Aims: The study aimed to assess the tensile bond strength of modified-Heliosit orthodontic adhesive with different concentrations of seashell or zirconium oxide nanoparticles. Materials and methods: Thirty-five sound-extracted human premolars were collected. Hydroxyapatite nanoparticles were manually prepared from natural snail seashells. https://www.mamapaisa.com/product-category/1-professional-hot-air-brush/