<![CDATA[Introduction: Hydroxyapatite is widely used in toothpaste formulations because of its biocompatibility and its role in supporting enamel remineralization; however, its direct antimicrobial activity against oral microorganisms remains unclear. This study aimed to analyze the antimicrobial activity of hydroxyapatite toothpaste against Staphylococcus aureus and Candida albicans. Methods: An in vitro experimental study was conducted using the well diffusion method. The tested materials included hydroxyapatite toothpaste at concentrations of 1%, 3%, and 5%, sterile distilled water as a negative control, commercial toothpaste as a positive control, and chloramphenicol 100 ppm and nystatin 5,000 mg/L as comparator controls for S. aureus and C. albicans, respectively. Inhibition zones were measured after incubation for 24 hours at 37 °C. Results: Hydroxyapatite toothpaste at all tested concentrations did not produce inhibition zones against either Staphylococcus aureus or Candida albicans, whereas the comparator controls demonstrated clear inhibitory effects. Statistical analysis using the Kruskal-Wallis test revealed significant differences among treatment groups for Staphylocossus aureus (p = 0.0005) and Candida albicans (p = 0.028). Conclusion: Hydroxyapatite toothpaste did not demonstrate direct antimicrobial activity against Staphylococcus aureus and Candida albicans when assessed using the well diffusion method. These findings indicate that hydroxyapatite is not optimal as a sole antimicrobial agent and should be combined with other active ingredients to enhance antimicrobial effectiveness]]>
