The influence of implant diameter and length on stress distribution of osseointegrated implants related to crestal bone geometry: A three-dimensional finite element analysis

Abstract

Numerical results suggest that implant diameter may be more effective than implant length as a design parameter to control the risk of bone overload. For a given implant in the molar region, the worst load transmission mechanisms arise with maxillary placement, and implant biomechanical behavior greatly improves if bone is efficiently preserved at the crest. Statement of problem.Load transfer mechanisms and possible failure of osseointegrated implants are affected by implant shape, geometrical and mechanical properties of the site of placement, as well as crestal bone resorption. Suitable estimation of such effects allows for correct design of implant features.Purpose. The purpose of this study was to analyze the influence of implant diameter and length on stress distribution and to analyze overload risk of clinically evidenced crestal bone loss at the implant neck in mandibular and maxillary molar periimplant regions. Material and methods.Stress-based performances of 5 commercially available implants (2 ITI, 2 Nobel Biocare, and 1 Ankylos implant; diameters of 3.3 mm to 4.5 mm, bone-implant interface lengths of 7.5 mm to 12 mm) were analyzed by linearly elastic 3-dimensional finite element simulations, under a static load (lateral component: 100 N; vertical intrusive component: 250 N). Numerical models of maxillary and mandibular molar bone segments were generated from computed tomography images, and local stress measures were introduced to allow for the assessment of bone overload risk. Different crestal bone geometries were also modelled. Type II bone quality was approximated, and complete osseous integration was assumed.Results. Maximum stress areas were numerically located at the implant neck, and possible overloading could occur in compression in compact bone (due to lateral components of the occlusal load) and in tension at the interface between cortical and trabecular bone (due to vertical intrusive loading components). Stress values and concentration areas decreased for cortical bone when implant diameter increased, whereas more effective stress distributions for cancellous bone were experienced with increasing implant length. For implants with comparable diameter and length, compressive stress values at cortical bone were reduced when low crestal bone loss was considered. Finally, dissimilar stress-based performances were exhibited for mandibular and maxillary placements, resulting in higher compressive stress in maxillary situations.Conclusions. Implant designs, crestal bone geometry, and site of placement affect load transmission mechanisms. Due to the low crestal bone resorption documented by clinical evidence, the Ankylos implant based on the platform switching concept and subcrestal positioning demonstrated better stress-based performance and lower risk of bone overload than the other implant systems evaluated. (J Prosthet Dent 2008;100:422-431) The influence of implant diameter and length on stress distribution of osseointegrated implants related to crestal bone geometry: A threedimensional fi...

Three-Dimensional Finite Element Analysis of Varying Diameter and Connection Type in Implants with High Crown-Implant Ratio

“…These results corroborate previous biomechanical studies that found a lower stress concentration for wide diameter implants (9,(12)(13)(14), especially in short implants (12).…”

The influence of platform switching in dental implants. A literature review

“…e402 underlying bone loss have not been fully established (9), the main causal factors of crestal bone loss are occlusal overload and peri-implantitis (10). Characteristics such as implant design, crestal bone geometry and the location within the oral cavity must be taken into consideration for the optimum support and distribution of occlusal loading forces to the bone components (11). Biomechanical studies of dental implants using finite elements analysis software are increasingly common (11)(12)(13)(14).…”

“…Characteristics such as implant design, crestal bone geometry and the location within the oral cavity must be taken into consideration for the optimum support and distribution of occlusal loading forces to the bone components (11). Biomechanical studies of dental implants using finite elements analysis software are increasingly common (11)(12)(13)(14). Such analyses are used by engineers to simulate loading situations involving different materials.…”

Biomechanical evaluation of internal and external hexagon platform switched implant-abutment connections: An in vitro laboratory and three-dimensional finite element analysis

“…It has been suggested that the inward shift of the implant-abutment gap may physically minimize the impact of the inflammatory cell infiltrate in the peri implant tissues, potentially reducing bone loss [2,[6][7][8][9][10][11]. From a biomechanical perspective, previous in vitro studies [12][13][14][15][16][17] have shown reduced levels of stress on peri-implant bone in platform-switched implants relative to matched implant-abutment diameters. Such potential for crestal bone level preservation has been shown in animal [18][19][20] and clinical studies [11,21,22].…”

“…When considering platform-switched implants, previous studies [14,17] have shown an increased stress on the abutment and fixation screw, which may compromise the system biomechanical performance. Controversially, several published studies [1,12,13,15,16,19,[25][26][27] related to the mechanics of platformswitched implants have been restricted to analyzing the stress distribution on peri-implant bone and not on the overall system biomechanical behavior. To date, studies evaluating the mechanical behavior of platform-switched implants considering the stress distribution in implantabutment complex are scarce and restricted to computer simulations [14,17,28,29], which do not consider several clinical variables (influence of fatigue damage accumulation and wet environment) previously reported as important factors to reproduce clinically observed failure modes [30].…”