الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
7- Summary Fiber posts and cores are usually used for the restoration of endodontically treated teeth with extensive coronal destruction. The most common cause of failure of fiber posts is debonding at the adhesive resin- dentin interface as a result of bond deficiency. This study evaluated the effect of self- etch adhesive system, Er,Cr:YSGG laser irradiation and Er,Cr:YSGG laser irradiation followed by self- etch adhesive system on the push out bond strength of fiber posts to radicular dentin.
Fifteen maxillary central incisors roots were endodontically treated and then post spaces were prepared. The roots were divided according to the radicular dentin surface treatment method used into three groups: Optibond XTR self- etch adhesive system, Er,Cr:YSGG laser irradiation, Er,Cr:YSGG laser irradiation followed by self- etch adhesive system (Optibond XTR). After different dentin surface treatments, Dentoclic glass fiber posts were cemented using dual cure resin cement NX3 Nexus. Then each root was sectioned into three sections (coronal, middle and apical) with 2 mm thickness of each section.
Each root section was subjected to push out test using a universal testing machine with a crosshead speed of 0.5 mm/min until failure. The force at which failure occurred was recorded in Newton (N) then push out bond strength was calculated in Mpa.
The mode of failure whether adhesive, cohesive or mixed failure was determined using stereomicroscope at 12.5 magnification. The changes that happened to the radicular dentin surface after different root dentin surface treatments were examined using a scanning electron microscope at 5000 magnification.
The results showed that the group that was treated by self- etch adhesive system had the highest push out bond strength value (10.99±1.58 MPa) followed by the group that was treated by Er,Cr:YSGG laser irradiation followed by self- etch adhesive system (8.92±1.22 MPa), while the group that was treated by Er,Cr:YSGG laser irradiation alone had the lowest bond strength value (7.87±1.23 MPa). Related to different root sections, the coronal and middle sections of the roots had higher bond strength values (10.63±1.66 and 9.46±1.42 MPa) compared to the apical sections of the roots (7.69±1.20 MPa).