Affiliations: Department of Dental Technology, Matsumoto Dental University School of Dentistry, Nagano, Japan | Department of Biomaterials, Institute for Dental Science, Matsumoto Dental University School of Dentistry, Nagano, Japan | Dental Materials Division, Department of Restorative Dentistry, Indiana University School of Dentistry, Indianapolis IN, USA
Note: [] Corresponding author: Dr. Yoshiki Oshida, PhD, Professor, Dental Materials Division, Department of Restorative Dentistry, Indiana University School of Dentistry, 1121 West Michigan Street, Indianapolis, IN 46202‐5186, USA. Tel.: +317 274 3725; Fax: +317 274 2419; E‐mail: [email protected].
Abstract: A plurality of repeated porcelain‐baking procedures are normally practiced in order to achieve the final adjustment metal–porcelain restorations. By increasing the number of baking cycles, the undesired internal strain would be built‐up, causing the reduction of mechanical properties and deterioration of color characteristics. However the extensive studies on such deterioration have not been done. In this study, effects of numbers (up to 10 times) of repeated baking cycles on baking shrinkage, surface roughness, bend strength, color changes and internal microstructure were investigated when opaque, body and enamel was individually applied or when a triple‐player comprising of these three porcelains was repeatedly applied. It was concluded that (1) the bend strengths increased by increasing baking cycles, (2) the average surface roughness decreased by increasing number of baking procedures, (3) changes in color characteristics was very small in the Vintage halo porcelain system, and (4) since the pores entrapped in the porcelain remained even by increasing baking cycles, it is recommended to remove the surface pores before forming the next layer when handling the high viscous opaque porcelain.
Keywords: Baking cycles, bend strength, porcelain (opaque, body, enamel), color characteristics, surface roughness
