Interdependence of the hue, value, and chroma in the middle site of anterior human teeth.

Purpose: This study examines how the color coordinates of human teeth are related to each other and describes a mathematical relationship between Hue, Value, and Chroma of the middle site of anterior teeth.

Materials And Methods: The color coordinates obtained from a previous instrumental survey of the colors of vital teeth (see Goodkind and Schwabacher) were examined statistically, and equations were sought to describe their distribution in color space. The resulting single equation was applied to the colors of 100 extracted teeth.

Leaching of nickel, chromium, and beryllium ions from base metal alloy in an artificial oral environment.

The use of base metal alloys in dentistry has gained wide popularity in recent years. However, claims of their safety have not been universally accepted. An artificial oral environment capable of reproducing three-dimensional force-movement cycles of human mastication was used to determine whether nickel, chromium, and beryllium ions were leached from base metal alloy.

Teaching of color in predoctoral and postdoctoral dental education in 1988.

This is a report of a 1988 survey of faculty involved in undergraduate and graduate programs concerning the teaching of color science. This survey indicates that the dental profession is making progress in color theory, application, and research in the dental curriculum. Manufacturers have been slow to respond to the needs of the profession.

Shade color discrimination by men and women.

Women have traditionally been believed to be more capable of matching colors than men. Because of this factor women should tend to agree with one another more often than men regarding tooth shade selection. This study tested differences in dental color perception between men and women.

Deformation of crowns during cementation.

Deformation of crowns during cementation was investigated by a simple loading system of defined crowns with silicone fluids as cements. Deformation of the crowns was measured by long stain gauges that encircled the cervical margins. Die spacing was simulated by etching the die.

Three-dimensional color coordinates of natural teeth compared with three shade guides.

The three-dimensional color coordinates of 2832 human teeth were measured in vivo and were plotted in a cylindrical Hue, Value/Chroma space, using a program in BASIC. The commonly used Vita, and Bioform shade guides, and a surviving shade guide of E. B.

Residual stress in several ceramometal systems.

Residual stress caused by a mismatch of alloy-porcelain thermal contraction can contribute to clinical failure of a ceramometal restoration. This investigation assessed thermal compatibility of three ceramometal alloys and two opaque porcelains. Thermal expansions of the alloys and porcelains were measured by using a straight push-rod dilatometer.

A status report of possible risks of base metal alloys and their components.

Sensitivity to base metal alloys and the components, both generalized skin reactions and local reactions, has been well documented. With the present trend toward increased use of these alloys by the dental profession, the short- and long-term implications of their use needs to be investigated. This article reviews the background, intake, and current use of two of the most commonly used metal alloys and their components.

The effect of the resilient-layer distal-extension partial denture on movement of the abutment teeth: a new methodology.

The new methodology presented in this article is simple, reliable, and accurate. The testing casts represented a reasonable simulation of human dentition. The artificial mouth reproduced major mandibular movement in a physiologic manner and applied controlled load instead of static load.

A shear test for the bond strength of ceramometals.

An innovative shear-testing method was introduced to study the effect of firing temperature, type of metal, and surface texture on the bond strength of the ceramometals. Two common ceramic/metal alloys were used: Olympia, a precious alloy, and Talladium, a base alloy. A Ceramco II Paint-O-Pake opaque was selected for the study.

The compressive strength of nonprecious versus precious ceramometal restorations with various frame designs.

This study was designed as a comparative analysis of the compressive strengths of precious versus nonprecious metals with various framework designs used in clinical restorations. One hundred thirty-five statistically uniform ceramometal restorations were fabricated. The restorations were cemented to the die and then subjected to stroke-control compression forces in an Instron loading machine.

Comparative study of two treatment methods for internal derangement of the temporomandibular joint.

Orthopedic mandibular repositioning and flat plane occlusal splint therapy were compared in the treatment of 20 patients with internal TMJ derangement with reduction. The following conclusions can be drawn. Mandibular repositioning treatment produces significant subjective and objective improvement in the dysfunction of patients with internal joint derangements with reduction.

Corrosion-fatigue of the bond between nickel-chrome casting alloys and porcelain.

This study was designed to determine if corrosion-fatigue might play a part in early failure of the porcelain-fused-to-metal bonds with Ni-Cr alloys. A qualitative test was used that compared the bond strengths of a control group with those of samples subjected to corrosion-fatigue. One Au-Pd alloy was used for comparison with the Ni-Cr alloys.

Effects of opaque and porcelain surface texture on the color of ceramometal restorations.

This study demonstrated the difference between Hue, Chroma, and Value between Ceramco shades A3 and B1 when the porcelain and opaque textures were modified. Porcelain surface texture, whether rough or smooth, did not make a difference in Hue. However, the glossy type surface in the opaque layer shifted for shade A3 from yellow toward yellow-red, and toward yellow for shade B1.