Effect of the Parafunctional Occlusal Loading and Crown Height on Stress Distribution

Abstract

The aim of this study was to assess, by the three-dimensional finite element method, the influence of crown-to-implant ratio and parafunctional occlusal loading on stress distribution in single external hexagon implant-supported prosthesis. Computer-aided design software was used to confection three models. Each model was composed of a block bone and an external hexagon implant (5x10.0 mm) with screw-retained implant prostheses, varying the height crown: 10, 12.5 and 15 mm. Finite element analysis software was used to generate the finite element mesh and to establish the loading and boundary conditions. Normal (200 N axial and 100 N oblique load) and parafunctional forces (1,000 N axial and 500 N oblique load) were applied. The results were visualized by von Mises and maximum principal stress. In comparison with the normal occlusal force, the parafunctional occlusal force induced an increase in stress concentration and magnitude on implant (platform and first threads) and screw (neck). The cortical bone showed the highest tensile stress under parafunctional force (oblique load). The stress concentration increased as the crown height increased. It was concluded that: increasing the C/I increased stress concentration in both implant components and cortical bone; parafunctional loading increased between 4-5 times the value of stresses in bone tissue compared with functional loading; the type of loading variation factor is more influential than the crown-to-implant factor.

Finite element analysis of implant-supported prosthesis with pontic and cantilever in the posterior maxilla

“…The finite element analysis is usually used to assess the biomechanical behavior of situations that involve osseointegrated implants (Torcato et al 2014;Verri et al 2016Verri et al , 2017. Furthermore, the results of these studies have already been indicated for improving the biomechanical understanding of several materials or situations used in dentistry and could have their results carefully extrapolated to daily clinical (Van Staden et al 2006).…”

“…Each model was composed of a bone block comprising from the first premolar to first molar, with three or two implants of external hexagon (EH) of 4.0 × 10 mm (Conexao Sistemas de Protese Ltda., Aruja, Sao Paulo, (see number of nodes and elements in the Table 1). Mechanical properties of each simulated material were attributed to the meshes using literature values (Sevimay et al 2005;Torcato et al 2014;Verri et al 2014;Santiago et al 2016) (Table 2). All materials were considered isotropic, homogeneous and linearly elastic (Verri et al 2014;Santiago et al 2016).…”

“…By this study, the ideal surgical/prosthetic planning in the posterior maxilla should be done with an implant for each missing tooth (M1) and in situations in which this is not possible should be considered as alternative treatments (M2, M3 and M4). Moreover, if the use of cantilevers (mesial or distal) are required, the clinicians should be aware of existing biomechanical risk, especially using distal cantilever or in patients with bruxism since this dysfunction can be prejudicial to the rehabilitation (Torcato et al 2014).…”

“…The design of bone block was composed of trabecular bone in the center surrounded by 1 mm of cortical bone layer, simulating bone type IV (Lekholm & Zarb 1985). Bone tissue was obtained based on previous studies (Torcato et al 2014;Ramos Verri et al 2015), in which the data of computerized tomography were used for 3D modeling (InVesalius software, CTI, Campinas, São Paulo, Brazil), and realized further surface simplification with Rhinoceros 4.0 software (NURBS Modeling for Windows, Seattle, Washington, USA).…”

Finite element analysis to study the effects of using CAD/CAM glass-fiber post system in a severely damaged anterior tooth

“…The mechanical properties of the materials used in this study are listed in Table 1. A load of 100 N was applied to the crown at 45 degrees, 3 mm below the incisal edge of the lingual surface [14]. The maximal von Mises stresses in different regions and under different conditions were calculated.…”