Full Cast Research Articles

Histopathological observation on the reaction of gingival pigmentation to full cast crown. Part 1 (author's transl)

In order to determine the cause of gingival pigmentation appearing after restoration by full cast crown, the gingival tissues showing gingival pigmentation apparently due to the full cast crown were investigated histopathologically using light and electron microscopy. Additionally, elements in some of the samples were studied with an electron probe microanalyser. Under the light microscope, many dark brown depositions of varying sized were observed in a wide area of the gingival lamina propria. Reduction in the arrangement of the basal cells were observed in the epithelial layer in the neighborhood of these depositions. Examination under the electron microscope clarified that these depositions were accumulations of minute granules, that large depositions had been formed by the fusion of small ones, becoming depositions of high electron density, and that around these large depositions were fibroblasts injecting minute granules. Many minute granules were observed attached too bundles of collagen fibers. The full cast crowns contained Ag, Au, Pd, Cu and Zn, on the other hand, the depositions contained Ag, S, Ca, P and Si. The element of the minute granule was Ag, which was considered to be in the form of AgS Calcification was occurring in some of the large depositions.

The Effect of Thermal Stress on the Marginal Seal of Cast Gold Full Crowns

An experiment was conducted to observe the effect of fluctuations in temperature on the marginal seal of full veneer cast gold crowns. Forty crowns were fabricated and allotted into two groups of 20 crowns each. One group was cemented with zinc phosphate and the other group, with zinc polycarboxylate cement. Ten crowns from each group were subjected to thermal stress of fluctuating temperatures (4 and 60 C) and the remaining ten crowns from each group were held at the constant temperature of 37 +/- 1 C. The experiment demonstrated the following results: --Microleakage was evident in all groups. --The degree of microleakage with zinc phosphate was less than with zinc polycarboxylate cement. --Contrary to the claim that zinc polycarboxylate cement adheres to enamel through chelation, we were unable to observe better results. The degree of penetration of dye in the tooth-cement interfaces of crowns cemented with zinc polycarboxylate was not less despite the remaining layers of enamel for bonding. The cause of microleakage with cast gold restorations is apparently multifactorial. Research should formulate a luting agent which forms a strong bond to gold alloy and tooth substrate and has a high tensile and shearing strength.

Convergence Angle of the Abutment Preparation on Full Cast Crowns

Convergence Angle of the Abutment Preparation on Full Cast Crowns

Measurement of the Three-dimensional Displacement of the Full cast metal crown in the Cementation

Measurement of the Three-dimensional Displacement of the Full cast metal crown in the Cementation

Art and Artifice in Erasmus’ Convivium Profanum

Of Erasmus’ six banquet pieces, the Convivium Profanum was the only one to appear in the earliest versions of the Colloquia. Unlike the others, therefore, it always retained much of the formulary quality that characterized the slender original collection, primarily a series of models after which schoolboys might fashion their conversational Latin. Yet even in Johannes Froben's unauthorized first printing of the pedagogical materials that Erasmus had composed twenty years earlier for use by his pupils at Paris, the purely formulaic matter is interspersed with considerable stretches of lively table talk, the full cast of participants in the convivium is introduced, and distinguishable personalities for the principal interlocutors have begun to be fashioned.

A two‐year clinical study comparing the effect of dentifrices on selected dental materials

1 A two-year double-blind human clinical study has been conducted to determine the comparative effect of two commercially available dentifrices on selected dental materials. 2 Forty-three adult subjects were selected to participate. They received either acrylic resin or silicate restorations in their anterior teeth, or a full cast gold veneer crown with an acrylic surface. 3 The subjects were randomly assigned to either one of the two dentifrices and utilized the dentifrice in their normal manner at least 3 times per day. 4 The dental restorations were clinically evaluated in reference to their surface characteristics immediately after placement, and after 3, 6, 12 and 24 months' use of the dentifrices. The acrylic surfaces of the veneer crowns were also evaluated at these same time periods; however, in this case an in vivo tooth surface reflectance measurement technique was also utilized. 5 The results of this clinical study provide the following conclusion after 24 months use of the two dentifrices: There was no difference between the two dentifrices in that neither dentifrice produced any abnormal or unusual effect on the surface characteristics of either the acrylic or silicate anterior restorations, or the acrylic surfaces of the veneer crowns.

Dynamic Studies on the Force Distribution of Various Forms of Full Cast Crown Abutment Teeth

There are a lot of studies on the abutment teeth of the full cast crown, and its reasonable forms were investigated with the photoelastic studies from a dynamic point of view. The two-dimensional studies have mainly been found, but the three-dimensional photoelastic ones have been researched little.So as to analyze the stress concentration at the inner part of abutment on the axis, occlusal face and marginal form, the author carried out the three-dimensional photoelastic studies applied to the anatomical solid specimen.To insure uniformity of the specimens tested, the basic plaster model is the simplified form of the maxillary second premolar enlarged three times. The epoxy specimens were made of the master model.The abutment models consist of three groups and nine kinds, that is A group (cusp angle: 0°, marginal form knife-edge, axial angle: 5°, 10° and 20°), the B group (axial angle: 10°, marginal form: knife-edge, cusp angle: 10°, 20° and 30°) and the C group (axial angle: 10°, cusp angle: 0°, marginal form: bevel-edge, chamfer-edge and shoulder-edge).The photoelastic and stress freezing apparatus, product of Riken-Keiki Co., are used for these studies. The load direction was applied to the long axis of the specimens, and the resulting isochromatic fringe patterns of each section in the specimens were recorded photoelastically. The circumferential stress distribution of each specimen was analyzed and the following conclusions were obtained.1. In all of the specimens, the highest concentration of stress was observed at the cervical area, but the stress was not concentrated in the area of the pulp horns.2. The stress in the cervical marginal area with the buccolingual section of axialangle 20° and the mesio-distal section of axial angle 10° showed the least concentration.3. The stress concentration in the cervical marginal area is decreased, when the cusp angle is increased. And it exhibits very little stress at the cusp angle of 30°.4. The marginal form of the chamfer-edge developed a tendency to have the same degree stress as did the bevel-edge is best mechanically. The end of the marginal ledge with the shoulder-edge showed very higher stress concentration. The knife-edge showed much higher stress concentration at the end of the marginel ledge.

Dinarnic Study on the Force Distribution of Various Forms of Full-cast Crown Abutment Teeth

There are many studies on the full cast crown, but the all-out dynamic studies foraxial, ocolusal and margunal form, that is very important factors, have not been find. The author tries to analyze the dynamic effect of differences of full cast crown abutment on the abutment, then the two-dimesnional photoelastic studies are carried out. The maxillar bicuspid for specimens is bucco-lingual synmetrical form, and the specimens being enlarged the three times of this teeth. are made by the B-hardner #901. The photoelastic apparatus, product of the Riken-keiki Co., is used for this study. The load direction is arranged at the long axis of specimen, the monochromatic fringe photographes are taken and analyzed.The abutment forms of full cast crown consist of three factors, that is the axial angle (5, 10, 20 and 30 degrees), the cusp angle (0, 10, 20, 30 and 40 degrees) and the marginal form (knife edge type, chamfer edge type, bevel edge type, bevel-shoulder edge type and shoulder edge type), and are carried out to analyze by the two-dimensional photoelastic test. Futhermore, the specimens with the axial angle of 5 degrees the cusp angle of 30 degrees are preparated of three marginal forms (knife edge type, chamfer edge type and shoulder edge type) and they are analyzed. The dynamic effects of differences of abutment forms on the abutment are investigated and the following conclusions are obtained.1. Regarding the axial angles, the each specimen with 5, 10, 20 and 30 degrees is researched. The maximum stress concentration in each specimen is observed at the pulp horn. Its value is tend to increase according as the axial angle increases. Therefore, it is concluded that theless the axial angle is, the more the abutment is dynamically. Consquently, the best axial angle is 5 degrees.2. As regards the cusp angle, the each specimen with 0, 10, 20, 30 and 40 degrees is studies. The strees concentration is observed at the pulp horn and margin. It is find that the more the cusp angle increases, the less its values are. Then, the cusp angle is best according as it increase, especially, it is effect as to decrease the stress concentration at the pulp horn and margin.3. As for the marginal forms, the specimens with knife edge type, chamfer edge type, bevel edge type, bevel-shoulder edge type and shoulder edge type are investigated. Regarding the stress concentration at the pulp horn, the knife edge type is minimum, and the chamfer edge type, bevel edge type, bevelshoulder edge type and shoulder edge type are increased in order of magnitude. Consquently, the knife edge type is best, the chamfer edge type, bevel edge type, bevel-shoulder edge type and shoulder edge type are in order of magnitude.4. As regards the specimen with the axial angle of 5 degrees and the cusp angle of 30 degrees being preparated for the marginal forms of knife edge type, chamfer edge type and shoulder edge type, the knife edge type is best. The chamfer edge type and shoulder edge type is in order of stability. In case of the shoulder edge type with the cusp angle of 30 degrees, the stress of margin and pulp horn is remarkably decreased. As to use of this type, this is careful consideration.

A Report on the Preparation of the Maxillary Left First Molar for a Full Cast Crown in a Manikin Head

A Report on the Preparation of the Maxillary Left First Molar for a Full Cast Crown in a Manikin Head

A Method of Constructing a Full Cast Crown by Using Refractory Die-Investing Materials

A Method of Constructing a Full Cast Crown by Using Refractory Die-Investing Materials

Effect of Types of Preparated Abutment Teeth on Full Cast Metal Crowns

Effect of Types of Preparated Abutment Teeth on Full Cast Metal Crowns

Television Micromeasurement of Vented and Non-Vented Cast Crown Marginal Adaptation

Ten extracted maxillary molar and ten maxillary premolar teeth, and one maxillary first molar and one maxillary second premolar Columbia Dentoform mold (5° to 7° taper) teeth were prepared for full cast crowns. One original silver plated master die was made from each of the dentoform preparations. This master die was used to prepare 20 premolar and 20 molar silver plated dies. Eighty gold crowns were fabricated for the dies and extracted teeth preparations in which onehalf of the crowns were vented on the bucco-occlusal surface. The marginal adaptation was measured with the intra-oral television microscope measurement instrumentation pre- and post-cementation. A zinc phosphate cement utilizing a standardized cementing apparatus with a 33-pound static load was used for all the cementation procedures. The vented crowns seated farther than the non-vented crowns in all the groups. However, the difference between venting and nonventing in the silver plated molar group was not significant. The intra-oral television microscope measurement instrumentation can be utilized in a clinical study with minor alterations in the methodology of this study.

Partial veneer retainers

lh’ 1s article is a discussion of partial veneer retainers, Specifically, three-quarter crowns and their modifications will be considered. Dentists should understand the basic preparation form, where this form could be used, and what modifications are available to meet most patient treatment situations. Partial veneer retainers may be used on anterior or posterior teeth of either arch where parallel proximal grooves of an adequate length and retentive walls and planes can be obtained to insure stability. Maximal retention with minimal sacrifice of tooth structure and encroachment upon the pulp is possible with this type of retainer. Esthetically, it can be acceptable in either anterior or posterior teeth. The retention attained with the partial veneer is comparable to that of a full cast crown provided that there is sufficient natural tooth structure remaining, and providing the preparation is properly made. All tooth surfaces are usually covered by these retainers except the labial or buccal surfaces of the maxillary teeth, and the mandibular anterior teeth. In mandibular molars, sometimes the buccal instead of the lingual surfaces are covered.

Cadmium bands in construction of full cast crowns

A technique is described that modifies the construction of a full cast crown. A cadmium band is adapted around the prepared tooth and incorporated into the wax pattern. The band is eliminated during the casting procedure. The advantages of this procedure are discussed.

The Oregon Shakespeare Festival, 1967

HE Shakespeare Festival at Ashland, Oregon, this summer for its rotating plays chose two hard ones: Pericles and Antony and Cleopatra, in addition to Richard III, and, for its fourth play, the perennially popular The Taming of The Shrew. How did Ashland fare with the difficult plays: Pericles, of questioned authorship, an ancient romance put on the stage narrative fashion, and Antony and Cleopatra, high tragedy, but with the loose construction, digressions, and off-stage complexities of a history play? The impossible Pericles was turned into a hit by the sheer perfection of style of Nagle Jackson's production. The tragedy of passion with a world conflict for its background had a Cleopatra and at least half an Antony. Pericles, when I had seen it before at Ashland, was a handsome spectacle. This summer's production made the preposterous succession of romantic events exciting and even had moments that were moving. This was accomplished with no imposed interpretation, no attempt to link the play with some contemporary theory, but solely by penetrating to the heart of the play, seeing it for what it is. Janus-masked stage managers, comedy facing one way and tragedy the other, opened the play, and the full cast in splendid costume was brought on as Old Gower began his tale. The cast withdrew as Gower set the stage for the wicked court at Antioch, and the heads of knights who had lost the trial of the riddle were placed in the inner below, suspended from a frame. The incestuous King, in black and sinister green, appeared on the balcony above. At the end of the play, as the cast went off to celebrate with Pericles, they froze in position while Gower pointed the moral in the life of each character. A color scheme for each episode changed the moods as clearly as Gower's interpolations and the restrained and patterned pantomimes. Pericles, the good hero, was in blue; a white King Creon and black Queen on the balcony, with hooded grey famine figures below illustrating the narration, saved the awkwardness of dialogue that recounts facts known to the speakers. Later, a red veil changed Dionyza to a murderess. The dark shipwreck scene, with square sails flashing in the light, was succeeded by a sunburst of red and orange and gold in the court of the jolly King who made a match of it between Pericles and his daughter, a splendid scene of feasting and dancing with musicians playing from the gallery. The somber, earthy colors of the brothel gave place to the temple with white Vestals and Diana with her silver bow descending from the clouds. The production was more than spectacle. The wicked Antiochus (Glen Mazen) was played with restrained, melodramatic villainy, in a precise style caught by every member of the cast. Pericles was a princely figure by Tom

37. 全部鋳造金属冠支台形態とセメント装着の関係に就いて

37. 全部鋳造金属冠支台形態とセメント装着の関係に就いて

Dynamic Study on the Force Distribution of Various Forms of Full-Cast Crown Abutment Teeth

There are many studies on the full cast crown, but the all-out dynamic studies foraxial, ocolusal and margunal form, that is very important factors, have not been find. The author tries to analyze the dynamic effect of differences of full cast crown abutment on the abutment, then the two-dimesnional photoelastic studies are carried out. The maxillar bicuspid for specimens is bucco-lingual synmetrical form, and the specimens being enlarged the three times of this teeth. are made by the B-hardner #901. The photoelastic apparatus, product of the Riken-keiki Co., is used for this study. The load direction is arranged at the long axis of specimen, the monochromatic fringe photographes are taken and analyzed.The abutment forms of full cast crown consist of three factors, that is the axial angle (5, 10, 20 and 30 degrees), the cusp angle (0, 10, 20, 30 and 40 degrees) and the marginal form (knife edge type, chamfer edge type, bevel edge type, bevel-shoulder edge type and shoulder edge type), and are carried out to analyze by the two-dimensional photoelastic test. Futhermore, the specimens with the axial angle of 5 degrees the cusp angle of 30 degrees are preparated of three marginal forms (knife edge type, chamfer edge type and shoulder edge type) and they are analyzed. The dynamic effects of differences of abutment forms on the abutment are investigated and the following conclusions are obtained.1. Regarding the axial angles, the each specimen with 5, 10, 20 and 30 degrees is researched. The maximum stress concentration in each specimen is observed at the pulp horn. Its value is tend to increase according as the axial angle increases. Therefore, it is concluded that theless the axial angle is, the more the abutment is dynamically. Consquently, the best axial angle is 5 degrees.2. As regards the cusp angle, the each specimen with 0, 10, 20, 30 and 40 degrees is studies. The strees concentration is observed at the pulp horn and margin. It is find that the more the cusp angle increases, the less its values are. Then, the cusp angle is best according as it increase, especially, it is effect as to decrease the stress concentration at the pulp horn and margin.3. As for the marginal forms, the specimens with knife edge type, chamfer edge type, bevel edge type, bevel-shoulder edge type and shoulder edge type are investigated. Regarding the stress concentration at the pulp horn, the knife edge type is minimum, and the chamfer edge type, bevel edge type, bevelshoulder edge type and shoulder edge type are increased in order of magnitude. Consquently, the knife edge type is best, the chamfer edge type, bevel edge type, bevel-shoulder edge type and shoulder edge type are in order of magnitude.4. As regards the specimen with the axial angle of 5 degrees and the cusp angle of 30 degrees being preparated for the marginal forms of knife edge type, chamfer edge type and shoulder edge type, the knife edge type is best. The chamfer edge type and shoulder edge type is in order of stability. In case of the shoulder edge type with the cusp angle of 30 degrees, the stress of margin and pulp horn is remarkably decreased. As to use of this type, this is careful consideration.

Solving the problems of cementing the full veneer cast gold crown

Tests were performed to indicate the accuracy with which full crowns can be cemented on prepared teeth. Findings indicated that using both internal relief for cement, plus a vent for escape of cement permitted a minimal gingival discrepancy following cementation. This discrepancy may be compensated for by constructing the crown with a slight gingival overlap properly contoured and polished. A simple technique for venting, fabricating a prefitted pin, and the procedure for permanent sealing of the escape-way vent within the normal interim period of cementation was described.

Properties of die materials: A comparative study

A comparative study of the pertinent properties of die materials used for the indirect materials has been made. Eight classes of materials were evaluated. No one material proved to be superior in all properties. The stones were superior from the standpoint of dimensional accuracy but their abrasion resistance was low. All of the dies, with the exception of those made from stone or low-fusing alloy, were undersize at the cervical margin of the simulated full cast crown preparation. An abrasion apparatus, designed to duplicate certain of the conditions to which such dies are subjected, was devised. On the basis of these tests it was not always possible to predict the abrasion resistance from the corresponding hardness. The dies made from the ceramic material, silicophosphate cement, one of the resins and by electrodeposition were superior in abrasion resistance. The surface of the electroplated dies, the ceramic material, stones and silicophosphate cement provided excellent duplication of detail. Differences were observed in the compatibility of certain die materials and rubber impression products, as compared to the duplication produced when the die material was poured against an inert surface.

The Cervical Appearances on the Prepared Tooth of the Full Cast Crown

The Cervical Appearances on the Prepared Tooth of the Full Cast Crown