Bonding Reliability of All-in-one Adhesive Systems with/without Thermo-mechanical Cyclic Stress

Objectives: The purpose of this study was to examine the bonding reliability of three all-in-one adhesive systems, two latest experimental systems; EXL759(EXL, 3M ESPE) and MTB200(MTB, KURARAY), and a system on the market; Adper Easy Bond(EB, 3M ESPE), as compared with that of a self-etching adhesive system; Clearfil SE Bond(SE, control, KURARAY).

Methods: Standardized V-shaped cavity was prepared in the cervical region of 80 extracted human premolars. The cavities were pretreated with the four systems(20 each) and then restored clinically according to the manufacturer’s instructions. A half of the restored specimens were subjected to thermo-mechanical cyclic stress condition simulating oral environment; thermocycling(5ºC/55ºC×2,000 sets) and simultaneous repeated-load(12kgf×10⁵ times). Another half of specimens were supplied as non-stress control group. Micro-tensile bond strengths(µ-TBS) to the gingival dentin wall of the specimens with and without the stress were measured. The data of µ-TBS(n=20) were examined using Tukey’s q-test and Weibull analysis. 

Results: Mean µ-TBS(s.d.) in MPa and [Weibull modulus value; Wm] of the specimens with/without the stress were EXL;21.7(3.7)[4.5]/23.3(3.9)[5.7], MTB;21.1(3.2)[4.4]/22.2(5.0)[3.5], EB;26.9(8.4)[2.7]/27.8(5.0)[4.3], SE;14.8(5.5)[2.5]/22.0(5.7)[2.9]. The µ-TBS of all-in-one systems was not influenced by the stress mode. The µ-TBS without stress of EXL and MTB were similar to that of SE, but the values with stress of the two systems were greater than that of SE at p<0.01. Wm without stress of all-in-one systems were similar to or greater than Wm of SE. Wm with stress of EXL and MTB were greater than the values of SE and EB at p<0.01. The µ-TBS with stress at 10% and 90% probability of failure levels of all-in-one systems were greater than that of SE at p<0.05.

Conclusions: The bonding reliability of three all-in-one systems was superior to SE. Especially latest experimental adhesive systems; EXL and MTB demonstrated stable and high-rated bonding reliability even under a severe stress condition simulating oral environment.