title: The effect of cement thickness on the fracture strength of all-ceramic crowns.
abstract: The effect of increasing cement thickness on the fracture strength of aluminous porcelain jacket crowns was investigated in this study. Thirty-three aluminous porcelain jacket crowns were divided into three groups. In Group 1, only platinum foil was used to provide cement space. In Group 2 two layers and Group 3 four layers of die spacer were painted onto the metal die before impression taking. Each crown was cemented onto a metal die with zinc phosphate cement and loaded until fracture. The maximum force to break each crown was recorded. The average fracture load was 408 N for Group 1,365 N for Group 2 and 324 N for Group 3. ANOVA (SPSS) found a significant difference (p < 0.05) between groups. A Scheffe Test revealed a significant difference between Groups 1 and 3. It was concluded that increasing the cement thickness above 70 microns reduced the fracture strength of porcelain jacket crowns.
authors.affiliation: School of Dental Science, University of Melbourne.
authors.forename: M
authors.initials: M
authors.lastname: Tuntiprawon
authors.forename: P R
authors.initials: PR
authors.lastname: Wilson
mesh_terms: D000535:Aluminum / Q000737:chemistry; D002484:Cementation; D002516:Ceramics / Q000737:chemistry*; D003442:Crowns; D003761:Dental Impression Technique; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design / Q000295:instrumentation; D008422:Materials Testing; D010984:Platinum / Q000737:chemistry; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D013499:Surface Properties; D015036:Zinc Phosphate Cement / Q000737:chemistry*
chemical_list: D003776:Dental Porcelain; D010984:Platinum; D015036:Zinc Phosphate Cement; D000535:Aluminum