Abstract
OBJECTIVES: To investigate the biomechanical behavior of three distinct types of narrow-diameter implants (NDIs) supporting a single-cantilever fixed bridge for mandibular central incisors using three-dimensional finite element analysis. METHODS: Three commonly used NDIs were selected: group Z1, Osstem one-piece implant with a dia-meter of 2.5 mm; group Z2, Anthogy Morse taper connected two-piece implant with a diameter of 2.8 mm; group Z3, Nobel Active screw-retained two-piece implant with a diameter of 3.0 mm. The three-dimensional finite-element model of cantilever fixed bridge supported by NDIs was constructed using finite element software. Vertical loads of 65 and 130 N and 45° oblique load were applied. von Mises stress of the implants and metal components, principal stress of the bone tissue, and stress distribution cloud map were calculated and analyzed. RESULTS: Under vertical load, only Z3 group implant reached a von Mises stress peak of 1 004.5 MPa at a load of 130 N, exceeding the material's yield strength. Under the 45° oblique load, the von Mises stress peaks of all three groups of NDIs excee-ded the material's yield strength. The stress cloud map revealed that the implant neck and surrounding bone tissue were the stress concentration areas. CONCLUSIONS: All three NDIs groups proved theoretically feasible under a 65 N axial load, with this study delineating the biomechanical safety boundary and highlighting the important risks posed by excessive or oblique loading.