PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “DENTAL PORCELAIN”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed1994

Surface cracking identified in polished and self-glazed dental porcelain.

PURPOSE: Polishing and glazing porcelain surfaces of restorations is thought to help reduce the wear on the opposing occlusion because of reduced roughness. MATERIALS AND METHODS: To test this theory, samples of a variety of dental porcelains were prepared and subjected to various polishing and self-glazing treatments commonly used in dentistry and then viewed using scanning electron microscope (SEM). Fine cracks were discovered in the surface of the samples that had been polished and then self-glazed. These cracks were typically greater than 50 microns in length with submicron surface openings and crack depths less than 20 microns. To establish the treatments responsible for the formation of these cracks, a more controlled study was performed. Samples of Vita VMK 68 no. 559 incisal porcelain (Vita Zahnfabrik, Bad Såchingen, Germany) were prepared and subjected to six treatments (sample size = 3): treatment no. 1, as-fired condition; treatment no. 2, self-glazed (32 degrees C per minute to 960 degrees C, then cooled); treatments no. 3 and 4, wet ground followed by 1 micron diamond polish (no. 4 was then self-glazed); treatments no. 5 and 6, ground and polished using a Shofu porcelain adjustment kit (Shofu Inc, Kyoto, Japan) (no. 6 was then self-glazed). The samples were observed using SEM. RESULTS: Treatments no. 1, 2, 3, and 5 showed no cracking; however, treatments no. 4 and 6 showed cracking in all specimens (approximate levels 5,100 microns/mm2 and 3,600 microns/mm2, respectively). CONCLUSIONS: Polishing followed by self-glazing produces fine surface cracks. The rougher surface resulting from the surface cracks and subsequent porcelain chipping may cause wear of opposing occlusal surfaces.

Dental Alloys↗
PubMed1999

In vitro investigation of the wear of human enamel by dental porcelain.

STATEMENT OF PROBLEM: Metal ceramic systems are advocated when both esthetics and strength are required. A major drawback to many porcelains is their wear and destruction of opposing natural dentition. PURPOSE: This study evaluated the wear of enamel opposing 1 traditional and 2 recently introduced low-fusing feldspathic dental porcelains. MATERIAL AND METHODS: Six blocks of Ceramco II, Finesse, and Omega 900 feldspathic porcelain materials were fabricated and fired according to manufacturer recommendations. Porcelain blocks were polished through 0.25 microm diamond polishing paste. Thirty-six enamel specimens were obtained and milled to a 2 mm (+0.5 mm) diameter. Enamel specimens were attached to an offset cam motor operating at 60 Hz. Enamel specimens were in constant contact with the stationary porcelain blocks under a load of 600 g and traversed a distance of 8 mm. Diameter and height of enamel specimens were measured at times of 0, 6, 12, 24, and 48 hours and subsequent determination of enamel volume loss recorded. Profilometric surface roughness of the ceramic blocks was also measured for the corresponding times. RESULTS: Statistical analysis revealed that both Finesse and Omega 900 feldspathic porcelains caused significantly less enamel volume loss when compared with Ceramco II porcelain at all time intervals. Surface roughness revealed no consistent significant differences among porcelains. CONCLUSION: Both Finesse and Omega 900 porcelains were not as destructive to human tooth structure as Ceramco II porcelain. These results suggest an advantage of the new, lower-fusing porcelains in conditions where natural dentition wear is a concern.

Aluminum Silicates↗
PubMed1997

Glass transition temperatures of dental porcelains determined by DSC measurement.

The differential scanning calorimetry (DSC) curves for three commercial dentin and incisal porcelains fused-to metal were measured using high-temperature DSC. The glass transition temperatures (Tg) were determined from the DSC curves at heating rates of 7-20 degrees C/min, and the activation energy was derived from an Arrhenius plot of negative reciprocal Tg vs. logarithm of heating rate. The Tg of the dental porcelains depended on the content of aluminum oxide, whereas the activation energy depended on the content of sodium oxide. The ultra-low fusing type porcelains had a low activation energy due to the higher content of sodium oxide than the other porcelains.

Aluminum Oxide↗
PubMed1999

Effect of cooling condition on leucite crystals in dental porcelains.

X-ray diffractometry (XRD) was used to analyze the crystal phases of three commercial dentin and incisal porcelains prepared by normal cooling, quenching in water, and controlled slow annealing after normal firing. There were no remarkable differences in the contents of either tetragonal and cubic leucite in the fired porcelain discs prepared under the three cooling conditions. Furthermore, there were no significant differences in the parameters of the a-axis and c-axis of tetragonal leucite, and the a-axis of cubic leucite among them. These results suggest that the cooling condition has little effect on the microstructural changes of leucite crystals in the dental porcelains, since the leucite crystals were formed at a higher temperature range than the firing- and cooling-temperature range and were stabilized by incorporation of additives into the lattice.

Aluminum Silicates↗
PubMed1989

Performance assessment of colorimetric devices on dental porcelains.

The selection of an appropriate material that duplicates the appearance of natural tooth structure is very important in restorative dentistry. Photometric and colorimetric analysis techniques offer great potential as a tool for aiding in the duplication process. The degree to which these techniques will be useful depends on the accuracy and precision with which they can be applied to translucent as well as opaque surfaces. The purpose of this investigation was to evaluate the performance of three currently-available photometric devices. The performance capabilities of the instruments were tested on various shades of opaque and translucent dental porcelain surfaces. The performance tests were designed for evaluation of the accuracy and precision of the instrument relative to a well-studied reference instrument. CIELAB color difference metrics were used for the performance analysis. The results revealed that each of the photometric instruments evaluated was capable of producing color measurements with precision. However, the degree of accuracy with which the color measurements were made varied depending on the instrument used and the type of material surface being measured. A photo-electric tristimulus colorimeter showed the best overall performance on the porcelain surfaces, supporting its use as a valuable tool for evaluating color in dentistry.

Analysis of Variance↗