Titanium migration and bone response in loaded osseointegrated implants: ESEM-EDX analysis in Macaca fascicularis

Titanium nanoparticle (TP) migration into peri-implant bone may influence osseointegration. It remains unclear how loading protocols may affect TP distribution. This study aimed to detect TP in the bone around implants undergoing different loading protocols in Macaca fascicularis.

Nine histological samples containing 21 implants with two loading groups were analyzed. In the delayed-loaded (DL) group (n = 16), the implants were loaded after 3 months and retrieved after 3 months, and in the immediately loaded (IL) group (n = 5), they were loaded on the day of surgery and retrieved after 3 months. Environmental scanning electron microscopy (ESEM) grayscale-level detection and energy-dispersive X-ray spectroscopy (EDX) microchemical analysis were used to assess TP and bone mineralization. Regions of interest (ROI) located at the implant coronal/apical portion (100×) and at the bone-implant interface (1000×) were selected. Bone area distribution (mean% ± SD%) and titanium content were analyzed using two-way analysis of variance (ANOVA) (p < 0.05).

Titanium granules (2-10 µm) were detected in all regions, with a higher prevalence in the coronal portions of DL implants. In IL implant sections, bone closer to the implants showed a lower prevalence of titanium (p < 0.05). EDX analysis demonstrated a decreasing trend in titanium from the nearest areas to those more distant (up to 2.0 mm). DL implants exhibited lower percentages of mineralized bone compared to IL implants in the coronal portion (mean values 31.0 ± 13.7 and 11.6 ± 2.8) (p < 0.05). IL implants showed a higher percentage of mineralized bone (p < 0.05) in the apical region (mean values 51.8 ± 15.5 and 32.2 ± 15.6).

TP were widely present in bone tissues adjacent to the implant surface, particularly at the coronal bone. In the coronal portion of the DL group, a less mineralized bone area was observed compared to the IL group, suggesting higher bone remodeling activities.

Titanium particles were widely present in bone tissues adjacent to the implant areas, with greater distribution observed in regions experiencing significant wear (i.e., the coronal portion of the cortical bone), likely due to surgical insertion and related procedures.