Effect of incisal relationship on biomechanical performance of different narrow-diameter implants supported restoration in mandibular anterior teeth: a finite element analysis

Objectives: The studies have investigated the effect of incisal relationship ( ICR) and diameter of narrow diameter implant (NDI) in the biomechanical performance are limited. The aim of this study was to investigate the impact of incisal relationship in various NDI diameter located right lower central incisor on the von Mises stress in the implant and screw including equivalent elastic strain in surrounding bone. Materials and methods: Three-dimensional finite element ( FE) models were conducted including the maxilla and mandibular alveolar bone, upper and lower anterior teeth (canine, lateral incisor and central incisor) and NDI system. The maxillary and mandibular alveolar bone with upper and lower anterior teeth obtained from a patient’s cone beam computed tomography data were simulated. Clinical simulations of three classification of ICR ( normal bite, deep bite and edge to edge) and two category of NDI [category 1( 2.9x10 mm.) and category 2 ( 3.3x10 mm.) ] were conducted to simulating three-dimensional model. Six finite element models were analyzed. The applied load was 60 N. using FE software to investigate the von Mises stress of implant and screw equivalent elastic strain in surrounding bone. Results: The maximum von Mises stress in deep bite models were highest . A less NDI (2.9 mm.) demonstrated higher stress in implant and screw compared with wider NDI. However wider NDI show higher strain value in surrounding bone. The distribution pattern of the von Mises stress of implant was similar whereas the neck of screw experienced the highest stress under any clinical simulating models. Conclusions: In biomechanical point of view implant diameter and Incisal relationship are influenced to biomechanical performance. A larger diameter result in better biomechanical stability. In addition, in the case of deep bite, the use of NDI category 1 in adequate bone must be careful to prevent biomechanical complication, which affects long term implant success.