Cast Gold Crowns Research Articles

Microleakage of crowns cemented with glass ionomer cement: Effects of preparation finish and conditioning with polyacrylic acid

This study compared the marginal leakage of cast gold complete crowns cemented with glass ionomer and with zinc phosphate cement. The effect of polishing the preparations and conditioning with polyacrylic acid was also evaluated for glass ionomer cement. The cast gold crowns cemented with glass ionomer cement demonstrated significantly lower marginal leakage than did those with zinc phosphate cement. The extent of microleakage was not substantially different between crowns when the preparations were polished and conditioned with polyacrylic acid.

Effect of internal microblasting on retention of cemented cast crowns

Microblasting of cast metal crowns is considered a standard procedure in most laboratories and an effective alternative to acid pickling. During the process of devesting and finishing, the surfaces of cast restorations are microblasted with an abrasive agent. This investigation measured the retention of type III cast gold crowns after cleansing with pickling solution (group I) or microblasting with 50-micron aluminum oxide (group II) or 50-micron glass beads (group III). Microblasting the internal surface of cast crowns with 50-micron aluminum oxide significantly improved the retention of castings luted with zinc phosphate cement.

支台築造に関する研究 歯冠部残存歯質量の影響について

The purpose of this study was to investigate the effect of the height of remained coronal tooth structure on the retention of post and core. This study was directed to detect micro-separation after application of intermittent compressive force using India ink. 130 extracted human teeth were prepared for samples, and complete cast gold crowns were cemented with zinc-phosphate cement on the two types of post and core: composite resin core with steel post, cast core and dowel. Conclusions were as follows: 1. Application of force to the crown on the tooth which lost coronal structure caused micro-separation between the tooth and the core. 2. The height of remained intact coronal tooth structure was effective to increase in the retention of post and core.

Comparative study of luting agents with composite resin cores

This study compared bond strengths of zinc phosphate and polycar☐ylate cements in cementing cast gold crowns to composite resin cores. The study also compared the effect of thermocycling on the bond strengths in tension of the two cements under varied storage and thermocycling conditions. Sixty standard cores were made from composite resin material. Gold alloy crowns were cast for each core and cemented with zinc phosphate or polycar☐ylate cement. The samples were stored for 1 day or 1 month and then cycled with 60-second dwell times between 5 °C and 55 °C distilled water baths for 5, 100, or 1000 cycles. The controls were stored for the same periods and were not cycled. Overall comparison of both storage periods and all cycled and noncycled groups revealed that zinc phosphate cement had significantly higher bond strengths than polycar☐ylate cement. Increasing the storage time before cycling significantly increased the bond strengths for both cements. There was no difference between any of the cycle periods or the noncycled controls for either cement.

Microleakage of core materials for complete cast gold crowns

This study evaluated the microleakage patterns of complete cast-gold crowns cemented onto teeth rebuilt with pin-retained cores made from cast gold, amalgam, composite resin, and silver-reinforced glass ionomer by using three different cements (zinc phosphate, glass ionomer, and resin cement). Crowns cemented onto unrebuilt tooth preparations with zinc phosphate cement served as controls. The cemented specimens were thermocycled between 4 degrees and 50 degrees C in waterbaths. They were then embedded in epoxy resin and sectioned. The extent of marginal microleakage was evaluated with a stereomicroscope and scored. The findings indicated that the type of luting agent used appeared to affect microleakage more than the core material. No significant differences in the degree of microleakage were found under crowns cemented onto teeth rebuilt with the four core materials when cemented with the same luting cement.

Nondestructive, three-dimensional internal fit mapping of fixed prostheses

Crown fit may be three-dimensionally mapped by using a nondestructive optical technique. Reflected light transmission through thicknesses of a colored impression material was shown to follow the Beer-Lambert relationship over a range of approximately 10 to 300 μm, a useful range of interest for study of cement layer thickness. Control thicknesses of impression material were first formed between the measuring platens of a micrometer, and light transmission values (relative reflections) were measured through these control thicknesses of impression material held against air-abraded, noncast gold alloy. Relative reflection values were similarly measured from impression material formed inside cast gold crowns seated on their respective dies and these values were plotted against direct thickness measurements by using the Beer-Lambert relationship. It was established that the micrometer-produced control specimens yielded a valid standard curve for use with the cast gold crowns. Precementation space measurements determined photometrically were found to correlate significantly (r = 0.72, p < 0.001) with zinc phosphate cement thickness measured on subsequently cemented and cross-sectioned crowns. A three-dimensional representation of the precementation space inside one crown was developed after mapping of 45 points in less than 5 minutes.

Effects of thermocycling on amalgam and alloy-glass ionomer cores luted to cast gold crowns

The effectiveness of dental alloy-glass ionomer cores and dental amalgam cores for the retention of castings luted with polycarboxylate cement was investigated. Extracted human teeth were reduced horizontally, revealing a flat pulpa floor where 4 regular T.M.S. pins were placed and restored with amalgam or alloy-glass ionomer mixture. Crown tapers were standardized between 5° and 9° and the surface area was measured for each core. Castings were fabricated with Type III gold and cemented to the cores. Half of the samples were subjected to thermal stress for 1 week, 5 weeks or 10 weeks, while the other half were stored in room temperature deionized water. Bond strengths of the cores were measured in tension with a Universal testing machine. The effect of thermocycling increased the bond strength of the alloyglass ionomer cores and decreased the bond strength of the amalgam cores during each repective time period.

The effects of surface roughness and surface area on the retention of crowns luted with zinc phosphate cement.

AbstractThe retention of cast gold crowns luted with zinc phosphate cement to smooth and rough surfaced extracted teeth was examined. No significant difference in retention was observed between smooth and rough surfaced teeth. A significant linear association existed between the surface area of the teeth tested and the retentive force but, statistically, area could not be used as a useful predictor for crown retention.

The use of porcelain-fused-to-metal restorations in current dental practice: A survey

The survey of members and guests of the American Academy of Esthetic Dentistry revealed the following: Porcelain-fused-to-metal crowns are the most commonly used crowns in dentistry, Cast gold crowns are infrequently placed compared to PFM, most dentists consider PFM crowns extremely successful restorations; although porcelain occlusal surfaces are considered acceptable by most dentists, dentists prefer metal on occlusal surfaces for restorations in their own mouths; the anterior 3/4 crown is infrequently placed, but the posterior 3/4 crown is commonly used; the Cerestore crown is gaining acceptance; Porcelain-jacket-crown use is reduced, but still a viable alternative; and the most desired improvement for PFM restorations was less wear on opposing teeth.

Effect of die spacer on the seating of complete cast gold crowns with grooves

Fifty crowns were constructed with an indirect technique for a standardized Ivorine tooth preparation to determine whether casting relief would improve the seating of complete cast crowns with zinc phosphate cement. The variables were two grooves in the preparations and die spacer casting relief of approximately 20 to 40 micron. The tooth preparations of two groups had no grooves, but castings were made with internal relief for only one group. Three groups had buccal and lingual grooves in the preparation. One group had no relief, a second group had complete relief, and a third group had relief but not in the grooves. The discrepancies noted before and after cementation of the castings were measured. The average discrepancy for each group and the significance between groups was determined. Results of this study demonstrated the following. Die relief significantly improved the seating of complete cast-gold crowns with or without grooves. Omitting die spacer from grooves did not reduce the benefits of relieving the remainder of the die. Partial internal relief was better than no relief. The grooves did not disrupt seating when die spacer application was complete or specifically omitted from the grooves alone.

Comparison of methods of clinical evaluation of the marginal fit of complete cast gold crowns

Three clinical methods for testing marginal fit of complete cast crowns were investigated: the exploration, radiograph, and impression techniques. This work proved that the impression technique is the superior test and should become a standard part of the evaluation routine for complete cast crowns.

Nonanatomic patterns for full cast gold crowns

lhe combination of anatomic-nonanatomic artificial teeth is a recommended posterior arrangement for complete denture occlusion.‘,’ The advocated advantages over nonanatomic teeth arrangements include improved cusp efficiency, concentration of vertical forces, improved esthetics, and elimination of lateral planes.3-5 In situations in which an upper complete denture is occluded with mandibular cast gold crowns, this occlusal scheme is incorporated through the use of acrylic patterns.

The Internal Escape Channel: A Solution to Incomplete Seating of Full Cast Crowns

An experiment was conducted to investigate the effect of internal escape channels and perimetric occlusal bevel on the completeness of seating of full veneer cast-gold crown during cementation. Twenty-four crowns were fabricated on Ivorine dies and cemented by standardized procedures. Two experimental groups were reused to study the effect of the addition of a perimetric occlusal bevel. The vertical dimension was significantly reduced in all four test groups when compared with the control. We concluded that an internal escape channel improves the complete seating of a full veneer cast-gold crown.

A comparative evaluation of three post and core techniques

An in vitro study was performed evaluating three post and core techniques with and without full crown coverage on extracted mandibular molar teeth. The materials evaluated were amalgam, composite resin, and stainless steel posts, and a combination of cast-gold and stainless steel posts. The results indicate that the method of post and core technique may not be as significant as the placement of full coverage cast-gold crown restorations with sound design and placement of margins beyond the buildup restoration.

Effect of multiple axial grooves on the marginal adaptation of full cast-gold crowns

Twenty-seven crowns were fabricated on the standardized ivorine dies to determine the effect of multiple axial grooves. No grooves were placed on the control (group I). In groups II and III, respectively, two and four grooves were replaced. The mean value of the occlusal cement film thickness was used to appraise the vertical discrepancy (lack of seating) of the crown on the die. This value was obtained by averaging seven measurements of the occlusal cement film thickness taken at different areas. These measurements were recorded from the photomicrographs at x 100 magnification. There were significant differences between the control group and both test groups. Results of this study show that the presence of the grooves has an adverse effect on the seating of full cast-gold crowns.

Retention of cast crowns cemented to amalgam and composite resin cores

An in vitro study was conducted to determine the tensile bond strength of complete cast gold restorations cemented with zinc phosphate cement on composite resin and amalgam crown cores. The samples were thermocycled and tested at 1-week, 1-month, and 3-month intervals. Results of the study showed that: (1) the amalgam core provides more retention for the cast gold crown than does the composite resin core and (2) the composite resin core provides increasing retention over a longer time period.

Influence of some factors on the fit of cemented crowns

In the study, cast gold crowns were cemented similar to methods used for patients. Conclusions were that: 1. Fresh cement painted with a camel brush in the part of the crown to be cemented promotes a better fit than when the crown is completely filled with cement. 2. Mechanical vibration of the crown at cementation promotes a better fit. 3. Venting the crown, an internal relief by acid etching, or a combination of both these procedures improve the seating of the crown during cementation. 4. The association of one or numerous variables used in this study considerably improves the fit of the cemented crown.

Restoration of endodontically treated molar with root fracture

The management of an unusual and extreme tooth and root fracture has been presented and discussed. A somewhat unorthodox approach was used in preparing the fractured root surfaces to fit the cast gold crown instead of making a crown to fit a prepared tooth surface. Diagnosis and treatment planning is a key factor in treating unusual patients. All factors must be carefully considered. Condition of adjacent teeth, periodontal support, size and form of remaining tooth structure, and occlusion are all important considerations. With careful and proper study, simple and conservative restorations can frequently be made that will provide excellent service for extended periods of time.

Auxiliary retention for complete crowns provided by cement keys

1. Cement keys were an effective means of increasing the retention of complete cast gold crowns to preparations in extracted teeth. 2. Single grooves placed in either the dentin or in the crown alone were not effective in increasing retention in 30-degree crowns. In 7-degree crowns, a single groove in the crown gave better retention than a single groove in the dentin. 3. Crowns with a 7-degree taper had greater retentive strengths than 30-degree crowns treated identically. The retentive strength of 7-degree crowns with cement keys approached the tensile strength of zinc phosphate cement.

Microleakage of composite resin and amalgam core material under complete cast crowns

Ninety extracted human teeth were used to compare the microleakage of composite resin over, amalgam core, and regular crown preparations under a complete cast gold crown cemented with zinc phosphate cement as determined by 2% fluorescein dye solution. Specimens were compared with and without aging after cementation in a thermal bath by cycling some of them between 4 degrees C and 60 degrees C in a 2% fluorescein dye bath and others in a similar bath held at 37 degrees C. Fluorescein dye (under ultraviolet light) demonstrated microleakage of the specimens between the crown-tooth interface and the core-tooth interface. There were no significant differences in the microleakage due to aging. The specimens held at 37 degrees C in the fluorescein dye bath showed no significant differences between the core preparations and the regular crown preparations. However, when specimens were thermally cycled between 4 degrees C and 60 degrees C, there were significant differences. With thermal cycling, the regular crown preparations were better able to resist microleakage at the crown-tooth interface than either the composite resin core or the amalgam core preparations. The results of this investigation seem to indicate a need for further evaluation of core build-ups under cemented complete gold crowns.