Microleakeage and Resin Cement Film Thickness of Luted All-ceramic and Gold Electroformed Porcelain-fused-to-metal Crowns

The purpose of this study was to evaluate the sealing ability of single-unit all-ceramic and gold-electroformed crowns luted with a resin cement under laboratory conditions. Thirty extracted maxillary premolars were selected. Standardized abutments were prepared for full-crown restorations with cervical margins located 1 mm below the cementoenamel junction. Samples were divided into two groups (n = 15) based on type of restorative system: Group 1: a heat-pressed all-ceramic system (IPS Empress 2, Ivoclar-Vivadent); Group 2: a gold-electroformed porcelain-fused-to-metal system (Gramm Technik). Crowns were luted with Excite DSC bonding system (Ivoclar-Vivadent) and Variolink II resin cement (Ivoclar-Vivadent) following manufacturer's instructions. After luting procedures and 700 thermal cycles (5°C and 55°C, 1 min dwell time), 20 specimens (n = 10 per group) were randomly selected and processed for microleakage evaluation at cervical sites. The remaining specimens (n = 5 per group) were prepared for SEM investigation on film thickness. Microleakage and film thickness data were statistically evaluated using the Mann-Whitney U-test (p 0.05). Fifty percent of group 1 and 60% of group 2 samples showed leakage. For group 1, dye penetration was mostly observed between metal and resin material, while group 2 specimens showed leakage mainly between ceramic margins and resin cement. Samples from group 1 showed a cement thickness of 82 µm, while 71 µm was found for group 2. Statistically significant differences were not found between samples from the two groups. Regarding microleakage and film thickness, both restorative systems evaluated in this study performed similarly.