Quantitative biomechanical analysis of the influence of the cortical bone and implant length on primary stability

Abstract

The aim of the study was to investigate the influence of cortical bone and increasing implant fixture length on primary stability. Further investigation considered the correlation between the presence of cortical bone at the marginal bone and implant stability measured by insertion torque (IT) and resonance frequency analysis (RFA), as well as implant length, were determined. Two different types of polyurethane bone models were compared. (Group 1: with cortical and cancellous bone; Group 2: with cancellous bone only). A total of 60 external type implants (∅ 4.1, OSSTEM(®), US II(®)) with different lengths (7, 10, and 13 mm) were used. IT was recorded automatically by a computer which was connected to the Implant fixture installation device during the placement. RFA was conducted to quantify the primary implant stability quotient (ISQ). All two measurements were repeated 10 times for each group. All these differences were statistically significant between the two groups (P < 0.001) and intragroups (P < 0.001). Upon comparing the IT, cortical bone appears to have a greater influence on implant stability than implant lengths, whereas the RFA value strongly affects implant length rather than the presence of the crestal cortical bone. The quantitative biomechanical evaluations clearly demonstrated that primary implant stability seems to be influenced by the presence of a cortical plate and total surface area of the implant fixture appears to be the decisive determinant for ISQ value.