The laser has been used as an alternative effective method of etching enamel surface for direct bonding of orthodontic brackets instead of phosphoric acid. The aim of this study was to compare shear bond strength of orthodontic brackets following Er-
YAG versus Nd-YAG Laser etching. Eighty human extracted upper premolars were collected and divided randomly into two equal groups; the buccal enamel surface of the first group was etched by Er-YAG laser while the second group was etched by Nd-YAG laser. Each group was divided into two equal subgroups according to the bonding material type (chemical cure resin or light cure resin). The mechanical test has occurred by using a universal testing machine (Instron). The finding showed that no statistically significant differences in mean of shear bond strength between (Nd-YAG, Er-YAG) Laser etching group were found regardless of the bonding type.
