الفهرس 
Title PageOnly 14 pages are availabe for public view
 |  | from | 151 |  |  |
| | | from | 151 | | |
Abstract
Background: Increasing the retention of zircon restorations depending on the micro roughness of the fitting surface of zirconia crowns. There are several methods to achieve this purpose such as sandblasting, chemical bonding, acid etching, and the recently applied method is laser treatment for zirconia. Objectives: This study evaluated the surface roughness of zirconia treated with erbium-doped yttrium aluminum garnet 2,940 nm (Er-YAG) and Erbium chromium: yttrium scandium gallium garnet 2,780 nm (Er, Cr: YSGG), and shear bond strength evaluation and finally bonding failure type assessment. Materials and Methods: ninety-nine disc-shaped Zirconia specimens (10 mm in diameter and 5 mm in thickness) were fabricated by a computer-aided design and computer-aided manufacturing (CAD/CAM) system according to the manufacturer’s instructions. Samples were divided into nine groups (n = 10 +1). One group as a control, which was airparticle abraded with Al2O3 particles. For the laser treatment groups, the two types of lasers irradiation were applied at two different pulse length long pulse and ultra-short pulse and for each two different scanning times 15 sec and 60 sec Surface roughness was evaluated with contact profilometer and specimens were evaluated with scanning electron microscopy (SEM). The specimens were cemented to composite resin discs with dual cure adhesive resin cement, then shear bond strength was measured for the cemented samples, also type of bond failure was assessed as cohesive or adhesive failure. Data were analyzed by ANOVA test. Results: Sandblasting was more effective method for zirconia roughness than the laser roughness. There was no significance difference between the two laser types for zirconia etching. Regarding to shear bond strength, there was no significance difference between the two laser types and the sand-blasting groups. Conclusion: Laser etching could be alternative method like the sandblasting for increasing surface irregularities of zirconia restoration enhancing the retention.