Comparison of biomechanical anchorage between apatite- and calcium titanate-modified implant surfaces

Implant surface chemistry and microstructure can substantially influence early osseointegration even when overall roughness is comparable. This study compared the surface characteristics, in vitro ion release, and in vivo osseointegration of a calcium titanate (CaTiO₃) nanofilm formed on a sandblasting combined with acid etching (SLA) surface (C surface) and an SLA surface bearing an additional ultrathin apatite nanolayer (A surface).

Implant surface morphology and roughness were evaluated using field-emission scanning electron microscopy, laser confocal microscopy, and contact profilometry. Calcium ion release was quantified using the Arsenazo III colorimetric assay. Eight male mongrel dogs underwent extraction of the mandibular premolars and first molars. After a 3-month healing period, C- or A-surface implants were placed using standardized drilling protocols, and insertion torque was recorded. At 3 and 6 weeks, removal torque (RT) was measured, and histomorphometric analysis was performed to calculate the proportion of the implant surface in direct contact with newly formed bone.

Both surfaces exhibited moderately rough micro- and nanostructured topographies with similar roughness parameters. However, calcium ion release was significantly greater from the A surface. RT was also significantly higher for the A surface than for the C surface at both 3 and 6 weeks.

Despite similar macrodesign and overall roughness, an ultrathin apatite nanolayer can accelerate early interfacial strengthening without altering midterm osseointegration.