Objectives: The aim of this study is to compare the initial stability of three types of implants (i.e. Neodent Titamax CM EX (EX), Straumann Bone Level (STRM) and Nobel ACTIVE (ACTIVE)) using standard high (HD)- and low (LD)-density bone cylinders of swine origin through resonance frequency (RFA) and micro computed tomography (Micro CT) analyses. 
Material and Methods: HD bone cylinders were removed from the femoral head, while LD bone cylinders were removed from the mandibular condyle. Prior to the experiments, the bone cylinders were certified by three-dimensional imaging analysis to ensure uniformity and intra-group differentiation between specimens. After certification, the bone cylinders were scanned by micro CT at two different regions (D1 and D2). The implants were installed, and RFA measurement was performed following micro CT of the same regions of the cylinders.
Results: The RFA analysis results of both HD and LD bone showed ISQ (Implant Stability Quoficient) values higher than 60 and an ISQ trend of EX > STRM > ACTIVE for both cases (p < 0.05). In the within-group comparison of EX and STRM, LD bone > HD bone (p < 0.05), while for Active, LD = HD (p > 0.05). Micro CT parameters showed a pattern of bone compression primarily in areas in contact with the implant threads of EX and STRM in HD bone. Bone compression appeared to occur at a distance of 0.5 mm from the surface of the implants, especially when STRM was implanted into both HD and LD bone. 
Conclusions: The macrostructure of the implant may influence the occurrence of bone compression directly below its surface, as the distance too, may increase the primary stability.

Micro CT and resonance frequency analysis of the levels of alteration of trabecular morphology and primary stability of implants installed in different bone types.