Effect of placement angle on the stability of loaded titanium microscrews: a microcomputed tomographic and biomechanical analysis.

Introduction: The aim of this study was to evaluate the impact of the placement angle on the stability of loaded microscrews.

Methods: Forty-eight microscrews were placed at 4 angles ( 30°, 50°, 70°, and 90°) into the tibiae of 12 beagles, loaded with a force of 2 N immediately, and maintained for 8 weeks. Microcomputed tomography and pullout tests were used for morphometric and biomechanical analyses, respectively.

Results: All microcomputed tomography parameters and the peak loads at extraction of the microscrews were influenced by the placement angles of the microscrews. The higher microcomputed tomography parameters and the peak load at extraction were measured at angles from 50° to 70°. Oblique and vertical placement angles resulted in reduced stability of the loaded microscrews (P <0.05).

Conclusions: To achieve the best stability of microscrews, a placement angle of 50° to 70° is advisable.