Interaction Between Implant Macrogeometry and Osteotomy Preparation on Immediate Mechanical Fixation and Regional Thread Alterations: An Ex Vivo Biomechanical Study

Immediate implant mechanics may depend on the interaction between implant macrogeometry and osteotomy preparation, but their combined influence on complementary measures of immediate fixation and regional thread alterations remains insufficiently characterized. This ex vivo study evaluated two implant macrogeometries and four osteotomy techniques in 80 bovine rib specimens (n = 10 per group). Reverse torque resistance remained the primary mechanical outcome; prospectively recorded insertion torque and resonance frequency analysis (implant stability quotient [ISQ]) were incorporated in the revision as complementary immediate mechanical outcomes. Thread alterations were assessed qualitatively after removal in the cervical, body, and apical regions. Insertion torque was significantly influenced by macrogeometry and preparation technique, without a significant interaction. Reverse torque resistance showed significant effects of macrogeometry, preparation technique, and their interaction (all p < 0.001). ISQ showed a significant macrogeometry-by-technique interaction. Insertion torque correlated strongly with reverse torque resistance (r = 0.645, p < 0.001), whereas ISQ showed a more moderate association (r = 0.370, p < 0.001), supporting related but non-interchangeable mechanical constructs. Cervical alterations were mainly associated with undersized drilling, whereas apical alterations occurred predominantly in the Quattro design; none were observed in the implant body. External surface temperature showed no overall change or consistent technique-dependent increase. Under these experimental conditions, implant macrogeometry and osteotomy preparation acted as interdependent determinants of immediate mechanical behavior and were associated with distinct regional patterns of post-removal, visually detectable thread alterations.