a comparative study between bond strength of rebonded and recycled orthodontic brackets

introduction a large number of orthodontists prefer to rebond the failed bonded brackets or use recycled brackets in some instances. the aim of this study was to compare the shear bond strength of rebonding with using recycled brackets on enamel surface. methods bonding of brackets on the surface of extracted first bicuspids was tested in five different groups to compare their shear bond strength (sbs): group n, new bracket on enamel surface of newly extracted teeth as a control group; group r, recycled bracket on newly extracted teeth; group nr, new bracket on the cleaned enamel surface of previously bonded teeth with tungsten carbide bur; group re, reused bracket on cleaned surface of previous teeth; and rr group, with brackets undergone two times of recycling on the newly extracted bicuspids. adhesive remnant index was specified for each group. results the highest sbs was related to control group (group n) which rated as 12.00 mpa, and the next scores were related to groups nr, re, rr, and r with 11.85, 10.80, 10.00 and 9.94 mpa, respectively. the differences between groups n and nr with groups r and rr were significant. discussion rebonding had no significant effect on reduction of sbs. tungsten carbide burs are suitable for removing of remaining composite from brackets and enamel surface and finally, chemically recycled brackets had a clinically acceptable sbs. key words bracket, chemical recycling, shear bond strength