Long term retentive strength of self adhesive cements

Objectives: The in vitro retentive strength of six self adhesive cements (RelyX Unicem Aplicap, RelyX Unicem Clicker/3M ESPE, iCEM/Heraeus, Maxcem Elite/sds Kerr, Bifix SE/VOCO, SpeedCEM/Ivoclar), a self adhesive cement with self etch primers (Panavia 21/Kuraray) one glass ionomer-cement (Ketac Cem Aplicap/3M ESPE), one resin modified glass ionomer-cement (Meron Plus/VOCO), and a zinc-phosphate cement (Harvard) were examined for luting zircon-oxide ceramic crowns (LAVA, 3M ESPE) on extracted human teeth after thermocycling followed by one year of water storage. Method: 100 extracted teeth (n = 10) were prepared in a standardized manner (10°, h = 3mm). The resin cements and the adhesive system were used according to manufacturers' recommendations; in dual-curing systems, only the self-curing approach was conducted. The crowns' inner surfaces were sandblasted (Rocatec Pre). After thermocycling (5000x, 5-55°C) and one year of water storage, the cemented ceramic crowns (Rocatec-pretreatment at the outer surface; bound over a low shrinkage epoxy resin to a resin block, made of Paladur denture base material) were removed along the path of insertion using a Zwick universal testing device. The retention surface was determined individually for each tooth (Dahl & Oilo, Dent Mater 2, 1986). Statistical analysis was made using SPSS 11.0 (Wilcoxon rank test, Bonferroni-adjustment). Results: The retentive strength values [N/mm2] were (Min/Q1/Median/Q3/Max): RelyX Unicem Aplicap: 1.7/2.1/3.4/4.0/4.7, RelyX Unicem Clicker: 3.2/3.6/4.2/4.6/5.5, iCEM: 0.8/2.1/2.7/3.1/3.2, Maxcem Elite:1.7/2.6/3.2/4.0/4.6, Bifix SE: 1.1/1.3/1.7/2.1/2.7, SpeedCEM: 0.9/1.3/1.6/2.2/2.7, Panavia 21: 1.3/2.4/2.5/3.4/3.6, Ketac Cem: 1.0/1.3/1.4/2.3/3.2, Meron Plus: 1.3/1.4/2.7/3.3/4.1, Harvard: 0.8/1.5/1.6/1.7/1.8. Conclusion: The performance of the different self adhesive cements varied significantly within this group. A significantly higher retentive strength can be obtained with particular self adhesive cements compared to glass ionomer or zinc phosphate cement. This study was supported by Heraeus, Ivoclar Vivadent, and VOCO