Effect of diamond bur cutting efficacy on dentin bond strength

Objectives:To compare the shear bond strength (SBS) of two adhesives to human dentin prepared with new or used rough diamound bur. Methods:sixty caries free human 3rd molar were sectioned in occlusal surface to expose dentin , then pulished with silicon carbide paper and randomly devided into four groups.Each qroup was cutted in a depth of 0.5 mm of dentin,using new diamound bur , or used diamound bur.To change into a used bur , each new rough diamound bur had to work on bovine enamel for 30 minutes , under a load of 150g.After that , each group was bonded , using a total etch adhesive (single Bond) or a self etch adhesive (clearfil SE Bond) So there were 4 groups : 1-SE Bond , New bur ; 2-SE Bond , used bur ; 3-Single Bond , New bur ; 4-Single Bond , used bur .Unique composite capsules were bonded to dentin surface and cured . specimens were stored in physiologic serum for 48h at 37 c , then put under shearing load to define composite – dentin SBS . Results were interpreted via statistical analysis (T-test & two – way variance) Results:SBS of each group was as follows : 1-(27.3Mpa),2-(33.5Mpa),3-(16.9Mpa) 4-(19.3Mpa) . statistica analysis proved that SBS of used diamond bur groups (2,4) was more than new diamond bur ones (1,3). This statistical difference, specially, was seen between SE Bond groups but not between single Bond groups .Also , SBS of (SE Bond ) bonded groups were more than single Bond bonded ones. Conclusion:Bur cutting efficiency influences composit – dentin SBS specially when the adhesive is SE Bond (used bur> new bur) Also type of adehesive affects on commpostie – dentin SBS . (SE Bond > Single Bond)