Using air polishing with sodium bicarbonate powders with grain size 65 µm provides efficacy in the removal of dental stains but it can cause gingival trauma if used towards the gingiva. Since having big size particles is uncomfortable, the current recommendation according to literature is to use a smaller grain size (40 µm) that results in more patient comfort. However, the efficacy of small grain size on stain removal has not been studied adequately. This study aimed to compare the stain removal efficacy between sodium bicarbonate powders with grain size 65 µm and 40 µm and also to evaluate patient's acceptance after treatment and operator's opinion after using both air polishing powders.