background and aims. the aim of this study was to compare shear bond strength (sbs) of metal and ceramic brackets bonded to enamel using acid versus er:yag laser etching. materials and methods. eighty premolars were divided into 4 groups: am (acid etching/ metal brackets), ac (acid etching/ ceramic brackets), lm (laser etching/ metal brackets) and lc (laser etching/ ceramic brackets). enamel co...