Influence of thermal and mechanical load cycling on the microtensile bond strength of self-etching adhesives.
OBJECTIVE
To evaluate the influence of thermal and mechanical load cycling on the microtensile dentin bond strength of two self-etching and one total-etch adhesives.


METHODS
The adhesive materials were: a two-step self-etch adhesive (Clearfil SE Bond), a one-step self-etch adhesive (Hybrid Bond), and a total-etch one-step adhesive (Admira Bond). Sixty freshly extracted human third molars were used. In each tooth, a Class I cavity (4 x 4 mm) was prepared in the occlusal surface with the pulpal floor extending about 1 mm into dentin. The teeth were divided into three groups (n=20). Each group was restored with the resin composite Clearfil APX using one of the adhesives. After restoration, 10 teeth in each group were thermocycled between 5 degrees C and 55 degrees C, (dwell time 3 minutes, 5,000 cycles). The same teeth were then mounted in a fatigue loading machine to receive an intermittent load of 125 N at 52 cycles/minute for 4,000 cycles. Subsequently, each tooth was sectioned longitudinally, bucco-lingually and mesio-distally to get rectangular slabs 1-1.2 mm in thickness for the microtensile test. Each slab was then placed in a universal testing machine and tensile load was applied at a cross-head speed of 0.05 mm/minute.


RESULTS
Without loading procedures, there was no significant difference in the bond strength of the tested adhesives. In contrast to Admira Bond and Clearfil SE Bond, fatigue loading resulted in a significant reduction of the bond strength for Hybrid Bond when compared to the unloaded restorations.
Abdalla
Ali I
AI
Department of Restorative Dentistry, Faculty of Dentistry, University of Tanta, Tanta, Egypt. aliebraheem01@yahoo.com
El Zohairy
Ahmed A
AA
Aboushelib
Moustafa M N
MM
Feilzer
Albert J
AJ
D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D019279:Resin Cements / Q000737:chemistry*; D018709:Statistics, Nonparametric; D013718:Tensile Strength; D016474:Weight-Bearing
C438313:Clearfil SE Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C514345:Hybrid Bond; D019279:Resin Cements; C479085:admira bond