Biomechanical evaluation of laser-etched Ti implant surfaces vs. chemically modified SLA Ti implant surfaces: Removal torque and resonance frequency analysis in rabbit tibias

Abstract

Purpose: To compare osseointegration and implant stability of two types of laser-etched (LE) Ti implants with a chemically-modified, sandblasted, large-grit and acid-etched (SLA) Ti implant (SLActive(®), Straumann, Basel, Switzerland), by evaluating removal torque and resonance frequency between the implant surface and rabbit tibia bones. We used conventional LE Ti implants (conventional LE implant, CSM implant, Daegu, Korea) and LE Ti implants that had been chemically activated with 0.9% NaCl solution (LE active implant) for comparison with SLActive(®) implants

Materials and methods: Two types of 3.3×8mm laser-etched Ti implants - conventional LE implants and LE active implants were prepared. LE implants and SLActive(®) implants were installed on the left and right tibias of 10 adult rabbits weighing approximately 3.0kg LE active implants and SLActive(®) implants were installed on the left and right tibias of 11 adult rabbits. After installation, we measured insertion torque (ITQ) and resonance frequency (ISQ). Three weeks (LE active) or 4 weeks (conventional LE) after installation, we measured removal torque (RTQ) and ISQ.

Results: In the conventional LE experiment, the mean ITQ was 16.99±6.35Ncm for conventional LE implants and 16.11±7.36Ncm for SLActive(®) implants (p=0.778>0.05). After 4 weeks, the mean of RTQ was 39.49±17.3Ncm for LE and 42.27±20.5Ncm for SLActive(®) (p=0.747>0.05). Right after insertion of the implants, the mean ISQ was 74.8±4.98 for conventional LE and 70.1±9.15 for SLActive(®) implants (p=0.169>0.05). After 4 weeks, the mean ISQ was 64.40±6.95 for LE and 67.70±9.83 for SLActive(®) (p=0.397>0.05). In the LE active experiment, the mean ITQ was 16.24±7.49Ncm for LE active implants and 14.33±5.06Ncm for SLActive(®) implants (p=0.491>0.05). After 3 weeks, the mean RTQ was 39.25±16.41Ncm for LE active and 41.56±10.41Ncm for SLActive(®) implants (p=0.698>0.05). Right after insertion of the implants, the mean ISQ was 58.64±10.51 for LE active implants and 53.82±15.36 for SLActive(®) implants (p=0.401>0.05). After 3 weeks, the mean ISQ was 63.82±5.88 for LE active and 66.27±6.53 for SLActive(®) (p=0.365>0.05).

Conclusion: We observed no significant differences in biomechanical bond strength to bone or implant stability in bone between the conventional LE Ti implant surface and the surface of the SLActive(®) implant or between the chemically activated LE Ti implant surface and the surface of the SLActive(®) implant during the early stage of osseointegration.

Keywords: Chemically modified surface; ISQ; Laser-etched; Removal torque; SLA; Surface analysis.