| dc.description.abstract | Bonding orthodontic attachments to molars is difficult in the presence of extensive buccal amalgam restorations.so,the aim of this study was to Compare two method of amalgam surface preparations (air abarasion, Er,Cr:YSGG laser) on shear bond strength of orthodontic bracket to amalgam surface. Material and Methods: 54 cylinderical amalgam were prepared and they were divided in to 3 groups after rubber point polishing : Group I: Without any surface preparasion. group II: prepared speciments surface with air abrasion system with 50?m oluminum oxide for 3 seconds, at 60 psi .group III : prepared speciments surface with Er,Cr:YSGG laser irradiation at 1 w pulse- energy and 1mm distance for 5 sec . then premolar brackets were bonded to speciment surface by using panavia F20 resin cement. all speciments were placed in distilled water and stored at 37 C for 24 hours in ancobator. In order to measure shear bond strength by using universal testing machine. debonded speciment failure mode were inspected under a stereomicroscope with amagnification of 16. Shear bond strength data were analysed by ANOVA and Tukey HSD tests. Results: The highest shear bond strength was obtained in laser group (6.303.13) and control group (2.71 1.35) showed the lowest strength. There was a significant difference in shear bond strength in laser and other groups. (for laser and airabrasion P=0.002 and for laser and control group P<0.001) , there is no significant difference between control group shear bond strength and airabrasion group. (P=0.5). Adhesive failure mode was reported in all groups. Conclusion: Amalgam surface preparation with Er,Cr:YSGG laser increase the shear bond strength of orthodontic bracket to Amalgam surface . | |
