In itro retentive strength of self-adhering cements to zirconium-oxide crowns

Objectives: The retentive strength of a resin cement in combination with a new but conventional type adhesive (XP Bond-SCA-Calibra/DENTSPLY), five self adhering cements (RelyX Unicem Aplicap, RelyX Unicem Clicker/3M ESPE, Maxcem/sds Kerr, Multilink Sprint/Ivoclar (2x), exp. cement/DENTSPLY), two glass ionomer-cements (Ketac Cem/3M ESPE, Meron/VOCO) and a resin modified glassionomer-cement (Meron Plus/VOCO) were examined for luting zircon-oxide ceramic crowns (LAVA, 3M ESPE) on extracted human teeth.

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 (5000 x, 5-55°C), the cemented ceramic crowns (Rocatec-pretreatment at the outer surface; connected over a low shrinkage epoxy resin to macro-mechanical undercuts in a resin block, made out 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 the SPSS 11.0 program (Wilcoxon rank test, Bonferroni-adjustment).

Results: The retentive strength values [N/mm2] were (Min/Q1/Median/Q3/Max): RelyX Unicem Aplicap: 1,8/2,6/3,6/4,3/4,7 RelyX Unicem Clicker: 1,1/2,0/2,2/2,9/6,7; Multilink Sprint – trial #1: 0,5/0,6/0,7/1,2/2,3; Multilink Sprint – trial #2: 0,8/1,3/1,4/1,5/4,8; Maxcem: 0,6/0,9/1,3/1,6/2,3; Exp. cement DENTSPLY: 0,8/1,3/2,4/3,1/4,8; Ketac Cem: 0,2/1,0/1,8/2,2/3,0; Meron: 1,1/1,8/2,0/2,3/3,1; Meron Plus: 2,0/2,5/3,7/5,0/7,4; XP Bond/SCA/Calibra: 0,8/2,2/2,5/3,4/5,0. RelyX Unicem Aplicap and Meron Plus showed statistically significant higher median retentive strength than Multilink Sprint and Maxcem (p < 0.0005)

Conclusion: Meron Plus and RelyX Unicem showed the highest median retentive strength values. The group of self adhering cements showed a wide variety in retentive strength.

This study was supported by Ivoclar Vivadent, 3M ESPE, VOCO, and DENTSPLY