kinds of circumferential clasps in different amounts of undercuts: one with a half-round retentive arm and the other with a round retentive arm under tensile load. Three commonly used undercuts were created on six cast crowns, premolars, and molars. Each clasp was exposed to adequate tensile load until dislodgment occurred. The test was run six times for the same clasp. The means of tensile load required to dislodge each of the different clasps were compared statistically. However, no significant difference was detected for the main effects of the three variables studied: tooth type, undercut, and amount and clasp type. Findings indicated the possible use of cast round clasps where advantages of clinical fit and reduction of transmitted forces to the abutments can be gained.

Analysis of Variance↗
PubMed1984

A modified indirect cast post and core technique.

An indirect post and core technique in which the core is waxed and invested with the die has been described. The post and core are cast directly into the invested die, which has the advantage of an accurate casting of the post preparation obtained with less laboratory time and without the disadvantages of retrieving an intact wax pattern. This technique is particularly suited for long, narrow post preparations; short preparations where precise fit is necessary for retention; and multiple adjacent post preparations.

Calcium Sulfate↗
PubMed1996

Establishing the gingival emergence profile of restorations by using a resilient gingival replica.

All references to gingival morphology are destroyed once the die is trimmed during construction of crowns, onlays, or veneers. The need for reconstruction of a gingival replica to assist in the reproduction of a restoration's gingival contour and emergence profile is discussed. A simple, practical approach to duplicate the natural sulcus and free gingival morphology with currently available materials is presented. The advantages and limitations of implementing this technique and its multiple uses in prosthodontic and implant reconstructions and implant cases are presented.

Crowns↗
PubMed1997

Modifications of the impression to prevent cast breakage.

Broken teeth on a diagnostic or master cast, which usually occurs during separation from the impression, is a common problem experienced by dentists. This article aids in diagnosing and modifying noncritical areas of the impression to prevent this problem. One advantage of this method is that casts of periodontally involved teeth can be prevented from breaking. Disadvantages include time involved in modification and loss of noncritical areas of the tooth.

Calcium Sulfate↗
PubMed1997

The effect of a surface wetting agent on void formation in impressions.

STATEMENT OF PROBLEM: Impressions free from voids are important for the fabrication of accurate restorations. Any material or technique that reduces the incidence of bubbles is welcome. PURPOSE: The aim of this study was to determine whether the use of a surfactant designed for clinical use (Hydrosystem) reduced the number of visible air bubbles on the surface of a range of impression materials. MATERIAL AND METHODS: The surfactant was used before impressions were recorded with one of the following: a putty-wash condensation silicone, four polyvinyl siloxane materials, a polyether, a polysulfide, and an irreversible hydrocolloid impression material. Impressions recorded without the use of Hydrosystem acted as controls. Impressions were made of two prepared acrylic resin teeth in vitro and examined for surface voids by an examiner who was blind to whether the surfactant was used. RESULTS: Hydrosystem surfactant significantly reduced the number of surface voids when it was used with low-viscosity addition-cured silicone material but not when used with irreversible hydrocolloid, polysulfide, a hydroactive monophase addition-cured silicone, or a putty-wash condensation silicone. CONCLUSION: The use of Hydrosystem surfactant may result in a clinically significant improvement in impression quality.

Alginates↗
PubMed1997

A new method to simplify and increase the precision of maxillary cast mounting procedures in fully adjustable or semiadjustable articulators.

This study introduces a new impression procedure that permits mounting the maxillary stone cast in an articulator for any patient treatment and is applicable to any dental arch with any impression material. A transfer tray was designed that makes it possible to transfer the patient's maxillary impression to the articulator in a one-stage procedure without the need for making record bases and occlusion rims or the need to use a face-bow bite fork.

Dental Articulators↗
PubMed1999

Marginal gap of crowns made with a phosphate-bonded investment and accelerated casting method.

STATEMENT OF PROBLEM: Numerous materials and methods have been used for complete crown fabrication. Conventional investing and casting procedures for phosphate-bonded investments require a 2- to 4-hour process before completion. Accelerated laboratory techniques have been used, but may not result in castings with equal marginal accuracy. PURPOSE: This study measured the marginal gap and determined the clinical acceptability of single castings invested in a phosphate-bonded investment with the use of conventional and accelerated methods. MATERIAL AND METHODS: Forty-four individual stone casts were poured from impressions made from a master die. Conventional and accelerated methods of investing and casting were followed in the fabrication of 44 single-unit castings. Twenty-two casts were used in each of the 2 groups. Each casting and its respective stone die were examined with a microscope at 4 predetermined sites. Perpendicular and 25-degree tilted measurements of marginal gap were documented for each. Evidence of marginal gap was then evaluated by t test. RESULTS: Measurements recorded on the perpendicular and on a 25-degree tilt showed no statistically significant difference between conventional and accelerated groups. All gap measurements except one were within the range of clinical acceptability. The measurements revealed that conventional and accelerated perpendicular gap means were 13.2 and 13.6 microm, respectively, and the average tilted gap means were 31.6 and 32.2 microm, respectively. CONCLUSIONS: A phosphate-bonded investment (Ceramigold) selected for an accelerated casting technique produced single castings within 30 minutes with marginal gaps comparable to those found that used conventional methods.

Crowns↗