Abstract:

Objective   To evaluate the influence of different endodontic irrigants (5.25%NaClO & 15%EDTA, distilled water and 0.2% chlorhexidine) on the micropush-out bond strength of an adhesive system used to cement glass fiber posts to dentin. Methods   Thirty single root canal premolar teeth were selected and their dental crowns were cut 2mm above the cementum line.After general root canal filling preparation,they were divided into 3 groups according to the solution used during instrumentation: group A: 5.25%NaClO & 15%EDTA；group B：Distilled water (control group); group C: 0.2% chlorhexidine. The glass fiber posts-POPO were cemented with Clearfil DC Bond. The specimens were submitted to micropush-out strength testing and the results were analyzed. The dentin-cement-post adhesive interface of each specimen and failure modes were evaluated by stereomicroscope observation. Results   There were statistically significant differences regarding the irrigant solution factor. The group C（5.58±0.49）MPa resulted in significantly higher shear bond strengths than group A(3.31±0.46) MPa, (P＜0.05); and resulted in higher shear bond strengths than group B（2.06±0.26）MPa (P＜0.001). Interface morphology observed by stereomicroscope indicated that almost all specimen failure modes focused on mixed type. Conclusion   Different irrigant solutions affect the micropush-out bond strength of the fixation system used to cement the glass fiber posts.2. 2% chlorhexidine can be used for obtaining an effective adhesion to root canals. Interface morphology observed by stereomicroscope indicated that almost all specimen failure modes mostly focus on mixed type.

Key words: Fiber post; Wash;Shear bond strength; Interface morphology