Effect of neck and microthread design of narrow implants on peri-implant bone tissue: A nonlinear finite element analysis.

Purpose: The biomechanical effects of neck shape and microthread design on the bone tissue surrounding narrow-diameter implants (NDIs) were investigated using finite element analysis.

Methods: Fifteen models with different neck designs (including straight, wide, and triangular neck designs as well as smooth necks and four microthread designs with pitches of 0.15 mm, 0.2 mm, 0.25 mm, and 0.3 mm, respectively) were analyzed under a load of 100 N perpendicular to the occlusal plane.

Results: The results showed that the wide neck design (183 MPa, 5447 με) significantly reduced von Mises compressive stresses and bone strains in the implants, enhanced stress dispersion, and reduced cortical bone compressive stresses by 42.8% compared with the straight neck design (320 MPa, 6089 με). Microthreads with a pitch of 0.25-0.30 mm optimized stress distribution and minimized strain concentration.

Conclusion: The findings suggest prioritizing wide necks and 0.25 mm microthread pitch to mitigate the risk of bone resorption.