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Surface Cracking Identified in Polished and Self‐Glazed Dental Porcelain
Author(s) -
Edge Marion J.,
Wagner Warren C.
Publication year - 1994
Publication title -
journal of prosthodontics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.902
H-Index - 60
eISSN - 1532-849X
pISSN - 1059-941X
DOI - 10.1111/j.1532-849x.1994.tb00142.x
Subject(s) - glazing , polishing , materials science , scanning electron microscope , cracking , dental porcelain , composite material , diamond , surface roughness , glaze , dentistry , metallurgy , ceramic , medicine
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 μm in length with submicron surface openings and crack depths less than 20 μm. 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°C per minute to 960°C, then cooled); treatments no. 3 and 4, wet ground followed by 1 μm 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 μm/mm 2 and 3,600 μm/mm 2 , 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.