Bond strength of primer/cement systems to zirconia subjected to artificial aging.
BACKGROUND
Creating reliable and durable adhesion to the nonactive zirconia surface is difficult and has limited zirconia use. The introduction of functional monomers such as 10-methacryloyloxydecyl dihydrogen phosphate (MDP) appears to have enhanced bond strength to zirconia.


OBJECTIVE
The purpose of this in vitro study was to evaluate the long-term bond strength of several MDP-containing primer/cement systems to zirconia.


METHODS
Zirconia blocks were divided into 6 groups (n=24) according to the 3 primers/cements to be bonded, as follows: Scotchbond Universal/RelyX Ultimate (SU/RU; consisting of MDP-containing primer/MDP-free cement); Clearfil ceramic primer/Panavia F (CCP/PAN; consisting ofMDP-containing/MDP-containing); and Z-Prime Plus/Duo-Link (ZP/DUO; consisting ofMDP-containing/MDP-free), which were compared with 3 nonprimed groups, RU, PAN, and DUO. After bonding, each group was further divided into 3 subgroups (n=8) according to the level of aging: 24-hour storage in water at 37°C (24H); 30-day storage at 37°C (30D); and 30-day storage at 37°C followed by 3000 thermal cycles (30D/TC). After aging, a shear bond strength test and failure mode analysis were performed. The data were analyzed using 2-way ANOVA (α=.05).


RESULTS
After aging, nearly all primer/cement groups presented significantly higher bond strength than the related nonprimed groups for each level of aging (P<.05), except for CCP/PAN versus PAN with 24H (P=.741). SU/RU had the highest bond strength among the groups for all treatments (P<.05), except for CCP/PAN versus SU/RU with 30D/TC (P=.171). Among the nonprimed groups, only RU went through 30D/TC without premature debonding. With 24H and 30D, the failure modes in SU/RU and CCP/PAN were purely mixed, whereas those in the other groups were mainly adhesive, except for RU.


CONCLUSIONS
The superiority of the initial bond strength in SU/RU may result from some functional components other than MDP. The presence of MDP in the cement did not appear to have a positive effect on long-term bond strength to zirconia.
Staff Dentist, Department of Prosthodontics, Guanghua School of Stomatology, Sun Yat-sen University, and Guangdong Engineering Research Center of Technology and Materials for Oral Reconstruction, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China.
Li
L
Zhao
Associate Professor, Institute of Stomatological Research, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China.
Yu-Tao
YT
Jian
Staff Dentist, Department of Prosthodontics, Guanghua School of Stomatology, Sun Yat-sen University, and Guangdong Engineering Research Center of Technology and Materials for Oral Reconstruction, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China.
Xiao-Dong
XD
Wang
Professor, Department of Prosthodontics, Guanghua School of Stomatology, Sun Yat-sen University, and Guangdong Engineering Research Center of Technology and Materials for Oral Reconstruction, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China. Electronic address: zhaoke@mail.sysu.edu.cn.
Ke
K
Zhao
D001840:Dental Bonding; D003799:Dental Stress Analysis; D008422:Materials Testing; D008689:Methacrylates; D019279:Resin Cements; D033081:Shear Strength; D013499:Surface Properties; D015040:Zirconium
D008689:Methacrylates; D019279:Resin Cements; D015040:Zirconium; C028541:zirconium oxide