Evaluation of the osseointegration of dental implants coated with calcium carbonate: an animal study

Abstract

In an attempt to overcome the limitations of titanium in dental and orthopaedic clinical applications, a new method has been developed to prepare calcium carbonate coatings on sandblasted and acid-etched (SA) titanium implants. The purpose of this study was to investigate the effect of calcium carbonate-SA (CC-SA) implants on osseointegration in vivo. The surfaces of SA and CC-SA implants were characterised for surface morphology and surface chemistry. Subsequently, these two kinds of implants were implanted in the femoral condyles of rabbits. The implants were retrieved and prepared for histological and histomorphometric evaluation 1, 2, 4, 8 and 12 weeks after implantation. Significantly higher values of bone-to-implant contact of the entire implant except the gap area (BIC_ALL) and the bone-to-implant contact of the gap area (BIC_GAP) were found in animals with the CC-SA implants than in those with the SA implants at 4 weeks. Higher values of total gap bone were found in those with the CC-SA implants than in those with the SA implants at 1, 2 and 4 weeks. In conclusion, the current findings demonstrate that the calcium carbonate coating can improve and accelerate the early ingrowth of bone and osseointegration at the early healing phase. This may reduce clinical healing times and thus improve implant success rates.

Figure 1

Illustration of the experimental setup for preparation of the calcium carbonate coating on the SA implant surface. Two vials—one containing a 20 mmol·L⁻¹ CaCl₂ solution, the other containing ammonium carbonate powder—were placed in a desiccator. SATi implants were placed vertically in the CaCl₂ solution. CaCl₂, calcium chloride; SATi, sandblasted and acid-etched titanium.

Figure 2

Field-emission scanning electron microscope micrographs showing the surface topography of the tested titanium implants. (a) SATi; (b) CC-SATi. CC-SATi, calcium carbonate-SATi; SATi, sandblasted and acid-etched titanium.

Figure 3

Fourier transform infrared spectra of CaCO₃ crystals deposited on the sandblasted and acid-etched titanium surface.

Figure 4

Light micrographs of bone–implant interfaces. SA implants implanted in rabbits at 1 (a), 2 (b), 4 (c), 8 (d), 12 weeks (e) and CC-SA implants implanted in rabbits at 1 (f), 2 (g), 4 (h), 8 (i), 12 weeks (j). Basic fuchsin and methylene blue staining, × 20. Scale bar=100 μm. CC-SA, calcium carbonate-SA; SA, sandblasted and acid-etched.

Figure 5

Light micrographs of the gaps. SA implants implanted in rabbits at 1 (a), 2 (b), 4 (c), 8 (d), 12 weeks (e) and CC-SA implants implanted in rabbits at 1 (f), 2 (g), 4 (h), 8 (i), 12 weeks (j). Basic fuchsin and methylene blue staining, × 20. Scale bar=100 μm. CC-SA, calcium carbonate-SA; SA, sandblasted and acid-etched.

Figure 6

Bone-to-implant contact, expressed as the percentage of implant length showing a direct bone-to-implant contact without any intervening soft tissue layer. The parameter was further differentiated into (a) the percentage of bone-to-implant contact of the entire implant except the gap area (BIC_ALL) and (b) the percentage of bone-to-implant contact of the gap area (BIC_GAP). Error bars represent means±standard deviation for n=6. *P<0.05, **P<0.01. CC-SA, calcium carbonate-SA; BIC, bone-to-implant contact; SA, sandblasted and acid-etched.

Figure 7

Bar graph showing the percent bone area at a distance of 0.5 mm from the implant surface except the gap area (BT05). Significant differences were not found between CC-SA and SA implants. Error bars represent means±standard deviation for n=6. CC-SA, calcium carbonate-SA; SA, sandblasted and acid-etched.

Figure 8

Bar graph showing the amount of bone inside the gap between the implant and the cancellous bone. The TGB in the CC-SA implants was significantly higher than in the SA implants at 1, 2 and 4 weeks. Error bars represent means±standard deviations for n=6. *P<0.05, **P<0.01. CC-SA, calcium carbonate-SA; SA, sandblasted and acid-etched; TGB, total gap bone.