Implant macro-design and primary stability, an ex vivo study

The aim of the study was to compare the impact of three different implant macro-designs on the primary stability. 25 cylindrical non self-tapping implants (Straumann® SP/TL), 30 hybrid self- tapping implants (Straumann® BL) and 30 tapered selftapping implants (Straumann® BLT) with the same diameter and length (4.1/10mm) were inserted randomly in 30 different bone bloc types on beef ribs. The assessment of the primary stability was carried out by recording the maximum insertion torque IT (DTA device) and the implant stability quotient ISQ using the resonance frequency analysis RFA (with the Osstell device) for each implant design in a same quality of bone. In all bone types mingled, BLT implants showed significantly higher mean insertion torque when compared to TL and BL with respectively 59.97, 48.82 and 31.06 (p<0.0001 each as per the Anova test) and higher mean ISQ with respectively 85.17, 81.60 and 80.67 (p<0.0001 each as per the Anova test). These higher values for the BLT were very important in bone type II and III. Within the limitation of this study, the tapered self-tapping implant (Straumann® BLT), showed a better primary stability in all types of bone which promises its indication in immediate placement and loading and in immediate loading in soft bone.The two methods used to assess the primary stability of the different implant macro-designs, the maximum insertion torque and the resonance frequency analysis, showed a weak correlation. Further clinical studies are required to better evaluate the different biological responses to this enhancement of the primary stability.