Fleming, GJP,Maguire, FR,Bhamra, G,Burke, FM,Marquis, PM

2006

March

Journal of Dental Research

The strengthening mechanism of resin cements on porcelain surfaces

Validated

()

aluminous porcelain bi-axial flexure strength surface flaw distribution AXIAL FRACTURE STRENGTH CLINICALLY INDUCED VARIABILITY CERAMIC DENTAL RESTORATIONS FLEXURE STRENGTH STATIC FATIGUE GLASS DISCS ROUGHNESS SURVIVAL DESIGN

85

272

276

All-ceramic crowns bonded with resin cements have increased performance, and two theories have been proposed. Marquis (1992) suggested that the resin modified defects by crack healing, while Nathanson (1993) proposed that resin polymerization shrinkage strengthened porcelains. Both theories imply a sensitivity of strengthening to defect size. The hypothesis tested was that resin strength enhancement is independent of defect severity. We ground 200 porcelain discs to remove imperfections and indented 120 to create a large defect. Discs were tested dry, wet, and after being coated with 75-100 mu m of resin cement in bi-axial flexure. Disc strength with and without indentations was increased significantly when coated with 2 resin cements. Both cements significantly increased the strength independent of defect population, and the hypothesis was accepted. It is proposed that the combination of surface pre-treatment and cement moved the fracture origin from the porcelain/cement interface to the cement surface, consistent with resin strength enhancement independent of defect severity.