<p>Composite fillings, which are widely used today with their aesthetic advantages, constitute the main subject of our study. In this study, it was investigated how Antep pistachio shells added as micro-sized powder to composite fillings affected the mechanical properties of composite fillings. The Antep pistachio shell powders with biocompatibility were added to existing composite filling materials at 15%, 20% and 25% by weight. The samples were subjected to hardness test, vertical compression test and horizontal compression test. Maximum theoretical tensile loads were determined with the values obtained as a result of the horizontal compression test. Additionally, SEM images were also taken to examine the distribution of micro-sized powders added to composite fillers. Increasing the content of micro-sized powders leads to a reduction in the strength of the produced samples.</p> Graphical abstract <p></p>