Shaimaa Mostafa Omar, Mohamed Farag Ayad And Mohammed Sedikk Mohammed,

ABSTRACT
Statement Of Problem: Most Clinical Failures Of Endodontically Treated Teeth Restored With Dowels Are The Result Of Cementation Failure At The Resin / Dentin Interface. Purpose : This In-vitro Study Evaluates The Influence Of Reinforced Dental Adhesive On Push-out Bond Strength Of Glass Fiber Dowels. Materials And Method: Thirty Freshly Extracted Human Upper Central Incisors Were Selected. All Root Canals Were Instrumented, Obturated And The Dowel Space Was Prepared To Depth 9 Mm. The Specimens Were Classified Into Two Groups According To Cementation Technique Of The Dowels. Group I: Self-etch Adhesive Cement. Group II: Self-etch Adhesive Cement With Bond Incorporate With Hydroxyapatite Nanoparticles. Relyx? Ultimate Resin Cement Was Used For Dowels Cementation. From Each Specimen, 3 Dowel/dentin Sections Were Obtained, Each 1-mm Thick. Three Sites Along The Root Were Evaluated (cervical , Middle And Apical). Specimens Were Submitted To Push-out Bond Strength Test Using A Computer Controlled Materials Testing Machine With A Load Cell Of 5 KN And Loaded At A Crosshead Speed Of 0.5 Mm/min. Data Were Analyzed With One-way Analysis Of Variance (ANOVA) And Independent T-test (? =0.05).

Results: The Bond Strength Of Fiber Dowels Affected By Hydroxyapatite Nanoparticles Incorporation. It Was Found That Experimental Group Recorded Statistically High Significant Mean Value (10.3?2.5 MPa) Than Control Group (8.3 ? 1.6 MPa) As Indicated By Independent T-test. Conclusion: Incorporation Of Hydroxyapatite Nanoparticles In Self-etch Adhesive System Increase Push Out Bond Strength Of Fiber Dowels In Comparison To Conventional Type.