Numerical analysis and mechanic theoretical derivations for optimizing the V-thread profiles in dental implant system

Background: The thread design of the dental implant is an important feature to be considered in the optimization of the dental implant structure. The present study aimed to investigate the effects of V-thread profile design dimensions, including depth, width, pitch, thread helix angle and triangle thread apex angle on the mechanical characteristics of the bone-implant interface. A total of 588 V-thread implant system models were constructed to investigate the effects of the dimension parameters on the stress distribution generated around the bone-implant interface under vertical occlusal force. Furthermore, the force transfer at the bone-implant interface was analyzed theoretically to analyze the force transmission mechanism at bone-implant for an optimized V-thread profile in the implants. Results The optimum thread pitch ranged from 1.0 mm to 1.2 mm, when the triangle thread depth and width was 0.1 mm. The theoretically derived results showed that, with the same implant diameter, when the thread depth was 0.1 mm and the thread pitch was 0.9 mm, the optimal thread width was found to be 0.1026 mm. This derived result was consistent with the simulation analysis results. Conclusions To design the optimal V-shape threads, the implant and thread dimensions, such as the implant diameter, thread pitch, thread width, thread helix angle and triangle thread apex angle should be comprehensively considered. The optimal designed thread in this study can dissipate the chewing load, as a result of the appropriate ratio of tensile force and shear force on bone-implant interface. The optimum designed thread profile can take full advantage of the carrying capacity of the tensile and shear of the bone, thereby bearing a high chewing load.