surface morphology and mechanical properties of extracted teeth after coating with nanohydroxyapatite and graphene oxide

Objective: this study evaluated surface morphology and compressive strength of teeth after application of a bioactive coating composed of nanohydroxyapatite (nha), graphene oxide (go), and calcium carbonate (caco₃). methods: twelve human teeth were collected and divided into two groups (n=6). the test group was coated with the bioactive mixture of nha, go, and caco₃, while the control group remained uncoated. the coating was applied to cleaned tooth surfaces using the dip-coating method. the surface morphology of the coated teeth was examined after immersion in simulated body fluid (sbf) for 14 and 21 days using high-resolution scanning electron microscopy (hrsem). the compressive strength and elastic modulus of teeth were measured with an instron machine. an independent samples t-test was used to compare values between groups, with significance set at p<0.05.results: coated teeth showed a rough and dense surface after sbf immersion, suggesting enhanced surface interactions and an increased potential to support mineral nucleation. the average thickness of the bioactive coating was 14.4 ± 1.2 μm. coated teeth showed significantly higher compressive strength than uncoated specimens (p=0.01). the elastic modulus of coated teeth (65.20 ± 12.56 gpa) was lower compared to uncoated teeth (69.50 ± 10.11 gpa), but this difference was not statistically significant (p=0.53).conclusions: the bioactive coating of nha, go, and caco₃ significantly increased the compressive strength of teeth while having no significant effect on their elastic modulus. given its potential ability to enhance surface interactions and promote mineralization, this coating method shows promise for applications of tooth particles in ridge preservation and bone regeneration.