The effect of nano hydroxyapatite coating implant surfaces on gene expression and osseointegration

Hironori Kasai, Edmara T.P. Bergamo, Ísis de Fátima Balderrama, Kentaro Imamura, Lukasz Witek, Ernesto B. Benalcázar Jalkh, Estevam A. Bonfante, Kenji Inoue, Paulo Coelho, Seiichi Yamano

Research output: Contribution to journalArticlepeer-review


Background: Hierarchical micro-nano structured topography along with surface chemistry modifications of dental implants have been suggested to positively contribute to the osseointegration process. However, the effect of such surface modifications on the molecular response as well as bone formation rate and quality are still unclear, especially in the early healing period. This study aimed to evaluate the effect of coating a double acid etched (DAE) implant surface with nano-sized (20 nm) hydroxyapatite (Nano) with respect to gene expression, histologic parameters, and nanomechanical properties when compared to DAE control at 1 and 2 weeks after implant placement in a rodent femur model. Material and Methods: Expression of bone-related genes was determined by qRT-PCR (Col-I, Runx-2, Osx, Opn, Ocn, Alp). Histomorphometric evaluation of bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) within implant threads was performed using photomicrographs after histologic processing. Mechanical properties, reduced elastic modulus and hardness, were determined through nanoindentation. Results: At 1 week, the Nano group demonstrated significantly higher expression of Col-I and Ocn compared to the DAE group, indicating upregulation of osteoprogenitor and osteoblast differentiation genes. At 2 weeks, Nano surface further exhibited enhanced gene expression of Col-I and Osx in comparison to the DAE surface, suggesting an increased mineralization of the newly formed bone. Nanoindentation analysis revealed that the Nano group presented no significant difference on the ranks of reduced elastic modulus and hardness compared to DAE for both timepoints. Histomorphometric analysis yielded no significant difference in the percentage of BIC and BAFO between the Nano and DAE surfaces at 1 and 2 weeks. However, Nano implants did present a higher mean value, ~50%, of BIC compared to DAE, ~30%, after 2 weeks in vivo. Conclusions: While no significant differences were observed in the amount and mechanical properties of newly formed bone, nano surface positively and significantly increased the expression osteogenic genes compared to DAE surface at early healing periods.

Original languageEnglish (US)
Article number26303
Pages (from-to)e326-e333
JournalMedicina Oral Patologia Oral y Cirugia Bucal
Issue number3
StatePublished - May 2024


  • Dental implants
  • gene expression
  • histology
  • mechanical properties
  • osseointegration

ASJC Scopus subject areas

  • Surgery
  • Otorhinolaryngology
  • General Dentistry


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