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Biomedical subjects

R J Goodkind

Publications and source records attributed to R J Goodkind.

At least 37 records · Page 2Linked to original sources
PubMed1985

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. Flat plane occlusal splint treatment produces no significant change in the dysfunction level of patients with internal joint derangements with reduction. Mandibular repositioning treatment may eliminate the reciprocal click of internal joint derangement with reduction. To realize improvement in dysfunction of internal joint derangement, it appears that the reciprocal click must be eliminated. Mandibular repositioning treatment produces a significant improvement in muscle pain associated with internal joint derangement.

Adolescent↗
PubMed1984

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. The bond strengths were determined with a shear-push through test in an M.T.S. hydraulic testing machine. Two additional groups of samples were tested with corrosion only and fatigue only. All samples except those used for controls were placed in an oral environment chamber that had an aerated artificial saliva circulating through it maintained at 37 degrees C. (Samples subjected to fatigue only used unaerated distilled water). Corrosion was accelerated by enforcing a potential of approximately 500 mV on the test samples. The samples subjected to fatigue were stressed with a haversine waveform with a force between 5 and 45 pounds at a rate of 200 Hz for 10(6) cycles.

Chemical Phenomena↗
PubMed1981

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. This study demonstrated that Chroma is greater for dull opaque than for glossy opaque with shade B1, but for shade A3 the statistical interaction between dull opaque and smooth porcelain texture decreased the Chroma. Value had essentially an additive effect of opaque and porcelain textures for shade A3. The smooth surface porcelain texture increased the Value of shade B1 compared to the rough porcelain surface. The interactions that occur between the texture of porcelain and opaque affecting color are complex phenomena. They may be related to the modification of light by transmission, absorption, refraction, scattering, and reflection.

Color↗
PubMed1979

An investigation of tensile strength of dental solder joints.

Tensile specimens of dental solder joints were tested to determine the effect of gap distance on the strength of solder joints. Two dental alloys were used; a Type III gold alloy and a gold-palladium (Au-Pd) alloy. The Type III alloy was joined with the recommended gold solder. The Au-Pd alloy was joined using preceramic and postceramic application soldering techniques. Gap distances of 0.13 mm, 0.5 mm, and 1 mm were used with each soldering technique. All solder specimens were machined to a uniform diameter and then tested for tensile strength. It was concluded that: 1. There was a significant increase in strength for the Type III gold as the gap distance was increased. 2. The trend toward stronger joints at narrow gap distances for Au-Pd alloy joined with presolder was not statistically significant. 3. The trend toward stronger joints at wide gap distances for the Au-Pd alloy joined with the postsolder was not statistically significant. 4. The postsolder joints were statistically stronger than the presolder joints. 5. The trends observed could be partially explained in terms of competing effects of yield strength (triaxially), wettability, and void or inclusion content at the various gap distances.

Dental Alloys↗
PubMed1979

Spectrophotometric study of five porcelain shades relative to the dimensions of color, porcelain thickness, and repeated firings.

A total of 125 ceramo-metal samples were used representing: 1. Five different porcelain shades a. Ceramco shades A3, B2, and D3. b. Vita B2. c. Biobond B62. 2. Thicknesses of 1, 2, and 3 mm for each shade fired two times 3. Additional 2 mm samples for each shade fired five and 10 times. Each sample was analyzed by a recording spectrophotometer. Data received was converted to Munsell notation for evaluation of the dimensions of color, i.e., Hue, Chroma, and Value, as related to (1) shade differences, (2) thickness of porcelain, and (3) numbers of firings.

Color↗
PubMed1978

Tear strength of elastomeric impression materials.

1. Under simulated clinical conditions the maximum tear strength of those materials tested was reached in 10 to 15 minutes. 2. The polysulfide materials showed three to six times the tear strength of the silicones. 3. The polyether material displayed a tear resistance slightly higher than that of the silicones but one third to one fifth as high as that of the polysulfides. 4. The clinical significance of the differences in tear strength was undetermined since other factors (such as adhesion) were not considered.

Chemical Phenomena↗
PubMed1977

Bond strength studies of precious, semiprecious, and nonprecious ceramic-metal alloys with two porcelains.

One-hundred cylindrical pull-through ceramic-metal test specimens were subjected to shear loading forces. Two porcelain systems were treated in association with five ceramic alloys--one precious, one semiprecious, and three nonprecious alloys. 1. There was no significant difference in bond strength between Ceramco and Vita porcelains. 2. The various alloys tested demonstrated significantly different bond strengths. 3. Differential statistical tests suggested that nonprecious alloys performed better with Ceramco porcelain than with Vita porcelain. 4. The bond strength of Ceramco porcelain fused to nonprecious alloy N-C2 was significantly greater than that of Ceramic and traditional gold-based alloys. 5. Nonprecious alloy N-C1 produced significantly less bond strength than the traditional gold-based alloys. 6. Semiprecious alloy W produced high bond strengths with both Ceramco and Vita porcelains. 7. The cylindrical pull-through test was a reliable, reproducible method of testing ceramic-metal bond shear strength. 8. The surface roughness appears to be the one common factor in nonprecious alloys that relates to large differences in bond strength. Additional tests must be made to verify this hypothesis.

Ceramics↗
PubMed1977

Viscosity of elastomeric impression materials.

(1) Some elastomeric impression materials (Omniflex and Impregum) exhibited extreme shear thinning properties. This property was considered useful and these materials can be considered all-purpose. (2) The use of impression materials in syringing applications should not be precluded simply because the substances are thick or heavy during spatulation. A tenfold reduction in viscosity with increasing shear rate was found for three of the materials tested. (3) Viscosity characteristics of the impression rubbers were linked to filler content. (4) The viscosity rise during cross-linking was monitored for various impression products. It was found that each manufacturer's specifications of the length of time for syringing were relatively accurate.

Chemical Phenomena↗
PubMed1976

Design and technique variables affecting fracture resistance of metal-ceramic restorations.

An attempt was made in this study to make a clinically meaningful measure of fracture resistance in metal-ceramic restorations. Forty-four solid metal-ceramic crown forms were fabricated and subjected to compressive load testings. Variables included the presence or absence of a metal coating agent, the type of metal preparation (using stones of different abrasives), and three designs of the underlying metal. The following conclusions were arrived at: (1) The design of the underlying metal structure had a significant relation to the ultimate fracture strength. (2) A design with a definite acuteness of the underlying metal structure failed at significantly lower ultimate fracture strengths. (3) A metal conditioning agent did not decrease fracture resistance if applied properly. (4) Fracture strength was severely decreased when (a) improper thickness of the coating agent was used and (b) porcelain was fused to an unoxidized metal surface. (5) Bond strength, although a contributing factor, may not be as important as metal design and proper manipulation of materials during fabrication of the restoration.

Ceramics↗