Abstract: BACKGROUND: Implant restoration has become an important means to treat anterior tooth loss, and it is particularly important to select appropriate implant restoration materials. However, at present, there are some deficiencies in clinical implant materials, and researchers have been exploring suitable implant materials.
OBJECTIVE: To compare the biomechanical characteristics of implants made of different materials in restoring single missing maxillary anterior teeth. 
METHODS: The cone beam CT data of a patient with single maxillary central incisor loss were imported into 3-matic software to establish a three-dimensional finite element analysis model of single maxillary anterior tooth loss. The model was then imported into Marc Mentat. Eight sets of implant restoration models were designed according to different implant materials (polyetheretherketone, titanium-zirconium alloy, titanium alloy, and zirconia, with the elastic modulus of the four materials increasing in sequence) and cancellous bone density (high density, low density) to simulate the stress conditions of the maxillary anterior teeth in centric occlusion. The total displacements and von Mises stresses of implants, cortical bone stresses and cancellous bone strains were compared and analyzed. 
RESULTS AND CONCLUSION: (1) The maximum displacement of the implant gradually decreased with the increase of the modulus of elasticity of the material, and the value of the maximum displacement of the implant in the polyetheretherketone group exceeded 10 μm; the implant stress was concentrated in the labial neck in the models. The maximum stress gradually increased with the increase of the modulus of elasticity of the implant material, among which, the zirconia-low density bone model had the highest stress, which was 21.31 MPa; the cortical bone stress was concentrated in the cortical bone at the junction of the implant with the labial side, and the polyetheretherketone-low density bone group had the highest value, which was 29.90 MPa. (2) From the biomechanical point of view, titanium-zirconium alloy, titanium alloy, and zirconia can be used as implant materials for restoration of a single missing anterior tooth, and implant displacement is one of the common problems during implant restorations, but pure polyetheretherketone material may cause excessive implant displacement in implant restorations of anterior areas, causing implant failure. 

Key words: three-dimensional finite element analysis, missing anterior tooth, implant, titanium, titanium-zirconia alloy, zirconia, polyetheretherketone